i'm not trying to be rude but most of you seem to know very little about the big bang and should at least read up on it a little before you comment. i couldn't make it through this whole thread but i'll comment on some of the misconceptions i read.

1. from our current understanding and evidence, the universe is not going to collapse in on itself. space contains dark energy (we do not know what it is but we can measure it) which has a repulsive force. as the space between galaxies become larger so will the dark energy repulsive force, causing the galaxies to accelerate at an increasing rate.

2. we only know what happened at 10^-43 second onwards. our theories don't make any sense when we put in t=0. the main reason for this is because we have two conflicting theories, general relativity and quantum mechanics. general relativity is good and describing things that are large and heavy while quantum mechanics is good and describing things that are very small and light. the problem is when something is extremely heavy and also extremely small such as black holes and the big bang. to come up with a theory that marries these tow is the holy grail of science and has been called the theory of everything (or the unified field theory to be technical). we've made some progress on this such as string theory, unfortunately there is not a test that can falsify it so we still have a ways to go.

3. there is a lot of evidence for the big bang. the first was discovered by Edwin Hubble who saw that all galaxies are red shifted meaning they are all moving away from us suggesting that if you turned back the clock all galaxies would come from a single place. the second big discovery and the best evidence for the big bang was made by bell labs (this won the discovers the Nobel prize). they built a radiometer for astronomy and satellite communications but they notice something strange, everywhere they pointed it there seemed to be a constant uniform source of microwave radiation. at first they thought it was faulty equipment, then thought it might be the birds in the radiometer after discounting all of the possible problems with their set up, they realized there seemed to be microwave radiation coming from every direction of space at the same temperature.

to understand why there is a uniform radiation permeating space (called cmb or cosmic microwave background radiation) one must understand what happened a trillionth of a trillionth of a second or something like that after the big bang. the following is our best understanding of what happened.

the universe started out as a minuscule point smaller than an atom. it contained some twenty pounds of matter, the rest was energy. this point was trillions upon trillions of degrees hot and for some unknown reason it exploded for lack of a better term. this energy spontaneously turned to matter as according to e=mc^2 (energy=mass*speed of light squared).this energy turned into matter and anti matter. for those who don't know what happens when matter and anti matter get together, they annihilate each other releasing a very large amount energy in the form of light (to give you an idea of how much energy is released from matter/anitmatter reaction, only a few grams of antimatter would be needed to send the space shuttle into orbit).

so a split second after the big bang there was a tremendous explosion from the matter and anti matter annihilating each other. luckily for us there was more matter than anti matter or we wouldn't be here today (that is also a great mystery why there was more matter than anti matter). all this energy created from this explosion continued to expand with the universe. due to ever increasing space this light was stretched becoming a lower and lower wavelength until we reach today some 13.7 billion years where it now peeks in the microwave range. i find it incredibly amazing that this explosions was so huge that we still see the remnants 13 billion years later.

this was an extremely simplified version of events but i hope it shed some light on what happened.