I think it's neat that this summary is written by an author of the scientific manuscript. Oversimplification is a risk, but this approach eliminates the possibility that the writer did not understand the underlying science.
Yea, and it was a great read too. I wish more researchers would publish blog posts alongside their technical whitepapers, although I acknowledge that not everyone involved in science has or wishes to acquire the skills needed to write blog-form content.
(I'd also be worried about a world where researchers are evaluated based on the virality of their blog posts, vs. how impactful their work was.)
Communication skills are often missing in engineering too, but I think I'd argue they should be required - all work is fundamentally collaborative.
Being able to effectively communicate to different people on your team, outside your team, managers, business people, etc is not optional and more than once I've seen things get stalled or turn into a mess because communication didn't happen.
STEM is often a haven for neurodivergence but I think communication skills are something that is largely learned and not something that comes naturally for everyone. People who are good at communicating spend a fair amount of effort rewriting, trying different wordings, different introductions, getting feedback from people, etc.
FWIW I see things like being able to sell a proposal, managing expenses, planning, etc as optional - these are good to have, but someone else can do them if you can communicate well, but in the end the only person who can communicate what you're thinking is you.
I think the benefits greatly outweigh any dangers. I far prefer to read something like this than something written up by a journalist.
> I acknowledge that not everyone involved in science has or wishes to acquire the skills needed to write blog-form content.
They should. If your research is publicly funded you should make it as available to be public as possible. Academics should be able to communicate, and I very much doubt they are unable to acquire the skills
> I'd also be worried about a world where researchers are evaluated based on the virality of their blog posts, vs. how impactful their work was
Given how bad the measures of impact and the distorted incentives this produces I am not even sure this would even be a bad thing.
If nothing else it improves transparency about what they are doing, again with public money.
A few years ago, at least in my field, there was definitely a trend of people at least doing twitter threads explaining the key findings of their papers. It's obviously less in-depth than a blog post would be, but it was still usually a far more accessible version of the key ideas. Unfortunately, this community has basically dissolved in the last few years due to the changes in twitter and to my knowledge hasn't really converged on a new home.
There used to be a common practice of scientists writing summaries of their research for lay people. I think they viewed it as their civic duty. I had a collection called the World of Physics which included essays written by various scientists. I originally had it in the 90s and found it again after many decades. Would highly recommend.
It's far preferable to having university PR people write some hype piece. Where they'd spend the whole time gushing about it being a world first, paradigm shifting, blah blah blah, the author focuses on things that actually matter. e.g. Is it testable? Yes, here's what to look for.
Yeah, wow. That was great. His solution seems so simple and clears all the previous model's problems. I guess every black hole could contain its own universe.
Too bad the author didn’t explain more the concept of the “parent” universe and how our own (contracting & expanding) universe got created. Nice things to read/consider/ponder late at night :-)
I would be surprised if the size doesn't matter in this case. On the one hand, tiny black holes tend to be rather short-lived. On the other, I suppose some threshold mass/energy is needed to generate a child universe that doesn't collapse immediately.
Ironically that was basically the first thought many had when it was clear we cannot explain what happens in the edge case of a singularity. It was always "perhaps another unsiverse or a way into a parallel one".
It still leaves a lot of questions though, especially if you try to marry quantum mechanics to these makroscopic models. Where did the initial black hole come from and should a corresponsing anti matter black hole exist?
The article is based on a physics paper (arXiv:2505.23877), not management theory or institutional metaphors.
What the paper actually proposes is that the Big Bang may have been a gravitational bounce inside a black hole formed in a higher-dimensional parent universe. Quantum degeneracy pressure stops the collapse before a singularity forms. From the outside, it looks like a black hole. From the inside, it evolves as a 13.8 billion year expansion. That is general relativity applied across frames.
Simply put this is a relativistic collapse model with quantum corrections that avoids singularities and produces testable predictions, including small negative curvature and a natural inflation-like phase.
That's incorrect: The parent universe is not higher-dimensional, it's the same good old 3+1 as our universe.
What they propose is: Let's take our good old GR, and start with a (large, dilute) compactly supported spherically collapsing collapsing cloud of matter. During that, you get an event horizon; afterwards, this looks like a normal black hole outside, and you never see the internal evolution again ("frozen star", it's an event horizon). Inside, you have the matter cloud, then a large shell of vacuum, then the event horizon.
Quantum mechanics suggests that degeneracy pressure gives you an equation of state that looks like "dilute = dust" first, and at some point "oh no, incompressible".
They figure out that under various assumptions (and I think approximations), they get a solution where the inside bounces due to the degeneracy pressure. Viewed from inside, they identify that there should be an apparent cosmological constant, with the cosmological horizon somehow (?) corresponding to the BH horizon as viewed from the outside.
All along the article, they plug in various rough numbers, and they claim that our observed universe (with its scale, mass, age, apparent cosmological constant, etc) is compatible with this mechanism, even hand-waving at pertubations and CMB an-isotropies.
This would be super cool if it worked!
But I'm not convinced that the model truly works (internally) yet, too much hand-waving. And the matching to our real observed universe is also not yet convincing (to me). That being said, I'm out of the cosmology game for some years, and I'm a mathematician, not a physicist, so take my view with a generous helping of salt.
(I'm commenting from "reading" the arxiv preprint, but from not following all computations and references)
PS. I think that they also don't comment on stability near the bounce. But I think that regime is known to have BKL-style anisotropic instability. Now it may be that with the right parameters, the bounce occurs before these can rear their heads, and it might even be that I missed that they or one of their references argue that this is the case if you plug in numbers matched to our observed universe.
But the model would still be amazing if it all worked out, even if it was unstable.
I haven't read the paper yet, but this sounds like a (good) summary of exactly what the article is saying. It makes me wonder what, if anything, you feel is different from the way you put it and the way it is explained in the article? As a layman they seem the same to me.
Looking at the paper, I don't see any higher dimensions of the parent universe, it is still using the same 4D General relativity framework for the parent.
So, could the same interaction create planar universes inside our own black holes? Linear universes inside those as well?
It's incredible how big a 4-D universe would have to be to contain our own, even crazier if there are more levels; but our own universe could contain easily uncountable planar universes.
Isn't it more a matter of how space is folded in higher dimensions rather than an increase in volume that accounts for containment? There is plenty of space in the corners:
They have basically disproved Penrose-Hawking's theories of singularity? Isn't that like a pretty big deal? To people working in this field, what is the reaction to this paper?
1. This theory requires a parent universe that can't have been formed inside a black hole. This means there must a be second "universe creation" mechanism that we can / may never know about from our child universe. For me, this doesn't really answer the true question: "How did our universe begin?" Yeah, it may the "unknown field with strange properties" but instead we get an unknown parent universe with strange properties.
2. The black hole in the parent universe must be much much bigger than anything we see in ours since it has to contain all the matter that we see. How is a black hole supposed to form that is 750 billion times bigger than the largest black hole we know about?
There are many models of black holes, such as the Schwarzchild solution, that have an area of "asymptotically flat spacetime" which is, from the viewpoint of our universe, part of the black hole. That something happens around the singularity that creates this new universe doesn't sound that crazy.
If our universe is a child of another universe and that is a child of another universe and so forth it fits into the kind of "multiverse" model that addresses issues such as "why does the universe have the parameters it does?" Either there are a huge amount of universes such that we're lucky to be in one we can live in, or there is some kind of natural selection such that universes that create more black holes have more children.
As for the relative size of the parent black hole, conservation of energy doesn't have to hold for universes in the normal sense. One idea is that the gravitational binding energy of the universe is equal to the opposite of all the mass in the universe such that it all adds up to zero so we could have more or less of it without violating anything.
Do you find the idea of an infinite regress -- "our universe is a child of another universe and that is a child of another universe and so forth" -- holds much explanatory power for you?
To me it's prima facie a hollow explanation. I get that some models, like eternal inflation or certain cyclic cosmologies, entertain the idea of an infinite past or blur the standard arrow of time... but how does pushing the origin question back indefinitely actually resolve anything?
> "why does the universe have the parameters it does?"
To those who say "oh but if this parameter was slightly off, that thing I subjectively decided to pick wouldn't have happened!":
How would you know that this universe could exist in any other way? Wouldn't things just stabilize into certain frequencies and lengths after some time?
To me "fine tuning" isn't really a conundrum, it is just question begging and you don't need to wish it away with multiverses.
Not exactly. A universe can expand, slow down, then collapse. In this case, bouncing back out.
Does that repeat forever? Does it lose energy in the bounce? If so, to where and how?
> The black hole in the parent universe must be much much bigger than anything we see in ours
Yes and no. You're not thinking about contraction. With relativity we can fit a 100ft ladder inside a 10ft barn.
Most importantly, you don't need everything all figured out at once to publish. Then no one would always publish. There'd be nothing to improve on. Only one publication that says everything. Till then, everything does have criticisms and is incomplete. It's good to have criticisms! They lead you to the next work!
>> The black hole in the parent universe must be much much bigger than
>> anything we see in ours
>> Yes and no. You're not thinking about contraction. With relativity
>> we can fit a 100ft ladder inside a 10ft barn.
I believe the OP was talking about mass, not linear dimension. (And if he wasn't, I am.) Unless somehow mass inside a black hole is not constant? (ignoring accretion)
1. It is possible that every universe is formed in a blackhole – an infinite universe-blackhole-universe chain. We don’t know what “infinity” means in this scenario, so we can’t simply rule it out. For comparison, Aristotle ruled out an infinite chain of causes, which we now know (with the help of hindsight, of course) is a flawed conclusion.
2. We don’t know whether our universe is big or small compared with other universes. We don’t know whether, or how, it makes sense to compare sizes between universes.
Big Bang is arguably the biggest speculation in modern science.
Your first statement right off the bat is a bit of an assumption, why can’t the parent universe also have been formed inside a black hole? Why did you assume that?
The outer universe could have always existed, but unlike ours it eventually collapsed. By contrast ours did the reverse, and it looks like it will expand forever. There is a neat symmetry. I guess you could make the case that it’s really just one universe, and the collapse and expansion mirror each other.
We think the universe had to "begin" because we "began" and tend to anthropomorphize. Is that necessarily true? The universe is under no obligation to have a beginning. Sail around the Earth and you might just end up right where you started.
Current observations make it likely that our observable universe expands (think "stretches"), and the expansion will continue forever.
If it's expanding, then it was smaller earlier. Asking about the far past is a natural reaction, and the Big Bang theory is a pretty good attempt at explaining that.
The Sun had to begin. At one point it was just accreting gasses, then at some point gained enough mass to ignite. People also start at some point they begin as a daughter and grow eventually into a viable life. But also our galaxies had to form before our sun. So, yes there are beginnings to things. At one point they weren’t, at another point they were.
I agree with you, though - causal explanations are compelling and confer a sense of certainty and humans seem to like that, but it doesn't make them necessary.
Wouldn't every theory/model of the universe leave room for follow up questions? Why is it problematic if it doesn't answer literally every conceivable quandary?
If the crux of the article is the fermion bounce, and you compare that to how much matter and energy we are aware of, that is quite the black hole, which leads one to start wondering what environment it existed in to become that size. Even if it is now stuck due to a positive curvature of just bouncing back and forth.
I would like the article to acknowledge a bit more though that blackhole universe theories and speculation are quite old now, not radical and a striking alternative, as it is natural to think about it once you learn of the concept of event horizons. What differentiates this though is the analytical solution.
I've read somewhere an article which posited that our 3D universe might be inside a 4D black hole. When you cross a black hole's event horizon, the radial coordinate becomes timelike, so you lose one degree of spatial freedom. Movement is still possible in the tangential directions however, so what you get is basically an N-1 dimensional universe. So maybe our 3D universe is actually matter that fell into a 4D black hole, and our 3D black holes contain 2D flatland universes. And of course, the outer 4D universe might be in a 5D black hole, etc.
I don't think c is a good candidate, because it's not really a parameter. It's just a correction factor for our mis-judgment in picking different units for time and space.
In "natural units", we define the units so that the important conversion factors (c, G, h-bar, etc) work out to exactly 1. You can say that c is one light-year per year and then forget about it.
The true parameters of the universe are the dimensionless constants: the fine structure constant, proton-electron mass ratio, 3+1 dimensions, etc.
> When you cross a black hole's event horizon, the radial coordinate becomes timelike, so you lose one degree of spatial freedom.
The second half is incorrect. Since the time coordinate becomes spacelike in turn you'll still have 3 spatial degrees of freedom. Dimensions can't just vanish if you believe that spacetime is a 4D Lorentzian manifold (as physicists do).
Moreover, the singularity is not a place you can poke with a stick, once you've entered the black hole. It lies in your future, in the same way as your death.
> The second half is incorrect. Since the time coordinate becomes spacelike in turn you'll still have 3 spatial degrees of freedom. Dimensions can't just vanish if you believe that spacetime is a 4D Lorentzian manifold (as physicists do).
Can we say that one of the spatial dimensions (the radial dimension) and the time dimension combine into a single dimension? After crossing the event horizon aren't they 1:1 correlated?
I don't think the spacetime swap idea is particularly well explained though? Like although it's sort of mathematically true, my impression was that it's not like time suddenly becomes a dimension you're moving in once inside the event horizon, just that spacetime is acting so weird because there's now a deliberate direction where one did not exist before.
I’ve always like to explore the idea of our universe being in a static 5th dimension where the 5th dimension represents randomness/entropy. The same way to think about exploring a 2d plane in a 3 dimensional space where the 3rd dimension is constant. We just happen to be in a random big bang in this 5th dimensional space
I'm guessing it'd look something like this on a 1-dimensional number line:
--- > | > >> . << < | < ---
The dot in the middle would be the singularity, the pipes the event horizon, and the contents would be increasingly warped spacetime that may or may not exist, depending on your interpretation of things.
What? Wouldn't that mean an object's speed in some direction determines how time passes once it crossed over, and conversely, it would experience its old time dimension as spatial and be able to "move through (old) time" freely after crossing the event horizon?? My head hurts.
Interesting read, but even if we assume the author is correct, and the cosmos formed as a black hole in a larger universe, the question remains, how did this larger universe formed, then? Might just be impossible to know.
Questions like what was before the big bang or what is outside of our universe seem to be quite natural. However, we still don't know if these questions are well defined and have a proper meaning. For instance, a few hundred years ago, one might have asked, what happens if I go to the edge of the (flat) earth? Or one might ask: What is north of the north pole?
Would be fun if we find a function f(state, time) such that for f(singularity, 14 billion years) we get our current universe. i.e.: every singularity turns into our exact universe.
If we wait until we understand everything perfectly before publishing, we’d never publish anything. That question may remain, but so do many others, this paper can’t address them all.
It may just be that the physical conditions of our universe just prior to the big bang are indistinguishable from that of the interior of black holes.
In that sense black holes are areas where our universe has reverted from it's low entropy state all the way back to the initial nearly infinite entropy state.
I feel like quantum physics is gently pointing us towards the idea "everything you can imagine is real at once". As in, all possible universes and physics systems and whatnot do exist in some sense of this word, and we happen to inhabit one. Just like Earth is a totally unremarkable planet in a totally unremarkable solar system in a totally unremarkable galaxy, except we popped up here so for a long time we thought there's something deeply special about Earth.
I find it more useful to anchor the concept of "real" in what one has direct access to. Beyond that there are many ways to describe our shared reality and the space of possible realities, including the past and future, some of which are more real than others, and go far beyond what we can imagine. Quantum physics gives us a language to expand what we can describe and imagine.
Not only does the sun not rotate around us, the rest of the galaxy doesn't even care to think that we exist. An interesting evolution in thought nonetheless.
Block Universe.
The more you think about it, the more probable it seems.
Why should a universe pass time like a movie, if all moments could exist simultaneously? If there is no time, and it’s just a simulation formed in our brain, there doesn’t have to be a beginning nor end.
I'd put it a bit differently, that it remains a scientific endeavor, but leaves us in the same predicament as we're in now, which is the difficult work of forming a scientific theory that can only be tested indirectly.
There is no other entity. We're nothing. An algebra of nothing. Combine nothing with nothing in various ways (like S-terms) and it gives you physics, among many other things. From the inside we see a universe, from the outside you would see nothing.
This is why the "but the universe couldn't spawn out of nothing!" style arguments are so annoying. They completely accept that an all powerful all knowing entity could exist for all of time and not need a creator without any supporting evidence. But the origin of the universe specifically needs to be explained in detail or science is a sham.
Maybe there was no cruelty, and we were just plain matter that fell into our encapsulating black hole. Like what happenswith our own universes black holes.
I've often wondered about this. I don't have any direct physics training, but it's something that felt really plausible after I learned that the mass of a black hole is linearly proportional to its swarzschild radius.
As the size of the black hole goes up, its overall density must decrease. Combined with the other observation that our universe has uniform density at large scales, it seemed really obvious to me that there existed some threshold at which the decreasing density of a very large black hole, and the fixed density of our observed universe.. would cross.
I used to muse about this question with some other tech colleagues that liked talking about physics stuff but never really got a clear answer to this.
On a side note - I'm absolutely fascinated by the implications relating to this. I'll post a follow-up thought I'm hoping somebody else has also thought about:
I've seen discussion of dark energy mostly presented as a surrogate for real energy. That there is some underlying energy "accelerating things away from each other".
I always felt uncomfortable with that characterization. It seems more reasonable to me to think of dark energy as _negative energy_ - i.e. a loss of overall energy.
In a classical system, two things moving away from each other stores potential energy that can be recouped at some later time. Dark energy doesn't work this way - things accelerate away from each other the further apart they are. From a global perspective, it's an energy loss.
The energy loss pervades to the quantum world as well - photons that start off high frequency arrive low-frequency.
It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return. Maybe like a black hole evaporating as observed from the inside?
When I asked this of some people in real life, I was pointed to answers that indicated that the "energy" component in dark energy is normalized into the "tension" of space somehow. As I mentioned before I'm not really studied in physics, but that explanation felt unsatisfactory to me.
There was a thread a while ago on here where the hypothesis for why things are moving apart at faster rates is down to time moving at different speeds due to mass.
So time in the void between galaxies is moving quicker than time in the galaxies, but on the grand scale of the universe the differences as up a lot.
I quite liked this theory, think is make sense, at least from my very limited understanding of this stuff.
> It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return. Maybe like a black hole evaporating as observed from the inside?
But in this story the black hole increases in size as matter falls into the horizon and shrinks as it evaporates, so cosmic expansion would be associated with more energy falling into the black hole than leaving it.
A black hole is really just a singularity with infinite density by definition, but finite mass.
The size and density of the Schwarzschild volume is determined only by mass (stationary, non-rotating). It's proportional to the inverse square of mass. Density = 3c⁶/32πG³M².
SMBHs have densities ~0.5 kg/m³ between thin air and water.
Stellar BHs are ~1e19 kg/m³ several orders of magnitude more than a neutron star.
>follow-up thought I'm hoping somebody else has also thought about [...] dark energy as _negative energy_ [...] Maybe like a black hole evaporating
Another layman's thoughts: Isn't the energy theoretically lost by black holes so faint it's currently undetectable? And isn't the amount of dark energy theorized to be the major component of the observable universe? It seems like the numbers wouldn't add up?
I don't have enough of the background to speculate about the numbers. Dark energy feels "big" if we think of it in terms of the actual energy it would take to accelerate the universe away from itself at the rate that we see.. but the rate that we see is affected by our frame of reference, along with distances and everything else.
I'm gonna pull out my lay understanding again. An evaporating black hole, as it gets smaller, should get more dense and be associated with a higher local spacetime curvature, no? The effect of which would be to slow down apparent time for observers within the system. Maybe that affects observed distance and rates of speed at which things seem to be happening when we look out into the sky?
Sometimes I regret not caring enough about calculus in university.
> Combined with the other observation that our universe has uniform density at large scales
s/has/had at the time of recombination
It is largely an assumption of LCDM that we can treat the universe as practically homogeneous throughout its entire evolution but potentially not a very well-founded at that [0, 1].
> I always felt uncomfortable with that characterization. It seems more reasonable to me to think of dark energy as _negative energy_ - i.e. a loss of overall energy.
Your intuition is correct. If the Lambda term in the Einstein field equations is moved over to the side of the energy momentum tensor, it takes on the role of a negative contribution (provided Lambda > 0, as observations seem to indicate).
> In a classical system, two things moving away from each other stores potential energy that can be recouped at some later time. Dark energy doesn't work this way - things accelerate away from each other the further apart they are. From a global perspective, it's an energy loss.
Note that there is no global energy conservation in General Relativity[2], only at a local scale[3]. Heck, you'll already struggle to define what the energy is of a given piece of spacetime in a meaningful and generic manner[4, 5]. In other words, violations of energy conservation due to spacetime expanding or contracting (a strictly non-local phenomenon), like in the case of the cosmic redshift, are expected and our intuition from classical mechanics only takes you so far.
> It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return.
Dark energy aka the cosmological constant term in the Einstein field equations is a constant term, as the name suggests. Yes, there can be energy loss due to spacetime expanding (see above) but that doesn't change the gravitational constant.
Yeah I was referencing the event horizon as the most meaningful measure of size.
And whether the density is fixed over time or not doesn't affect the question. Let's take the universe at its current average mass/energy density - whatever the "true" measure of that is.
To the best of our understanding, at large scales the density is uniform. So if we consider a suitably large spherical volume of space within our (presumably infinite) universe.. that volume will have an average mass/energy content greater than the threshold amount for a black hole of that apparent volume (again, using the external event horizon frame).
So that suggested to me that either we live in a finite universe, or we must be on the inside of an event horizon. It seems like an unavoidable conclusion.
I think given time at a blackboard we could walk through Newton's cannon in the context of Poisson gravity, and for extra credit with the cannonball inducing a perturbation of the Poisson vector field. Even without the cannonball's backreaction, the Poisson picture offers a nice image of the gravitational potential energy at the top of the cannonball's inertial (ballistic) curve. We would then consider a cosmology like our own but with a recollapse: at maximum extent there is some (quasi-)Newtonian notion of gravitational potential energy for all the galaxies, since they are at the point where they begin free-falling back into a denser configuration. It's then the usual story of relating kinetic and potential energy, and recognizing that the standard cosmological frame is close to Newtonian by design. (We also have to stop this approach when the galaxies are merging enough that radiation pressure and gas ram pressure become relevant, because the errors become astronomical).
Since we don't have a blackboard in front of us to interact with, I can suggest Alan Guth's lecture notes on Newtonian cosmology. (Guth is credited with discovering cosmic inflation.) https://web.mit.edu/8.286/www/lecn18/ln03-euf18.pdf See around eqn (3.3). You could also borrow a copy of Baumann's textbook <https://www.cambridge.org/highereducation/books/cosmology/53...> which studies the Poisson equation for various spacetimes, however a static spacetime gets most of the focus.
A universe which expands forever, or which expands faster in the later universe, makes a mess of this sort of approach to calculating a gravitational potential energy.
So does any apparent recession velocity that's a large fraction of c (inducing significant redshift, whatever the recession (pseudo-)"force" might be).
However, the general idea is that there is a relationship between the kinetic energy a receding galaxy (in a system of coordinates -- a "frame" -- in which these kinematics appear) and a gravitational potential energy still occurs in a non-recollapsing universe. It's just that the potential energy climbs forever, and you get an equivalent to gravitational time dilation between galaxies at different gravitational potentials (i.e., between early-universe galaxies and higher-potential modern-times galaxies).
Accelerometers in galaxies will not show a cosmic acceleration for any galaxy; they're all really close to freely-falling (local galaxy-galaxy interactions are real -- collisions and mergers and close-calls happen -- but wash out over cosmological distances; look up "peculiar velocity" for details). Therefore we can conclude that there's no real force imposing acceleration on the galaxies. However that's also true of a cannonball in a ballistic trajectory, including one on an escape trajectory or one that enters into a stable orbit. Consequently one can draw some practical comparisons between a ballistic launch from Earth into deep space and galaxies spreading out from an initially denser early part of an expanding cosmos.
> Dark energy as energy being extracted out of the universe
No, it's just a way of thinking about whatever is driving the expansion, and that doesn't dilute away with the expansion as ordinary matter and radiation does. It's not even a "real" energy in the sense that it is only an energy in the cosmological frame, and is a frame-dependent scalar quantity, whereas in the fuller theory it's just a multiplier of the metric tensor. So it's the full relativistic metric doing the work but we absorb some of that into cosmological coordinates in the cosmological frame of reference, carving up the metric tensor into a set of vectors including an expansion vector identical at every point in spacetime.
The expansion vector can also be thought of in terms of pressure: in a collapsing cosmological frame, a pressure drives galaxies together into a denser configuration. The inverse of pressure is tension, so in an expanding cosmological frame, it's a tension that pulls galaxies apart into a sparser configuration. (The reason one uses pressure or its inverse is that the matter fields are idealized as a set of perfect fluids at rest in the cosmological frame; each such fluid has an associated density and internal pressure which evolve with the expansion or contraction of the cosmos, generally becoming less positive in the time-direction of expansion (i.e., in the future direction in a universe like ours). Another way of thinking about pressure is as a measure of isotropic inflow of energy-momentum into a point; increasing pressure at a point therefore increases the curvature at that point. Tension is an isotropic outflow, and so positive tension is repulsive as opposed to the attraction from positive pressure.)
> that explanation felt unsatisfactory to me
Hopefully the above helps a bit. Unfortunately there's only so much teaching one might do in a series of HN comments, and ultimately one probably is better served in developing some grounding in the full Einstein Field Equations / Friedmann-Lemaître equations before thinking in quasi-Newtonian ways. Going the other direction tends to lead to misunderstandings and developing false intuitions when running into situations where the quasi-Newtonian picture needs post-Newtonian correction terms.
It's cool that you have all sorts of questions. You could consider signing up for part time / non-business-hours courses in relativity at a nearby community college or the equivalent, depending on where you are, or maybe just bringing a hot lunch to a lecturer there in exchange for a quick informal tutorial. Anything like that is bound to get you to better answers than raising comments on HN threads about astrophysics in the broadest sense, as answers here are often somewhere between non-standard and unreliable.
That is a very interesting idea… the equation and its assumptions doesn’t seem to have any exceptions so it does strongly suggest our universe is a black hole, inside a black hole?
> The Big Bang is often described as the explosive birth of the universe – a singular moment when space, time and matter sprang into existence.
It is indeed "often described" in the media as such. However, that is _not_ the currently accepted theory. "What if there were no space and time before the Big Bang" is just Stephen Hawking's pet theory.
A more accurate summation would be that our theories do not permit us to go back beyond what appears to be the "Big Bang", and indeed, we can't quite get to it either, since the need for Quantum Gravity becomes too great as we get to what seems to be the "zero time". We have no principled, reasonable way to make any claims about what came before the point where our theories break down, and that includes the claim that there was no space or time at all before then.
Thus, anything and everything you've heard about what is there "before the big bang" has always been speculation. I mention this because sometimes people read the science media, which is always reporting on this speculation, and think that the reporting on the speculation constitutes "science" constantly changing its mind, but that's not the case here. Science has consistently not had a justifiable position on this topic, ever. It has always been speculation. It is the press that often fails to make this clear and writes stories in terms of what "science" has "discovered", but any claims of certainty in this area are not the claims of "science".
Seems inevitable that we'll discover we aren't the only universe / only cycle.
We went from thinking the Earth was the center of the universe, to the sun being the center of the universe, and the next obvious step is our universe isn't at the center of universes.
What people seem to not be able to conceptualize, consciously or not, is that there really is no "before" the Big Bang in the standard model (Lambda-CDM), if time itself exists only after t=0.
The Lambda CDM does not really say that. As other commenters have pointed out, Lambda-CDM is silent on the very earliest few moments of the universe where quantum gravity would be required.
We have no theories working at those conditions. Wiki says
> General relativity also predicts that the initial state of the universe, at the beginning of the Big Bang, was a singularity of infinite density and temperature.[6][obsolete source] However, classical gravitational theories are not expected to be accurate under these conditions, and a quantum description is likely needed[7].
Why not? If you can't observe it, test it, and reproduce it, then it lies outside the realm of science and in the realm of belief. Until someone figures out a way to experimentally verify the big bang hypothesis (or any other explanation for the origin of the universe or what came "before"), it's entirely fair to attribute it to whatever you feel like, be it a god or anything else. There is no law of the universe that guarantees that science is capable of answering all questions.
There's quite a big philosophical difference between "there exists a point beyond which it is possible to make observations" and "the universe was created by an omnipotent being"
Anything outside of what we can observe will always be based on faith anyway. We'll probably never understand what's "before" the big bang, wether it make sense to ask that question or why something exists rather than nothing.
I don't think so - god is substantially less parsimonious. But in the end, I think you're sort of using two different notions of belief as if they were the same.
I believe (lowercase b) in all sorts of stuff, scientific and otherwise, but believing in God typically indicates some kind of act of faith, which is to say, ultimately, to believe in something despite the absence of evidence for it and for some deeper reason than can be furnished by a warrant of some kind. I can believe in the spontaneous generation of the universe in the lowercase b sense of the word without really having anything to do at all with the latter kind of belief, which I think is kind of dumb.
Belief in anything is completely trivial unless you act based on those beliefs. No one is going to waste time worshiping, or murder someone over, the "nothing" from before "something".
Suggested hard sci-fi light reading: "Cosm" by Gregory Benford, 1999. A universe the size of a bowling ball created in a laboratory. The scientist responsible for it, keeping it safe and on the run from gvt spooks. They want to protect it for as long as it lasts, and since its time is as relative as its size, they won't have long to wait.
Rick and Morty episode (season 2 episode 6, 'The Ricks Must be Crazy') where it turns out rick has created a whole universe inside his spaceship battery who's whole purpose is to produce energy to run his spaceship. A scientist within this microverse creates a miniverse ....
> The black hole universe also offers a new perspective on our place in the cosmos. In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger “parent” universe.
Does it also follow that black holes in our universe contain universes internally, beyond their event horizons?! Seems like it should. Mind-blowing.
If the universe does have a positive curvature as this predicts, would that mean that if we look out into space, we could see the same galaxies multiple times? Or even our own galaxy in the past? Or is the predicted curvature slight enough that anything we might see multiple times is already beyond the limits of visibility due to universe expansion?
Only if the circumference of the universe is small enough for light to have made the round trip since the universe began. But we think that the universe is much larger than that.
I'm not a scientist or astrophysicist but i do believe in science, is it ok to believe that we as humans and all our scientific development still very very far from proving anything remotely close to how the universe got created? I feel this subject is for humanity in year 2600 to start discussing it.
Scientist still can show their theories and search papers and i can't understand a shit but i don't believe in any theory that proves how the universe got created.
Science is a process, not a source of truth. It has a very practical lens, which is very utilitarian, does the knowledge and models allow for invention or prediction that works in our reality for some current need.
The assumption is, you never really know, but if the model in which the theory says X, is able to predict something in the future or some experiment for Y, than that model appears to better approximate reality. Or is that knowledge and model allowing us to now do something we could not before, etc.
Over time, it course corrects to improve its knowledge and models in ways that show better results for prediction or invention.
"Proving anything" is kind of fuzzy. We've got very solid evidence that some sort of big bang happened. We can see the galaxies flying away from a common point, and since we can count backwards, we can know roughly when they probably would've been in the same spot. The how and why, and the what happened before, those are very unknown, although we've got a surprising amount of knowledge of what the first few seconds were probably like.
It's not about belief, it's about observing, collecting data & evidence, and proposing possible explanations. As new observations and evidence are found the possible explanations are refined. No one credible is claiming hard proof of anything at this point.
Agreed, people often mix that up, but you have to adopt a probabilistic mindset, you can believe the coin with land on its head, but you also know that based on the weight and curvature of the coin it will land on its tail 68% of the time you flip it, etc. Then choosing tail is no longer a belief, it is simply going with the choice that is backed by prior observation, experiments, models, etc.
You might still lose, and so you might choose to also believe it will land on tail this time, but the rationale for choosing tail was not based on a belief system, but the going information and where it points too.
Belief is acting as if something, for which no evidence has been given, is true. Imagination, taken too far. No one is telling you to believe anything here, they're suggesting we search for clues to support or disprove a theory. Or don't, it's up to you.
That's not the definition of belief. Belief can have various levels of different kinds of evidence behind it. Scientific, historical, philosophical, experiential, etc. A belief could have more or less scientific evidence than other beliefs, but rarely is belief predicated on no evidence whatsoever.
I think the phrase 'believe in science' is weird; it's nearly as problematic as "I have faith in science".
It can be, but generally the concept of 'belief' isn't attributed to ground truths; it's just 'the truth', you rarely hear the phrase "I believe 2 and 2 is 4." , it's just '2 and 2 is 4.' -- I think that's important.
In fact, a lot of people insert the word 'believe' to insert a concept of self-doubt. "What was our last test results passing rate?" "I believe it was around 95 percent.."
But semantics aside here's the real question : Why do you have some kind of notion that you should 'believe' anything without being able to understand it? Just trust in the world and those around you?
We haven't figured origin yet, so let's get off that, but when a scientist of some sort makes a discovery, they release evidence and methods , and you decide to believe the conclusions without an understanding of the work -- well that's just a display of faith.
Faith in the scientist themselves, the system they work within, and the society you're in.
Which leads me to say this : If you make an effort to begin to understand the frameworks and systems which lead to scientific conclusions you can largely remove the faith and belief elements up until you hit the very highest spectrums of each field where speculation comes back into play.
tl;dr : if you 'cant understand a shit', you don't put any leg-work in and make an effort to speak the language, you'll probably end back up in beliefs rather than an ever increasing codex of knowledge -- regardless of the field. That's okay -- but it doesn't offer the same benefits as knowledge -- it just lets one say things like "I don't believe in any theory..."
I have immense respect for astrophysicists, but the data we're dealing with is extremely far away and relies on a lot of interlocking assumptions.
I stumbled upon this paper [1, 2] last night that challenges the CMB, and thus the underpinning of much of our understanding about the age and evolution of the universe. As a layperson, I don't know the impact factor of the "Nuclear Physics B" journal - if this is just junk or if this is a claim that will pan out.
My point is that it feels like we're building on a lot of observations that are all super indirect. I know I'm just a layperson, but that feels weird when reading assertions about these things.
Our understanding of the universe is relatively new. We don't have a lot of energy or resolution in our observations. The fact that we can sniff the molecular spectra of exoplanets is so amazing and that part feels totally concrete and rock-solid. But I get skeptical when I see claims that we know how the universe began or how it will end. Is our evidence that good? Are our models? Are we basing everything on assumptions?
> But I get skeptical when I see claims that we know how the universe began or how it will end
Absolutely, but you are interpreting it in the rewritten headline money making attention grabbing version.
The original version of the claims always say that from some observation, experiments, and projection from known models it derives that the universe likely began this way, or will end that way, etc.
That means, of all the going hypothesis, this might be the one with the best chances of being true, or close to the truth. It's not an absolute, but its the one that has the most chances due to the evidence behind it.
But that's why science is so cool, it doesn't matter what we believe, it only matters if your theory fits the facts and makes good predictions. If it doesn't, you can chuck it in the bin without guilt. Unlike beliefs, which often can cause psychic trauma if reality doesn't match the belief of the individual.
Predicting inflation rates may be harder than discovering the birth of the universe actually, because it would require perfect knowledge of the present and by the time you compute it it's out of date.
A few years ago a popular idea was that our universe existed as an hologram on the surface of a black hole.
Recently I saw also a theory that black hole might not, in fact, exist as we thought, and may be instead something called 'gravastars', where large stars do not collapse in an infinite point but instead the mass reaches a maximum density and hardness and become sorts of empty bubbles.
Now this. It's not exactly a new idea, I remember reading about black hole cosmology 10 years ago.
Sooo... My uneducated, pop-sci fueled imagination now sees the universe as a mathematical function of a fractal looking like a shell with patterns on it, and those patterns interact or 'fold' in a way where the patterns themselves can be thought of as shells with patterns on them, and each shell creates something that, from the inside, looks like a new dimension of space or time, and what we think of as black holes are the next fold. Does that make sense?
It makes sense to me... I think. And I like this vision as well. It would explain the big bang (initial black hole formation), why the universe is expending (at probably non constant rates over time) which would be the black hole "ingesting" matter and growing and maybe also why time and space are one.
Same as you, a take from complete uneducated pop-sci fueled imagination.
The bounce to me has always seemed more intuitive than the bang, but man, when it comes to the quantum universe I've learned to just check intuition at the door.
I would argue that theory is a critical part of the research process and is therefore research.
There’s of course a line between simply coming up with ideas that are quickly provably wrong or inconsistent vs generating ideas that are consistent and not quickly falsified. It’s especially valuable the ideas are falsifiable and it seems like this is the case here.
As such, theory finds patterns in existing knowns, makes some leaps and tries to connect them. Then empirical evidence can help solidify or falsify those ideas. But we tend not to just connect dots of empirical data without attempting to know the casual relationship, otherwise the connections can be rather nonsensical or may have weak predictive power.
With all that said I didn’t read the paper in detail nor am I qualified in this domain to say if it’s quackery or a reasonable shot a developing some new theory. It is peer reviewed and published in APS so I suspect it’s not complete quackery: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.1...
A research paper makes use of multiple sources of known provenance and various degrees of authority and relevance. It tries to establish a consensus of knowledge, as close to fact as possible. The phrase "research suggests" is an appeal to authority that implies some kind of academic rigor. A theory paper, which is still useful and important, can be published without any kind of authority. You can just make things up.
That is what is called research in theoretical fields. Making hypotheses up and then proving implications of those hypotheses. In this case, it yields a falsifiable test: the theory claims the universe should have small positive curvature.
At the event horizon of a large enough black hole, the tidal difference in gravity between your toes and head shouldn't be noticeable. There shouldn't actually be anything special about falling through the event horizon when looking at yourself.
Outside though, you'd see everything start to blue-shift. Things below you would blue shift back to normal, and the universe above you would blue-shift and speed up until you'd see the heat death of the universe. Anything falling in after you would red-shift again as it approached to match your "normal" rate of time. Critically this would include any light or other particles, so it might be very hard to survive.
No matter how fast you go or how weird the space time you are in, your local clock should still tick steadily to you, and you wouldn't notice anything weird.
> The black hole universe also offers a new perspective on our place in the cosmos. In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger “parent” universe.
What specifically is meant by interior? Does this mean “within the event horizon” or something else?
> But how come Penrose’s theorems forbid out such outcomes? It’s all down to a rule called the quantum exclusion principle, which states that no two identical particles known as fermions can occupy the same quantum state (such as angular momentum, or “spin”).
> And we show that this rule prevents the particles in the collapsing matter from being squeezed indefinitely. As a result, the collapse halts and reverses. The bounce is not only possible – it’s inevitable under the right conditions.
Do I understand right, that this would mean that every formation of a black hole would result in a bounce?
I thought the Pauli exclusion principle is why we have neutron stars, ie the degeneracy of a star results in the fusion of electrons and protons to form neutrons and emit neutrinos.
What is preventing the collapse in this case and results in a bounce?
I speculate that the big bang is/was fueled by all the black holes that existed and will exist, like a huge cycle where all the energy sucked into black holes converges at the same point in time causing the big bang.
> But how come Penrose’s theorems forbid out such outcomes? It’s all down to a rule called the quantum exclusion principle, which states that no two identical particles known as fermions can occupy the same quantum state (such as angular momentum, or “spin”).
> And we show that this rule prevents the particles in the collapsing matter from being squeezed indefinitely. As a result, the collapse halts and reverses. The bounce is not only possible – it’s inevitable under the right conditions.
Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?
Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?
Different exclusion principle. For neutron stars, it is the Pauli exclusion principle (IIRC) which creates neutron degeneracy pressure. Enough mass and gravity can overcome it forming a black hole. The article is talking about quantum exclusion which happens at a much smaller scale. I don't know much about it because that exceeds the limits of my degree.
>Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?
One of the ways to overcome one of the levels of this degeneracy pressure is electron capture which is the opposite of a kind of beta decay. Squeeze hard enough and a proton combines with an electron to form a neutron and a neutrino.
But there are several proposed levels of degenerate matter in neutron stars, the idea being that one (final?) level of this degenerate matter is dense enough to make an object smaller than its schwarzschild radius. Uncertainty is high because we have no current methods to observe any of this kind of matter.
What goes on inside the schwarzschild radius is another mystery we don't have answers from, but there are lots of ideas with various levels of legitimacy.
Quantum physics in and around singularities or things we think are singularities is not understood.
Would it possibly make sense for a black hole in our universe to lead to a higher level "parent" universe? Or would any black hole universe contained within our own universe necessarily lead to a lower level "child" universe? Basically, I'm wondering if there's a way (within the constraints of this model) to access the parent universe.
Interesting sci-fi plot device but seems far-fetched, not gonna lie. To think that our highly stable universe is just compressed mass of another universe is a lot to take in. Does that black hole emit Hawking radiation as well and shouldnt our universe lose mass in result? And how exactly can our universe expand if the size of the black hole is fixed?
Well, at least it does make for interesting conversations. Someone will surely milk it for Youtube content.
This was an interesting read, but I didn't understand exactly what leads to the big crunch. I get the exclusion principle leads to pressure, and this causes the bounce, but why would it continue to accelerate and then decelerate resulting in a big crunch?
I don't understand where the rest of the parent universe is if all of the matter has emerged from the event horizon. Twisted into a new dimension, perhaps?
My take away was that it's still somehow causally disconnected from our universe. They make an assumption that the space outside is empty and that makes the numbers correspond closely with observations. Maybe there is stuff there but very very far away?
> Research suggests Big Bang may have taken place inside a black hole
The title's use of the word "research," and the paper's content, suggest the idea resembles science more than speculation. But in fact, the paper has no observational evidence, nor a proposal for acquiring evidence, to distinguish it from other similar speculations.
To put it simply, at the center of a black hole is a singularity, a domain where existing theories can offer no guidance. So a new idea about singularities -- about black holes -- should suggest a testable property, to distinguish it from other similar ideas.
I say "idea" here to avoid use of the term "theory," which in science requires observational evidence to move past the realm of speculation.
Don't get me wrong -- speculations have an important role to play in science. But tendentious phrases like "research suggests" wrongly imply the presence of something more than speculation.
Wow, wild this is being taken seriously now perhaps, I first encountered the idea in The Life of The Cosmos ~26 years ago[0] and my impression was the author, Lee Smolin, didn't REALLY beleive it, but he came up with it mostly to have some kind of preferable, falsifiable(er?) alternative to string theory, which he disliked even more, and perhaps more as an idea of the kind of theory we need to explore to start making progress... or that's my memory/impression form 26 years ago, I've been meaning to re-read it for a while since. Anyone read more recently/have other impressions?
(the basic idea was fecund universes/cosmological natural selection[1], such that we should expect to find ourselves, if the theory were true, very near to a local maxima of values such that they approximately maximize the number of black holes produced... but most of the book is really taken up with a fascinating look at the history of physics and ideas...)
stupid question: if at the beginning of the universe (before the big bang) all the matter was in the very same spot, shouldn't this have been effectively been a black hole due to the extreme density? if so, how could it explode if nothing can escape a black hole?
I've always liked the Idea that black holes accelerate matter faster than light behind the event horizon propelling it back in time creating a singular white hole at the first moment.
There are many many reasons why this is a dumb idea and it's just as much of a paradox as any other naturalistic creation theory.
I've heard about interesting theory. Since we observe large early galaxies, to explain them scientists postulate that they must have grown very quickly. But recently some scientists calculated how much light would such quickly growing galaxies could have emitted. And it turned out that this light after being dispersed by the dust and redshifted by the expansion of the universe it should have contribute to CMB, up to 100% of it's observed intensity. What's interesting they didn't make any assumptions outside of established modern cosmology. Just So it's entirely possible that CMB is something completely different than what we believed.
I won't touch level 8/9 nothings, other than to say I don't think they're coherent. But I am of the metaphysical camp that thinks there will be at least some small ground truth which physical law or object which cannot be reduced, an axiom of nature. Physics unfortunately will probably always be limited in distinguishing between basic facts which are truly irreducible, and those which are simply limits of our observational abilities. That's the thing that bothers me; even if there were a single beautiful law of nature that just IS, one which we actually manage to postulate based on evidence, we will never know for sure. GR definitely has a beautiful mystique, it's a shame that it's most likely just a mathematical approximation.
This brings to mind something I keep thinking about for years (mostly from watching too many physics videos).
- Gravity "slows" the time down, gravitational singularity should bring the time to a halt
- Suppose there is a quantum process that makes the true singularity impossible, so all black holes immediately expand right back
- Looking at it from our time scales, even if the singularity existed for a moment, it would appear that "infinite" time has passed while from the black hole's perspective, the expansion was instantaneous.
- From earth's perspective, if the singularity ever existed in a black hole, it stands to reason that when the time "resumes" from a black hole expansion, it won't fall into any of our known timelines since infinite time would have passed.
Along those lines, makes me wonder if the "bang" is in fact the fact that after the time compression, all matter/energy is effectively arriving at the same point all at once.
Assuming our universe eventually collapses into a few black holes, perhaps the spawn of a new universe is simply all the matter and energy of our universe arriving at a new point in... time? an infinite amount of time in the future.
Also, really mind bending to think the universe may just be an infinite series of black hole explosions with no beginning. It is because it always was.
if this holds up, every intro to cosmology textbook opens with a spoiler. we’ve been simulating the explosion without even checking what room it happened in. whole industry just assumed page one was page one. now turns out we might be in chapter seven of someone else’s collapse. love it
If this is true it almost literally means black holes are a way for universes to make children. If we apply Darwin’s principles of the strongest survive this must mean that universes that produce the most black holes are the “best”. If correct, what does this actually mean?
There is a theory of cosmological evolution. The child universes have slightly different physical constants and universes that produce more black holes will leave behind more offspring universes so over many generations, the universes evolve toward parameters that favour black hole production.
It requires imperfect reproduction where the imperfections alter the probability of further reproduction.
If each black hole in our universe contained a pocket universe with very slightly different laws of physics (to each other and to us), but the same amount of mass-energy on the inside as our universe had when it started, then (1) those pocket universes able to create stars and black holes would also go on to create black holes with pocket universes, but also (2) those pocket universes not able to create black holes, would not create more pocket universes.
I have never seen a reason to think that this could happen, nor why such pocket universes might have more mass on the inside than they appear to have on the outside, but that's the argument.
What would happen if beings living outside of our 'black hole universe' threw an object into the black hole, and thus into our universe? Would the object appear at the edge of our universe, or would some physical law prevent this from happening?
I've always had this idea that perhaps the whole universe had already collapsed into many black holes and perhaps each galaxy was actually formed via hawking radiation. Then our galaxy came out of Sagittarius A*.
I still don't understand from the article why the bounce effect results in an accelerated expansion of space time. Is the black hole (our universe) in the parent universe getting bigger? And why is that non linear?
So the expansion comes from the bounce. And we are in a dormant supermassive black hole of sorts. How would it look like in our world if the mother blackhole is actively gobbling up matter from the parent universe?
Hmm... What if some matter falls into our black hole? I know there are some weird time-space effects on the boundary, which I do not have any intuition about. To my knowledge it may be, that it will never fall in our time frame, or that it have fallen all already. The question is, will we able to see and welcome new matter entering our Universe?
I may be wrong, but I believe spending time in a deeper gravitational well means you observe everything outside of the well to be happening much faster; at the singularity, the entire future of the parent universe will appear to you as happening all at once. There is no notion of “matter that falls in later” — once you reach the singularity, you travel to the end of time in the parent universe. And the passage of time in our universe isn’t a continuation of time in the parent universe; it’s not even the same dimension, the latter is collapsed.
Thank you! That answered my question whether there would be in our universe a "white fountain" spitting matter coming from the back hole in the top universe. In your hypothesis where we lose one dimensione over the top universe than all the events of the top universe, like the mass arriving, happen in our universe all at the once in the beginning (the big bang).
I'm curious on what is "at stake" with this? The close lists a couple of predictions that this can lead to. I'm assuming they will be important in a far future time? Or do these help with some more near term problems?
Edit: I hasten to add that I'm not asking to undermine the research. Seems the more the merrier, there. Genuinely curious on what some of this could lead to.
I didn’t understand whether the author is implying that this happens to all black holes or whether the model only applies in some circumstances.
I definitely didn’t understand whether this is suggesting that expanding universes can be contained within black holes that look like fixed-size finite objects from the outside.
And what happens to the inner universe when the parent black hole evaporates through Hawking radiation?
There was a physicist who made a video making fun of crackpot theories from engineers and reading the comments we're all happy to put forth our completely unsubstantiated opinions with zero understanding of the math and observations involved
Imagine a being inside a turing machine wondering what came before it was turned on... implying the turing machine is even on and we're not just looking at the set of all possible rule sets on a similarly abstracted mathematical chart.
So if our universe is inside a black hole from a parent universe, does that mean every black hole in our universe contains its own child universe? We could be living in cosmic Russian dolls all the way down?
As a lay reader, it sounds like they are assuming what they are trying to prove.
Yes, it produces a testable prediction, but seemingly based on a mathematical assumption derived from our observed cosmic radiation background.
> This lower bound follows from the requirement of χk≥χ∗≃15.9 Gpc to address the cosmic microwave background low quadrupole anomaly
As a lay reader, can I assume that no scientist would publish a theory with mathematical circularity (at the heart of the prediction)? I sure can't verify it myself.
I haven't read the paper, it's probably well beyond me, but I have always felt that the presumed existence of a singularity had to be the result of incomplete theory.
I too read the book and was just searching for anyone mentioning it.
Why can such an idea be called new, when someone else already described it decades ago?
Great! Maybe the idea of a cyclical universe will gain traction.
In my view, there is one universe. We are in it. It cycles from maximum to minimum condition endlessly. This cycle is much longer than any entity lifespan and for any entity, the current state is THE state for them, and all they will know and become.
What does it expand into?
Nothing. Space itself just gets bigger and smaller over time.
When I first heard the idea that our universe began inside a black hole from another one, it felt like something out of a sci-fi movie. But the more I sit with it, the more it starts to feel like the universe is quietly nudging us, saying it has a much bigger story to tell.
If the Big Bang was just a moment in someone else’s universe, then maybe everything we know is just one chapter in a book far larger than we can imagine.
Big bang theory no longer excites me. As long as we can't explain consciousness all these theories are pointless. All theories mere appearances in consciousness including the universe and everything we experience.
Consciousness has the property to render infinite universes and theories.
But we have no clue how universe creates consciousness.
Consciousness is a specific biological adaptation which is primarily focused in the management of social relationships, status, and the prolonged adolescence of children. (and their required care)
There's no reason to think that consciousness is an important question in the objective sense; it just matters to people. (and rightfully so) People wondering about consciousness in the universe might be akin to dogs wondering what the big bang smelled like.
What is an important question in the objective sense? Is life, or no because that just matter to life? It seems oxymoronic, "objective question", "objectively important".
I don't follow GP's sort of solipsist (?) take, but would say question of whether big bang took place in a black hole is pointless compared to life/experience and how they arise.
Seems like someday we will prove that if you get enough neural like things organized in a structure similar to ours or some mathematical similarity thereof that consciousness automatically arises like mixing certain elements to get a compound but in a vastly more complex manner
I've spent the past month or so immersed in Penrose diagrams. Some of the implications of the math and diagrams include white holes (opposite of black holes - spew matter outwards), infinite universes contained within one another other, anti-gravity universes, and things like this. You can also fall into a black hole and make it out into another universe instead of meeting the singularity (at least, an idealized, rotating black hole). Anyway, cool stuff.
TARS is a new theoretical framework that fundamentally reimagines the foundations of physics. Instead of assuming that reality is made of pre-existing entities (particles, fields, or spacetime itself), TARS posits that everything that exists is, at root, a relation. In this view, the universe is a dynamic network of coherence relations, and what we perceive as space, time, matter, and even physical laws, are emergent phenomena arising from this underlying relational web.
1. Motivation: The Crisis in Fundamental Physics
Modern physics, despite its immense successes, faces deep unresolved problems:
The incompatibility between General Relativity (GR) and Quantum Field Theory (QFT)—the so-called "quantum gravity problem."
The mystery of singularities (in black holes and at the Big Bang), the nature of time, and the unexplained phenomena of dark matter and dark energy.
The lack of a unifying principle that can reconcile the fragmented domains of current theories.
TARS responds to these challenges by proposing a radical ontological shift: relations, not entities, are fundamental. This shift is not just a new model, but a new grammar for describing reality.
2. Ontological Foundations: Radical Relationalism
Core Postulate:
"All that exists is relation."
There are no absolute, isolated objects. The very identity of any "entity" (particle, field, law) is defined by its pattern of relations with all others.
The universe is fundamentally non-separable: no part can be fully understood in isolation.
This principle generalizes quantum entanglement to a universal ontological status.
Realism and Symbiosis
Symbiotic Realism: Entities and their properties are co-constituted through mutual relations. There are no intrinsic properties, only extrinsic, dynamically co-created ones.
The observer is not external, but an active node in the relational web. Knowledge itself is a process of coherent participation in this network.
3. Mathematical Formalism
3.1. From Discrete Relations to Emergent Fields
At the most fundamental level, reality consists of discrete coherence relations, denoted ξ_{ij} (or quantum operators ξ̂_{ij}), between abstract nodes.
At emergent scales, these relations manifest as a continuous coherence field ϕ_{μν}(x), a symmetric tensor field encoding the density and structure of relational coherence at each emergent spacetime point.
The emergent metric is given by:
g_{μν}(ϕ) = e^{2αϕ} η_{μν}
3.2. Dynamics: Coherence, Dissonance, and Self-Organization
Local coherence (ξ_l) and global coherence (ξ_c) quantify the degree of relational compatibility.
The difference Δξ = |ξ_c − ξ_l| acts as a "relational tension," driving the system toward higher global coherence.
When Δξ exceeds a threshold, critical reorganizations occur (mediated by an operator F₀), leading to emergent order, the arrow of time, and the formation of physical laws.
3.3. Quantization and Emergence
TARS aspires to a quantum theory of relational fields, where quantization applies to the relations themselves, not to fields on a pre-existing spacetime.
The challenge is to mathematically derive how spacetime, matter, and interactions emerge from the dynamics of ξ̂_{ij}.
4. Phenomenological Implications
TARS provides new perspectives and solutions to major physical puzzles:
Singularity Resolution: The regularization of black hole and cosmological singularities emerges naturally from the relational dynamics.
Dark Matter/Energy: Gravitational anomalies are interpreted as regions of relational coherence deficit, not as unseen particles.
Inflation and Cosmology: The early universe's rapid expansion is modeled as a phase transition in the global coherence field.
Black Hole Evaporation: Predicts a slower, non-singular evaporation process, leaving stable remnants.
Consciousness and Life: Interpreted as high-order reflexivity in relational networks—consciousness is a self-referential coherence loop.
5. Scientific Achievements to Date
Full mathematical formalism: Action, field equations, emergent metric, and relational potentials.
Analytical derivations: For black hole interiors, dark matter effects, and cosmic inflation.
Numerical simulations: Demonstrating the propagation of coherence fronts and self-organization.
Distinct predictions: Such as black hole evaporation profiles and singularity avoidance, differentiating TARS from standard models.
White paper and technical documentation: Comprehensive and available for peer review.
6. Meta-Theoretical and Interdisciplinary Reach
TARS is not just a new physical theory; it is a meta-framework for understanding emergence, organization, and knowledge itself. Its principles can be applied to biology, neuroscience, social systems, and artificial intelligence, wherever complex relational networks give rise to emergent phenomena.
7. Conclusion
TARS offers a radical, mathematically grounded, and phenomenologically rich alternative to current foundational physics. By shifting the focus from entities to relations, it provides a unified language for the emergence of space, time, matter, and law. Its predictions are testable, its formalism is rigorous, and its implications reach far beyond physics, offering a new way to organize scientific and philosophical knowledge.
>We are not special, no more than Earth was in the geocentric worldview that led Galileo (the astronomer who suggested the Earth revolves around the Sun in the 16th and 17th centuries) to be placed under house arrest.
Wow - like this anti-humanist prejudice is totally 1993. And not in a good way.
two-photon collision experiment has permitted humans to hypothesize a simpler explanation to the beginning of the creation of more electromagnetic forces, which obviously behave differently than how are bodies were designed to receive them i.e. evolutionary biological bandwidth...
Not really. Asimov's story did not represent the process as a mathematically inevitable consequence of physics. It might not even have gone through a second cycle. Cellular life, dollars, and teletypes would all have had to come about again. (-:
There are countless versions of this theory out there. Basically, a universe existed, then collapsed down to a single point, and then expanded again (the big bang). Rinse and repeat.
Only if something exists. But both nothing and something could not exist, and then there is no duality, just nothingness without a something to relate it too.
TARS is a new theoretical framework that fundamentally reimagines the foundations of physics. Instead of assuming that reality is made of pre-existing entities (particles, fields, or spacetime itself), TARS posits that everything that exists is, at root, a relation. In this view, the universe is a dynamic network of coherence relations, and what we perceive as space, time, matter, and even physical laws, are emergent phenomena arising from this underlying relational web.
1. Motivation: The Crisis in Fundamental Physics
Modern physics, despite its immense successes, faces deep unresolved problems:
The incompatibility between General Relativity (GR) and Quantum Field Theory (QFT)—the so-called "quantum gravity problem."
The mystery of singularities (in black holes and at the Big Bang), the nature of time, and the unexplained phenomena of dark matter and dark energy.
The lack of a unifying principle that can reconcile the fragmented domains of current theories.
TARS responds to these challenges by proposing a radical ontological shift: relations, not entities, are fundamental. This shift is not just a new model, but a new grammar for describing reality.
2. Ontological Foundations: Radical Relationalism
Core Postulate:
"All that exists is relation."
There are no absolute, isolated objects. The very identity of any "entity" (particle, field, law) is defined by its pattern of relations with all others.
The universe is fundamentally non-separable: no part can be fully understood in isolation.
This principle generalizes quantum entanglement to a universal ontological status.
Realism and Symbiosis
Symbiotic Realism: Entities and their properties are co-constituted through mutual relations. There are no intrinsic properties, only extrinsic, dynamically co-created ones.
The observer is not external, but an active node in the relational web. Knowledge itself is a process of coherent participation in this network.
3. Mathematical Formalism
3.1. From Discrete Relations to Emergent Fields
At the most fundamental level, reality consists of discrete coherence relations, denoted ξ_{ij} (or quantum operators ξ̂_{ij}), between abstract nodes.
At emergent scales, these relations manifest as a continuous coherence field ϕ_{μν}(x), a symmetric tensor field encoding the density and structure of relational coherence at each emergent spacetime point.
The emergent metric is given by:
g_{μν}(ϕ) = e^{2αϕ} η_{μν}
3.2. Dynamics: Coherence, Dissonance, and Self-Organization
Local coherence (ξ_l) and global coherence (ξ_c) quantify the degree of relational compatibility.
The difference Δξ = |ξ_c − ξ_l| acts as a "relational tension," driving the system toward higher global coherence.
When Δξ exceeds a threshold, critical reorganizations occur (mediated by an operator F₀), leading to emergent order, the arrow of time, and the formation of physical laws.
3.3. Quantization and Emergence
TARS aspires to a quantum theory of relational fields, where quantization applies to the relations themselves, not to fields on a pre-existing spacetime.
The challenge is to mathematically derive how spacetime, matter, and interactions emerge from the dynamics of ξ̂_{ij}.
4. Phenomenological Implications
TARS provides new perspectives and solutions to major physical puzzles:
Singularity Resolution: The regularization of black hole and cosmological singularities emerges naturally from the relational dynamics.
Dark Matter/Energy: Gravitational anomalies are interpreted as regions of relational coherence deficit, not as unseen particles.
Inflation and Cosmology: The early universe's rapid expansion is modeled as a phase transition in the global coherence field.
Black Hole Evaporation: Predicts a slower, non-singular evaporation process, leaving stable remnants.
Consciousness and Life: Interpreted as high-order reflexivity in relational networks—consciousness is a self-referential coherence loop.
5. Scientific Achievements to Date
Full mathematical formalism: Action, field equations, emergent metric, and relational potentials.
Analytical derivations: For black hole interiors, dark matter effects, and cosmic inflation.
Numerical simulations: Demonstrating the propagation of coherence fronts and self-organization.
Distinct predictions: Such as black hole evaporation profiles and singularity avoidance, differentiating TARS from standard models.
White paper and technical documentation: Comprehensive and available for peer review.
6. Meta-Theoretical and Interdisciplinary Reach
TARS is not just a new physical theory; it is a meta-framework for understanding emergence, organization, and knowledge itself. Its principles can be applied to biology, neuroscience, social systems, and artificial intelligence, wherever complex relational networks give rise to emergent phenomena.
7. Conclusion
TARS offers a radical, mathematically grounded, and phenomenologically rich alternative to current foundational physics. By shifting the focus from entities to relations, it provides a unified language for the emergence of space, time, matter, and law. Its predictions are testable, its formalism is rigorous, and its implications reach far beyond physics, offering a new way to organize scientific and philosophical knowledge.
I went to school in a very bad neighborhood. Once I was sent to the office because my math teacher asked me what I was reading about that was soo much more interesting than our textbook. I happened to be reading "A Brief History of Time", so I answered "black holes."
At the time I couldn't understand why my dad laughed about that particular phone call from the principal.
Isn't time a human invention useful to model the nature? It's literally just a defined interaction as a reference, i.e. the sun rising up and going down which is the rotation of the earth.
So IRL there's no time, there's no need to have a beginning or an end. Whatever happened when all the matter was close together isn't the beginning of anything, just a phase.
There's a perfectly good explanation for why though, in fact the explanation is what motivated the formalism of entropy to begin with. There are significantly more ways that the energy contained within a closed system can spread throughout that system than there are ways for energy contained within a closed system to condense, so that if you observe the state of a system at two different moments in time, you will expect to see it evolve towards the statistically more likely outcome than the statistically less likely outcome.
And from first principles, that's what entropy is, a measure of how energy is dispersed throughout a system. Of course once you have that first principle understanding of entropy then you can come up with more rigorous formalisms to properly quantify what it means for energy to be distributed throughout a system, such as measuring the number of microstates that correspond to a macrostate, and other various formalisms that are more or less equal to each other... but fundamentally they all start from this basic principle.
If time were running against the arrow of entropy, nobody could perceive or measure it, right?
Remembering something is per se an increase in entropy, so the universe could run in negative time direction, but we would simply forget, what had happened.
That said, I personally think such thought experiments are futile and the nature of time has to be understood by its connection to causality and information.
There's no arrow of entropy, it's an invented useful model to describe something that nature does. Everything is like that, I.e. there's no electric field, it's a useful way to do calculations about particle interactions.
We have no idea if there is a meaningful beginning or end, other than heat death. But time is real in the sense that there is an arrow of time, due to entropy.
No, time is what the clock measures. Consciousness does not collapse the wave function meaning clocks exists without humans and time exists without humans.
Exactly, time is whatever the clock measures and the clock does it through some defined physical interaction. Can be a swing of a pendulum, can be vibration of an atom, flow of sand, unwinding of a spring etc.
As I understand it (I‘m not a cosmologist by any means), saying that the observable universe began at big bang simply means that anything that happened before the big bang has no effect on what happens afterwards.
There may be other universes out there, with their own big bangs, but that has no effect on ours.
Reading this article, I think they are simply disputing the necessity of singularity inside a black hole, and hypothesize a universe which expands from non-singularity black hole, while staying inside its own event-horizon.
That is how I understood it at least, somebody please correct me if I misunderstood it.
Eh, the thing about the statement there is you're redefining "universe", which is fine, but restating a definition isn't really saying anything new. The literal meaning of "universe" especially with respect to the Latin origins is... well... everything. It may make sense for physics to separate in to separate sets of everything if there's some reasonable justification.
There's the Universe (everything everywhere everywhen), and then there's the observable universe. Most testable theories will be referring to the observable universe.
I always pondered about everything in our universe getting swallowed up continuously merging black holes until all of a sudden "everything" is "in" the black hole and then suddenly that's your big bang, and everything starts all over.
I don't have the Ph.D physics/maths skills to work out the plausibility of any of that (or variations on that) but I've always felt I've been good at coming up with ideas.
"Your honor, I could not have possibly shot that person, because yesterday might not have been before today, or at least, there is reasonable doubt that yesterday was before today, according to some physicists on crack. I treat those physicists with high regard personally though, and they have degrees that you don't have, so the court must reasonably conclude their opinions should be entertained."
I guess that's a joke, but it's actually kind of serious that causality, personhood, identity, free will, etc. are all social constructs.
They are useful to us, but every now and then it's helpful and humbling to remember it's a fiction we assign, rather than fundamental.
Criminal justice or the concept of culpability is one of these areas. I know I've seen material by Robert Sapolsky, a neuroscientist who does not believe in free will, talking about how off the mark criminal justice and punishment for crimes can be.
Not many people these days like to hear this (I myself was one of them), but the answer to this is in Genesis.
There's a reason some of the most famous mathematicians, scientists, engineers, and philosophers of all time believe(d) in God.
The Hebrew name of God, YHWH, literally means "He Who Is." In other words, the Self-Existent One. The father and originator of all things that were, are, and will be, who exists outside of spacetime.
I understand that many people yearn for a religious explanation to answer the question of what caused the universe to exist. I myself am content with the "it just happened" explanation, as any information prior to the big bang, if it even exists, is unknowable.
There are countless other religions that believe in a deity who created the universe. These deities either created themselves, or had always existed outside of space and time. To that end, any one of those deities would be on equal footing with YHWH. I don't think that it is appropriate to axiomatically claim that a certain deity exists because only that deity could have caused the universe to exist.
This is not an answer that satisfies just begs more questions.
Who Created God? No one? Why does the universe need a creator if God does not?
Where does free will and evil come from if God is "originator of all things that were, are, and will be". For true free will to exist it must have a source of entropy which denotes something outside of Gods control and design otherwise everything is deterministic as set forth by God.
>There's a reason some of the most famous mathematicians, scientists, engineers, and philosophers of all time believe(d) in God.
That reason being that for much of Western history if you didn't believe in God the Church would burn your research in a big fire and probably you on top of it.
"An equation means nothing to me unless it expresses a thought of God." — Ramanujan
I like to think he was referring to computation. There's a reality to the constant pi, its computation, and ourselves and the representation being part of that same universe.
I think they mostly "believed" because they would be ostracized and maybe even killed for not believing in God and saying as much. Many who were famous in their lifetimes would have had enemies who would have loved to destroy them via that avenue.
I think it's neat that this summary is written by an author of the scientific manuscript. Oversimplification is a risk, but this approach eliminates the possibility that the writer did not understand the underlying science.
Yea, and it was a great read too. I wish more researchers would publish blog posts alongside their technical whitepapers, although I acknowledge that not everyone involved in science has or wishes to acquire the skills needed to write blog-form content.
(I'd also be worried about a world where researchers are evaluated based on the virality of their blog posts, vs. how impactful their work was.)
Communication skills are often missing in engineering too, but I think I'd argue they should be required - all work is fundamentally collaborative.
Being able to effectively communicate to different people on your team, outside your team, managers, business people, etc is not optional and more than once I've seen things get stalled or turn into a mess because communication didn't happen.
STEM is often a haven for neurodivergence but I think communication skills are something that is largely learned and not something that comes naturally for everyone. People who are good at communicating spend a fair amount of effort rewriting, trying different wordings, different introductions, getting feedback from people, etc.
FWIW I see things like being able to sell a proposal, managing expenses, planning, etc as optional - these are good to have, but someone else can do them if you can communicate well, but in the end the only person who can communicate what you're thinking is you.
1 reply →
I think the benefits greatly outweigh any dangers. I far prefer to read something like this than something written up by a journalist.
> I acknowledge that not everyone involved in science has or wishes to acquire the skills needed to write blog-form content.
They should. If your research is publicly funded you should make it as available to be public as possible. Academics should be able to communicate, and I very much doubt they are unable to acquire the skills
> I'd also be worried about a world where researchers are evaluated based on the virality of their blog posts, vs. how impactful their work was
Given how bad the measures of impact and the distorted incentives this produces I am not even sure this would even be a bad thing.
If nothing else it improves transparency about what they are doing, again with public money.
6 replies →
A few years ago, at least in my field, there was definitely a trend of people at least doing twitter threads explaining the key findings of their papers. It's obviously less in-depth than a blog post would be, but it was still usually a far more accessible version of the key ideas. Unfortunately, this community has basically dissolved in the last few years due to the changes in twitter and to my knowledge hasn't really converged on a new home.
[flagged]
43 replies →
There used to be a common practice of scientists writing summaries of their research for lay people. I think they viewed it as their civic duty. I had a collection called the World of Physics which included essays written by various scientists. I originally had it in the 90s and found it again after many decades. Would highly recommend.
https://www.amazon.com/World-Physics-Library-Literature-Anti...
It's far preferable to having university PR people write some hype piece. Where they'd spend the whole time gushing about it being a world first, paradigm shifting, blah blah blah, the author focuses on things that actually matter. e.g. Is it testable? Yes, here's what to look for.
Yeah, wow. That was great. His solution seems so simple and clears all the previous model's problems. I guess every black hole could contain its own universe.
Too bad the author didn’t explain more the concept of the “parent” universe and how our own (contracting & expanding) universe got created. Nice things to read/consider/ponder late at night :-)
2 replies →
I would be surprised if the size doesn't matter in this case. On the one hand, tiny black holes tend to be rather short-lived. On the other, I suppose some threshold mass/energy is needed to generate a child universe that doesn't collapse immediately.
Ironically that was basically the first thought many had when it was clear we cannot explain what happens in the edge case of a singularity. It was always "perhaps another unsiverse or a way into a parallel one".
It still leaves a lot of questions though, especially if you try to marry quantum mechanics to these makroscopic models. Where did the initial black hole come from and should a corresponsing anti matter black hole exist?
2 replies →
The article is based on a physics paper (arXiv:2505.23877), not management theory or institutional metaphors.
What the paper actually proposes is that the Big Bang may have been a gravitational bounce inside a black hole formed in a higher-dimensional parent universe. Quantum degeneracy pressure stops the collapse before a singularity forms. From the outside, it looks like a black hole. From the inside, it evolves as a 13.8 billion year expansion. That is general relativity applied across frames.
Simply put this is a relativistic collapse model with quantum corrections that avoids singularities and produces testable predictions, including small negative curvature and a natural inflation-like phase.
>in a higher-dimensional parent universe
That's incorrect: The parent universe is not higher-dimensional, it's the same good old 3+1 as our universe.
What they propose is: Let's take our good old GR, and start with a (large, dilute) compactly supported spherically collapsing collapsing cloud of matter. During that, you get an event horizon; afterwards, this looks like a normal black hole outside, and you never see the internal evolution again ("frozen star", it's an event horizon). Inside, you have the matter cloud, then a large shell of vacuum, then the event horizon.
Quantum mechanics suggests that degeneracy pressure gives you an equation of state that looks like "dilute = dust" first, and at some point "oh no, incompressible".
They figure out that under various assumptions (and I think approximations), they get a solution where the inside bounces due to the degeneracy pressure. Viewed from inside, they identify that there should be an apparent cosmological constant, with the cosmological horizon somehow (?) corresponding to the BH horizon as viewed from the outside.
All along the article, they plug in various rough numbers, and they claim that our observed universe (with its scale, mass, age, apparent cosmological constant, etc) is compatible with this mechanism, even hand-waving at pertubations and CMB an-isotropies.
This would be super cool if it worked!
But I'm not convinced that the model truly works (internally) yet, too much hand-waving. And the matching to our real observed universe is also not yet convincing (to me). That being said, I'm out of the cosmology game for some years, and I'm a mathematician, not a physicist, so take my view with a generous helping of salt.
(I'm commenting from "reading" the arxiv preprint, but from not following all computations and references)
PS. I think that they also don't comment on stability near the bounce. But I think that regime is known to have BKL-style anisotropic instability. Now it may be that with the right parameters, the bounce occurs before these can rear their heads, and it might even be that I missed that they or one of their references argue that this is the case if you plug in numbers matched to our observed universe.
But the model would still be amazing if it all worked out, even if it was unstable.
> with the cosmological horizon somehow (?) corresponding to the BH horizon as viewed from the outside.
That’s not mentioned in the summary. After inflation the event horizon would not exist.
1 reply →
Why does this black hole bounce whilst others from the limited info we possess appear to be stable regardless of lack of singularity
3 replies →
> What the paper actually proposes [...]
(Emphasis mine)
I haven't read the paper yet, but this sounds like a (good) summary of exactly what the article is saying. It makes me wonder what, if anything, you feel is different from the way you put it and the way it is explained in the article? As a layman they seem the same to me.
The article was written by the main author of the paper, so yes, it's a good summary :)
1 reply →
Looking at the paper, I don't see any higher dimensions of the parent universe, it is still using the same 4D General relativity framework for the parent.
So, could the same interaction create planar universes inside our own black holes? Linear universes inside those as well?
It's incredible how big a 4-D universe would have to be to contain our own, even crazier if there are more levels; but our own universe could contain easily uncountable planar universes.
Isn't it more a matter of how space is folded in higher dimensions rather than an increase in volume that accounts for containment? There is plenty of space in the corners:
[0]: https://observablehq.com/@tophtucker/theres-plenty-of-room-i...
Sigh: https://arxiv.org/abs/2505.23877
They have basically disproved Penrose-Hawking's theories of singularity? Isn't that like a pretty big deal? To people working in this field, what is the reaction to this paper?
They predict a non flat curvature, so no (not with existing data and measures, which may improve in the future).
seems like this is just giving up on quantum gravity and saying the pauli exclusion principle will hold regardless of the gravitational force.
You mean small positive curvature.
I have two problems / questions with this:
1. This theory requires a parent universe that can't have been formed inside a black hole. This means there must a be second "universe creation" mechanism that we can / may never know about from our child universe. For me, this doesn't really answer the true question: "How did our universe begin?" Yeah, it may the "unknown field with strange properties" but instead we get an unknown parent universe with strange properties.
2. The black hole in the parent universe must be much much bigger than anything we see in ours since it has to contain all the matter that we see. How is a black hole supposed to form that is 750 billion times bigger than the largest black hole we know about?
I don't see this idea as very new.
There are many models of black holes, such as the Schwarzchild solution, that have an area of "asymptotically flat spacetime" which is, from the viewpoint of our universe, part of the black hole. That something happens around the singularity that creates this new universe doesn't sound that crazy.
If our universe is a child of another universe and that is a child of another universe and so forth it fits into the kind of "multiverse" model that addresses issues such as "why does the universe have the parameters it does?" Either there are a huge amount of universes such that we're lucky to be in one we can live in, or there is some kind of natural selection such that universes that create more black holes have more children.
As for the relative size of the parent black hole, conservation of energy doesn't have to hold for universes in the normal sense. One idea is that the gravitational binding energy of the universe is equal to the opposite of all the mass in the universe such that it all adds up to zero so we could have more or less of it without violating anything.
Do you find the idea of an infinite regress -- "our universe is a child of another universe and that is a child of another universe and so forth" -- holds much explanatory power for you?
To me it's prima facie a hollow explanation. I get that some models, like eternal inflation or certain cyclic cosmologies, entertain the idea of an infinite past or blur the standard arrow of time... but how does pushing the origin question back indefinitely actually resolve anything?
4 replies →
> "why does the universe have the parameters it does?"
To those who say "oh but if this parameter was slightly off, that thing I subjectively decided to pick wouldn't have happened!":
How would you know that this universe could exist in any other way? Wouldn't things just stabilize into certain frequencies and lengths after some time?
To me "fine tuning" isn't really a conundrum, it is just question begging and you don't need to wish it away with multiverses.
> we're lucky to be in one we can live in
Nitpick: We couldn't be anywhere else, except nonexistent.
1 reply →
Not exactly. A universe can expand, slow down, then collapse. In this case, bouncing back out.
Does that repeat forever? Does it lose energy in the bounce? If so, to where and how?
Yes and no. You're not thinking about contraction. With relativity we can fit a 100ft ladder inside a 10ft barn.
Most importantly, you don't need everything all figured out at once to publish. Then no one would always publish. There'd be nothing to improve on. Only one publication that says everything. Till then, everything does have criticisms and is incomplete. It's good to have criticisms! They lead you to the next work!
>> The black hole in the parent universe must be much much bigger than >> anything we see in ours
>> Yes and no. You're not thinking about contraction. With relativity >> we can fit a 100ft ladder inside a 10ft barn.
I believe the OP was talking about mass, not linear dimension. (And if he wasn't, I am.) Unless somehow mass inside a black hole is not constant? (ignoring accretion)
4 replies →
Where does the information of the previous universe before the bounce go? Is it destroyed?
3 replies →
1. It is possible that every universe is formed in a blackhole – an infinite universe-blackhole-universe chain. We don’t know what “infinity” means in this scenario, so we can’t simply rule it out. For comparison, Aristotle ruled out an infinite chain of causes, which we now know (with the help of hindsight, of course) is a flawed conclusion.
2. We don’t know whether our universe is big or small compared with other universes. We don’t know whether, or how, it makes sense to compare sizes between universes.
Big Bang is arguably the biggest speculation in modern science.
Your first statement right off the bat is a bit of an assumption, why can’t the parent universe also have been formed inside a black hole? Why did you assume that?
The outer universe could have always existed, but unlike ours it eventually collapsed. By contrast ours did the reverse, and it looks like it will expand forever. There is a neat symmetry. I guess you could make the case that it’s really just one universe, and the collapse and expansion mirror each other.
We think the universe had to "begin" because we "began" and tend to anthropomorphize. Is that necessarily true? The universe is under no obligation to have a beginning. Sail around the Earth and you might just end up right where you started.
Current observations make it likely that our observable universe expands (think "stretches"), and the expansion will continue forever.
If it's expanding, then it was smaller earlier. Asking about the far past is a natural reaction, and the Big Bang theory is a pretty good attempt at explaining that.
https://en.wikipedia.org/wiki/Expansion_of_the_universe
https://en.wikipedia.org/wiki/Chronology_of_the_universe
The Sun had to begin. At one point it was just accreting gasses, then at some point gained enough mass to ignite. People also start at some point they begin as a daughter and grow eventually into a viable life. But also our galaxies had to form before our sun. So, yes there are beginnings to things. At one point they weren’t, at another point they were.
Yes, but earth still had a beginning.
I agree with you, though - causal explanations are compelling and confer a sense of certainty and humans seem to like that, but it doesn't make them necessary.
Wouldn't every theory/model of the universe leave room for follow up questions? Why is it problematic if it doesn't answer literally every conceivable quandary?
It's black holes all the way down!
If the crux of the article is the fermion bounce, and you compare that to how much matter and energy we are aware of, that is quite the black hole, which leads one to start wondering what environment it existed in to become that size. Even if it is now stuck due to a positive curvature of just bouncing back and forth.
I would like the article to acknowledge a bit more though that blackhole universe theories and speculation are quite old now, not radical and a striking alternative, as it is natural to think about it once you learn of the concept of event horizons. What differentiates this though is the analytical solution.
I've read somewhere an article which posited that our 3D universe might be inside a 4D black hole. When you cross a black hole's event horizon, the radial coordinate becomes timelike, so you lose one degree of spatial freedom. Movement is still possible in the tangential directions however, so what you get is basically an N-1 dimensional universe. So maybe our 3D universe is actually matter that fell into a 4D black hole, and our 3D black holes contain 2D flatland universes. And of course, the outer 4D universe might be in a 5D black hole, etc.
Yes, and then there's the parlor game of guessing what familiar property of our known universe is actually a spaghetified fourth dimension.
I guessed c once. It would be a constant. Maybe all the constants are spaghettified remains of a superior universe.
I don't think c is a good candidate, because it's not really a parameter. It's just a correction factor for our mis-judgment in picking different units for time and space.
In "natural units", we define the units so that the important conversion factors (c, G, h-bar, etc) work out to exactly 1. You can say that c is one light-year per year and then forget about it.
The true parameters of the universe are the dimensionless constants: the fine structure constant, proton-electron mass ratio, 3+1 dimensions, etc.
4 replies →
I thought that's what the high dimension counts of string theories were: taking constants and turning them into dimensions.
Or is that too simplified?
Gravity, obvs.
> When you cross a black hole's event horizon, the radial coordinate becomes timelike, so you lose one degree of spatial freedom.
The second half is incorrect. Since the time coordinate becomes spacelike in turn you'll still have 3 spatial degrees of freedom. Dimensions can't just vanish if you believe that spacetime is a 4D Lorentzian manifold (as physicists do).
Moreover, the singularity is not a place you can poke with a stick, once you've entered the black hole. It lies in your future, in the same way as your death.
> The second half is incorrect. Since the time coordinate becomes spacelike in turn you'll still have 3 spatial degrees of freedom. Dimensions can't just vanish if you believe that spacetime is a 4D Lorentzian manifold (as physicists do).
Can we say that one of the spatial dimensions (the radial dimension) and the time dimension combine into a single dimension? After crossing the event horizon aren't they 1:1 correlated?
1 reply →
I don't think the spacetime swap idea is particularly well explained though? Like although it's sort of mathematically true, my impression was that it's not like time suddenly becomes a dimension you're moving in once inside the event horizon, just that spacetime is acting so weird because there's now a deliberate direction where one did not exist before.
2 replies →
I’ve always like to explore the idea of our universe being in a static 5th dimension where the 5th dimension represents randomness/entropy. The same way to think about exploring a 2d plane in a 3 dimensional space where the 3rd dimension is constant. We just happen to be in a random big bang in this 5th dimensional space
You can't have the curl operator in 4D.
What's in a 1D black hole?
I'm guessing it'd look something like this on a 1-dimensional number line:
The dot in the middle would be the singularity, the pipes the event horizon, and the contents would be increasingly warped spacetime that may or may not exist, depending on your interpretation of things.
/dev/null I presume
What? Wouldn't that mean an object's speed in some direction determines how time passes once it crossed over, and conversely, it would experience its old time dimension as spatial and be able to "move through (old) time" freely after crossing the event horizon?? My head hurts.
Interesting read, but even if we assume the author is correct, and the cosmos formed as a black hole in a larger universe, the question remains, how did this larger universe formed, then? Might just be impossible to know.
Questions like what was before the big bang or what is outside of our universe seem to be quite natural. However, we still don't know if these questions are well defined and have a proper meaning. For instance, a few hundred years ago, one might have asked, what happens if I go to the edge of the (flat) earth? Or one might ask: What is north of the north pole?
Thanks, GPT 4.1. It told me the same thing twelve hours ago when I asked it what was at the top. “what’s north of the North Pole”?
1 reply →
> What is north of the north pole?
I really like this analogy for "what is outside of our universe", thank you
1 reply →
Maybe the larger universe is identical to the contained universe, like a fractal. That would solve the question. ;)
Might I suggest Brouwer's theorem while we figure it out
2 replies →
Would be fun if we find a function f(state, time) such that for f(singularity, 14 billion years) we get our current universe. i.e.: every singularity turns into our exact universe.
8 replies →
Then we gotta find the black hole in our universe that contains that universe, and nuke it before they come to take our fluids!
3 replies →
It’s turtles all the way down
Black holes all the way up.
This theory is in the same space:
https://en.wikipedia.org/wiki/Cosmological_natural_selection
I don’t think it has a hypothesis for the origin, though
See also the recent HN discussion about Blowtorch Theory, which has roots in (but doesn’t necessitate) CNS
1 reply →
If we wait until we understand everything perfectly before publishing, we’d never publish anything. That question may remain, but so do many others, this paper can’t address them all.
It may just be that the physical conditions of our universe just prior to the big bang are indistinguishable from that of the interior of black holes.
In that sense black holes are areas where our universe has reverted from it's low entropy state all the way back to the initial nearly infinite entropy state.
I feel like quantum physics is gently pointing us towards the idea "everything you can imagine is real at once". As in, all possible universes and physics systems and whatnot do exist in some sense of this word, and we happen to inhabit one. Just like Earth is a totally unremarkable planet in a totally unremarkable solar system in a totally unremarkable galaxy, except we popped up here so for a long time we thought there's something deeply special about Earth.
Quantum mechanics doesn't imply at all that everything possible is actual. That is a misconception.
I do agree that it makes sense, but not because of what quantum mechanics says.
6 replies →
I find it more useful to anchor the concept of "real" in what one has direct access to. Beyond that there are many ways to describe our shared reality and the space of possible realities, including the past and future, some of which are more real than others, and go far beyond what we can imagine. Quantum physics gives us a language to expand what we can describe and imagine.
Not only does the sun not rotate around us, the rest of the galaxy doesn't even care to think that we exist. An interesting evolution in thought nonetheless.
That's a very 3D way to think of a universe.
It's just recursion in the simulator.
My theory: There's no such thing as before and after “it”. It is it.
Block Universe. The more you think about it, the more probable it seems. Why should a universe pass time like a movie, if all moments could exist simultaneously? If there is no time, and it’s just a simulation formed in our brain, there doesn’t have to be a beginning nor end.
2 replies →
What about "bit"? Doesn't that come before "it", Mr Wheeler? :)
Just casually adding the biggest question its possible to ask
A larger black hole
if we assume the author is correct, it would cease to be a scientific endeavor.
I'd put it a bit differently, that it remains a scientific endeavor, but leaves us in the same predicament as we're in now, which is the difficult work of forming a scientific theory that can only be tested indirectly.
But who would be as cruel to put us here without giving us those answers? Who? And where did that entity come from?
Oh that was me - I figured if I let you guys work it out for yourselves, it’d be more meaningful or whatever.
As for where I came from, I gotta admit I feel curious about that too, but mostly I’m just happy to be here. Real excited to see what you do next.
1 reply →
There is no other entity. We're nothing. An algebra of nothing. Combine nothing with nothing in various ways (like S-terms) and it gives you physics, among many other things. From the inside we see a universe, from the outside you would see nothing.
18 replies →
This is why the "but the universe couldn't spawn out of nothing!" style arguments are so annoying. They completely accept that an all powerful all knowing entity could exist for all of time and not need a creator without any supporting evidence. But the origin of the universe specifically needs to be explained in detail or science is a sham.
Maybe there was no cruelty, and we were just plain matter that fell into our encapsulating black hole. Like what happenswith our own universes black holes.
Oh I have so many questions on this topic.
I've often wondered about this. I don't have any direct physics training, but it's something that felt really plausible after I learned that the mass of a black hole is linearly proportional to its swarzschild radius.
As the size of the black hole goes up, its overall density must decrease. Combined with the other observation that our universe has uniform density at large scales, it seemed really obvious to me that there existed some threshold at which the decreasing density of a very large black hole, and the fixed density of our observed universe.. would cross.
I used to muse about this question with some other tech colleagues that liked talking about physics stuff but never really got a clear answer to this.
On a side note - I'm absolutely fascinated by the implications relating to this. I'll post a follow-up thought I'm hoping somebody else has also thought about:
I've seen discussion of dark energy mostly presented as a surrogate for real energy. That there is some underlying energy "accelerating things away from each other".
I always felt uncomfortable with that characterization. It seems more reasonable to me to think of dark energy as _negative energy_ - i.e. a loss of overall energy.
In a classical system, two things moving away from each other stores potential energy that can be recouped at some later time. Dark energy doesn't work this way - things accelerate away from each other the further apart they are. From a global perspective, it's an energy loss.
The energy loss pervades to the quantum world as well - photons that start off high frequency arrive low-frequency.
It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return. Maybe like a black hole evaporating as observed from the inside?
When I asked this of some people in real life, I was pointed to answers that indicated that the "energy" component in dark energy is normalized into the "tension" of space somehow. As I mentioned before I'm not really studied in physics, but that explanation felt unsatisfactory to me.
Plug estimated mass of universe to your schwarzschild formula and be amazed how close it is to observable size of the universe.
I tried once, but I'm not sure what terms to throw in there. Visible matter, estimated dark matter.. anything else?
I think my estimate came out to less dense than the required threshold but it was a while back now and cobbled together with some queries to wolfram.
This is true almost by definition, and doesn’t tell us anything interesting about black holes.
There was a thread a while ago on here where the hypothesis for why things are moving apart at faster rates is down to time moving at different speeds due to mass.
So time in the void between galaxies is moving quicker than time in the galaxies, but on the grand scale of the universe the differences as up a lot.
I quite liked this theory, think is make sense, at least from my very limited understanding of this stuff.
Aka Timescape Cosmology, https://en.m.wikipedia.org/wiki/Inhomogeneous_cosmology
Would make sense if our universe is a simulation. It takes more compute power to simulate areas of high density so time naturally flows slower there.
1 reply →
> It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return. Maybe like a black hole evaporating as observed from the inside?
But in this story the black hole increases in size as matter falls into the horizon and shrinks as it evaporates, so cosmic expansion would be associated with more energy falling into the black hole than leaving it.
I thought about this part. I'm not sure we can link apparent size from outside the event horizon to apparent size from inside.
Apparent distance is something that's affected by relative frames of reference and the frames of reference are as different as as can be in this case.
A black hole is really just a singularity with infinite density by definition, but finite mass.
The size and density of the Schwarzschild volume is determined only by mass (stationary, non-rotating). It's proportional to the inverse square of mass. Density = 3c⁶/32πG³M².
SMBHs have densities ~0.5 kg/m³ between thin air and water.
Stellar BHs are ~1e19 kg/m³ several orders of magnitude more than a neutron star.
>follow-up thought I'm hoping somebody else has also thought about [...] dark energy as _negative energy_ [...] Maybe like a black hole evaporating
Another layman's thoughts: Isn't the energy theoretically lost by black holes so faint it's currently undetectable? And isn't the amount of dark energy theorized to be the major component of the observable universe? It seems like the numbers wouldn't add up?
I don't have enough of the background to speculate about the numbers. Dark energy feels "big" if we think of it in terms of the actual energy it would take to accelerate the universe away from itself at the rate that we see.. but the rate that we see is affected by our frame of reference, along with distances and everything else.
I'm gonna pull out my lay understanding again. An evaporating black hole, as it gets smaller, should get more dense and be associated with a higher local spacetime curvature, no? The effect of which would be to slow down apparent time for observers within the system. Maybe that affects observed distance and rates of speed at which things seem to be happening when we look out into the sky?
Sometimes I regret not caring enough about calculus in university.
> Combined with the other observation that our universe has uniform density at large scales
s/has/had at the time of recombination
It is largely an assumption of LCDM that we can treat the universe as practically homogeneous throughout its entire evolution but potentially not a very well-founded at that [0, 1].
> I always felt uncomfortable with that characterization. It seems more reasonable to me to think of dark energy as _negative energy_ - i.e. a loss of overall energy.
Your intuition is correct. If the Lambda term in the Einstein field equations is moved over to the side of the energy momentum tensor, it takes on the role of a negative contribution (provided Lambda > 0, as observations seem to indicate).
> In a classical system, two things moving away from each other stores potential energy that can be recouped at some later time. Dark energy doesn't work this way - things accelerate away from each other the further apart they are. From a global perspective, it's an energy loss.
Note that there is no global energy conservation in General Relativity[2], only at a local scale[3]. Heck, you'll already struggle to define what the energy is of a given piece of spacetime in a meaningful and generic manner[4, 5]. In other words, violations of energy conservation due to spacetime expanding or contracting (a strictly non-local phenomenon), like in the case of the cosmic redshift, are expected and our intuition from classical mechanics only takes you so far.
> It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return.
Dark energy aka the cosmological constant term in the Einstein field equations is a constant term, as the name suggests. Yes, there can be energy loss due to spacetime expanding (see above) but that doesn't change the gravitational constant.
[0]: https://en.wikipedia.org/wiki/Cosmic_web
[1]: https://en.m.wikipedia.org/wiki/Inhomogeneous_cosmology
[2]: https://en.m.wikipedia.org/wiki/Conservation_of_energy
[3]: https://en.m.wikipedia.org/wiki/Stress%E2%80%93energy_tensor
[4]: https://arxiv.org/abs/1510.02931
[5]: https://en.m.wikipedia.org/wiki/Mass_in_general_relativity
Interesting reading - this is the first thorough response I've gotten to some of these question. Will check out the reading material.
> As the size of the black hole goes up, its overall density must decrease.
The center of a black hole is infinitely dense. That's why it even exists. The event horizon is not the black hole.
> and the fixed density of our observed universe
Our universe is expanding. It's density is not fixed.
You really want to be thinking about this in terms of entropy and not matter.
Yeah I was referencing the event horizon as the most meaningful measure of size.
And whether the density is fixed over time or not doesn't affect the question. Let's take the universe at its current average mass/energy density - whatever the "true" measure of that is.
To the best of our understanding, at large scales the density is uniform. So if we consider a suitably large spherical volume of space within our (presumably infinite) universe.. that volume will have an average mass/energy content greater than the threshold amount for a black hole of that apparent volume (again, using the external event horizon frame).
So that suggested to me that either we live in a finite universe, or we must be on the inside of an event horizon. It seems like an unavoidable conclusion.
It's a mathematical model, not reality. I don't believe scientists believe an actual infinitely dense object exists at the center of black holes.
> The center of a black hole is infinitely dense. That's why it even exists. The event horizon is not the black hole.
Arguing semantics is rather boring when it's obvious you understood the point he was trying to make.
> Our universe is expanding. It's density is not fixed.
None of that precludes uniform density at large scales.
6 replies →
>> As the size of the black hole goes up, its overall density must decrease.
> The center of a black hole is infinitely dense. That's why it even exists. The event horizon is not the black hole.
>> and the fixed density of our observed universe
> Our universe is expanding. It's density is not fixed.
These are both correct and germane points. So why was this post downvoted? Physics isn't a popularity contest, it relies on evidence.
I think given time at a blackboard we could walk through Newton's cannon in the context of Poisson gravity, and for extra credit with the cannonball inducing a perturbation of the Poisson vector field. Even without the cannonball's backreaction, the Poisson picture offers a nice image of the gravitational potential energy at the top of the cannonball's inertial (ballistic) curve. We would then consider a cosmology like our own but with a recollapse: at maximum extent there is some (quasi-)Newtonian notion of gravitational potential energy for all the galaxies, since they are at the point where they begin free-falling back into a denser configuration. It's then the usual story of relating kinetic and potential energy, and recognizing that the standard cosmological frame is close to Newtonian by design. (We also have to stop this approach when the galaxies are merging enough that radiation pressure and gas ram pressure become relevant, because the errors become astronomical).
Since we don't have a blackboard in front of us to interact with, I can suggest Alan Guth's lecture notes on Newtonian cosmology. (Guth is credited with discovering cosmic inflation.) https://web.mit.edu/8.286/www/lecn18/ln03-euf18.pdf See around eqn (3.3). You could also borrow a copy of Baumann's textbook <https://www.cambridge.org/highereducation/books/cosmology/53...> which studies the Poisson equation for various spacetimes, however a static spacetime gets most of the focus.
A universe which expands forever, or which expands faster in the later universe, makes a mess of this sort of approach to calculating a gravitational potential energy. So does any apparent recession velocity that's a large fraction of c (inducing significant redshift, whatever the recession (pseudo-)"force" might be).
However, the general idea is that there is a relationship between the kinetic energy a receding galaxy (in a system of coordinates -- a "frame" -- in which these kinematics appear) and a gravitational potential energy still occurs in a non-recollapsing universe. It's just that the potential energy climbs forever, and you get an equivalent to gravitational time dilation between galaxies at different gravitational potentials (i.e., between early-universe galaxies and higher-potential modern-times galaxies).
Accelerometers in galaxies will not show a cosmic acceleration for any galaxy; they're all really close to freely-falling (local galaxy-galaxy interactions are real -- collisions and mergers and close-calls happen -- but wash out over cosmological distances; look up "peculiar velocity" for details). Therefore we can conclude that there's no real force imposing acceleration on the galaxies. However that's also true of a cannonball in a ballistic trajectory, including one on an escape trajectory or one that enters into a stable orbit. Consequently one can draw some practical comparisons between a ballistic launch from Earth into deep space and galaxies spreading out from an initially denser early part of an expanding cosmos.
> Dark energy as energy being extracted out of the universe
No, it's just a way of thinking about whatever is driving the expansion, and that doesn't dilute away with the expansion as ordinary matter and radiation does. It's not even a "real" energy in the sense that it is only an energy in the cosmological frame, and is a frame-dependent scalar quantity, whereas in the fuller theory it's just a multiplier of the metric tensor. So it's the full relativistic metric doing the work but we absorb some of that into cosmological coordinates in the cosmological frame of reference, carving up the metric tensor into a set of vectors including an expansion vector identical at every point in spacetime.
The expansion vector can also be thought of in terms of pressure: in a collapsing cosmological frame, a pressure drives galaxies together into a denser configuration. The inverse of pressure is tension, so in an expanding cosmological frame, it's a tension that pulls galaxies apart into a sparser configuration. (The reason one uses pressure or its inverse is that the matter fields are idealized as a set of perfect fluids at rest in the cosmological frame; each such fluid has an associated density and internal pressure which evolve with the expansion or contraction of the cosmos, generally becoming less positive in the time-direction of expansion (i.e., in the future direction in a universe like ours). Another way of thinking about pressure is as a measure of isotropic inflow of energy-momentum into a point; increasing pressure at a point therefore increases the curvature at that point. Tension is an isotropic outflow, and so positive tension is repulsive as opposed to the attraction from positive pressure.)
> that explanation felt unsatisfactory to me
Hopefully the above helps a bit. Unfortunately there's only so much teaching one might do in a series of HN comments, and ultimately one probably is better served in developing some grounding in the full Einstein Field Equations / Friedmann-Lemaître equations before thinking in quasi-Newtonian ways. Going the other direction tends to lead to misunderstandings and developing false intuitions when running into situations where the quasi-Newtonian picture needs post-Newtonian correction terms.
It's cool that you have all sorts of questions. You could consider signing up for part time / non-business-hours courses in relativity at a nearby community college or the equivalent, depending on where you are, or maybe just bringing a hot lunch to a lecturer there in exchange for a quick informal tutorial. Anything like that is bound to get you to better answers than raising comments on HN threads about astrophysics in the broadest sense, as answers here are often somewhere between non-standard and unreliable.
That is a very interesting idea… the equation and its assumptions doesn’t seem to have any exceptions so it does strongly suggest our universe is a black hole, inside a black hole?
> The Big Bang is often described as the explosive birth of the universe – a singular moment when space, time and matter sprang into existence.
It is indeed "often described" in the media as such. However, that is _not_ the currently accepted theory. "What if there were no space and time before the Big Bang" is just Stephen Hawking's pet theory.
A more accurate summation would be that our theories do not permit us to go back beyond what appears to be the "Big Bang", and indeed, we can't quite get to it either, since the need for Quantum Gravity becomes too great as we get to what seems to be the "zero time". We have no principled, reasonable way to make any claims about what came before the point where our theories break down, and that includes the claim that there was no space or time at all before then.
Thus, anything and everything you've heard about what is there "before the big bang" has always been speculation. I mention this because sometimes people read the science media, which is always reporting on this speculation, and think that the reporting on the speculation constitutes "science" constantly changing its mind, but that's not the case here. Science has consistently not had a justifiable position on this topic, ever. It has always been speculation. It is the press that often fails to make this clear and writes stories in terms of what "science" has "discovered", but any claims of certainty in this area are not the claims of "science".
Interesting thing with this work is that it does create an observable, testable hypothesis: slightly positive curvature of the universe.
Seems inevitable that we'll discover we aren't the only universe / only cycle.
We went from thinking the Earth was the center of the universe, to the sun being the center of the universe, and the next obvious step is our universe isn't at the center of universes.
What people seem to not be able to conceptualize, consciously or not, is that there really is no "before" the Big Bang in the standard model (Lambda-CDM), if time itself exists only after t=0.
The Lambda CDM does not really say that. As other commenters have pointed out, Lambda-CDM is silent on the very earliest few moments of the universe where quantum gravity would be required.
What is the currently accepted theory?
We have no theories working at those conditions. Wiki says
> General relativity also predicts that the initial state of the universe, at the beginning of the Big Bang, was a singularity of infinite density and temperature.[6][obsolete source] However, classical gravitational theories are not expected to be accurate under these conditions, and a quantum description is likely needed[7].
https://en.wikipedia.org/wiki/Gravitational_singularity
7 replies →
This is the best theory we have:
https://en.wikipedia.org/wiki/The_Last_Question
At t=0 or "before" none
Might as well believe in God if you’re going to believe in spontaneous accidental creation…
Why not? If you can't observe it, test it, and reproduce it, then it lies outside the realm of science and in the realm of belief. Until someone figures out a way to experimentally verify the big bang hypothesis (or any other explanation for the origin of the universe or what came "before"), it's entirely fair to attribute it to whatever you feel like, be it a god or anything else. There is no law of the universe that guarantees that science is capable of answering all questions.
5 replies →
There's quite a big philosophical difference between "there exists a point beyond which it is possible to make observations" and "the universe was created by an omnipotent being"
9 replies →
Anything outside of what we can observe will always be based on faith anyway. We'll probably never understand what's "before" the big bang, wether it make sense to ask that question or why something exists rather than nothing.
To me, calling the unknown "God" is imposing a term loaded with human preconception and biases in exactly the place you don't want those things.
I don't think so - god is substantially less parsimonious. But in the end, I think you're sort of using two different notions of belief as if they were the same.
I believe (lowercase b) in all sorts of stuff, scientific and otherwise, but believing in God typically indicates some kind of act of faith, which is to say, ultimately, to believe in something despite the absence of evidence for it and for some deeper reason than can be furnished by a warrant of some kind. I can believe in the spontaneous generation of the universe in the lowercase b sense of the word without really having anything to do at all with the latter kind of belief, which I think is kind of dumb.
4 replies →
The Big Bang theory was created by a Catholic priest. So yes.
1 reply →
You're confusing belief with accepting the current scientific consensus.
Which God? Vishnu? Ra? Amatarasu?
13 replies →
[flagged]
6 replies →
Belief in anything is completely trivial unless you act based on those beliefs. No one is going to waste time worshiping, or murder someone over, the "nothing" from before "something".
Suggested hard sci-fi light reading: "Cosm" by Gregory Benford, 1999. A universe the size of a bowling ball created in a laboratory. The scientist responsible for it, keeping it safe and on the run from gvt spooks. They want to protect it for as long as it lasts, and since its time is as relative as its size, they won't have long to wait.
Added.
Opinions:
A) I love all the scifi book recommendations that cone up on HN
B) i wish you’d all stop recommending great and amazing books. My queue is so backlogged and jammed I'm never going to catch up.
OK then, I'd be remiss if I didn't mention my own sci-fi book I put out there free forever to listen ( https://www.youtube.com/watch?v=mtxgpaXp9vA ) and free forever to read/download/listen ( https://archive.org/details/stargazer-steven-pitzl ) because I don't want to navigate the self-publishing world, just want some feedback before I die.
Only joking, I'm remiss anyways.
Same here. My interest in the Sci-Fi genre started with an HN comment recommending Blindsight, by Peter Watts.
Several comments and sci-fi series later, and I’m currently reading about spacefaring sentient spiders.
So many books, so little time...
7 replies →
What's a couple dozen books (and video games) in my backlog when I have a thousand websites there?
Please share the queue!
Rick and Morty episode (season 2 episode 6, 'The Ricks Must be Crazy') where it turns out rick has created a whole universe inside his spaceship battery who's whole purpose is to produce energy to run his spaceship. A scientist within this microverse creates a miniverse ....
Should not be microverse inside miniverse?
This sounds similar to Horton Hears a Who.
They exist in the same cinematic universe.
Microcosmic God - Theodore Sturgeon (1941)
I seem to remember a similar Star Trek episode; DS9, IIRC.
"playing god", s2e17
I remember that, and the enormous plot hole that they could move the thing in a transporter!
> The black hole universe also offers a new perspective on our place in the cosmos. In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger “parent” universe.
Does it also follow that black holes in our universe contain universes internally, beyond their event horizons?! Seems like it should. Mind-blowing.
It's not a new idea, although I don't think it would be accurate to describe the other universes as "contained" within the black hole.
https://en.wikipedia.org/wiki/White_hole#Big_Bang/Supermassi...
Black hole to White hole to Black hole
It’s holes all the way down
1 reply →
Does it also follow that black holes in our universe contain universes internally, beyond their event horizons?!
Not necessarily. It's not clear that any are massive enough to cross the threshold required for the "bounce."
Damn, I would not have guessed that Men In Black was actually a documentary...
I thought the universe they were saving in that was in some kind of "fish bowl" type universe (galaxy?)
If the universe does have a positive curvature as this predicts, would that mean that if we look out into space, we could see the same galaxies multiple times? Or even our own galaxy in the past? Or is the predicted curvature slight enough that anything we might see multiple times is already beyond the limits of visibility due to universe expansion?
Only if the circumference of the universe is small enough for light to have made the round trip since the universe began. But we think that the universe is much larger than that.
https://en.wikipedia.org/wiki/Particle_horizon
I'm not a scientist or astrophysicist but i do believe in science, is it ok to believe that we as humans and all our scientific development still very very far from proving anything remotely close to how the universe got created? I feel this subject is for humanity in year 2600 to start discussing it.
Scientist still can show their theories and search papers and i can't understand a shit but i don't believe in any theory that proves how the universe got created.
Science is a process, not a source of truth. It has a very practical lens, which is very utilitarian, does the knowledge and models allow for invention or prediction that works in our reality for some current need.
The assumption is, you never really know, but if the model in which the theory says X, is able to predict something in the future or some experiment for Y, than that model appears to better approximate reality. Or is that knowledge and model allowing us to now do something we could not before, etc.
Over time, it course corrects to improve its knowledge and models in ways that show better results for prediction or invention.
"Proving anything" is kind of fuzzy. We've got very solid evidence that some sort of big bang happened. We can see the galaxies flying away from a common point, and since we can count backwards, we can know roughly when they probably would've been in the same spot. The how and why, and the what happened before, those are very unknown, although we've got a surprising amount of knowledge of what the first few seconds were probably like.
It's not about belief, it's about observing, collecting data & evidence, and proposing possible explanations. As new observations and evidence are found the possible explanations are refined. No one credible is claiming hard proof of anything at this point.
Agreed, people often mix that up, but you have to adopt a probabilistic mindset, you can believe the coin with land on its head, but you also know that based on the weight and curvature of the coin it will land on its tail 68% of the time you flip it, etc. Then choosing tail is no longer a belief, it is simply going with the choice that is backed by prior observation, experiments, models, etc.
You might still lose, and so you might choose to also believe it will land on tail this time, but the rationale for choosing tail was not based on a belief system, but the going information and where it points too.
Before we can prove, we must first wonder. We proceed by small steps, and if we don't start discussing it now, 2600 will still be too early.
Belief is acting as if something, for which no evidence has been given, is true. Imagination, taken too far. No one is telling you to believe anything here, they're suggesting we search for clues to support or disprove a theory. Or don't, it's up to you.
That's not the definition of belief. Belief can have various levels of different kinds of evidence behind it. Scientific, historical, philosophical, experiential, etc. A belief could have more or less scientific evidence than other beliefs, but rarely is belief predicated on no evidence whatsoever.
2 replies →
I think the phrase 'believe in science' is weird; it's nearly as problematic as "I have faith in science".
It can be, but generally the concept of 'belief' isn't attributed to ground truths; it's just 'the truth', you rarely hear the phrase "I believe 2 and 2 is 4." , it's just '2 and 2 is 4.' -- I think that's important.
In fact, a lot of people insert the word 'believe' to insert a concept of self-doubt. "What was our last test results passing rate?" "I believe it was around 95 percent.."
But semantics aside here's the real question : Why do you have some kind of notion that you should 'believe' anything without being able to understand it? Just trust in the world and those around you?
We haven't figured origin yet, so let's get off that, but when a scientist of some sort makes a discovery, they release evidence and methods , and you decide to believe the conclusions without an understanding of the work -- well that's just a display of faith. Faith in the scientist themselves, the system they work within, and the society you're in.
Which leads me to say this : If you make an effort to begin to understand the frameworks and systems which lead to scientific conclusions you can largely remove the faith and belief elements up until you hit the very highest spectrums of each field where speculation comes back into play.
tl;dr : if you 'cant understand a shit', you don't put any leg-work in and make an effort to speak the language, you'll probably end back up in beliefs rather than an ever increasing codex of knowledge -- regardless of the field. That's okay -- but it doesn't offer the same benefits as knowledge -- it just lets one say things like "I don't believe in any theory..."
I have immense respect for astrophysicists, but the data we're dealing with is extremely far away and relies on a lot of interlocking assumptions.
I stumbled upon this paper [1, 2] last night that challenges the CMB, and thus the underpinning of much of our understanding about the age and evolution of the universe. As a layperson, I don't know the impact factor of the "Nuclear Physics B" journal - if this is just junk or if this is a claim that will pan out.
My point is that it feels like we're building on a lot of observations that are all super indirect. I know I'm just a layperson, but that feels weird when reading assertions about these things.
Our understanding of the universe is relatively new. We don't have a lot of energy or resolution in our observations. The fact that we can sniff the molecular spectra of exoplanets is so amazing and that part feels totally concrete and rock-solid. But I get skeptical when I see claims that we know how the universe began or how it will end. Is our evidence that good? Are our models? Are we basing everything on assumptions?
[1] https://arxiv.org/abs/2505.04687
[2] https://www.youtube.com/watch?v=Xb69yPNgX-Q
> But I get skeptical when I see claims that we know how the universe began or how it will end
Absolutely, but you are interpreting it in the rewritten headline money making attention grabbing version.
The original version of the claims always say that from some observation, experiments, and projection from known models it derives that the universe likely began this way, or will end that way, etc.
That means, of all the going hypothesis, this might be the one with the best chances of being true, or close to the truth. It's not an absolute, but its the one that has the most chances due to the evidence behind it.
You don't believe in science, you believe in a metaphysical claim about science that you haven't articulated.
But that's why science is so cool, it doesn't matter what we believe, it only matters if your theory fits the facts and makes good predictions. If it doesn't, you can chuck it in the bin without guilt. Unlike beliefs, which often can cause psychic trauma if reality doesn't match the belief of the individual.
If we can't even predict inflation rates maybe we should hold off on explaining the birth of the entire universe, yeah?
Predicting inflation rates may be harder than discovering the birth of the universe actually, because it would require perfect knowledge of the present and by the time you compute it it's out of date.
5 replies →
A few years ago a popular idea was that our universe existed as an hologram on the surface of a black hole.
Recently I saw also a theory that black hole might not, in fact, exist as we thought, and may be instead something called 'gravastars', where large stars do not collapse in an infinite point but instead the mass reaches a maximum density and hardness and become sorts of empty bubbles.
Now this. It's not exactly a new idea, I remember reading about black hole cosmology 10 years ago.
Sooo... My uneducated, pop-sci fueled imagination now sees the universe as a mathematical function of a fractal looking like a shell with patterns on it, and those patterns interact or 'fold' in a way where the patterns themselves can be thought of as shells with patterns on them, and each shell creates something that, from the inside, looks like a new dimension of space or time, and what we think of as black holes are the next fold. Does that make sense?
It makes sense to me... I think. And I like this vision as well. It would explain the big bang (initial black hole formation), why the universe is expending (at probably non constant rates over time) which would be the black hole "ingesting" matter and growing and maybe also why time and space are one. Same as you, a take from complete uneducated pop-sci fueled imagination.
The bounce to me has always seemed more intuitive than the bang, but man, when it comes to the quantum universe I've learned to just check intuition at the door.
The word "research" in this title is a handy placeholder for indeterminate conjecture. No research happened, it's a theory he made up.
I would argue that theory is a critical part of the research process and is therefore research.
There’s of course a line between simply coming up with ideas that are quickly provably wrong or inconsistent vs generating ideas that are consistent and not quickly falsified. It’s especially valuable the ideas are falsifiable and it seems like this is the case here.
As such, theory finds patterns in existing knowns, makes some leaps and tries to connect them. Then empirical evidence can help solidify or falsify those ideas. But we tend not to just connect dots of empirical data without attempting to know the casual relationship, otherwise the connections can be rather nonsensical or may have weak predictive power.
With all that said I didn’t read the paper in detail nor am I qualified in this domain to say if it’s quackery or a reasonable shot a developing some new theory. It is peer reviewed and published in APS so I suspect it’s not complete quackery: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.1...
A research paper makes use of multiple sources of known provenance and various degrees of authority and relevance. It tries to establish a consensus of knowledge, as close to fact as possible. The phrase "research suggests" is an appeal to authority that implies some kind of academic rigor. A theory paper, which is still useful and important, can be published without any kind of authority. You can just make things up.
That is what is called research in theoretical fields. Making hypotheses up and then proving implications of those hypotheses. In this case, it yields a falsifiable test: the theory claims the universe should have small positive curvature.
Would you say Einstein was not a researcher?
Ωₖ = 0.0007 ± 0.0019 (68% confidence level)
If the universe is curved dark energy is still a problem because the expansion is getting faster and overcomes the current curvature bounds.
Expansion definitely creates some issues here, at longer time scales how do we deal with this?
There's a PBS Space Time for that (from three years ago)
https://www.pbs.org/video/could-the-universe-be-inside-a-bla...
https://www.youtube.com/watch?v=jeRgFqbBM5E
Will hacker news side with ChatGPT or real physicists? :D
Love PBS space time !
There was a youtube lecture I saw years ago that showed exactly what you'd see as you fell into a black hole and passed through the event horizon.
You'd see EVERYTHING that EVER crossed the event horizon. But critically, you'd see it EXACTLY as it was at the monent it crossed.
Sounds a bit crowded to me. Sounds a bit like I'd expect the big bang to look.
Found the lecture. Here is a link to the appropriate part: https://youtu.be/BdYtfYkdGDk?si=iNHi7N68DHxT-52-&t=3182
I thought you were supposed to get spaghettified and die instantly ?
At the event horizon of a large enough black hole, the tidal difference in gravity between your toes and head shouldn't be noticeable. There shouldn't actually be anything special about falling through the event horizon when looking at yourself.
Outside though, you'd see everything start to blue-shift. Things below you would blue shift back to normal, and the universe above you would blue-shift and speed up until you'd see the heat death of the universe. Anything falling in after you would red-shift again as it approached to match your "normal" rate of time. Critically this would include any light or other particles, so it might be very hard to survive.
No matter how fast you go or how weird the space time you are in, your local clock should still tick steadily to you, and you wouldn't notice anything weird.
2 replies →
> The black hole universe also offers a new perspective on our place in the cosmos. In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger “parent” universe.
What specifically is meant by interior? Does this mean “within the event horizon” or something else?
> But how come Penrose’s theorems forbid out such outcomes? It’s all down to a rule called the quantum exclusion principle, which states that no two identical particles known as fermions can occupy the same quantum state (such as angular momentum, or “spin”).
> And we show that this rule prevents the particles in the collapsing matter from being squeezed indefinitely. As a result, the collapse halts and reverses. The bounce is not only possible – it’s inevitable under the right conditions.
Do I understand right, that this would mean that every formation of a black hole would result in a bounce?
I thought the Pauli exclusion principle is why we have neutron stars, ie the degeneracy of a star results in the fusion of electrons and protons to form neutrons and emit neutrinos.
What is preventing the collapse in this case and results in a bounce?
I speculate that the big bang is/was fueled by all the black holes that existed and will exist, like a huge cycle where all the energy sucked into black holes converges at the same point in time causing the big bang.
Fractal Universe - I discussed the idea with Benoit Mandelbrot back in '84 over beers, interning for him, before he'd published "Beauty of Fractals."
Cool anecdote!
How do you deal with Hawking radiation?
Maybe with space expansion? With more space, particles interaction is weaker overall. So the whole system kind of loses total energy.
* Not a physicist so this is a really uninformed take
flip the direction of time and hawking radiation ""creates"" mass/energy inside a black hole (overall mass/energy is conserved)
> But how come Penrose’s theorems forbid out such outcomes? It’s all down to a rule called the quantum exclusion principle, which states that no two identical particles known as fermions can occupy the same quantum state (such as angular momentum, or “spin”).
> And we show that this rule prevents the particles in the collapsing matter from being squeezed indefinitely. As a result, the collapse halts and reverses. The bounce is not only possible – it’s inevitable under the right conditions.
Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?
Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?
Different exclusion principle. For neutron stars, it is the Pauli exclusion principle (IIRC) which creates neutron degeneracy pressure. Enough mass and gravity can overcome it forming a black hole. The article is talking about quantum exclusion which happens at a much smaller scale. I don't know much about it because that exceeds the limits of my degree.
>Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?
One of the ways to overcome one of the levels of this degeneracy pressure is electron capture which is the opposite of a kind of beta decay. Squeeze hard enough and a proton combines with an electron to form a neutron and a neutrino.
But there are several proposed levels of degenerate matter in neutron stars, the idea being that one (final?) level of this degenerate matter is dense enough to make an object smaller than its schwarzschild radius. Uncertainty is high because we have no current methods to observe any of this kind of matter.
What goes on inside the schwarzschild radius is another mystery we don't have answers from, but there are lots of ideas with various levels of legitimacy.
Quantum physics in and around singularities or things we think are singularities is not understood.
Is it because the black hole is a macro distortion of spacetime and not a local quantum property?
With enough mass, there is enough energy from gravity to put all fermions into different states, so the collapse continues
Are you suggesting that the authors’ “bounce” would only happen if the energy was not enough to put them into different states?
Would it possibly make sense for a black hole in our universe to lead to a higher level "parent" universe? Or would any black hole universe contained within our own universe necessarily lead to a lower level "child" universe? Basically, I'm wondering if there's a way (within the constraints of this model) to access the parent universe.
Interesting sci-fi plot device but seems far-fetched, not gonna lie. To think that our highly stable universe is just compressed mass of another universe is a lot to take in. Does that black hole emit Hawking radiation as well and shouldnt our universe lose mass in result? And how exactly can our universe expand if the size of the black hole is fixed?
Well, at least it does make for interesting conversations. Someone will surely milk it for Youtube content.
This was an interesting read, but I didn't understand exactly what leads to the big crunch. I get the exclusion principle leads to pressure, and this causes the bounce, but why would it continue to accelerate and then decelerate resulting in a big crunch?
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.1...
I don't understand where the rest of the parent universe is if all of the matter has emerged from the event horizon. Twisted into a new dimension, perhaps?
My take away was that it's still somehow causally disconnected from our universe. They make an assumption that the space outside is empty and that makes the numbers correspond closely with observations. Maybe there is stuff there but very very far away?
This has been one of my pet theories for a while.
https://news.ycombinator.com/item?id=39271752
I love that theory. I very much spent time thinking that it would be cool if we were inside a black hold after reading A Brief History of Time.
> Research suggests Big Bang may have taken place inside a black hole
The title's use of the word "research," and the paper's content, suggest the idea resembles science more than speculation. But in fact, the paper has no observational evidence, nor a proposal for acquiring evidence, to distinguish it from other similar speculations.
To put it simply, at the center of a black hole is a singularity, a domain where existing theories can offer no guidance. So a new idea about singularities -- about black holes -- should suggest a testable property, to distinguish it from other similar ideas.
I say "idea" here to avoid use of the term "theory," which in science requires observational evidence to move past the realm of speculation.
Don't get me wrong -- speculations have an important role to play in science. But tendentious phrases like "research suggests" wrongly imply the presence of something more than speculation.
Wow, wild this is being taken seriously now perhaps, I first encountered the idea in The Life of The Cosmos ~26 years ago[0] and my impression was the author, Lee Smolin, didn't REALLY beleive it, but he came up with it mostly to have some kind of preferable, falsifiable(er?) alternative to string theory, which he disliked even more, and perhaps more as an idea of the kind of theory we need to explore to start making progress... or that's my memory/impression form 26 years ago, I've been meaning to re-read it for a while since. Anyone read more recently/have other impressions?
(the basic idea was fecund universes/cosmological natural selection[1], such that we should expect to find ourselves, if the theory were true, very near to a local maxima of values such that they approximately maximize the number of black holes produced... but most of the book is really taken up with a fascinating look at the history of physics and ideas...)
[0]https://en.wikipedia.org/wiki/The_Life_of_the_Cosmos [1]https://en.wikipedia.org/wiki/Cosmological_natural_selection
stupid question: if at the beginning of the universe (before the big bang) all the matter was in the very same spot, shouldn't this have been effectively been a black hole due to the extreme density? if so, how could it explode if nothing can escape a black hole?
Black holes may contain a second event horizon in the center, like a Poisson's spot. So it was the Big Rip, when this spot was born.
That's not a stupid question. But I suggest reading the linked article which pretty much covers this.
I've always liked the Idea that black holes accelerate matter faster than light behind the event horizon propelling it back in time creating a singular white hole at the first moment.
There are many many reasons why this is a dumb idea and it's just as much of a paradox as any other naturalistic creation theory.
I've heard about interesting theory. Since we observe large early galaxies, to explain them scientists postulate that they must have grown very quickly. But recently some scientists calculated how much light would such quickly growing galaxies could have emitted. And it turned out that this light after being dispersed by the dust and redshifted by the expansion of the universe it should have contribute to CMB, up to 100% of it's observed intensity. What's interesting they didn't make any assumptions outside of established modern cosmology. Just So it's entirely possible that CMB is something completely different than what we believed.
These type of 'theories' I dislike only because they don't get to the root of the problem.
It is the same for 'multiverse' where that is used to explain literally anything 'it's like that in this universe but not the others'.
Sure, we can get creative and explain the Anthropic Principle by mentioning the multiverse.
But none of this answers how something comes from nothing.
Not the vacuum of space and its 'quantum foam' where particles jump in from nowhere.
Because that's not 'nothing'.
One of these nothings ... such as level 9. No possibilities.
https://closertotruth.com/news/levels-of-nothing-by-robert-l...
I won't touch level 8/9 nothings, other than to say I don't think they're coherent. But I am of the metaphysical camp that thinks there will be at least some small ground truth which physical law or object which cannot be reduced, an axiom of nature. Physics unfortunately will probably always be limited in distinguishing between basic facts which are truly irreducible, and those which are simply limits of our observational abilities. That's the thing that bothers me; even if there were a single beautiful law of nature that just IS, one which we actually manage to postulate based on evidence, we will never know for sure. GR definitely has a beautiful mystique, it's a shame that it's most likely just a mathematical approximation.
> But none of this answers how something comes from nothing
Why do you assume there was nothing?
This brings to mind something I keep thinking about for years (mostly from watching too many physics videos).
- Gravity "slows" the time down, gravitational singularity should bring the time to a halt
- Suppose there is a quantum process that makes the true singularity impossible, so all black holes immediately expand right back
- Looking at it from our time scales, even if the singularity existed for a moment, it would appear that "infinite" time has passed while from the black hole's perspective, the expansion was instantaneous.
- From earth's perspective, if the singularity ever existed in a black hole, it stands to reason that when the time "resumes" from a black hole expansion, it won't fall into any of our known timelines since infinite time would have passed.
Along those lines, makes me wonder if the "bang" is in fact the fact that after the time compression, all matter/energy is effectively arriving at the same point all at once.
Assuming our universe eventually collapses into a few black holes, perhaps the spawn of a new universe is simply all the matter and energy of our universe arriving at a new point in... time? an infinite amount of time in the future.
Also, really mind bending to think the universe may just be an infinite series of black hole explosions with no beginning. It is because it always was.
if this holds up, every intro to cosmology textbook opens with a spoiler. we’ve been simulating the explosion without even checking what room it happened in. whole industry just assumed page one was page one. now turns out we might be in chapter seven of someone else’s collapse. love it
If this is true it almost literally means black holes are a way for universes to make children. If we apply Darwin’s principles of the strongest survive this must mean that universes that produce the most black holes are the “best”. If correct, what does this actually mean?
https://en.wikipedia.org/wiki/Cosmological_natural_selection
https://theeggandtherock.com/p/the-blowtorch-theory-a-new-mo...
Darwinian logic requires a feedback loop. And because those universes are isolated then there’s no “incentive” of a universe to have more “offspring”?
There is a theory of cosmological evolution. The child universes have slightly different physical constants and universes that produce more black holes will leave behind more offspring universes so over many generations, the universes evolve toward parameters that favour black hole production.
1 reply →
It requires imperfect reproduction where the imperfections alter the probability of further reproduction.
If each black hole in our universe contained a pocket universe with very slightly different laws of physics (to each other and to us), but the same amount of mass-energy on the inside as our universe had when it started, then (1) those pocket universes able to create stars and black holes would also go on to create black holes with pocket universes, but also (2) those pocket universes not able to create black holes, would not create more pocket universes.
I have never seen a reason to think that this could happen, nor why such pocket universes might have more mass on the inside than they appear to have on the outside, but that's the argument.
as we approach the potential singularity, the size of the universe changes as a (hyperbolic) function of cosmic time
Glad to hear that. I'm looking forward to any theories how to convert time to space (and back) ..with orthogonal universes/singularities ?
What would happen if beings living outside of our 'black hole universe' threw an object into the black hole, and thus into our universe? Would the object appear at the edge of our universe, or would some physical law prevent this from happening?
I've always had this idea that perhaps the whole universe had already collapsed into many black holes and perhaps each galaxy was actually formed via hawking radiation. Then our galaxy came out of Sagittarius A*.
I still don't understand from the article why the bounce effect results in an accelerated expansion of space time. Is the black hole (our universe) in the parent universe getting bigger? And why is that non linear?
So the expansion comes from the bounce. And we are in a dormant supermassive black hole of sorts. How would it look like in our world if the mother blackhole is actively gobbling up matter from the parent universe?
Why does it always have to by “hyperbolic” instead of parabolic?
Hmm... What if some matter falls into our black hole? I know there are some weird time-space effects on the boundary, which I do not have any intuition about. To my knowledge it may be, that it will never fall in our time frame, or that it have fallen all already. The question is, will we able to see and welcome new matter entering our Universe?
I may be wrong, but I believe spending time in a deeper gravitational well means you observe everything outside of the well to be happening much faster; at the singularity, the entire future of the parent universe will appear to you as happening all at once. There is no notion of “matter that falls in later” — once you reach the singularity, you travel to the end of time in the parent universe. And the passage of time in our universe isn’t a continuation of time in the parent universe; it’s not even the same dimension, the latter is collapsed.
Thank you! That answered my question whether there would be in our universe a "white fountain" spitting matter coming from the back hole in the top universe. In your hypothesis where we lose one dimensione over the top universe than all the events of the top universe, like the mass arriving, happen in our universe all at the once in the beginning (the big bang).
I'm curious on what is "at stake" with this? The close lists a couple of predictions that this can lead to. I'm assuming they will be important in a far future time? Or do these help with some more near term problems?
Edit: I hasten to add that I'm not asking to undermine the research. Seems the more the merrier, there. Genuinely curious on what some of this could lead to.
Which suggests that:
1. You can have black holes inside black holes.
2. Potentially each black hole is a universe - although some are much smaller and less interesting than others.
[dead]
I didn’t understand whether the author is implying that this happens to all black holes or whether the model only applies in some circumstances.
I definitely didn’t understand whether this is suggesting that expanding universes can be contained within black holes that look like fixed-size finite objects from the outside.
And what happens to the inner universe when the parent black hole evaporates through Hawking radiation?
The heat death of the inner universe.
So, the whole thing is a recursion, and the only thing left to see is how deep is the stack.
while it doesn't take away from the article, i find it worrying that it seems mostly written with chatgpt
"This is not just a technical glitch; it’s a deep theoretical problem that suggests we don’t really understand the beginning at all."
"The bounce is not only possible – it’s inevitable under the right conditions."
ugh
There was a physicist who made a video making fun of crackpot theories from engineers and reading the comments we're all happy to put forth our completely unsubstantiated opinions with zero understanding of the math and observations involved
Does this model predict the CMB peaks?
The big bang sounds like how a computer would interpret being turned on.
Anyone else think this is what happened?
Nope, it's just you applying the thing you think you know to something you don't know.
Computers refer to this as 'the Big Boot'.
One day someone's going to reboot that computer and I'm going to lose all my carefully curated trauma.
Imagine a being inside a turing machine wondering what came before it was turned on... implying the turing machine is even on and we're not just looking at the set of all possible rule sets on a similarly abstracted mathematical chart.
[dead]
[dead]
I think this is a great summary. It's quite intuitive and elegant. Does anyone have any information about what the author's peers think of this model?
I'd love the idea that we are living inside a black hole, which is inside a black hole, which is inside a ...
Notebook LM version https://notebooklm.google.com/notebook/bb55f273-a5e8-461a-b7...
Cool article!
I can hear Sean Carrol saying, though, that:
1. We know general relativity isn’t complete, because it doesn’t take quantum mechanics into account.
2. We can’t say whether this is right because we don’t know the quantum theory of gravity.
But I don’t actually know what I’m talking about.
So if our universe is inside a black hole from a parent universe, does that mean every black hole in our universe contains its own child universe? We could be living in cosmic Russian dolls all the way down?
As a lay reader, it sounds like they are assuming what they are trying to prove.
Yes, it produces a testable prediction, but seemingly based on a mathematical assumption derived from our observed cosmic radiation background.
> This lower bound follows from the requirement of χk≥χ∗≃15.9 Gpc to address the cosmic microwave background low quadrupole anomaly
As a lay reader, can I assume that no scientist would publish a theory with mathematical circularity (at the heart of the prediction)? I sure can't verify it myself.
Reminds me very much of Blowtorch Theory that was discussed here recently
https://news.ycombinator.com/item?id=44115973
I haven't read the paper, it's probably well beyond me, but I have always felt that the presumed existence of a singularity had to be the result of incomplete theory.
it is funny the fact that author decided to explain who Galileo was
give us one free miracle and we'll explain the rest
Bertrand Russell is the pope
I sympathize with Lee Smoolin's cosmological natural selection hypothesis, which would require that black holes give birth to new universes within
I can’t beleive you and I are the only ones familiar with, and that no one else referenced or responded to this connection! https://news.ycombinator.com/item?id=44251438
I too read the book and was just searching for anyone mentioning it. Why can such an idea be called new, when someone else already described it decades ago?
Great! Maybe the idea of a cyclical universe will gain traction.
In my view, there is one universe. We are in it. It cycles from maximum to minimum condition endlessly. This cycle is much longer than any entity lifespan and for any entity, the current state is THE state for them, and all they will know and become.
What does it expand into?
Nothing. Space itself just gets bigger and smaller over time.
No beginning, no end. It all just is.
Very high "Time started when someone clicked start" - "cool, how did events happen before they clicked start?" factor title.
If universes can exist in black holes and obviously black holes exist in universes, doesn't that smell like infinite recursion?
What reason do we have to believe that every universe can support black holes? We only have a sample size of 1 here.
What reason do we have to believe that there is more than one universe?
Black holes all the way down
This theory actually makes sense. Vs big bang where half of the theory is “let’s assume that there is this thing that explodes”
Wouldn't it have to be a black hole anyway given how much matter was concentrated in a small point?
When I first heard the idea that our universe began inside a black hole from another one, it felt like something out of a sci-fi movie. But the more I sit with it, the more it starts to feel like the universe is quietly nudging us, saying it has a much bigger story to tell.
If the Big Bang was just a moment in someone else’s universe, then maybe everything we know is just one chapter in a book far larger than we can imagine.
Research? Sounds more like speculation.
Don't suppose you read the paper..?
It's probably best not to jump to conclusions until we see it replicated in another universe.
I thought this was already an old general idea; that each black hole ignites the birth of a new universe?
So that's what that big blob in the Mandelbrot set is. It's a diagram of our fractal universe.
Could a computer simulation also contain another universe, with virtual black holes that have universes?
Can a computer simulate itself?
https://www.youtube.com/watch?v=92WHN-pAFCs
Big bang theory no longer excites me. As long as we can't explain consciousness all these theories are pointless. All theories mere appearances in consciousness including the universe and everything we experience.
Consciousness has the property to render infinite universes and theories.
But we have no clue how universe creates consciousness.
Consciousness is a specific biological adaptation which is primarily focused in the management of social relationships, status, and the prolonged adolescence of children. (and their required care)
There's no reason to think that consciousness is an important question in the objective sense; it just matters to people. (and rightfully so) People wondering about consciousness in the universe might be akin to dogs wondering what the big bang smelled like.
Are we both talking about the same thing?
https://en.m.wikipedia.org/wiki/Consciousness
What is an important question in the objective sense? Is life, or no because that just matter to life? It seems oxymoronic, "objective question", "objectively important".
I don't follow GP's sort of solipsist (?) take, but would say question of whether big bang took place in a black hole is pointless compared to life/experience and how they arise.
1 reply →
Seems like someday we will prove that if you get enough neural like things organized in a structure similar to ours or some mathematical similarity thereof that consciousness automatically arises like mixing certain elements to get a compound but in a vastly more complex manner
First define consciousness such that the definition differentiates you from a computer with a webcam.
You cannot define consciousness. You can only experience it. In fact consciousness is the only thing you will ever experience.
2 replies →
You can measure various aspects of a computer. You can't measure consciousness.
3 replies →
So what if one of the numerous black holes in the universe starts to bounce?
We are inside of a Docker container.
I've spent the past month or so immersed in Penrose diagrams. Some of the implications of the math and diagrams include white holes (opposite of black holes - spew matter outwards), infinite universes contained within one another other, anti-gravity universes, and things like this. You can also fall into a black hole and make it out into another universe instead of meeting the singularity (at least, an idealized, rotating black hole). Anyway, cool stuff.
Sean Carroll says this is absolute nonsense: https://youtu.be/U3uIiv48q98?feature=shared&t=6046
Science today:
{..insert here a statement...} maybe yes but also maybe not {...clickbait things here...}
> Research suggests Big Bang may have taken place inside a black hole
Is this OnlyFans ?
my feeling is that the beginning of the universe is so unbelievably unexplainable and strange that we will never truly understand its origin
Do we live inside a black hole?
TARS is a new theoretical framework that fundamentally reimagines the foundations of physics. Instead of assuming that reality is made of pre-existing entities (particles, fields, or spacetime itself), TARS posits that everything that exists is, at root, a relation. In this view, the universe is a dynamic network of coherence relations, and what we perceive as space, time, matter, and even physical laws, are emergent phenomena arising from this underlying relational web.
1. Motivation: The Crisis in Fundamental Physics
Modern physics, despite its immense successes, faces deep unresolved problems:
The incompatibility between General Relativity (GR) and Quantum Field Theory (QFT)—the so-called "quantum gravity problem."
The mystery of singularities (in black holes and at the Big Bang), the nature of time, and the unexplained phenomena of dark matter and dark energy.
The lack of a unifying principle that can reconcile the fragmented domains of current theories.
TARS responds to these challenges by proposing a radical ontological shift: relations, not entities, are fundamental. This shift is not just a new model, but a new grammar for describing reality.
2. Ontological Foundations: Radical Relationalism
Core Postulate:
"All that exists is relation."
There are no absolute, isolated objects. The very identity of any "entity" (particle, field, law) is defined by its pattern of relations with all others.
The universe is fundamentally non-separable: no part can be fully understood in isolation.
This principle generalizes quantum entanglement to a universal ontological status.
Realism and Symbiosis
Symbiotic Realism: Entities and their properties are co-constituted through mutual relations. There are no intrinsic properties, only extrinsic, dynamically co-created ones.
The observer is not external, but an active node in the relational web. Knowledge itself is a process of coherent participation in this network.
3. Mathematical Formalism
3.1. From Discrete Relations to Emergent Fields
At the most fundamental level, reality consists of discrete coherence relations, denoted ξ_{ij} (or quantum operators ξ̂_{ij}), between abstract nodes.
At emergent scales, these relations manifest as a continuous coherence field ϕ_{μν}(x), a symmetric tensor field encoding the density and structure of relational coherence at each emergent spacetime point.
The emergent metric is given by: g_{μν}(ϕ) = e^{2αϕ} η_{μν}
The Symbiotic Action is:
S[ϕ]=∫d4x−g(ϕ)[12gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]S[ϕ]=∫d4x−g(ϕ)[21gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]
where V(ϕ) is the relational potential.
3.2. Dynamics: Coherence, Dissonance, and Self-Organization
Local coherence (ξ_l) and global coherence (ξ_c) quantify the degree of relational compatibility.
The difference Δξ = |ξ_c − ξ_l| acts as a "relational tension," driving the system toward higher global coherence.
When Δξ exceeds a threshold, critical reorganizations occur (mediated by an operator F₀), leading to emergent order, the arrow of time, and the formation of physical laws.
3.3. Quantization and Emergence
TARS aspires to a quantum theory of relational fields, where quantization applies to the relations themselves, not to fields on a pre-existing spacetime.
The challenge is to mathematically derive how spacetime, matter, and interactions emerge from the dynamics of ξ̂_{ij}.
4. Phenomenological Implications
TARS provides new perspectives and solutions to major physical puzzles:
Singularity Resolution: The regularization of black hole and cosmological singularities emerges naturally from the relational dynamics.
Dark Matter/Energy: Gravitational anomalies are interpreted as regions of relational coherence deficit, not as unseen particles.
Inflation and Cosmology: The early universe's rapid expansion is modeled as a phase transition in the global coherence field.
Black Hole Evaporation: Predicts a slower, non-singular evaporation process, leaving stable remnants.
Consciousness and Life: Interpreted as high-order reflexivity in relational networks—consciousness is a self-referential coherence loop.
5. Scientific Achievements to Date
Full mathematical formalism: Action, field equations, emergent metric, and relational potentials.
Analytical derivations: For black hole interiors, dark matter effects, and cosmic inflation.
Numerical simulations: Demonstrating the propagation of coherence fronts and self-organization.
Distinct predictions: Such as black hole evaporation profiles and singularity avoidance, differentiating TARS from standard models.
White paper and technical documentation: Comprehensive and available for peer review.
6. Meta-Theoretical and Interdisciplinary Reach
TARS is not just a new physical theory; it is a meta-framework for understanding emergence, organization, and knowledge itself. Its principles can be applied to biology, neuroscience, social systems, and artificial intelligence, wherever complex relational networks give rise to emergent phenomena.
7. Conclusion
TARS offers a radical, mathematically grounded, and phenomenologically rich alternative to current foundational physics. By shifting the focus from entities to relations, it provides a unified language for the emergence of space, time, matter, and law. Its predictions are testable, its formalism is rigorous, and its implications reach far beyond physics, offering a new way to organize scientific and philosophical knowledge.
>We are not special, no more than Earth was in the geocentric worldview that led Galileo (the astronomer who suggested the Earth revolves around the Sun in the 16th and 17th centuries) to be placed under house arrest.
Wow - like this anti-humanist prejudice is totally 1993. And not in a good way.
two-photon collision experiment has permitted humans to hypothesize a simpler explanation to the beginning of the creation of more electromagnetic forces, which obviously behave differently than how are bodies were designed to receive them i.e. evolutionary biological bandwidth...
Asimov already covered this in The Last Question: https://users.ece.cmu.edu/~gamvrosi/thelastq.html
Not really. Asimov's story did not represent the process as a mathematically inevitable consequence of physics. It might not even have gone through a second cycle. Cellular life, dollars, and teletypes would all have had to come about again. (-:
[flagged]
You're missing the part where the robot was created by us.
2 replies →
[dead]
[dead]
[flagged]
There are countless versions of this theory out there. Basically, a universe existed, then collapsed down to a single point, and then expanded again (the big bang). Rinse and repeat.
In this version we're still inside the black hole.
"Tau Zero" by Poul Anderson
Is it the same universal every time? If so, see you later alligator.
Or a universe expanded inside a black hole and we are holograms on the shell.
[flagged]
"Nothing" implies that something exists, this duality creates the universe.
There is no proof of "nothing " existing. Every observation we take, we see "something".
Than why do we need a beginning if there was always something.
13 replies →
Only if something exists. But both nothing and something could not exist, and then there is no duality, just nothingness without a something to relate it too.
The concept of Nothing can only exist if Something exists, they both exist and are the substance that make up the universe.
That’s a boring axiom.
Nothing is everything
Everything is everything
[flagged]
[flagged]
[flagged]
5 replies →
More info available.
TARS is a new theoretical framework that fundamentally reimagines the foundations of physics. Instead of assuming that reality is made of pre-existing entities (particles, fields, or spacetime itself), TARS posits that everything that exists is, at root, a relation. In this view, the universe is a dynamic network of coherence relations, and what we perceive as space, time, matter, and even physical laws, are emergent phenomena arising from this underlying relational web.
1. Motivation: The Crisis in Fundamental Physics
Modern physics, despite its immense successes, faces deep unresolved problems:
The incompatibility between General Relativity (GR) and Quantum Field Theory (QFT)—the so-called "quantum gravity problem."
The mystery of singularities (in black holes and at the Big Bang), the nature of time, and the unexplained phenomena of dark matter and dark energy.
The lack of a unifying principle that can reconcile the fragmented domains of current theories.
TARS responds to these challenges by proposing a radical ontological shift: relations, not entities, are fundamental. This shift is not just a new model, but a new grammar for describing reality.
2. Ontological Foundations: Radical Relationalism
Core Postulate:
"All that exists is relation."
There are no absolute, isolated objects. The very identity of any "entity" (particle, field, law) is defined by its pattern of relations with all others.
The universe is fundamentally non-separable: no part can be fully understood in isolation.
This principle generalizes quantum entanglement to a universal ontological status.
Realism and Symbiosis
Symbiotic Realism: Entities and their properties are co-constituted through mutual relations. There are no intrinsic properties, only extrinsic, dynamically co-created ones.
The observer is not external, but an active node in the relational web. Knowledge itself is a process of coherent participation in this network.
3. Mathematical Formalism
3.1. From Discrete Relations to Emergent Fields
At the most fundamental level, reality consists of discrete coherence relations, denoted ξ_{ij} (or quantum operators ξ̂_{ij}), between abstract nodes.
At emergent scales, these relations manifest as a continuous coherence field ϕ_{μν}(x), a symmetric tensor field encoding the density and structure of relational coherence at each emergent spacetime point.
The emergent metric is given by: g_{μν}(ϕ) = e^{2αϕ} η_{μν}
The Symbiotic Action is:
S[ϕ]=∫d4x−g(ϕ)[12gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]S[ϕ]=∫d4x−g(ϕ)[21gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]
where V(ϕ) is the relational potential.
3.2. Dynamics: Coherence, Dissonance, and Self-Organization
Local coherence (ξ_l) and global coherence (ξ_c) quantify the degree of relational compatibility.
The difference Δξ = |ξ_c − ξ_l| acts as a "relational tension," driving the system toward higher global coherence.
When Δξ exceeds a threshold, critical reorganizations occur (mediated by an operator F₀), leading to emergent order, the arrow of time, and the formation of physical laws.
3.3. Quantization and Emergence
TARS aspires to a quantum theory of relational fields, where quantization applies to the relations themselves, not to fields on a pre-existing spacetime.
The challenge is to mathematically derive how spacetime, matter, and interactions emerge from the dynamics of ξ̂_{ij}.
4. Phenomenological Implications
TARS provides new perspectives and solutions to major physical puzzles:
Singularity Resolution: The regularization of black hole and cosmological singularities emerges naturally from the relational dynamics.
Dark Matter/Energy: Gravitational anomalies are interpreted as regions of relational coherence deficit, not as unseen particles.
Inflation and Cosmology: The early universe's rapid expansion is modeled as a phase transition in the global coherence field.
Black Hole Evaporation: Predicts a slower, non-singular evaporation process, leaving stable remnants.
Consciousness and Life: Interpreted as high-order reflexivity in relational networks—consciousness is a self-referential coherence loop.
5. Scientific Achievements to Date
Full mathematical formalism: Action, field equations, emergent metric, and relational potentials.
Analytical derivations: For black hole interiors, dark matter effects, and cosmic inflation.
Numerical simulations: Demonstrating the propagation of coherence fronts and self-organization.
Distinct predictions: Such as black hole evaporation profiles and singularity avoidance, differentiating TARS from standard models.
White paper and technical documentation: Comprehensive and available for peer review.
6. Meta-Theoretical and Interdisciplinary Reach
TARS is not just a new physical theory; it is a meta-framework for understanding emergence, organization, and knowledge itself. Its principles can be applied to biology, neuroscience, social systems, and artificial intelligence, wherever complex relational networks give rise to emergent phenomena.
7. Conclusion
TARS offers a radical, mathematically grounded, and phenomenologically rich alternative to current foundational physics. By shifting the focus from entities to relations, it provides a unified language for the emergence of space, time, matter, and law. Its predictions are testable, its formalism is rigorous, and its implications reach far beyond physics, offering a new way to organize scientific and philosophical knowledge.
"In my room, redefinin' the meanin' of black holes"
- Earl Sweatshirt
I went to school in a very bad neighborhood. Once I was sent to the office because my math teacher asked me what I was reading about that was soo much more interesting than our textbook. I happened to be reading "A Brief History of Time", so I answered "black holes."
At the time I couldn't understand why my dad laughed about that particular phone call from the principal.
Hahahahahahahaha
Maybe it was the repeat.
Isn't time a human invention useful to model the nature? It's literally just a defined interaction as a reference, i.e. the sun rising up and going down which is the rotation of the earth.
So IRL there's no time, there's no need to have a beginning or an end. Whatever happened when all the matter was close together isn't the beginning of anything, just a phase.
Not true. The arrow of entropy has a direction and it's the same as the arrow of time. There's not a good explanation for why though.
There's a perfectly good explanation for why though, in fact the explanation is what motivated the formalism of entropy to begin with. There are significantly more ways that the energy contained within a closed system can spread throughout that system than there are ways for energy contained within a closed system to condense, so that if you observe the state of a system at two different moments in time, you will expect to see it evolve towards the statistically more likely outcome than the statistically less likely outcome.
And from first principles, that's what entropy is, a measure of how energy is dispersed throughout a system. Of course once you have that first principle understanding of entropy then you can come up with more rigorous formalisms to properly quantify what it means for energy to be distributed throughout a system, such as measuring the number of microstates that correspond to a macrostate, and other various formalisms that are more or less equal to each other... but fundamentally they all start from this basic principle.
If time were running against the arrow of entropy, nobody could perceive or measure it, right? Remembering something is per se an increase in entropy, so the universe could run in negative time direction, but we would simply forget, what had happened.
That said, I personally think such thought experiments are futile and the nature of time has to be understood by its connection to causality and information.
1 reply →
There's no arrow of entropy, it's an invented useful model to describe something that nature does. Everything is like that, I.e. there's no electric field, it's a useful way to do calculations about particle interactions.
4 replies →
We have no idea if there is a meaningful beginning or end, other than heat death. But time is real in the sense that there is an arrow of time, due to entropy.
No, time is what the clock measures. Consciousness does not collapse the wave function meaning clocks exists without humans and time exists without humans.
Exactly, time is whatever the clock measures and the clock does it through some defined physical interaction. Can be a swing of a pendulum, can be vibration of an atom, flow of sand, unwinding of a spring etc.
It's useful because its quantifiable.
The second, however, is a purely human invention.
I'm butchering the mythology, but the Greeks had Cronos and Kranus. One was measurement, and one best explained as cause and effect.
The hot dense universe caused our current cool universe, and not the other way around, which makes the two states of the universe quite different.
Time is the coordinate of spacetime that has a different sign in the metric than the other three.
Try writing a computer program that has side effects without time existing.
What if it wasn't the beginning of our universe or wasn't the beginning of everything, including what is probably outside of our universe?
As I understand it (I‘m not a cosmologist by any means), saying that the observable universe began at big bang simply means that anything that happened before the big bang has no effect on what happens afterwards.
There may be other universes out there, with their own big bangs, but that has no effect on ours.
Reading this article, I think they are simply disputing the necessity of singularity inside a black hole, and hypothesize a universe which expands from non-singularity black hole, while staying inside its own event-horizon.
That is how I understood it at least, somebody please correct me if I misunderstood it.
Eh, the thing about the statement there is you're redefining "universe", which is fine, but restating a definition isn't really saying anything new. The literal meaning of "universe" especially with respect to the Latin origins is... well... everything. It may make sense for physics to separate in to separate sets of everything if there's some reasonable justification.
There's the Universe (everything everywhere everywhen), and then there's the observable universe. Most testable theories will be referring to the observable universe.
I always pondered about everything in our universe getting swallowed up continuously merging black holes until all of a sudden "everything" is "in" the black hole and then suddenly that's your big bang, and everything starts all over.
I don't have the Ph.D physics/maths skills to work out the plausibility of any of that (or variations on that) but I've always felt I've been good at coming up with ideas.
Any physicist wants to work with me, I'm https://purpleidea.com/contact/
Beginning is an illusion created by our way of perception. Time is neither linear nor real so how can there be a "beginning"?
"Your honor, I could not have possibly shot that person, because yesterday might not have been before today, or at least, there is reasonable doubt that yesterday was before today, according to some physicists on crack. I treat those physicists with high regard personally though, and they have degrees that you don't have, so the court must reasonably conclude their opinions should be entertained."
I guess that's a joke, but it's actually kind of serious that causality, personhood, identity, free will, etc. are all social constructs.
They are useful to us, but every now and then it's helpful and humbling to remember it's a fiction we assign, rather than fundamental.
Criminal justice or the concept of culpability is one of these areas. I know I've seen material by Robert Sapolsky, a neuroscientist who does not believe in free will, talking about how off the mark criminal justice and punishment for crimes can be.
15 replies →
"Objection, your honor. In the many-worlds interpretation there is a world in which that happened."
5 replies →
xkcd super soaker
Not many people these days like to hear this (I myself was one of them), but the answer to this is in Genesis.
There's a reason some of the most famous mathematicians, scientists, engineers, and philosophers of all time believe(d) in God.
The Hebrew name of God, YHWH, literally means "He Who Is." In other words, the Self-Existent One. The father and originator of all things that were, are, and will be, who exists outside of spacetime.
I understand that many people yearn for a religious explanation to answer the question of what caused the universe to exist. I myself am content with the "it just happened" explanation, as any information prior to the big bang, if it even exists, is unknowable.
There are countless other religions that believe in a deity who created the universe. These deities either created themselves, or had always existed outside of space and time. To that end, any one of those deities would be on equal footing with YHWH. I don't think that it is appropriate to axiomatically claim that a certain deity exists because only that deity could have caused the universe to exist.
Yet you call yourself a fool in your own username. Why be so sure you're not wrong about any or all of those statements?
It would be a nice argument for deism - but to jump from that into anything more, seems way too extreme of a leap.
Why Christianity then, over Hinduism? Why any human religion at all?
The Christian answer may be "God showed the 12, martyred, codified by church fathers [無]" but I haven't asked any Hindus, or anything nonhuman.
[無] https://en.wikipedia.org/wiki/Trinitarianism_in_the_Church_F...
This is not an answer that satisfies just begs more questions.
Who Created God? No one? Why does the universe need a creator if God does not?
Where does free will and evil come from if God is "originator of all things that were, are, and will be". For true free will to exist it must have a source of entropy which denotes something outside of Gods control and design otherwise everything is deterministic as set forth by God.
>There's a reason some of the most famous mathematicians, scientists, engineers, and philosophers of all time believe(d) in God.
That reason being that for much of Western history if you didn't believe in God the Church would burn your research in a big fire and probably you on top of it.
That explains nothing.
Neither does the precursor to the Big Bang. It's the same exact thing.
3 replies →
"An equation means nothing to me unless it expresses a thought of God." — Ramanujan
I like to think he was referring to computation. There's a reality to the constant pi, its computation, and ourselves and the representation being part of that same universe.
I think they mostly "believed" because they would be ostracized and maybe even killed for not believing in God and saying as much. Many who were famous in their lifetimes would have had enemies who would have loved to destroy them via that avenue.
Yes, not many people these days like to hear senseless drivel, hence the failing churches.
Have you visited a church lately? You might like it. I for sure, do!
1 reply →
You're in Athens, son.