Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

In an episode of Discovery's Curiosity with host Stephen Hawking, he claims the Big Bang event can be explained from physics alone, and does not require the intervention of a creator.

1) His argument is based on that, in the beginning, the universe is an equivalent of a black hole behaving as a quantum mechanical particle that can simply "appear" like a Helium particle in alpha radiation. For a large gravitational field like the black hole in question, time did not exist, and therefore there could not exist a being to create the Big-Bang, since time did not exist.

2) During the Big-Bang, positive energy appeared and negative energy was stored in space, and the net energy created is zero and therefore nothing was created.

I am curious on the foundations of Hawking´s claims in the episode.

Is the Big-Bang black hole really modeled as a quantum mechanical particle? Was there really a black-hole at all? What is the resulting entropy change of this black-hole during an event such as the Big-Bang? Are his claims of negative energy stored in space sound or well accepted?

share|cite|improve this question
I would actually like to avoid these discussions, and I wanted to talk more about the physics. – l3win Dec 31 '12 at 11:30
This question I think covers most of what you are asking. This one might cover the energy bit. Basically this seems to be one of Dr. Hawking's pet theories, and is speculative at this point. – Retarded Potential Jan 2 '13 at 22:38
Oy vey. The truth is we really have no idea why the universe exists, whether or not it is eternal or began a finite time ago, or whether it is part of a larger multiverse of some kind. There are many theories of course, but one should be careful to distinguish between the (un)fashionable theories of the day and what is experimentally established. Shows like that often blur the boundaries a little (or a lot!) for ratings purposes. The big bang happened, but we don't know how or why or what, if anything, came before it. – Michael Brown Jul 1 '13 at 4:03

I don't remember where, but I remember seeing a similiar question here with a really good answer by someone whose name I forgot. But I remember that the gist of the answer was:

It is just some vacuous claim to keep people happy about conservation of energy. They simply use the Einstein field equations by saying, "Look, $T_{\mu\nu}$ is the SEM tensor, the energy of matter/etc. and just to make things nice, let us just say that $-\frac{c_0^4}{8\pi G}G_{\mu\nu}$ is the energy of the gravitational field (Without caring whether that make sense at all to do so), so that the Einstein-Field Equation says that the total energy would become$$-\frac{c_0^4}{8\pi G}G_{\mu\nu}+T_{\mu\nu}=-T_{\mu\nu}+T_{\mu\nu}=0$$ And the reason why this is completely vacuous is simply that the very reason why they chose the energy of the gravitational field is simply that the final answer should be 0.

So finally, this means that the claim is completely vacuous.

share|cite|improve this answer
But by that reasoning isn't any application of the conservation of energy vacuous? As in "well, if you define the potential energy such that it's the negative of the kinetic energy then of course they're going to sum to a constant." – Nathaniel Jun 30 '13 at 15:39
@Nathaniel: The thing is, that when you define potential energy like that, then there is still some kind of a reasoning; work done by gravitye etc. – centralcharge Jul 1 '13 at 2:57
I found the great answer I was talking about. It is Matt Reece's answer at: – centralcharge Jul 1 '13 at 4:47
@Nathaniel If you real Matt Reece's answer, be sure also to read Lubos's one too. In contexts other than GR, Noether's theorem motivates conservation of energy, because the physics is invariant under any time shift. In GR there is no such symmetry, hence conservation of energy doesn't have a sound physical interpretation as it does in time shift invariant physics. – WetSavannaAnimal aka Rod Vance Jul 31 '13 at 4:37
Evaluating the Hamiltonian of general relativity is meaningless unless you gauge fix first. – Jerry Schirmer Aug 30 '13 at 4:51

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.