I'm going to be very amused if the Steady State Model - an unpopular relic from the 1940s - turns out to be correct.
EDIT: There's also this super fun PBS Space Time episode on the theory: https://www.youtube.com/watch?v=9dqtW9MslFk
What would be even cooler is if it was warped like a moebius strip in a higher dimension, so that when we look out there, everything is mirrored from "our" reality :-D
It's actually an interesting thought experiment. If that theory were true, and assuming we could see ourselves face-on (rather than edge-on), then I wonder how far away and far back could we recognize ourselves.
And maybe if we actually look both ways, we could find another galaxy that could be proven to be the same (because of some particularly remarkable stars/quasars/supernovae etc. in them). Who knows, maybe the universe is smaller than we think and we just don't recognize the "same" galaxies on different images because they are billions of years apart?
Another commenter asked something like, what if the universe is much bigger than the observable universe, because everything beyond that 'border' has redshifted out of reach - or hasn't reached us yet / never will, because it's moving away faster than the speed of light.
I mean that we can't observe the expansion because we can't really triangulate at galactic scale. If there is another reason the light from distant galaxies turn to red, kind of a long-distance light fatigue, we couldn't really know.
The reason I always heard that would be a confirmation, because it comes from a different causal path, was precisely the different composition of old galaxies. And now it seems they're not so sure.
It's not just red shift that demands an explanation, but also that the sky (space) is dark. If space wasn't expanding then the skies would be bright white.
Another thing is the second law of thermodynamics, which very strongly implies a lot of standard cosmology.
Of course, standard cosmology could be all wrong, but these deductions are quite solid as far as the physics that we know today.
Inadequate explanation. Even if the universe was a closed box with perfectly reflecting borders, what you would actually see in the sky is something like an average brightness of the entire universe with some fluctuations.
Light scatters, gets absorbed and re-emitted, it's true, but if distances don't change then the universe would still be much brighter than it is today.
Only if you think that there is infinite matter, all of it forming the same kind of stars, uniformly spread over the infinite space and there is no unknown form of atenuation for waves traveling millions or billions of years light.
Another thing is the second law of thermodynamics, which very strongly implies a lot of standard cosmology.
Don't you feel that these evidences just make a case from models checked in small scales and tell the whole universe what it should do?
I don't mean the reasoning is incorrect or unwarranted, just that there could be alternative explanations that involve unknowns.
Of course, standard cosmology could be all wrong, but these deductions are quite solid as far as the physics that we know today.
When applying Occam's razor, you try to minimize entities and simplify. But what appears simpler for a physicist is sometimes surprising for the rest of us. The equations don't work as expected? No problem, let's say that the entire universe is expanding or, even better, that space is expanding. Or that all the universe was at some moment in the space of a tennis ball. Or that big bang happened everywhere at the same time...
While some explanation fits the maths, it doesn't matter if it's totally alien to common sense. Actually I find all those weird explanations strangely appealing, they give me a sense of wonder and empowerment. Cosmology feels like a superpower :)
Yes, we like to think that the laws of physics we can deduce locally are global. That could be wrong, for sure. But consider that we understand the physics of our solar system (which has a star), and we see other stars in the skies which... implies that at least as much of our local physics that makes stars possible also applies where we see those stars.
And you never heard of the CMB? That's generally considered the "smoking gun" evidence for the big bang.
Is there a name for this?
Edit: ha, found it: https://m.youtube.com/watch?v=ycvlJ9XMd94
Pascal:
[…] But to show him another prodigy equally astonishing, let him examine the most delicate things he knows. Let a mite be given him, with its minute body and parts incomparably more minute, limbs with their joints, veins in the limbs, blood in the veins, humours in the blood, drops in the humours, vapours in the drops. Dividing these last things again, let him exhaust his powers of conception, and let the last object at which he can arrive be now that of our discourse. Perhaps he will think that here is the smallest point in nature. I will let him see therein a new abyss. I will paint for him not only the visible universe, but all that he can conceive of nature's immensity in the womb of this abridged atom. Let him see therein an infinity of universes, each of which has its firmament, its planets, its earth, in the same proportion as in the visible world; in each earth animals, and in the last mites, in which he will find again all that the first had, finding still in these others the same thing without end and without cessation. Let him lose himself in wonders as amazing in their littleness as the others in their vastness. For who will not be astounded at the fact that our body, which a little while ago was imperceptible in the universe, itself imperceptible in the bosom of the whole, is now a colossus, a world, or rather a whole, in respect of the nothingness which we cannot reach? He who regards himself in this light will be afraid of himself, and observing himself sustained in the body given him by nature between those two abysses of the Infinite and Nothing, will tremble at the sight of these marvels; and I think that, as his curiosity changes into admiration, he will be more disposed to contemplate them in silence than to examine them with presumption.
For in fact what is man in nature? A Nothing in comparison with the Infinite, an All in comparison with the Nothing, a mean between nothing and everything. Since he is infinitely removed from comprehending the extremes, the end of things and their beginning are hopelessly hidden from him in an impenetrable secret, he is equally incapable of seeing the Nothing from which he was made, and the Infinite in which he is swallowed up.If steady state gained favor that would be super fun, but this quote from the article seems to throw a little cold water on that.
> At the same time, she notes that yesterday’s disks are different than modern ones. “They’re not today's Milky Way,” she notes. “They're turbulent, they're messy, and we need to study them more.”