Comment by lazide
4 days ago
It might make more sense of you think of spacetime as literally one thing, with one constant value. That value being c (or some meta value that boils down to the same thing).
Energy in all its forms (including velocity), mass, etc. or the lack thereof being ‘space’, and time being what you have ‘left over’ when you subtract ‘space’.
The more mass, or velocity, etc. you have, the less ‘time’ you get left over. That is time dilation, both in the presence of masses and when you’ve got a lot of velocity (because having a lot of velocity means you have a lot of energy).
That is an alternative formulation of e=mc^2. [https://en.m.wikipedia.org/wiki/Mass%E2%80%93energy_equivale...].
At the point your velocity hits c (somehow), you have no ‘time’ left over from your perspective, so wherever you go, you go there instantly from your perspective. No time has passed for you. Same if you are ‘inside’ a singularity like a black hole.
Space time curvature (aka gravity) may arise from that effect not just being a point one, but a subtle cumulative area effect.
In that model, time travel, FTL, and any other lack of causality (aka effect after cause) make no sense, because there is no ‘lever’ for such a thing to ever happen.
Maybe if someone could invent negative mass/energy (we currently have no evidence/idea such a thing could exist!), or a way to manipulate the fundamental factors that make spacetime spacetime. We have no concrete idea how to even conceive of trying such a thing idea right now though.
That result is terrifyingly boring in its implications though, which is why we try to avoid it.
> That result is terrifyingly boring in its implications though, which is why we try to avoid it.
What result? A result that the entire Universe is deterministic and already determined, like a movie already recorded to tape that we are somehow watching play from inside?
That could be one.
But I was referring to the possibility that it’s energetically impractical to ever get out of the solar system (or even travel within our solar system) in a way that any human is likely to ever want to do it. (Aka no FTL, or even near light speed)
And this likely applies to anything we’d call ‘life’ too.
And that time is actually one way, so no do overs, and no time travel. (Either because of the 2nd law of thermodynamics, or the 2nd law is an effect of this!)
If we accepted that, it would kill what - 95% of all Sci-fi ever?