On 10/8/2019 4:21 PM, Bruce Kellett wrote:
On Wed, Oct 9, 2019 at 9:53 AM 'Brent Meeker' via Everything List <everything-list@googlegroups.com <mailto:everything-list@googlegroups.com>> wrote:On 10/8/2019 2:41 PM, Bruce Kellett wrote:On Wed, Oct 9, 2019 at 4:35 AM 'Brent Meeker' via Everything List <everything-list@googlegroups.com <mailto:everything-list@googlegroups.com>> wrote: On 10/8/2019 12:10 AM, Bruce Kellett wrote:I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.What do you think he's selling? His book? Actually, he is selling a particular approach to QM, and claiming, in no uncertain terms, that his is the only "true" approach.No. He explicitly says (at 14:45) he's going to explain the interpretation he favors but there are others which he discusses in his book.I was talking about my impression of the lecture, not of his book (which I haven't read).
That's what I'm talking about; that's why I gave the time stamp of where he says it in the lecture.
I take particular exception to his claim that MWI is the SWE and nothing else. He elides the many additional assumptions that he has to make to get correspondence with experience, but derides other approaches for making assumptions! That is just dishonest.What additional assumptions do you mean?What assumptions does he have to make to get a probability interpretation? Probability is not an evident property of the SE. Like many approaches to probability in Everett, he has to assume decoherence to distinguishable branches to get anywhere. But that relies on using the Born rule to justify ignoring branches with low amplitude
The low amplitude branches aren't ignored. Do you mean cross-terms in the density matrix?
-- the notorious "trace over environmental degrees of freedom". Sean's "self-locating uncertainty" is not well-defined.
I tend to agree with you there. But if you assume that the human brain is a classical information processor of limited capacity I think you could get there.
In the lecture he hints that the observer is uncertain about the fate of the cat until he opens the box -- until then he is uncertain of which branch he is on. But given the timescale of decoherence, he has branched within 10^{-20} sec, so the is no longer any "self-locating uncertainty" -- he is definitely on one branch or the other, he just doesn't know which. And that is just classical probability due to lack of knowledge -- nothing quantum about it. In another interview, he does suggest that the "self-locating uncertainty" lasts only until decoherence reaches the observer, at which time copies become entangled within each branch. Now if you can think relevant thoughts in 10^{-20} sec, then his argument might make some sense. But it fails to convince.....
So you're faulting him for not calling 1e-20sec zero? Seems nit-picky. I see the problem as sloppy introduction of "the observer" harking back to CI. If observers are quasi-classical (no funny stuff in microtubles) then it should be enough to talk about uncertainty in the location of the geiger counter or the environment, but I understand Sean is trying to explain why, according to Everett, people don't see the superposition.
I think Carroll is a good speaker, a good popularizer, and a nice guy. He is certainly a polished speaker, and is probably a nice guy. But that does not make him right. I feel fortunate to have him representing physics to the public. He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI. Maybe so in his book, but that was not apparent in the lecture. Also, he's the only scientist who debated William Lane Craig and won by every measure. Bully for him. Debating William Lane Craig is not the height of science......No but several scientists have not done well at it, including Vic. That is probably an interest of yours.
It was a big part of the interests on this list when Vic was writing his books.
I fail to share it, and it is not science.
As Vic said, "Science isn't everything, but it's about everything."
There will always be people who fail to be convinced by science or by argument, and debating skills are not a prerequisite for good science.
No, but they can be important in communicating good science to people...and we could certainly use more of that.
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