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?

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    $\begingroup$ I would actually like to avoid these discussions, and I wanted to talk more about the physics. $\endgroup$ – l3win Dec 31 '12 at 11:30
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    $\begingroup$ 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. $\endgroup$ – Retarded Potential Jan 2 '13 at 22:38
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    $\begingroup$ 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. $\endgroup$ – Michael Brown Jul 1 '13 at 4:03

It's not standard gravitational potential energy that cancels out the positive energy of matter, this can be confirmed fairly easily by e.g. considering a two-mass system in freefall.

It's rather just a vacuous (and useless, since it defeats the point of defining energy) definition of $-G_{\mu\nu}/8\pi$ as a sort of "negative gravitational energy" which cancels out $G_{\mu\nu}$. This is pointless, and is not the right answer to the question "How did the big bang create stuff?".

See also https://physics.stackexchange.com/a/2844.

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  • $\begingroup$ 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." $\endgroup$ – Nathaniel Jun 30 '13 at 15:39
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    $\begingroup$ @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. $\endgroup$ – Selene Routley Jul 31 '13 at 4:37
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    $\begingroup$ Evaluating the Hamiltonian of general relativity is meaningless unless you gauge fix first. $\endgroup$ – Jerry Schirmer Aug 30 '13 at 4:51

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