Uploaded September 2013 | Updated September 2026, 1 day ago
"I think you represented what I wrote about the BGV theorem in my papers and to you personally very accurately." - Alexander Vilenkin's e-mail to William Lane Craig, dated September 6, 2013
In their debate in Australia (2013), Lawrence Krauss accused William Lane Craig of misrepresenting Alexander Vilenkin and the BGV Theorem. To prove his point Krauss presented his private e-mail from Vilenkin. However, Craig noticed a number of ellipsis in the e-mail and wanted to know what Krauss deleted. Krauss said he deleted portions of the e-mail because they were "technical." Guess what? Vilenkin's uncensored e-mail to Krauss has been made public and it paints a different picture than the one Krauss presented. Here's the uncensored e-mail from Vilenkin to Krauss:
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Hi Lawrence,
Any theorem is only as good as its assumptions. The BGV theorem says that if the universe is on average expanding along a given worldline, this worldline cannot be infinite to the past.
A possible loophole is that there might be an epoch of contraction prior to the expansion. Models of this sort have been discussed by Aguirre & Gratton and by Carroll & Chen. They had to assume though that the minimum of entropy was reached at the bounce and offered no mechanism to enforce this condition. It seems to me that it is essentially equivalent to a beginning.
On the other hand, Jaume Garriga and I are now exploring a picture of the multiverse where the BGV theorem may not apply. In bubbles of negative vacuum energy, expansion is followed by cocntraction, and it is usually assumed that this ends in a big crunch singularity. However, it is conceivable (and many people think likely) that singularities will be resolved in the theory of quantum gravity, so the internal collapse of the bubbles will be followed by an expansion. In this scenario, a typical worldline will go through a succession of expanding and contracting regions, and it is not at all clear that the BGV assumption (expansion on average) will be satisfied.
I suspect that the theorem can be extended to this case, maybe with some additional assumptions. But of course there is no such thing as absolute certainty in science, especially in matters like the creation of the universe. Note for example that the BGV theorem uses a classical picture of spacetime. In the regime where gravity becomes essentially quantum, we may not even know the right questions to ask.
Alex
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William Lane Craig's reaction to this uncensored e-mail:
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Whoa! That puts a very different face on the matter, doesn't it? Why didn't Krauss read the sentence, "It seems to me that it is essentially equivalent to a beginning"? Because it was too technical? Is this the transparency, honesty, and forthrightness that Krauss extols? (By the way, Vilenkin's criticism of these models is the same one that Vilenkin makes in his Cambridge paper: far from showing an eternal past, these models actually feature a universe with a common beginning point for two arrows of time.)
And why did Krauss delete Vilenkin's caveat that the BGV theorem can, in his estimation, be extended to cover the case of an expanding and contracting model such as Garriga and Vilenkin are exploring? And why delete the remark that such a model is usually assumed to be incorrect? It's evident that Vilenkin's email was selectively edited to give it the spin Krauss wanted.
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Lawrence Krauss is in deep trouble for taking Vilenkin out of context like this. This proves Krauss is more interested in ideology than scientific evidence. This dishonesty shows he fails as a serious academic and leading thinker in physics and science. To read more on Lawrence Krauss' misuse of Alexander Vilenkin go here (this a must-read article!): reasonablefaith.org/honesty-transparency-full-disclosure-and-bgv-theorem
"I think you represented what I wrote about the BGV theorem in my papers and to you personally very accurately." - Alexander Vilenkin's e-mail to William Lane Craig, dated September 6, 2013
In their debate in Australia (2013), Lawrence Krauss accused William Lane Craig of misrepresenting Alexander Vilenkin and the BGV Theorem. To prove his point Krauss presented his private e-mail from Vilenkin. However, Craig noticed a number of ellipsis in the e-mail and wanted to know what Krauss deleted. Krauss said he deleted portions of the e-mail because they were "technical." Guess what? Vilenkin's uncensored e-mail to Krauss has been made public and it paints a different picture than the one Krauss presented. Here's the uncensored e-mail from Vilenkin to Krauss:
===========================
Hi Lawrence,
Any theorem is only as good as its assumptions. The BGV theorem says that if the universe is on average expanding along a given worldline, this worldline cannot be infinite to the past.
A possible loophole is that there might be an epoch of contraction prior to the expansion. Models of this sort have been discussed by Aguirre & Gratton and by Carroll & Chen. They had to assume though that the minimum of entropy was reached at the bounce and offered no mechanism to enforce this condition. It seems to me that it is essentially equivalent to a beginning.
On the other hand, Jaume Garriga and I are now exploring a picture of the multiverse where the BGV theorem may not apply. In bubbles of negative vacuum energy, expansion is followed by cocntraction, and it is usually assumed that this ends in a big crunch singularity. However, it is conceivable (and many people think likely) that singularities will be resolved in the theory of quantum gravity, so the internal collapse of the bubbles will be followed by an expansion. In this scenario, a typical worldline will go through a succession of expanding and contracting regions, and it is not at all clear that the BGV assumption (expansion on average) will be satisfied.
I suspect that the theorem can be extended to this case, maybe with some additional assumptions. But of course there is no such thing as absolute certainty in science, especially in matters like the creation of the universe. Note for example that the BGV theorem uses a classical picture of spacetime. In the regime where gravity becomes essentially quantum, we may not even know the right questions to ask.
Alex
===========================
William Lane Craig's reaction to this uncensored e-mail:
===========================
Whoa! That puts a very different face on the matter, doesn't it? Why didn't Krauss read the sentence, "It seems to me that it is essentially equivalent to a beginning"? Because it was too technical? Is this the transparency, honesty, and forthrightness that Krauss extols? (By the way, Vilenkin's criticism of these models is the same one that Vilenkin makes in his Cambridge paper: far from showing an eternal past, these models actually feature a universe with a common beginning point for two arrows of time.)
And why did Krauss delete Vilenkin's caveat that the BGV theorem can, in his estimation, be extended to cover the case of an expanding and contracting model such as Garriga and Vilenkin are exploring? And why delete the remark that such a model is usually assumed to be incorrect? It's evident that Vilenkin's email was selectively edited to give it the spin Krauss wanted.
===========================
Lawrence Krauss is in deep trouble for taking Vilenkin out of context like this. This proves Krauss is more interested in ideology than scientific evidence. This dishonesty shows he fails as a serious academic and leading thinker in physics and science. To read more on Lawrence Krauss' misuse of Alexander Vilenkin go here (this a must-read article!): reasonablefaith.org/honesty-transparency-full-disclosure-and-bgv-theorem
