Comment by Alex-Programs
19 days ago
This is motivated pessimism. We knew in the 50s that breaking the speed of light was highly unlikely. We dreamed of the stars anyway. Now we refuse to dream, or to even attempt to solve the problems (a common pattern when discussing spaceflight is people who are blatantly searching for problems, rather than solutions), because we are pessimistic, devoid of imagination, and seek to legitimise our collective depression through scientific and engineering arguments.
You don't need to break the speed of light to get to the stars. Time dilation and space contraction mean that you can get there in as little time as you desire.
Everyone you knew on earth would be dead by the time you got back, but if it's just about you, the speed of light is no limitation at all. (The rocket equation, however, presents stupendous engineering challenges.)
Time dilation and space contraction only matter if you can reasonably achieve speeds of a significant portion of the speed of light. AFAIK nobody has even come up with a reasonable way to achieve this for lightweight probes, let alone for hundred-ton ships capable of carrying humans. And let's not forget the practical problems like all photons incoming from the front being blueshifted into ultrahard radiation that would make a point blank nuclear bomb seem like a small candle.
Realistically even getting to the nearest star in less than 400 years experienced time is way way WAY out of reach for now.
Laser accelerate a lightweight probe, probe lands on alien planet and self replicates a receiver and basic robot body. Send mind in the form of information at speed of light and download into robot body.
Something roughly along these lines was believable enough for the Altered Carbon universe.
6 replies →
>but if it's just about you, the speed of light is no limitation at all
It's a huge limitation, even just getting propelled to "big enough speed", say 1/10 the speed of light.
We barely do 1/1500 the speed of light, in unmanned probes, and only because we sling shot on Solar gravity, not as propulsion or anything, and at 1400 o Celcius, plus deadly radiation, not to mention any micro-meteor as big as a particle of dust could kill someone there).
> It's a huge limitation, even just getting propelled to "big enough speed", say 1/10 the speed of light.
If you can't even get up to 1/10 the speed of light, then you wish the speed of light was a huge limitation, but it's actually not affecting you at all.
1 reply →
> Time dilation and space contraction mean that you can get there in as little time as you desire.
This is confusing science fiction with physical reality. See e.g. https://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/... for a reality check.
Don't even need to do time dilatation - just make you lifetime longer by techjlnical means (ideally almost infinite) and you will be in the next star sumystem before you figure out how to exit your VIM session.
I don't think it's motivated pessimism so much as a shifting tastes and changes in media. There are tons of SF stories with starships in movies, games and streaming platforms. It just happens to be the case that fantasy is more popular then SF at the moment where books are concerned.
That would only rule out stories based on interstellar travel, which is a tiny subset of what you can do in space. After all, you'll just end up inside another solar system that won't be much different from ours. The planets will be in different orbits but there will most likely be an asteroid belt and the effects of temperature will remain the same even if the planets are in different temperature ranges from our planets.
If earth is big enough for fantasy, then the solar system is plenty big enough for science fiction.
If you wanted to watch hard science fiction I would recommend watching anthrofuturism on YouTube who focuses exclusively on the moon.
Our astrophysicists don't even know why the universe is expanding, don't know that Lambda CDM is correct, don't know if things are universally consistent, yet we're so damned sure this is it.
We don't even know that this isn't a simulation. Not non-falsifiable, sure. But we're convinced we're bound to this solar system with our crude tools and limits of detection.
One new instrument could upset our grand understanding and models. Maybe we should wait until they get better hardware to marry ourselves to their prognostications of the end of time.
During the postwar years of plenty, people stopped dreaming. We had bold dreams before WWII, but people stopped looking at how far we'd come and started comparing themselves to everyone else. We had no mortal enemy, tremendous wealth, and "keeping up with the Joneses" became the new operating protocol.
We have more than we did in the past. The manufacturing wealth of 1940-1970 was a fluke. The trade wealth of 1980-2020 was a fluke. We were upset over an unfair advantage that won't last forever. Even today we're still better off than a hundred years ago, yet everyone focuses on how bad things are.
Maybe a return to hardship will make us dream again.
We do know why the universe is expanding. That's due to general relativity. That's well attested to high confidence.
We don't know why the expansion is accelerating. For that we have only speculation.
It’s well understood that the expansion of the universe is not “due to general relativity”. General relativity does explain some details of that expansion.
3 replies →
The universe is expanding due to general relativity... in the sense that Einstein literally wrote "... plus the expansion of the universe" into his equations.
I have upvoted you, and perhaps you are right that there are shades of pessimism in this perspective.
The 2020s have not been known as reasons for great optimism. The pandemic and AI culling clades of the job market have been traumatizing experiences.
If you think this is something that started in the 2020s you need to review the chart.
[dead]