h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Big Bang
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Big bang theory says that the the cosmos came into existence at the moment of a Big great explosion known as a big bang.Observations in support of this theory are

1.Universe is expanding(as all galaxies shows Red shift only).
2.Presence of a uniform cosmic background radiation as predicted by the theory.

As I understand Big Bang is not like an ordinary explosion in the sense that before the big bang there was nothing ,not even the empty space.The space was created at the moment of big bang.It is said that Big bang took place everywhere in this universe.
I would like to know how this happens.Plese help me to get a clearer picture of Big bang.

I'm probably not the best person to reply to this, but here goes...

All the matter in the universe was compressed into a tiny, tiny space called a singularity. A singularity is infinately small, the smallest thing that could possibly exist without being nothing at all. There was no time and no space, only this teeny weeny pinprick. When it began to expand at a ridiculously fast rate, all kind of things sprang into being; time, nuclear forces, sub-atomic particles, forces and so on. It just all kind of whoooooshed out.

I do hope this helps in some small way.

Rich

How do we feel if we were inside that expanding singularity? Will we have the perception of the finite size of that fire ball?

> How do we feel if we were inside
> that expanding singularity?

Very good, thank you!

> Will we have the perception of the
> finite size of that fire ball?

Yes. If we cruised into one direction for a very long time, we'd get in the vicinity of the starting point eventually. I admit that this is not a realistic experiment though.

So it should also be possible in the present universe.ie If we continuously move in one direction for a long time ,we should be able to reach where we started.But this seldom happens-if it does then we should be able to see the same object by looking in two opposite directions(atleast some objects).

To be honest, when I re-think it, I'm not so shure anymore. It may well be that the expansion of the universe is fast enough so that even a voyage at light speed is not fast enough to get back to the starting point by just cruising in one direction. The same applies then to seeing one object in two direction (which is at light speed, too, of course).