Thanks for forwarding this post, Rebecca! Despite its confident--indeed, we have to say, smug--tone, this atheist’s post is riddled with errors, exposing his claim to have studied cosmology “
extensively” and to “
understand the subject well” as just so much empty posturing. You needn’t be intimidated by his condescending assertions that “
when you actually understand the cosmology, and when you actually ask real cosmologists. . . , you can see that theistic apologists exclusively misrepresent the BVG theorem.” You may be assured that I and my collaborator James Sinclair have discussed these issues personally (and carried on extensive correspondence) with not only Vilenkin, but also such prominent cosmologists as George Ellis, Christopher Isham, Donald Page, James Hartle, Robert Brout, and many others in order to ensure the accuracy of our work.
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Some of your friend’s mistakes are just amusing, some more serious.
For example, on the amusing end, if one is going to opine about the BGV theorem, then don’t you think one should at least get the name of the theorem right? -- the BGV theorem (for Borde-Guth-Vilenkin, in alphabetical order), not the BVG theorem. And one should cite one’s sources correctly, don’t you think? I was amazed to see an anonymous quotation (which is, in fact, from a blogger named Arizona atheist
[2]) in which your friend misrepresents what Vilenkin had said to Victor Stenger about cyclic models. In my debate with Peter Millican, who (innocently) also uses this quotation, I explained that in context Vilenkin says that such cyclic models fail for
other reasons to evade the beginning of the universe implied by the BGV theorem (a fact omitted by your atheist friend).
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More seriously, concerning the central claim from the 2003 BGV paper, as I explain in my debate with Sean Carroll and in my article “Big Bang Cosmology,”
The BGV theorem proves that classical spacetime, under a single, very general condition, cannot be extended to past infinity but must reach a boundary at some time in the finite past. Now either there was something on the other side of that boundary or not. If not, then that boundary is the beginning of the universe. If there was something on the other side, then it will be a non-classical region described by the yet to be discovered theory of quantum gravity. In that case, Vilenkin says,
it will be the beginning of the universe.
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Either way, the universe began to exist.
Therefore, your atheist friend is just misinformed when he says, “
Vilenkin has stated numerous times (such as in the quote I've provided above [NB the one from Arizona atheist!]
) that the theorem he worked on with Arvind Borde and Alan Guth does not prove that the Universe has a beginning.” Hmm! Here are Vilenkin’s reflections on the significance of that theorem in 2006:
The theorem proved in that paper is amazingly simple. Its proof does not go beyond high school mathematics. But its implications for the beginning of the universe are very profound. . . . With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape: they have to face the problem of a cosmic beginning.
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