Big Bang Question

[jgreen1124]

Q: Is it safe to say that the Big Bang had to create space first to hold what came after.
An explosion spreads out. It needs room (volume) to house the expansion. If I'm looking at this the wrong way, please correct me. I just don't understand as many others, how the universe can continue to expand into something that doesn't exist. It's like saying the Big Bang expanded into something that was already there. BUT! The Big Bang was first.
Thanks

Jay Green
Pembroke Pines, FL

[antoniseb]

Q: Is it safe to say that the Big Bang had to create space first to hold what came after.
A: No, that's not safe to say. The big bang isn't though of so much as an explosion as just the beginning of the expansion, and while it is true that the average energy density was much higher near the beginning than it is now, that energy density didn't necessarily drive the expansion.

Thinking of the universe is very different than thinking of some small thing (like a firecracker) which is a tiny part of the universe.

[01101001]

Sean Carroll's Preposterous Universe Cosmology Primer: The Expanding Universe (http://preposterousuniverse.com/writings/cosmologyprimer/expanding.html)


The concept of an expanding universe can be a tricky one, so it is worth being careful about what we mean. It is best to think of space itself stretching, so that the amount of space between any two distant galaxies is increasing.

Sean Carroll's Preposterous Universe Cosmology Primer: FAQ (http://preposterousuniverse.com/writings/cosmologyprimer/faq.html)


What is the universe expanding into?
As far as we know, the universe isn't expanding "into" anything. When we say the universe is expanding, we have a very precise operational concept in mind: the amount of space in between distant galaxies is growing. (Individual galaxies are not growing, as they are bound together by gravity.) But the universe is all there is (again, as far as we know), so there's nothing outside into which it could be expanding. This is hard to visualize, since we are used to thinking of objects as being located somewhere in space; but the universe includes all of space.

Carroll's whole primer is worth a read.

Welcome to the BAUT Forum.

[jgreen1124]

But don't we need room for the expansion? Yes firecracker explosions are small compaired to the expansion of the universe. But they do have one thing in common. They need a place to go.

[01101001]

The Big Bang is not an explosion.

Sean Carroll's Preposterous Universe Cosmology Primer: FAQ (http://preposterousuniverse.com/writings/cosmologyprimer/faq.html)


Does the universe have a center?
No. Our observable universe looks basically the same from the point of view of any observer. We see galaxies moving away from us in all directions, but an astronomer living in any one of those galaxies would also see all the galaxies (including our own) moving away from them. In particular, the Big Bang is not an explosion that happened at some particular point in space; according to the Big Bang model, the entire universe came into existence expanding at every point all at once.

Read the primer.

[jgreen1124]

Thanks for the link.
Sean Carroll's Preposterous Universe Cosmology Primer: FAQ
It did make some sense.