# B Did the big bang create something from nothing?

1. Aug 24, 2017

### 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?

2. Aug 24, 2017

### thorbjorn

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

3. Aug 24, 2017

### Lunct

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

4. Aug 24, 2017

### 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.

5. Aug 24, 2017

### Lunct

why?

6. Aug 24, 2017

### 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.

7. Aug 24, 2017

### Lunct

I understand.

8. Aug 24, 2017

### thorbjorn

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)

9. Aug 24, 2017

### Lunct

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

10. Aug 24, 2017

### thorbjorn

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

11. Aug 24, 2017

### jbriggs444

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.

12. Aug 25, 2017

### Chronos

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

13. Aug 25, 2017

### rootone

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

Last edited: Aug 25, 2017
14. Aug 28, 2017

### nikkkom

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.

15. Aug 28, 2017

### Lunct

the human brain cannot comprehend nothing.

16. Aug 28, 2017

### 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.

17. Aug 29, 2017

### ISamson

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.

18. Aug 29, 2017

### ISamson

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.

19. Aug 29, 2017

### Comeback City

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

20. Aug 29, 2017

### ISamson

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.