Ive been trying to understand a bit more about the Big bang theory and have a few questions in regards to it.

1) What was there before the big bang?

2) Where did all of this mass come from? Planets, stars, meteors. Thats a lot of mass. It must have come from something.

3) if the big bang started as a single point, how large was this point? I know noone probably knows for sure but whats the general concensus?

4) I am assuming that before the big bang there was just nothingness in space. Since space is infinite why couldnt there be many universes beyond our universe? I understand uni means one and having more than 1 would change the term but I dont know what the correct term would be if we were to find 50 other universes.

5) Why is space a vacuum?

6) Since space is infinite can I assume that beyond the universe there is just nothing but space and nothingness?

Im sure the answers to these questions will inspire more questions on my part.

Don't know. Probably never will.


The origin of mass is still uncertain. The matter, however, to the best of my knowledge, condensed out of the energy that was relased during the BB.

I personally don't know, but a point, by definition, has a radius of 0. So, if it was a point...

The problem you have here is that you assume there was space. There's really little reason to make that assumption.

I don't think anyone's saying there couldn't. But since they're not a part of our universe, we'll almost certainly never know about them.

Together, they're collectively known as the multiverse.

It's not. It's a very, very good approximation, though. It's this way because the ratio of matter:volume is very small.

Space != nothingness. If you have nothingness, you don't have space. Oh, and I think the current belief is that space is finite but unbounded, like the surface of a sphere.

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Thanks for the reply!! As anticipated it does bring up one other question. Of course There is probably not an answer to this but here goes.

Where did the material come from to create the energy that caused the big bang?
Again I am assuming that space was there before the BB and that this material somehow came together. I guess the next logical question is where did this material come from and why was it there in the 1st place?

Ok 1 more question. I see the threads on an expanding or contracting universe. I guess the universes could contract from cooling. Is this the case or is there a center of the universe that has a gravitational pull that would cause it to contract?

And one other question, Im assuming that spiral galxies spin. what causes this to happen?

The theory is that space and time were both created in the Big Bang. So there was no "before" the Big Bang.

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This one's over my head. Sorry.

I think you should drop this assumption. It's needless. We haven't the slightest clue what existed before the big bang. All we know is that our universe did not. Space is a part of our universe -- it's a physical thing, under the current BB model. The universe isn't expanding because everything in is is flying through space, but rather because space itself is stretching. When the universe existed within a supposed singularity, so did all of space. Time, too, it's sometimes said began with the big bang.

This question is unanswerable because it doesn't involve our universe. If you're thinking of the big crunch/big bang cycle, or string theory's big bounce, then it's ok to imagine, but it's impossible, or at least currently impossible, to gather any kind of evidence whatsoever from this period. Assuming time existed before the big bang (otherwise there is no time period before our universe for which any of this stuff to happen in).

The universe isn't expanding because it's hot, and therefore won't contract as it cools. The universe has no centre. If it's infinite, there's no centre to speak of. If it's finite and unbounded, there's no centre to speak of.

Conservation of angular momentum, for one. There's stuff about gravitational waves and pressure fronts that I don't know anything about, though. Others do. I'm sure they'll talk at length about it.

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I think i can give a little less nebulous answer on this question. The property that allows for hawking radiation combined with the inflation of space allows all the matter to come from nothing, as long as the universe is larger than we can see.

I need more coffee!!! Space didnt exist before the BB? If space was created with the BB what was there before it?
Would it have still been a vacuum?

Whatever was there before the BB should still be there just outside of our universe and beyond. Is this correct?

Is there a law of physics or something that says space didnt exist before the BB? If so my apologies for my ignorance in the matter. I was always under the impression that space was always an endless vacuum and that the BB happened in space and the results of which are still happening in space.

Picture an explosion in space in which everything expands outward and because of the vacuum of space, everything continues to expand outward from the center of the explosion.


Thanks for the replies.

This is way over my head but I will go do some googling to learn more!!

Well string theory suggests that the deeper universe, not just the observable and unobservable universe that we occupy, is a bunch of branes. Two or more of those branes colided, and our universe is the four dimensional space where they intersect.

If its hard to wrap your brain around 11 dimensional super branes, well dont feel bad, cosmology is a only a little harder than rocket science.

I think the simplest explanation is, we don't know. When people are prideful and dont know, they either blame God or another dimenson. I am happy to know I dont know, and if I knew with certainty, where would the mystery be?

There are enough mysteries to keep me occupied, that have the potential to be solved, or understood. I think questions like, what was the first cause, are a little vain, because every where we look, the universe seems to be infinite, both out into space, and down to the most fundamental quantum particles. In other words, worry about what you can know, and let the rest slide.

It's not really a good idea to think of space not existing before the BB. If we think of space as infinite, like the surface of a sphere, then by adding more space to it (the BB), we haven't created more space, because infinity + a bunch = infinity.

Again, it's not a good idea to think about what was "there" before the BB. It's just as bad to think about what is "beyond" our universe. The best way to think of it is like the video game screen in pac man. You can go to the "edge," but as soon as you cross it you just end up on the other side. It's infinite, yet finite. If that makes any sense...

I'm not really sure about this. Most of science today will deal with everything that happened after that BB, so everything before it (and even the "it" itself) is pure speculation.

Thinking of the BB having a "center" is more of a misnomer, since it wasn't a real "explosion." It happened everywhere, just like if you had a point and then filled it with air to make an expanding sphere. Even though it's expanding, the initial outburst happened everywhere.

Thank you again for a great response!! Ok more questions.

I read a little more on the big bang and if I understand this correctly the universe was much more dense at that time and basically the big bang just happened everywhere at once.

According to what you said and also this site(Which someone posted the link to earlier. Thank you!!) http://anzwers.org/free/universe/bigbang.html
If you go in a straight line across the universe you will eventually come back to where you started. This is because of the curviture of space? How does this affect time? Is time also curved. How is time affected by space? Whats the correlation there?

That's right. The most important concept is that the Big Bang was not an explosion taking place at a point in space, with matter then rushing out to fill that empty space - no, it was a inflationary expansion of space-time itself, from a single dimensionless point. There was no 'outside', and there was no 'before'.

The concept of space being finite but unbounded is easiest to grasp if you think of walking in a straight line along the surface of the Earth - eventually, after 25,000 miles, you would end up back where you started from, having not deviated from what you thought was a straight line. Now increase all the dimensions by one and you have 'finite but unbounded' 3-dimensional space.

AFAIK, there is still debate among cosmologists as to whether space is indeed closed in this way. I'm sure someone else here will set me right!

However, cosmologists tend not to separate time and space and instead refer to the concept of 'space-time' with time as a fourth dimension of space, the behaviour of which can be affected by large masses, large relative velocity and large gravitational fields. In fact the general concept of what causes gravity, is that it is a local distortion or 'curve' in space-time caused by the presence of matter.

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