I have asked this multiple times and no one has ever given me a straight answer:What astrophysical evidence would even possibly count as evidence that the universe is infinitely old? My understanding of the history of western thought is presuming the universe has/has no beginning is fundamentally a theological or metaphysical concern. No amount of finite evidence will ever confirm one over the other because the finite age can always be pushed back one layer of explanation so as to make sense with all of the observations made. What is the consensus on this dilemma in the theoretical physicist community? The way I see it is science simply has no say on whether the universe began to exist, unless scientists inject some metaphysical philosophy into their own theory.
>>16147523This is just the "you can't prove unicorns don't exist" shit
>>16147565No its not. If I scan the entire earth, and find no unicorn, then I can say unicorns don't exists.
>>16147523All we can really say is that at some point the universe was a lot smaller. The evidence for this is the CMB, age and types of distant stars, and the fact that the temperature of space throughout the universe is basically the same, because distant points in space are currently too far apart for temperature to be in equilibrium unless at some point they were closer to one another
>>16147615so there is no evidence that the universe has a beginning at all?
>>16147853No. Just that it was smaller. And because of the current state of the universe and the way expansion is assumed to work then the universe likely expanded from a very small space, possibly smaller than a single atom. That helps explaining why stuff is so uniform over the whole observable universe, extremely rapid expansion from an extremely small size. That's the big bang theory of course, but it doesn't say where the universe came from, only that at some point about 13 billion years ago it was a tiny ball of pretty much just energy, it was too dense and too hot to form atoms etc. So that ball of energy either appeared out of nowhere, or it was there forever, or it was the end state of a possible previous universe, or some other unknown reason.
>>16147523one model is that it's pulsing, and could have been for insanely many cycles. supposedly there could be some leakage from previous one, in CMB. but it becomes a question of how much anyway, so we won't be able to peer back 5 cycles ago at some Earth-like planet or something.or could be like a full reset for everything including causality, right after completely collapsing and right before starting expanding again.
>>16147523Good question. Led me down a small rabbit hole.As >>16148020 said, our direct measurements are that the universe was smaller and hotter before, which our models then turn into a timeframe.But we do also have entropic measurements of the CMB; roughly ~10^89 Kb. It's likely too difficult to create an entropic evolution model into a timeframe, but it should be able to give a maximum constraint. This is where the lack of large primordial black holes plays a big role. As the universe ages, more and more of it will be in large entropy gravity wells. This is a constraint against infinity for our universe.However, this doesn't necessarily rule out that there was universes before ours, before our cosmic inflation, that kept entropy the same but reduced its density, before our big bang, that returned gravity and black holes to the universe. And there may well be echoes of the prior universe! https://www.livescience.com/63392-black-holes-from-past-universes.html
>>16147523>the absence of evidence isn’t the evidence of absence You are asking a question that is not easily answered and because its not easily answered you feel you can reject it as a possibility, which is odd because gravity is still a concept in science but yet you wouldn’t go around saying “Gravity not real”.What truly triggers me is people like you, with not an iota of scientific training or background making the most elaborate dumbass logic-trap attempts and only end up trapping yourself
>>16148161>https://www.livescience.com/63392-black-holes-from-past-universes.htmlthats a great article>>16148415> you feel you can reject it as a possibilityi dont feel i can reject it as a possibility, I just can't see how an infinite universe is compatible with the scientific method. Even the people with more knowledge in this thread seem to be suggesting in some sense theres really no scientific answer
>>16148110>or could be like a full reset for everything including causality, right after completely collapsing and right before starting expanding again.and thats the whole issue. If all empirical information "resets" ever x cycles then is this even a coherent scientific belief? I mean if you open the floodgates to full universe resets then you are just playing theoretical games no?
bumping for interest
>>16149100>>16149108Sorta the way around this quandary is to differentiate between our current and very much finite causal universe, and the greater system of everything that might be/have been - often called the 'Multiverse'.Science primarily concerns itself with questions about our universe, which seems to have started from cosmic inflation/the big bang. There's still questions to be answered about whether it is infinite in size and will it be infinite in time. Questions regarding the Multiverse are, unfortunately with our technology, largely outside the realm of empirical science, though there's lots of speculation we can do.
>>16149383>largely outside the realm of empirical sciencethere may be ways, I don't think it's settled that it's impossible to test for it.
>>16149383>>16150220>literally just the concept of possible worldsthen its just philosophy
>>16150600just dropped todayhttps://www.youtube.com/watch?v=9M_qL3wUH9I
>>16148161>So, a universe filled with only gravitons or photons will not have any sense of what is time or what is space," An said.>At that point, some physicists (including Penrose) argue, the vast, empty, post-black-hole universe starts to resemble the ultra-compressed universe at the moment of the big bang, where there's no time or distance between anything.>"And then it starts all over again,"I'm sorry but that's just retarded, how could someone like Penrose mistake relative measurements with real physical properties
