# Naked Science Forum

## Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 31/01/2014 13:30:02

Title: Can we rewind the expansion of the Universe to pinpoint the site of the Big Bang?
Post by: thedoc on 31/01/2014 13:30:02
Frank Auer asked the Naked Scientists:

If the universe is expanding, is everything moving in definite directions? If so can we calculate the reverse directions and determine the "point" of creation?

What do you think?
Title: Re: Can we rewind the expansion of the Universe to pinpoint the site of the Big Bang?
Post by: yor_on on 31/01/2014 15:36:38
No :) I don't think so, it should be become a impossibly complicated and non linear back tracking. Thinking of it from any position being as valid as another you can pick any frame of reference (position) you want, as Earths, 'unwind it' backwards to some point where it just was 'photons', to then define it to a 'origin'. But that you can do from/with any other frame you like too, without reaching a same SpaceTime position, presuming we have a SpaceTime in a 'photon universe'.

It's not a inflation 'growing' from a center. It's a inflation 'creating' a SpaceTime where all positions are a 'origin', or none.
Title: Re: Can we rewind the expansion of the Universe to pinpoint the site of the Big Bang?
Post by: Bill S on 31/01/2014 17:52:22
Hi Frank, from your question I assume that, like me, you are not a cosmologist.

If we think of the Big Bang involving something very small, that is not a small spot within the present Universe; it was, and still is, the entire Universe.  The bit that is sometimes difficult for us non-experts to get our heads around is that the BB happened everywhere in the Universe.  As we wind the expansion back we do not progress towards a smaller part of the Universe, we cause the Universe to shrink.  When we shrink it to a point, we cannot ask: "where is this point?" The only acceptable answer, in the present state of our knowledge, would be: "nowhere".

It could be that some day we will work out that this nascent Universe is embedded in a multiverse, or an infinite cosmos; then, perhaps our answer could be different.