B Did the big bang create something from nothing?

[Lunct]

A lot of people talk about the big bang, saying it created something from nothing - it is even used against the big bang. People say "it is impossible to create something from nothing." However, to my understanding, the big bang never created something from nothing. I have read it in many book and websites the the universe started of as an (arguably) infinitely dense point that contained everything, and that makes sense. George LeMaitre, who I think discovered to big bang, said that the universe had a beginning because if Hubble found that it is expanding, then it must have been smaller. Therefore it makes sense that the universe started of as a tiny point of infinite density, a singularity.

So why do most people seem to think the big bang created something from nothing. Is it some kind of pop science over simplification?

 

[thorbjorn]

It's simply due to the fact that the big bang should be called the great expansion and not the big bang

 

[Lunct]

It's simply due to the fact that the big bang should be called the great expansion and not the big bang

I completely agree. I believe it in fact got that name from someone who was against the theory himself.

 

[thorbjorn]

Nevertheless that does not alter the fact that the question "what happened before the big bang" remains unanswered, because in the end there had to be something created from nothing.

 

[Lunct]

because in the end there had to be something created from nothing.

why?

 

[jbriggs444]

Both the notion that the Big Bang created something from nothing and the notion that a singularity is a point of infinite density are pop science over-simplifications.

A singularity is a feature of certain idealized models. Like the pole at x=0 in the graph of $f(x)=\frac{1}{x}$. There is no point on the graph there. Talking about the state of the universe at the singularity is like asking about the height of that graph at x=0. It doesn't have one.

 

[Lunct]

Both the notion that the Big Bang created something from nothing and the notion that a singularity is a point of infinite density are pop science over-simplifications.

A singularity is a feature of certain idealized models. Like the pole at x=0 in the graph of $f(x)=\frac{1}{x}$. There is no point on the graph there. Talking about the state of the universe at the singularity is like asking about the height of that graph at x=0. It doesn't have one.

I understand.

 

[thorbjorn]

why?

Because although time is infinite, it is only infinite in one direction. Since space and time were created in the big bang there was no time before the big bang, (if we stick to the theory)

 

[Lunct]

Because although time is infinite, it is only infinite in one direction. Since space and time were created in the big bang there was no time before the big bang, (if we stick to the theory)

Might be wrong, but time was created in the big bang because time stops at a singularity because of the overwhelming gravity.

 

[thorbjorn]

Might be wrong, but time was created in the big bang because time stops at a singularity because of the overwhelming gravity.

I do believe we are both talking about things we both do not fully comprehend so there is not point in this discussion.

 

[jbriggs444]

Might be wrong, but time was created in the big bang because time stops at a singularity because of the overwhelming gravity.

The phrase "time was created" tends to evoke a picture of some kind of time that includes a time before time. That's not really sensible.

In mathematics, the relevant notion is "geodesic incompleteness". Time-like geodesics come out of the neighborhood of the singularity without having gone in.

 

[Chronos]

It depends on your definition of 'nothing'. Well qualified scientists sometimes employ definitions that can be philosophically shocking.

 

[rootone]

What really does 'nothing' mean?.
Something which has no dimensions, no mass, and no other properties isn't very interesting.

 

[nikkkom]

A lot of people talk about the big bang, saying it created something from nothing - it is even used against the big bang. People say "it is impossible to create something from nothing."

This is conservation of energy. It is true only in theories with time translation symmetry. General Relativity is not such a theory: there are global solutions of GR equations which are not time-translation invariant.

In General Relativity, energy is conserved only locally (the law is valid in differential form, but not in integral one). In GR, it is not even possible to _define_ energy globally in an invariant way.

 

[Lunct]

What really does 'nothing' mean?.
Something which has no dimensions, no mass, and no other properties isn't very interesting.

the human brain cannot comprehend nothing.

 

[jbriggs444]

I would suggest that, unless one proceeds to specify a particular sort of nothingness, a discussion about the nature of "nothing" is either pure philosophy or a prescription for a long running television show.

A nothingness on the other side of a hypothetical point of discontinuity where differential equations fail to extrapolate is not something that is amenable to experiment.

 

[ISamson]

Since space and time were created in the big bang there was no time before the big bang, (if we stick to the theory)

How could time have a beginning? Something MUST have happened in order for the Big Bang to be created. Something MUST have been before the Big Bang. I do not believe that time had a start. However the theory of the Big Bang and the theory of Relativity both argue that the Big Bang has happened.

 

[ISamson]

A lot of people talk about the big bang, saying it created something from nothing - it is even used against the big bang. People say "it is impossible to create something from nothing." However, to my understanding, the big bang never created something from nothing. I have read it in many book and websites the the universe started of as an (arguably) infinitely dense point that contained everything, and that makes sense. George LeMaitre, who I think discovered to big bang, said that the universe had a beginning because if Hubble found that it is expanding, then it must have been smaller. Therefore it makes sense that the universe started of as a tiny point of infinite density, a singularity.

So why do most people seem to think the big bang created something from nothing. Is it some kind of pop science over simplification?

I share you opinion about the Big Bang not creating something from nothing.
How could nothingness create something?

Even if all the matter was infinitely dense, the matter must have come from somewhere. If it did, then physicists should have said that time started when all this matter was CREATED. Why did they not?
This is topic is very arguable.

 

[Comeback City]

If it did, then physicists should have said that time started when all this matter was CREATED. Why did they not?

We don't know what (if anything) happened before the Big Bang, so we cannot estimate the timeframe.

 

[ISamson]

We don't know what (if anything) happened before the Big Bang, so we cannot estimate the timeframe.

Something MUST have happened before the Big Bang in order for the Big Bang to happen. If something must have happened, then something MUST have been there to make it happen. No?
This is an assumption, however.

 

[Comeback City]

Something MUST have happened before the Big Bang in order for the Big Bang to happen. If something must have happened, then something MUST have been there to make it happen. No?
This is an assumption, however.

I'm just speaking in science terms... that sounds a bit too philosophical for me.

 

[ISamson]

I'm just speaking in science terms... that sounds a bit too philosophical for me.

Yeah, this is actually philosophy, not really science!

 

[XZ923]

This is one of those things that's always busted my brain. If energy/matter cannot be created or destroyed, how'd it get here in the first place?

Please, anyone with a better understanding of QM than me (which is pretty much everyone on this forum), I'd love to know the answer to this. I've always seen it as sort of a physics paradox.

 

[jbriggs444]

This is one of those things that's always busted my brain. If energy/matter cannot be created or destroyed, how'd it get here in the first place?

See #14 for one answer. Conservation of energy and matter is not actually an applicable principle of physics.

Another answer is that your question appears to assume that time is endless both into the future and into the past. But that assumption is unfounded.

 

[weirdoguy]

Yeah, this is actually philosophy, not really science!

So this forum is not the right place to discuss it.

 

[PeterDonis]

How could time have a beginning?

By spacetime having a geometry in which timelike curves have a finite extent into the past. Currently physicists don't know for sure whether that feature of idealized models based on GR actually applies to our universe; but the models themselves are perfectly consistent, and answer the question you pose here.

Something MUST have happened before the Big Bang in order for the Big Bang to happen

This, as you say, is an assumption. But it is not a necessary assumption, as there are consistent models in which it does not hold. See above.

 

[PeterDonis]

The OP question has been sufficiently addressed. Thread closed.