I know no physics, but I read that while the observable universe is finite, for all physicists know the universe is infinite. How is this compatible with the Big Bang hypothesis? Does it mean that it's possible that at some point space expanded at literally infinite speed? Or something else?

Edit: This question is answered by the comment referring to how the Big Bang did not occur at a point.

  • 1
    $\begingroup$ We don't know that the universe is infinite. Some may believe it and some may not. There is no proof of any kind. $\endgroup$ – Gonenc Feb 14 '16 at 21:08
  • 3
    $\begingroup$ I don't really know what you are trying to ask, but Did the Big Bang happen at a point? might clear up your confusion. $\endgroup$ – ACuriousMind Feb 14 '16 at 21:08
  • $\begingroup$ Also, the big bang is a theory. It is well tested. It is not a hypothesis. $\endgroup$ – user106422 Feb 14 '16 at 21:09
  • $\begingroup$ @ACuriousMind that answers my question. Thank you. $\endgroup$ – vhspdfg Feb 14 '16 at 22:30

As ACuriousMind comments, Big Bang wasn't an explosion at a point, dispersing matter in all directions. It was the creation of space, and its subsequent expansion. The Universe may or may not be infinite. If it is finite, is was born finite, and will always stay finite, although dark energy seems to expand it to an arbitrarily large size.

If it is infinite — and currently, observational evidence suggest it is — is was born infinite, and always will be. It still expands, i.e. the distance between galaxies (that are not gravitationally bound to each other) will increase indefinitely.

There is no way that the Universe can transit between being finite and infinite.

  • $\begingroup$ Thanks. The answer that ACuriousMind linked to, physics.stackexchange.com/questions/136860/…, explained how to think about this and fully resolved my question, which was based upon a faulty but culturally oft-depicted understanding of the Big Bang. $\endgroup$ – vhspdfg Feb 14 '16 at 22:35
  • $\begingroup$ @vhspdfg: You're welcome. I submitted my answer exactly at the same time that I saw that that link solved your question. But thanks for accepting. $\endgroup$ – pela Feb 14 '16 at 22:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.