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You are correct. > She’s pointed towards a few different articles saying that the most accepted theory of physics is that the universe started from a single po
by mr_mitm 3y ago
You are correct.
> She’s pointed towards a few different articles saying that the most accepted theory of physics is that the universe started from a single point, and that there is language such as “it grew to the size of an apple” within a small amount of time after the Big Bang.
These articles implicitly talk about the observable universe. Or they're just wrong. It definitely didn't start from a single point, but there was a time where the observable universe was the size of an apple (or anything else that is larger than a point).
- sillysaurusx 3y agoIsn’t it possible that there was a period before the Big Bang, and then for some reason the universe became hot everywhere? In other words, the idea that the observable universe could be the size of an apple has its own contradictions. An apple is a definite size, and can fit only a certain number of atoms. However the expansion of the universe doesn’t seem to be creating more atoms; it’s only moving them around. Therefore all apples would’ve been the same size they were today, just packed more closely together. Hence “the size of an apple” seems to lose all meaning. This contradiction seems to clear itself up if one allows for a “before the big bang”, since there’s no need to say that everything was compressed to a single small volume.
- mr_mitm 3y ago> Isn’t it possible that there was a period before the Big Bang, and then for some reason the universe became hot everywhere? Well, sure, it's possible. I was assuming the current cosmological standard model is correct, which might in fact be wrong, or at least incomplete. Actually, I'm certain it's incomplete. Today we can trace back the universe to when it was a tiny fraction of a second old using standard physics. Everything is well understood. Before that: who knows? > An apple is a definite size, and can fit only a certain number of atoms. There were no atoms when the current observable universe was the size of an apple. It was too hot for atoms. It was more like a quark-gluon plasma. > Therefore all apples would’ve been the same size they were today, just packed more closely together. Hence “the size of an apple” seems to lose all meaning. Obviously "the size of an apple" is a phrase for laymen. We could say "10cm in diameter" using the standard definitions of the meter and second. >This contradiction seems to clear itself up if one allows for a “before the big bang”, since there’s no need to say that everything was compressed to a single small volume. There is no contradiction.
- sillysaurusx 3y agoOkay, but 10cm can only fit a certain number of quarks and gluons, far fewer than today’s observable universe. Or is it true that there were always 10^80 atoms worth of quarks and gluons in the observable universe, and always will be? Galaxies recede faster than light, so atoms are shedded by that process. If anything it seems like there must have been more matter in the early observable universe than today. But “10cm in diameter” seems to imply otherwise.
- mr_mitm 3y ago> Or is it true that there were always 10^80 atoms worth of quarks and gluons in the observable universe, and always will be? Pretty much, yes. (Let's ignore the possibility of proton decay for now.) > Galaxies recede faster than light, so atoms are shedded by that process. If anything it seems like there must have been more matter in the early observable universe than today. But “10cm in diameter” seems to imply otherwise. Not sure what you mean by "shedding atoms", but I'm pretty sure I can say that this is not the case.
- sillysaurusx 3y agoAlright. Thank you.
- ClumsyPilot 3y agowell we loose access to them, so for all intents and purposes observable universe looses atoms. Very anthropo-centric, but not wrong.