Saturday, October 5, 2013

The Misleading Krauss? (p. 2)

Krauss and Craig
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My interaction with Krauss



There’s more to the story too. Craig made a response at Reasonable Faith arguing that Krauss’s use of the edited email was misleading, and Krauss made a post on Facebook that was appears to be a response to Craig’s claim about the use of the edited email being misleading. To quote Krauss’s Facebook post entry:
From me and Alex Vilenkin--sigh--in muted response to some claims that have been posted by some whose buttons have probably been pushed by being wrong:

"In response to the noise regarding the use of an email communication between the two of us in a dialogue with William Lane Craig, there are two relevant points we have decided to make.

1. we both willingly agreed to the request from Dr. Craig to have the full email, which had been edited on the powerpoint slide simply to save time during a 15 minute presentation by Krauss, as there was nothing in the full correspondence that either of us were concerned about sharing.

2. we both agree that the edited version does not distort the content or ideas expressed in the original email at all. Those who are claiming otherwise, including apparently Dr. Craig, are mistaken.

Lawrence Krauss and Alex Vilenkin"
Last week I had a little electronic interaction with Krauss himself. Here was my Facebook post (with the text formatted a bit for neatness).
@Lawrence Krauss

I think you ought to realize why some people might find the edited version of the email potentially misleading; certainly I would have been given a false impression if I hadn’t known a bit of Vilenkin’s background. To see why, let’s consider a concrete example:
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. . . . . .
Whether you realize it or not, this sort of thing might give one the impression that the BGV theorem doesn’t provide significant evidence for there being a beginning of the universe due to the loophole mentioned here. But now look at it in context:
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.
Look at this way: a person reading the edited email might say to a theist, “See! There’s a loophole here to get around the supposed evidential force the BGV theorem has for a beginning of the universe.” But when one reads the quote in context, a somewhat different impression is given. By leaving the “essentially equivalent to a beginning” etc. part out, the edited email delivers a false impression about the nature of the BGV theorem and the beginning of the universe, even if that wasn’t your intention.

Now consider another example:
. . . 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 contraction. . . 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, . . . it is not at all clear that the BGV assumption (expansion on average) will be satisfied.
Whether you realize this or not, this kind of gives the impression that Vilenkin might believe the multiverse avoids the evidential force of the BGV with respect to a beginning of the universe. Think of an atheist looking at this quote and using it against a theist saying, “See! Vilenkin doesn’t think the BGV theorem provides much evidence for a beginning of the universe.” But including the omitted parts would deliver a somewhat different impression:
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.
So there are a couple key omissions here: the sort of model which avoids a big crunch singularity is usually assumed to be incorrect, and Vilenkin suspects the theorem can be extended to this case. Omitting all this has at least the potential to deliver a false impression with respect to what Vilenkin believes about the evidential force the BGV theorem has for the beginning of the universe.

It seems to me that William Lane Craig asked some valid questions (http://www.reasonablefaith.org/...):
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?
Maybe there are valid answers to these questions, but the fact that these are pretty good questions to ask reveals that you might not realize how potentially misleading these omissions were when it came to the topic of the BGV theorem and the beginning of the universe. Again, maybe this wasn’t your intention, but omitting relevant details like this isn’t recommended if the goal is to prevent giving a false impression.
Krauss responded:
Wade thanks for your note.. however the points I made were, as I explained to Craig at the time: (1) it is possible that we live in a bouncing universe, even if I would suggest current evidence and theory make that less likely than the alternative. (2) BGV rely on extrapolating back to singularity.. quantum gravity could change everything and we don’t have a theory.. therefore at this point anything goes.. all points in Alex’s email as I showed it.. and beyond that, as I explained.. the universe having a beginning or not (especially poorly defined in the case that time arises after the big bang) is irrelevant anyway, and he should stop fixating on it.. Moreover, as you will see, it was one slide out of 15 or so in a 15 min presentation, and the issues regarding entropy are interesting, but not appropriate for a general, non-scientific audience discussion with craig.
Many of the points I brought up he did not address; indeed there was an almost complete lack of engagement with why the quote was potentially misleading (e.g. Krauss did not answer Craig’s question about why “It seems to me that it is essentially equivalent to a beginning” was omitted). His point about the universe having a beginning or not being irrelevant was puzzling as well as clearly false, since the beginning of the universe is a obviously crucial part of Craig’s argument. Krauss doesn’t address the “It seems to me that it is essentially equivalent to a beginning” sentence and instead continues to talk about entropy as if the “It seems to me…” sentence didn’t exist, just as he did with Craig earlier.

At that point I realized it was probably hopeless to convince Krauss that his edited email was potentially misleading, so I gave him some advice on how to better attack the argument. After all, if he agrees with Craig that the “universe begins to exist” premise is more plausible than its denial, it would be better to attack some other part of the argument. It was my modest hope that my advice would help lead to less misleading statements and more substantive objections.

It’s easy to see how some would suspect Krauss of intentionally misleading his audience with the edited email, e.g. leaving out the “essentially equivalent to a beginning” part, but I don’t think that’s what quite happened. But then how to explain what Krauss did?

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