The Big Bang

the interstellar medium is just a bunch of gas and dust that would have eventually slowed the "shrapnel", just my idea.

second off we will never know how the universe came to be, except if somehow we invented time travel of some sort, but if that was possible dont you think someone would have came back by now and told us? again just an idea.

lastly i dont think its called anti-matter, i thought it was called dark-matter.
dark-matter is what they think makes up our universe, because its alot more massive then we had expected.

all just ideas and short facts though, some of this may have been said in other replys though

Right... dont confuse Anti-matter with Dark-matter, two completely different things

There is much more matter than anti-matter, and matter is about 4-5% of the universe. Dark matter is something like 23%

"Outside" our universe is an invalid concept and can be considered nonexistant.

Perhaps the mechanism for expansion is particle gravity, the duality of the graviton.

Read this article carried by PhysOrg News. If you are not already confused by all the mumbo jumbo surrounding the Big Bang, I think this should do it:

www.physorg.com...