Various and Sundry

A few unrelated items:

  • Maybe Multiverse Mania in the popular press is fading. The Atlantic has The Multiverse Idea is Rotting Culture, where the author points out

    In 2014, the New Scientist published an article called “Multiverse Me,” revealing that various lonely boffins take succor from the fact that alternate versions of themselves are leading fun lives full of emotional and sexual fulfillment, instead of solitudinous slogs through the stupid infinity of high-level algebra.

    They’re not jealous; they want the best for their alternate selves, they want them to be happy. How can you help? The answers given are all cop-outs; the scientists have decided to keep on living as if the multiverse didn’t exist (“The multiverse,” one says, “tells us that we should behave as if we were valuing the risks according to probabilities in a classical universe”), because if it does exist the implications are horrifying. Right now, infinite versions of yourself are dying in really horrible ways, not in spite of the fact that you’re lazily giving answers to a New Scientist reporter, but because of it. Every second you live, their suffering increases. If you stand on a cliff-edge and decide not to die, how many billions are smashed on the rocks? Jump now, and save them all.

  • Over at Scientific American, Lee Billings has a story about dark matter and the lack of evidence for WIMPS.
  • At CASW Showcase, an interesting interview with Natalie Wolchover.
  • Carlo Rovelli has posted on the arXiv The dangers of non-empirical confirmation, his contribution to the Why Trust a Theory? meeting discussed here and here.
  • Next week there will be a Natifest at the IAS, celebrating Nati Seiberg’s 60th birthday. I’ll try and get down there for the first day, leaving on a trip (more about that to come) later in the week.

    There’s a wonderful discussion with Seiberg arranged by Hirosi Ooguri that is well worth reading.

  • Denny Hill wrote recently to tell me about an interesting article on the history of the study of gravitational wave solutions, by him and Pawel Nurowski, now on the arXiv here.

Update: One more. Congratulations to Nigel Hitchin, whose 70th birthday celebrations are now ongoing. See here, here and here.

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24 Responses to Various and Sundry

  1. Richard says:

    Is the content of the gravitational waves paper discussed in Janna Levin’s “Black Hole Blues” book?

  2. Prof CJ says:

    It’s Denny Hill and Pawel Nurowski

  3. Robert Levine says:

    Isn’t Kriss (following the New Scientist piece he refers to) conflating Everett’s many-worlds interpretation of QM with the landscape-type multiverse more recently promoted as a rationale for the vast space of vacuum states compatible with string theory? The two concepts *seem* to have very little to do with each other…

  4. Peter Woit says:

    Richard,
    Not really (from what I remember of the Levin book). There’s a well-known story about Einstein’s early mistake about gravitational waves that is in both places, but otherwise the Hill/Nurowski paper mostly discusses mathematical history not covered by Levin.

    Prof CJ,
    Thanks, fixed.

    Robert Levine,
    Yes, they’re two completely different things, but physicists promoting multiverse mania often conflate the two. The article is not about the physics but about the mania.

  5. bayes_or_bust says:

    Whilst I don’t quite agree with everything, Rovelli’s rebuttal is excellent.

    Dawid’s ideas weren’t ever very interesting. They gained traction because they supported string theorists at a time when many are questioning their modes of reasoning.

    I’d be curious to know historical examples of scientists acclaiming particular new ideas in philosophy at moments of (real or perceived) crisis or change.

  6. Peter, Robert, how do we know they’re different? Many worlds has to do with entanglement, and from enthusiastic theorists we learn that EPR = ER, and Einstein Rosen wormholes could connect different spacetimes or causally disconnected regions of our infinite universe…. (I kid, I kid. But you know Kaku will have a show on TV about this within a month.)

  7. Prof CJ says:

    One more time, it’s Pawel Nurowski. True,
    Americans are typically monolingual so they
    have little insight into how other languages
    function but this cannot be that difficult

  8. Peter Woit says:

    Prof CJ,
    Fixed. I think the problem here is not the number of languages I speak (two pretty well, a couple more badly) but distraction due to busyness of first week of classes. And also sleep deprivation due to time spent downtown watching Kieslowski’s(sp?) Dekalog (4 hours down, six to go…)

  9. Jeffrey M says:

    Peter,

    Dekalog is worth it. Also, if you haven’t already, go see Red, White, and Blue.

  10. John says:

    “In 2014, the New Scientist published an article called “Multiverse Me,” revealing that various lonely boffins take succor from the fact that alternate versions of themselves are leading fun lives full of emotional and sexual fulfillment, instead of solitudinous slogs through the stupid infinity of high-level algebra.”

    What is this repugnant rubbish? Multiverse theories are discredited because they are totally unsubstantiated by experiment, not because they may reflect fetishes and fantasies of individual researchers, or because they contradict peoples’ moral sensibilities. Sorry to be insulting to the blog author – I’ve had one drink too many, but you *are* mocking the piece, right?

    The original article makes some fair points at certain places, but dresses them in an unacceptably mocking rhetoric that, on top of everything, makes no sense. It invokes everyday experience to discredit ideas in a field where everyday experience goes out the window anyway.

    Again: multiverse theories are not rejected because they contradict our sensibilities, but because they are unsubstantiated by our data. At this point I wonder if it is better for certain people to believe that unicorns are possible rather than reject the existence of horses, because for some people this seems to be a dichotomy…

  11. Tim May says:

    I think you are correct: the multiverse/multiple worlds fascination seems to be a somewhat sterile dead end.

    (Understand, I read Larry Niven’s SF about multiple worlds with fascination around 1972 or so. And then Bryce DeWitt came out with his articles and his book on the same, circa around 1973 or so. I might be off by a year or two. Heady stuff. But even as I was taking a class in General Relativity from Jim Hartle himself, it never seemed appropriate to ask things like “But what if we’re just one of 10 to the 1427 power realities?”

    In my opinion, Peter’s “Not Even Wrong” moniker deserves something even stronger for this whole idea of many universes. However, as he notes, it seems to be running out of steam. (This doesn’t make it wrong, just not of much interest.)

    I often think in terms of many worlds to clarify my thinking in QM, but I don’t assume these other possible worlds have any tangible existence, application, etc.

    — Tim May

  12. Yatima says:

    Completely off-topic, but Tim May writes: “I read Larry Niven’s SF about multiple worlds with fascination around 1972 or so.”

    May I enquire which SF that was? Larry Niven was always talking about Big Engineering and Exploration with Magical Physics thrown in as needed in order to play around. We had: Transport Booths, Hyperdrive Shunt engines coming in quantized speed increments (with the Mark II extremely large and extremely expensive), General Products Indestructible Ship Hulls, Bussard Ramjets working with finely managed electromagnetic fields OUTSIDE the ship (how?), Scrith Ringworld Construction Material with supernatural tensile strength and able to stop neutrinos, Stasis Fields inside which time stops, Non-Newtonian drives, Sinclair wire that is practically indestructible and can cut anything, Autodocs, Longevity Drugs and more stuff of Pulp Magazine Wonder, but we didn’t have multiple worlds. Indeed, Quantum Mechanics wasn’t even mentioned once as far as I can remember.

  13. Dom says:

    Regarding Kieslowski, “Red” and “Double life of Veronique” both starring Irene Jacob are two of the best films I’ve ever seen.

  14. Peter Woit says:

    Please, enough about Larry Niven.

    John,
    Just about none of the popular discussion of the multiverse has any scientific content whatsoever. What I found interesting was just that this latest example was countering the usual “Gee whiz, isn’t this cool?” with “This is awful!”. I think it may be some indication of the (to me) long-awaited moment where people get sick of hearing the same nonsense about this.

  15. paddy says:

    Peter: Damn! And I was just typing up my critique of L. Niven. Actually just commenting to thank you for the Rovelli link.

  16. Prof CJ says:

    Kieślowski’s Dekalog is indeed powerful. I was
    going to recommend “Red” (one theme is Jungian
    synchronicity) and “Double Life of Veronique” but
    Dom beat me to it. “Blind Chance” is not bad, and
    at least conceptually is related to physics.

    I hope I wasn’t too harsh in posting my correction.

  17. Low Math, Meekly Interacting says:

    I conjecture such new-found disdain for the anthropic principle in the pop-sci press is connected to the failure to find experimental evidence for weak-scale SUSY. We’ve been hearing for literally decades that SUSY is part of a grander framework that implies a multiverse, and part of what makes it so grand is SUSY’s many testable virtues. With the latest crop of null results, it can no longer be avoided: the amount of baroqueness needed to keep weak-scale SUSY alive is past the “psychological threshold” of even many ardent supporters. Bottles of fine cognac have publicly changed hands. Since long-cherished ideas now face the likely prospect of failure, reliance on the speculative judgment of their proponents also seems questionable.

    I’d rather they pointed out anthropism’s obvious problems on their own much earlier, instead of finally dropping an argument from authority only when it’s become impossible to do otherwise and remain credible. But I suppose it’s a step in the right direction.

  18. Yatima: short story, “All the Myriad Ways”. (Sorry Peter.)
    Regarding the very nice SciAm piece about dark matter: Am I correct that the amount of microlensing that is seen/not seen places a strong limit on primordial blackholes as a possible dark matter explanation?

  19. IMHO says:

    Regarding MACHOS: it’s my understanding (and please correct me if I’m wrong) that the yet to be ruled out mass ranges overlap with the masses seen by LIGO. I think primordial black holes as dark matter is still breathing, if only barely.

  20. Mehmet Jon Jonnerson says:

    seems to me Rovelli’s Bayesian argument against string theory is

    PosteriorP(string theory | not SUSY pheno at LHC scale) = (1/P(not SUSY pheno at LHC scale))*P(not SUSY pheno at LHC scale | string theory)*PriorP(String Theory)

    am I right?

    But this seems to require knowledge of P(not SUSY pheno at LHC scale | string theory), which, I don’t think, is at all well known. Like, sure, you can find a guy (e.g. Kane) who will tell you he has *a* model in which the conjunction of clauses (string theory) && (SUSY pheno at LHC scale) is true. But nobody has done the *model counting*.

    So, to even know how to update P(string theory), you have to do SMT on a very complicated Domain Specific Language in which the state explosion problem is very real. Like, 10^500 real.

    So, the problem is, Rovelli’s making an argument which,* given more information about the string theory landscape/multiverse than is known to any string theorist*, may very well discredit string theory. This is, ironically, an argument to *do more string theory*.

    Or, maybe, when Rovelli complaint about string theory’s flexibility, he means there’s a Bayesian parameter estimation problem, where we would like to infer a probability distribution on the parameter space of string theories from our probability distribution of observables. The flexibility problem is that the observability grammian, so to speak, has tiny eigenvalues, at least for the observables available to us thus far- or, truth be told, we don’t even actually know that observability grammian. So, again, we must *do more string theory*.

    For the record, I think Rovelli’s a smart guy who has better things to do than post polemics to the arxiv. Here’s hoping someone sees something at that 7/6 r_{s} region him and Hal were talking about.

    By the way, regardless whether or not the multiverse is a bad idea, the fools in the multiverse me article aren’t fools because they believe in the multiverse, they’re fools because they don’t understand what independent and identically distributed random variables are.

  21. Anonyrat says:

    @Mehmet: Rovelli wrote: “From a Popperian point of view, these failures do not falsify the theory, because the theory is so flexible that it can be adjusted to escape failed predictions. But from a Bayesian point of view, each of these failures decreases the credibility in the theory, because a positive result would have increased it.” {emphasis added}.

    We do not require further knowledge of string theory for Rovelli’s argument to work.

  22. Peter Woit says:

    Mehmet Jon Jonnerson and anyone who wants to argue with him,
    Enough, I have serious trouble making sense of lots of arguments of this kind, and here I’m failing completely, so, while leaving this here in case others can, I’ll delete any more of it, on the simple grounds that I can’t moderate a discussion I can’t make sense of.

  23. Anonyrat says:

    Peter,
    Though the apriori probability of string theory being true and the conditional probability of seeing SUSY at LHC given string theory are both unknown, if we accept the proposition that seeing SUSY at LHC boosts the a posteriori probability of string theory, that gives us a simple inequality,

    Bayesian a posteriori > a priori;

    from which it is two minutes of symbol manipulation to prove that not seeing SUSY at LHC decreases the a posteriori probability of string theory.

  24. Peter Woit says:

    Anonyrat,
    Yes, but I don’t see how dressing this up in Bayesian probability and manipulating symbols does anything but encourage obfuscation of the obvious: if somebody tells you (or publishes a piece in the Wall Street Journal saying) “experiment X seeing Y will be evidence for theory Z” and then experiment X sees not Y, this is negative news for theory Z.

    Exactly how bad the news is for theory Z of course depends on the details of the original argument. If, in retrospect, it was a very weak argument since theory Z can give you pretty much anything, including Y or not Y, then attention should shift from theory Z to why in the world people are discrediting science by making very weak arguments for theory Z in the Wall Street Journal.

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