The vehicle I’m sitting in looks normal.turboscrew wrote: ↑Mon Jul 20, 2020 12:45 pmBut in the "vehicle" you are not moving relative to, everything looks normal?notFritzArgelander wrote: ↑Mon Jul 20, 2020 5:45 amThe consequences of the unobservable portions of the universe, have observable consequences, though. For instance we can never observe (because of Dark Energy and the accelerating expansion of the universe) all of the universe even if we wait for an infinite time. Nevertheless the observations we can make are consistent with the universe being flat, homogenous and isotropic. Noether's Theorem guarantees that an infinite, homogenous, isotropic universe (no need for flatness, yet) has momentum and angular momentum conservation. So every experiment that we do (and there are a lot of them) where momentum and angular momentum are conserved is in accord with there being parts of the universe that we can never see. Flatness guarantees zero average energy density and so infinite extent and energy conservation.turboscrew wrote: ↑Sun Jul 19, 2020 3:16 pm I also find this thread very interesting.
I think, to science there is no unobservable universe - because we can't observe it.
Science is models. "The real truth" is more or less religion.
Also, I've got this funny idea that if you travel in speed of light, you wouldn't notice. Everything would look normal to you. Just the time and spatial dilatations make everything look normal to you.
I may be totally wrong, though.
Science constructs models that explain the observations. It is rather rigorous in that a compelling contradiction to a theory chucks the theory out and demands a replacement. That, I think, is as close to "the real truth" as one can get. I don't think that "The Real Truth" is knowable. Others might differ. But I think Platonism (knowing The Real Truth) has been dead since the 14th century. YMMV.
As you approach light speed the appearances of objects become increasingly distorted. MIT had a neat game to play online that illustrated the distortion of optics caused by relativistic motion. I've tried to find it again but failed. Instead this 6 minute YouTube clip shows the same effects.
There are several different ways in which relativity distorts appearances and the video starts out simple and then adds each effect in turn.
And is indirectly observable unobservable...?
Unobservable means no signal in this context.