Not Even Wrong

John Horgan at Scientific American today has an interview with Martin Rees in which Rees says:

It’s presumptuous (as some people like Woit and Smolin have done) to deride the way some manifestly brilliant people choose to dedicate their scientific lives.

I generally try and be careful to criticize not people, but the arguments they are making. Rees and others (including a Cambridge University Press referee for Not Even Wrong, who basically thought I had good points, but was presumptuous to be making them) often seem offended that I or Lee Smolin are challenging arguments from those smarter than ourselves. It’s true that there is a problem with this: bad arguments of the kind I’m criticizing should be challenged by the leading figures in the field, not by me. In particular, many particle theorists smarter and more distinguished than myself are well aware of the problem of multiverse mania, but doing nothing about it, as it destroys the credibility of their field. Among the few personal criticisms of some leading theorists that I have is that they’re not doing the job they’re paid for here, and I’m not happy wasting my time trying to (presumptuously) do it for them.

On the presumptuous behavior front, here’s some more of it:

• Rees’s arguments are the usual multiverse propaganda, including the usual red-herring argument defending the multiverse as science:
  

  It’s sometimes claimed that domains that are in principle unobservable aren’t part of science. But not even the most conservative astronomer would take this line. We’re in an accelerating universe where distant galaxies will disappear over a horizon, and their far future would never be in principle observable. So it’s natural to suppose that there are galaxies that are already beyond the horizon and so forever unobservable. If you’re in the middle of the ocean, you’d be surprised if its boundary lay just beyond your horizon. Likewise, astronomers are confident that the volume of space-time within range of our telescopes — what astronomers have traditionally called ‘the universe’ – is only a tiny fraction of the aftermath of our big bang. We’d expect far more galaxies located unobservably beyond the horizon.

  As usual, Rees gives no evidence for his claim that those skeptical that the multiverse is science are just ignoramuses who don’t understand the notion of indirect evidence for a scientific theory.

  Multiverse mania goes on and on, for instance here and here.

• Among the more presumptuous things I’ve done, there’s last week’s talk.
• I recently noticed here the analysis that:
  

  I “predict” that if by about 2020 the LHC or cosmology do not show any concrete evidence of supersymmetry or superstrings, physicists will attack string theory the way the Huns attacked Rome. Like the Huns, Lee Smolin, Peter Woit, and Roger Penrose have already started encircling string theory, abiding their time, and waiting for the strike. They seem to have read The Rise and Fall of the Roman Empire carefully.

  I’ve never read Gibbon. If one accepts the analogy though, I think it’s conventional wisdom that the String Wars were back in 2006, we didn’t wait for 2020. All the evidence I’ve seen recently is that most string theorists have now given up on the idea that evidence for supersymmetry or string theory will appear at the LHC. Those attempting to defend Rome now are trying to backpedal on their claims from a decade ago. They now argue that finding nothing at the LHC isn’t surprising and doesn’t matter, but this rear-guard action likely will not be effective.

• More evidence that hopes for LHC-scale SUSY are now pretty much dead can be found by looking at the slides from the recent Aachen workshop on Naturalness, Hierarchy and Fine-Tuning. The debate among theorists has now moved on to trying to figure out what conclusion to draw from the failure of widely-promoted claims about “fine-tuning”. One motivation for such claims was that in string theory-based models the CC and Higgs potential are supposedly calculable, with expected results from dimensional analysis that are exponentially large (Planck scale) compared to observations. On this front, an obvious conclusion to draw is just that these models (which are complicated and predict nothing else anyway) are wrong.
• I suppose it really is presumptuous to make a snarky comment about a talk by someone clearly more hard-working and smarter than I am. In any case, I just noticed that slides for Nima Arkani-Hamed’s talk Three Cheers for Shut Up and Calculate! are now available here. I had written about this here without knowing what the talk had been about, based on the historical origin of the “Shut Up and Calculate!” slogan (and thus assuming the measurement problem would be a main topic). From the slides, Arkani-Hamed’s talk wasn’t at all about the measurement problem, but largely about quantum gravity, with many slides of speculative claims about new emergent versions of space-time and quantum mechanics (backed by one slide about calculating amplitudes as volumes). I’m quite sympathetic to what he has to say about the importance of prioritizing well-defined calculations over meaningless verbiage, but it seemed to me that in this talk he wasn’t really taking his own advice. I can’t help wondering who it is that Arkani-Hamed thinks should “Shut up” about vague ideas about quantum gravity and stick to well-defined calculations.

Update: For more presumption, see the latest at Backreaction.

Update: Lee Smolin has been edited out of the list of the presumptuous in the Rees interview, but I’m rather proud to be presumptuous, so I’m still there, and a link has been added to this blog posting.

Today is the 15th anniversary of the event that kicked off the Multiverse Mania that continues to this day, recently taking the form of a concerted attack on conventional notions of science. 2018 has seen an acceleration of this attack, with the latest example appearing this weekend.

On January 29, 2003, Kachru, Kallosh, Linde and Trivedi submitted a paper to the arXiv that outlined a construction of a supposed model of a metastable string theory state that had all moduli fixed. Ever since the first explosion of interest in string theory unification in 1984-5, it had been clear that a big problem with using string theory to get anything that looks like known physics was the so-called “moduli problem”. If you try and use 10d superstring theory to describe our universe, you need to somehow hide six of the dimensions, and the best way to do that seemed to be to argue that superstring theory implied one could do this by compactifying on an unobservably small approximately Calabi-Yau manifold. Such manifolds however come in families labeled by “moduli” parameters, which can be thought of as describing the size and shape of the Calabi-Yau. These moduli will show up as zero mass fields generating new long-range forces unless some dynamical mechanism could be found to fix their values. It was this that KKLT claimed to have found. I won’t even try to describe the complex KKLT proposal, which was aptly described by Lenny Susskind as a “Rube Goldberg mechanism”.

What string theorists had been hoping for was a moduli stabilization mechanism that would pick out specific moduli field values, getting rid of the unwanted dozens of new long-range forces and providing a way to make physical predictions. While the KKLT mechanism got rid of the unwanted forces, it had been observed three years earlier by Bousso and Polchinski, working with just parts of the Rube Goldberg mechanism, that this sort of thing led to not one specific value of the moduli fields, but an exponentially large number of possibilities. They had noted that this could allow an anthropic solution to the cosmological constant problem, and the KKLT fixing of all the moduli provided a model that accomplished this (without the long range forces).

KKLT did not mention anthropics and the multiverse, but less than a month later Lenny Susskind published The Anthropic Landscape of String Theory, a call to arms for anthropics and a founding document of Multiverse Mania. He immediately went to work on writing a book-length version of string theory multiverse propaganda aimed at the public, The Cosmic Landscape, which was published in 2005. Less than a month after Susskind’s manifesto, Michael Douglas published a statistical analysis of supposed string/M-theory vacua, and at some point the estimated number $10^{500}$ of vacua started appearing based on this sort of calculation.

I didn’t notice KKLT when it appeared, but did notice the Susskind arXiv article. I had just finished writing the first version of my book, and remember that my reaction to the Susskind article was roughly “Wow, if people like Susskind are arguing in effect that you can’t predict anything with string theory, that’s going to pull the plug on the subject.” The book took a while to find a publisher, and by the time it was published I had tacked on a chapter about the multiverse problem. I started this blog in March 2004, and recently looked back at some of the earliest postings, noticing that a huge amount of time was spent arguing with people about KKLT and its implications for the predictivity of string theory. It seemed clear to me from looking at the calculations people were doing that this kind of thing could not ever lead to a prediction of anything. I won’t go over those arguments, but claim that my point of view has held up well (no prediction of anything has ever emerged from such calculations, for reasons that are obvious if you start looking at them).

Back in 2003-4 I never would have believed that the subject would end up in the state it finds itself in now. With the LHC results removing the last remaining hope for observational evidence relevant to string theory unification, what we’ve been seeing the last few years has been a concerted campaign to avoid admitting failure by the destructive tactic of trying to change the usual conception of testable science. Two examples of this from last week were discussed here, and today there’s a third effort along the same lines, Quantum Multiverses, by Hartle. Unlike the others, this one includes material on the interpretation of quantum mechanics one may or may not agree with, but of no relevance to the fundamental problem of not having a predictive theory that can be tested.

I’m wasting far too much time discussing the obvious problems with articles like this, to no perceptible effect. Hartle like the others completely ignores the actual arguments against his position (he lists some references. describing them as “known to the author (but not necessarily read carefully by the author)”). In a section on “A FAQ for discussion” we find arguments that include

• The cosmological multiverse is falsifiable, because maybe you’ll falsify quantum mechanics.
• The cosmological multiverse is testable: “by experiment if a very large spacetime volume could be prepared with an initial quantum state from which galaxies, stars, life etc would emerge over billions of years.” Not surprisingly, no indication is given of how we will produce such a state or any theory that would describe what would happen if we did.
• The theory of evolution is just like the theory of the cosmological multiverse.

Both the absurdity and the danger of this last argument are all too clear.

By the way, for a while earlier this year the arXiv started allowing trackbacks again to this blog, but then this stopped again. The origin of the ban seems to have been in the story described here and my early criticism of the string theory multiverse. I have no idea what their current justification for the ban is.

Update: A good place to look for information about the current state of string landscape calculations is at the website for this workshop. The idea that the problems of this subject can be solved by “modern techniques in data science” seems to me absurd, but for a different point of view, look at the slides of Michael Douglas. For something more sensible, try the talk by Frederik Denef, which describes some of the fundamental intractable problems:

• You don’t have a complete theory, with only some non-perturbative corrections known, no systematic understanding of these.
• Dine-Seiberg Problem: When corrections can be computed, they are not important, and when they are important, they cannot be computed.
• Measure Problem: Whenever a landscape measure is strongly predictive, it is wrong, and when it’s not, we don’t know if it’s right.
• Tractability Problem: Whenever a low energy property is selective enough to single out a few vacua, finding these vacua is intractable.

Denef does make some very interesting comments about where modern techniques in data science might actually be useful: dealing not with the landscape of string vacua, but with the huge landscape of string theory papers (e.g. the 15,000 papers that refer to the Maldacena paper). He argues:

For obvious reasons, besides time constraints, incentives to write papers are much stronger for research scientists than to read them. So printed stacks pile up unread, PDFs remain ambitiously open until we reboot our laptops, recursive reference-backtracking gets sidetracked by the deluge of micro-distractions puncturing our days. This, plus the sheer volume of disorganized pages of important results, leads to loss of access to crucial knowledge, to repeated duplication of efforts, and to many other
inefficiencies. Worst of all, it becomes increasingly harder for young brilliant minds to stand on the shoulders of giants, and thus to make revolutionary new discoveries. It seems inevitable that we will have to outsource the tedious task of parsing the literature, in search for relevant results, insights, questions and inspiration, to the Machines.

Update: There’s an interesting article at Quanta magazine about “Big Bounce” models of the Big Bang, competitors to inflationary models. Paul Steinhardt gives his take on the multiverse: “hogwash.”