Expert: Courtney Seligman - 7/29/2009

Question
is it true that before the Big Bang all matter was joined together as 1 unit. so the entire universe including the earth were joined together ?

Answer
First, I apologize for the delay in answering your question. The electric company was working on our street today, and we had no power from early this morning until a few minutes ago.

The 'standard' theory of the Big Bang does not address what the Universe was like before the Big Bang, as all of the space, time, matter and energy in the Universe came into existence at that moment, and there was no 'before'. There are theories in which our Universe's space-time and matter-energy sprang into existence from a point/line/brane of otherwise empty space-time in some multidimensional superUniverse, but to the best of my knowledge, none of them suppose that any of the mass/energy in our Universe existed in any form, known or unknown, prior to the moment of our Universe's creation (the Big Bang).

However, if you start not before the Big Bang, but at the moment of the Big Bang, then yes, it is presumed that all of the mass and energy in our entire Universe was, for an infinitely brief moment, contained in a single point of zero size. None of the mass or energy would have been in any form which currently exists in the Universe, or in any form which we can imagine, save that any 'particles' of mass or energy would have had essentially infinite values, and been totally unlike anything we are familiar with. So although the Earth and the most distant currently existing galaxies were at that time in the same place, neither they nor the particles that they are made of existed at that time, so whether they were in the same place or not depends upon what you mean by 'they'.
Courtney Seligman