Various and Sundry

  • It seems to be too early for April Fool’s day, and yet the arXiv has Dark Matter as a Trigger for Periodic Comet Impacts by Lisa Randall and Matt Reece, a preprint described as “Accepted by Physical Review Letters, 4 figures, no dinosaurs.” The Register has a story: Dark matter killed the dinosaurs, boffins suggest.

    Also recently at the arXiv in a similar “too early for April 1″ category is Crossing Stocks and the Positive Grassmannian I: The Geometry behind Stock Market, which deals with the “stockmarkethedron”, also known as the Geometrical Jewel at the Heart of Finance.

  • The president’s FY2015 budget request is out, with news for HEP not so good: a 6.6% cut proposed in DOE HEP funding. No details about the NSF budget, but the proposal is basically for flat funding (an overall cut of .03% in the research budget). The NSF is proposing one big increase, 13.5% for management. This is just an initial proposal from the administration, with the possibility of something different ultimately emerging from Congress.
  • The particle physics documentary Particle Fever opens here in New York at Film Forum tonight, with appearances tonight and this weekend by the director and “physicists from the film”. There’s a review in today’s New York Times.

    I saw the film last fall at the New York Film festival and wrote about it here, with the summary:

    most of it I thought was fantastically good and I really hope it finds distribution and gets widely seen. On the other hand, some of it I thought was a really bad idea.

    The film is a very inspiring inside look at the LHC experimental search for and discovery of the Higgs. My misgivings were about the theoretical framing of the story, which was the Arkani-Hamed point of view that this is all about two alternatives: SUSY or the multiverse. The NYT review shows that these misgivings were quite justified, with the reviewer’s summary of what they learned about the significance of the Higgs from the film:

    While the discovery of the Higgs may not have immediate consequences for the way we live, or applications in the world of technology and industry, its implications, according to “Particle Fever,” could hardly be more profound. Through most of the film, the scientists are awaiting a specific bit of data, a single number that will either vindicate a theory of the universe known as supersymmetry or suggest the possibility of multiple universes.

    The differences between these two outcomes seem very stark. In the first case, more particles are likely to be found, contributing to a detailed and orderly picture of the nature of things. In the second, the Standard Model will be thrown into chaos, and the stability of the universe itself may be called into question. It won’t be the end of the world, but for some theorists, it will feel that way.

    Mr. Kaplan is hoping for supersymmetry. His friend and sometime table tennis partner, Nima Arkani-Hamed of the Institute for Advanced Study in Princeton, is in the multiverse camp.

    Physicists often get outraged when they feel journalists badly misrepresent science to the public. Will they get equally outraged when it is physicists doing the misrepresenting?

  • For some insight into the current concerns of particle theorists, you can watch some of the videos at last week’s KITP conference. In particular, there’s Matt Strassler’s talk, where he got all Peter Woit and argued that “one could make the argument” that not seeing SUSY (or anything else stringy) at the LHC “would be significant circumstantial evidence against string theory as a description of nature” and that just seeing the SM at the LHC would be “circumstantial evidence against effective quantum field theory as a complete description of known particle physics”. This got him an argument from Gross about his insufficient enthusiasm for a 100 TeV collider. Gross then also got all Peter Woit, arguing that the failure of the “naturalness” argument for new physics was no big deal since it wasn’t a very good argument to begin with (I get all sorts of grief when I do this..).
    The conference ended with a session of people trying to predict the future of the field 30 years hence. This was mostly pretty discouraging, with a lot of people envisioning more of the same: endless generalities about quantum gravity, firewalls etc. Prominent by its absence was any role of mathematics in theoretical physics, with only Greg Moore speaking up for the question of the significance of now popular 6d superconformal theories, and Nati Seiberg mentioning that connections of the field to mathematics were a good thing.

    Lots of talks mentioned people’s good experiences working with and interacting with Polchinski, who seems to be a very nice guy. I’ve never met him personally, but people have speculated to me that he had something to do with the decision of the arXiv to block links to my blog (he was unhappy about my characterization of his Scientific American article promoting the multiverse). What the truth is about that particular story I suppose I’ll never know.


Update
: Another review of Particle Fever leads with this explanation of the main point they got from the film:

Stakes come no higher than in Particle Fever, a dazzling, dizzying documentary about nothing less than whether we exist in a coherent universe of ordered, even beautiful laws — or whether, as Princeton physicist Nima Arkani-Hamed theorizes, our universe is one of an infinite set of other universes defined by a chaotic mash-up of unstable, inexplicable, random conditions.

Update: Reddit has a live Q and A with physicists involved in the film. Savas Dimopoulos (described as “considered the most likely to have a theory confirmed by the LHC”) argues for the multiverse and tells questioners that “We may know about whether Nature prefers the Multiverse or the more traditional (super)symmetry path after the second run of the LHC which will start in a year.” Arkani-Hamed also gives the multiverse argument, also claiming “I envy anyone who is jumping into fundamental physics as a grad student today!”. No theorists in sight who might think there’s more significance to the negative LHC results about SUSY than “must be the multiverse”.

Update: Reddit the next day hosted a live Q and A with Michio Kaku. He there explains to the public that:

The best theory comes from string theory, which states that dark matter is nothing but a higher vibration of the string. We are, in some sense, the lowest octave of a vibrating string. The next octave is dark matter….

The next big accelerator might be the ILC in Japan, a linear collider which might be able to probe the boundaries of string theory…

In the coming decades, I hope we find evidence of dark matter in the lab and in outer space. This would go a long way to proving the correctness of string theory, which is what I do for a living. That is my day job. So string theory is a potentially experimentally verifiable theory.

Seems that well-known theorists going on Reddit to mislead the public is now a daily phenomenon…

Posted in Multiverse Mania, Uncategorized | 25 Comments

All Hail Resonaances

I’m delighted to see Jester back in action, providing great material on the current state of HEP physics, with, over the past week and a half:

  • A sober look at the sparse prospects for near-term (i.e. 2014) input from experiment, with the Planck CMB polarization results one of the few things for which there are significant expectations.
  • An equally sober look at the problem of making the case for a 100 TeV collider, given that this will be the first time people don’t have a “no-lose theorem” showing that something new has to turn up in the new energy range being explored (of course the argument that it’s an unexplored new energy range remains an excellent one by itself for the exploration). About the arguments Arkani-Hamed is making, Jester has:

    Nima’s idea that we need a 100 TeV collider to prove that SUSY fine-tuning is larger than 0.01% is good. As a joke to relax the atmosphere. Certainly, the case for the new collider can be made stronger than that.Some ideas that are being bandied around are precision Higgs physics, double Higgs production, rare Higgs and top decays, non-perturbative electroweak effects, or WW scattering. These topics can be made more concrete and several more items can be added to the list.

  • To give us all some hope, he has some news about a possible astrophysical X-ray spectrum signal that could conceivably be evidence for a sterile neutrino dark matter candidate. Right-handed neutrino fields fit naturally into the SM pattern of fundamental fields, but with zero SU(3)xSU(2)xU(1) charges. That such fields have something to do with dark matter looks more promising than the SUSY or axion proposals of introducing a new and different sector of fields. My knowledge of neutrino physics isn’t what it should be, so I’d be curious to hear of good references about the sterile neutrino dark matter issue.

Update: For some idea of the case being made for a larger collider, one might want to take a look at talks in Beijing a few days ago, where there’s a proposal for the Chinese to build it. Talks at a conference are here, and last Sunday there was a big event featuring Yau, Gross, Witten, Arkani-Hamed, ‘t Hooft, Maiani and Incandela, video here. On the whole people seem to be pretty much sticking to making the generic case for high energy, not promising superpartners or extra dimensions this time.

Posted in Uncategorized | 19 Comments

Quantum Mechanics, The Theoretical Minimum

In recent years Leonard Susskind has been giving an excellent series of lectures on basic ideas of theoretical physics, under the title The Theoretical Minimum. The general idea seems to be to provide something in between the usual sort of popular book about physics (which avoids equations and tries to give “intutitive” explanations in ordinary language) and conventional undergraduate-level textbooks. Such textbooks generally assume college-level multi-variable calculus, differential equations and linear algebra, and often skip lots of detail and motivation, assuming that the book is a supplement to a standard course of lectures.

For Susskind’s lectures, you mostly just need high-school level mathematics, up to some some basic differential calculus, as well as two by two matrices. Actually though, if you’ve never seen matrices and very simple linear algebra, this is a good place to learn some basics examples of this subject.

A year ago the first book version of some of the lectures appeared as The Theoretical Minimum, with George Hrabovsky writing up Susskind’s lectures on classical mechanics. I wrote a little bit about the book here, and was quite impressed by the way it managed to give the details of the formalism of Hamiltonian mechanics, while sticking to as simple and concrete mathematics and calculational tools as possible.

Today is publication day for the next volume, Quantum Mechanics: The Theoretical Minimum, which is a joint effort this time with Art Friedman. It’s even better than the first volume, taking on a much more difficult subject. About the first two-thirds of the book sticks to the simplest possible quantum system, one with a two-dimensional state space. The linear algebra needed is developed from scratch and Susskind works out at a very leisurely pace all the details of what the quantum picture of reality looks like in this simplest context. There’s a lot about what “entanglement” really is, and this part ends up with an introduction to Bell’s theorem.

The last third of the book is a quicker-paced trip through the usual material about wave-functions and the Schrödinger equation, ending up with the details for the harmonic oscillator potential.

“The Theoretical Minimum” phrase is a reference to Landau, but it’s a good characterization of this book and the lectures in general. Susskind does a good job of boiling these subjects down to their core ideas and examples, and giving a careful exposition of these in as simple terms as possible. If you’ve gotten a taste for physics from popular books, this is a great place to start learning what the subject is really about.

I only noticed one mistake in the book, on its back cover, where one of the blurbs is attributed to a Professor of Mathematics at Columbia, when I know for a fact that his actual title there is “Senior Lecturer”. Susskind does have a bit of history of getting this point wrong, but probably the fault here lies with the publisher.

Update: Nature has a review here.

Posted in Book Reviews | 20 Comments

More Quick Links

First, a couple of examples of recent progress in mathematics

  • Terry Tao has some new ideas about the Navier-Stokes equation. See his blog here, a paper here, and a story by Erica Klarreich at Quanta here.
  • I’ve been hoping to find more time to learn enough to write something intelligible about a major new advance: Peter Scholze’s recent work on the p-adic geometry of Shimura varieties and results linking torsion classes and Galois representations. I’m still far from being up to that task, but Scholze’s Marston Morse lectures at the IAS are a good place to start (see here, here and here). Last week MSRI hosted a very successful week-long “Hot Topics” program on this, see here.
  • For more IAS talks, see “Cross-disciplinary” talks last week by Witten, Seiberg and Maldacena.
  • Nature has a story about a recent discovery by Cormac O’Raifertaigh and collaborators of an unpublished manuscript by Einstein containing a “steady-state” cosmological model.
  • A computer scientist has identified more than 120 papers published in supposedly peer-reviewed conference proceedings that were all randomly generated gibberish produced by the program SCIgen. No, these didn’t appear in bogus “open access” publications, but in subscription publications from Spring and the IEEE. What’s going on is described as a “spamming war at the heart of science”.
  • Update: One more, for those of you not getting enough multiverse. Today’s Washington post has an op-ed from Bush speech-writer Michael Gerson (at one point the ninth most influential evangelical Christian in the US, if you believe Wikipedia and Time). The title is Physics is Enjoying a Golden Age (also available here). Gerson thinks physics is in a Golden Age because he has just read Tegmark’s book and is very excited that physics has now become metaphysics, with room for God again:

    The point here is not that Tegmark’s theories are broadly accepted, only that such theories are no longer considered absurd. Physics has seen the return of the unseen — parallel universes, infinitesimal strings, floating and colliding branes — that are reasonably inferred without being physically observed. I can think of other creative forces in that category. Not for centuries has physics been so open to metaphysics, or more amenable to an ancient attitude: a sense of wonder about things above and within.

    Posted in Multiverse Mania, Uncategorized | 9 Comments

    US HEP Theory Funding News

    Laurence Yaffe has gathered some information about DOE funding of US HEP theory groups, showing sharp drops (average 23%) in such funding for groups reviewed in FY2013 and FY2014. These drops imply serious reductions in the numbers of theory graduate students supported and in the number of postdoc positions funded. To get an idea of the reaction to these numbers, the file name is calamity.pdf. Sean Carroll has a blog posting here, also with the “Calamity” title.

    There’s something very odd though about these numbers, with no explanation available from Carroll or Yaffe, who both interpret the situation as a sharp reduction in US government support for HEP theory. If you look at the numbers for total amount of funding, there’s no evidence of the 23% drop (for sources of numbers, see references in Yaffe’s document, the DOE HEP budgets here, and HEPAP presentations here). The recent Congressional agreement on a FY2014 budget puts the DOE HEP total at $798 million, significantly higher than FY2013 ($750 million) which was reduced by the sequester, and higher than FY2012 ($770 million) and FY2011 ($776 million). Of these amounts, the amount going to theory seems stable at around $50-$55 million/year (exact numbers depend on exactly what you include, Yaffe quotes FY12 and FY13 at an identical $51.3 million/year).

    So, the “calamity” of collapse of government support for theory is somehow taking place despite no collapse in the amount of money budgeted for this. What is going on? I’d love to hear from someone who understands this. The only explanation I’ve seen is that this is a temporary phenomenon having something to do with how the budgeting process works. Note that with the way typical multi-year grants are made, the DOE is promising to provide money several years in the future, despite the current US budgeting environment, where budgets are typically set not in advance, but often very late. The current fiscal year’s budget was set last month, although the fiscal year started Oct. 1. This was considered a huge success… One conjecture is that the DOE has been promising less to theory groups, partly because they only recently found out about the good FY2014 result, and partly because of a policy change to budget for future year outlays in current years. If this is the source of the calamity, it should quickly disappear as the FY2014 money comes in and the transition to new budgeting ends. Yaffe examines some other possibilities for explanations, but without anything conclusive.

    The main concern raised is about the effects of a reduction in the number of US HEP theory grad students and postdocs. Perhaps more worrying than this though should be the trend of numbers of permanent research positions in the subject, which Erich Poppitz has gathered here. These numbers come from the Theoretical Particle Physics Jobs Rumor Mill, and show a constant level of 11 jobs/year for the past three years, about half the level of the years 2000-2007. The number of jobs posted this year is so far only 13, which can be compared to around 20/year in recent years. It’s still early in the season, so more jobs may appear, and more may get filled than in recent years, but the trend of US institutions hiring significantly fewer permanent people in HEP theory is clear. Given this trend, there’s a reasonable argument to be made that numbers of grad students and postdocs should also be reduced. There’s no evidence though that some decision has been made to do this, or that this is the reason for the numbers Yaffe is looking at.

    Comments from anyone well-informed about this are strongly encouraged, while comments from people who just want to make the usual arguments about government funding for science rules/sucks will be deleted.

    Update: More commentary at Ted Bunn’s blog. He sees this as possibly an implementation of changes at DOE designed to “decrease the effect of historical inertia”, which might be moving money from historically well-funded major groups to others.

    Possibly all that’s going on though is just the “bridging” problem mentioned on slide 7 of this presentation. A decision was made to start grants later than in the past on April 1 (with the idea that typically it’s not going to be until that deep in the fiscal year that Congress has got its act together and given DOE a budget number). This meant though that money had to be taken out of upcoming grants to cover extending current ones until April 1 when new ones might start. The number on that slide reflects a 25% charge to new grants to cover this, suspiciously close to Yaffe’s 23% number.
    The same slide though does point out that this is a temporary problem: “will be better in 2015″. If that’s all it is, and grad student/postdoc number are slated to go back up a couple years from now, maybe “calamity” isn’t the right word here.

    Update: For more from Yaffe, see here.

    Posted in Uncategorized | 18 Comments

    The Multiverse, Evidence and Theology

    Yes, this multiverse business is tedious, but since it is becoming mainstream physics, with colloquium talks here at Columbia devoted to it, and the Columbia University Press publishing books about it, seems to me that someone at Columbia should be commenting on these, and I don’t see anyone else doing it. Will try to make this short.

    Yesterday Matthew Kleban’s talk here was entitled Testing the Multiverse. The only part that actually really was about testing the multiverse was the part describing work on bubble collisions with other universes. This has been heavily advertised in the press, see here, here, here, here, here and many others. Kleban described some of these ideas, but when it came to the experimental testing part, he just briefly acknowledged that all searches for these things have come up empty. The only prospect for the future mentioned was the polarization data to be released later this year by Planck, which would give some new things to look at, but he seemed unenthusiastic that this would realistically lead anywhere. So, as far as the “testing” goes, it has been done and the tests failed.
    The rest of the talk was about various inflationary models, including Kleban’s work on “unwinding inflation” (see here, here and here). Some of these models do have testable consequences, and many do lead to “eternal inflation”, so in such models you expect to continually produce new inflated universes, although with exactly the same physics. This is being sold as “testing the multiverse”, and string theory is brought in to justify lots of possible different physics in different universes, but this is not a testable part of these scenarios. What’s being advertised is a grandiose picture of the string landscape, laws of physics determined environmentally, etc., etc., but if you actually look at the product that you’re actually buying as “testable”, you don’t get any of the cool stuff. For slides of a somewhat similar recent talk by Kleban, see here.

    A while back I acquired a copy of the new book Worlds Without End: the many lives of the Multiverse, started reading it and was planning on writing a detailed review. I soon got bogged down in the first half of the book, which is a detailed intellectual history of speculation about multiple universes (so lots about relevant parts of Plato, Aristotle, Lucretius, the Stoics, Augustine, Nicholas of Cusa, Giordano Bruno, Kant and others). Finally I realized I just didn’t have the energy to serious read this material. People with other interests and/or more time on their hands may find this quite worthwhile.
    The second half of the book is devoted to the question of current speculation about physics, so more up my alley, but again I found it hard to focus on this. I fear it is only mildly interesting to see what a theologian/philosopher of religion makes of the current multiverse mania, not enough so though to do more than skim the text. From this skimming, what’s in the book is a lot of retelling (sometimes introducing misunderstandings) of the hype-laden tales of the multiverse told in dozens of books and magazine articles over the past decade or so.

    Rubenstein ends the section about what physicists have to say with Tegmark, seen as having reached the final endpoint of the “Ultimate Multiverse”:

    So some worlds will be linear, and some will be cyclical; some will be singular, and some will be plural; some will be infinite, and some will be finite; some will branch forward, and some will branch back. Some worlds will be manufactured, and some will be simulated; some designers will be kind and some will be cruel, some capable and some all but incompetent.
    And, presumably, some of the set of all possible world will have a creator-god who breathes over primordial waters, who separates the sea from dry land.
    How on earth did we get back here?

    I take Tegmark’s vision as empty, so a good thing to ignore, but Rubenstein sees this as an opening for theologians to get back into the mainstream cosmology business, and the rest of the book focuses on this. With the boundaries between science and religion now gone, all sorts of possibilities open up for theologians. The final part of the book begins by invoking (just like Henrich Päs, who comes at it from the mind-altering drug rather than theological angle) Nietzsche:

    Nietzsche concludes the Genealogy by expanding this vision, promising “all great things bring about their own destruction through an act of self-overcoming” (3.27, emphasis added). This promise then, has me wondering. If science can be regarded as the self-overcoming of a particular form of religion, might multiverse cosmologies be something like the self-overcoming of science? Might they mark the end of the fantasy that “science” has wrested itself free from “religion”, “objectivity” free from subjectivity, and matter free from meaning? After all, we have seen each of these multiverse cosmologies open onto metaphysics and mythology not in moments of lapse or weakness, but precisely where they are scientifically most compelling.

    It seems that, unlike most authors, Rubenstein actually has got the story of multiverse mania right: it’s left conventional notions of science behind and entered into the realm of theology. We do, however, disagree about whether or not this is a good thing…

    Update: Bogus claims about Multiverse “predictions” are now all the rage. For the latest, see the Caltech Quantum Frontiers blog, which has Yasunri Nomura writing about Making Predictions in the Multiverse. There of course are no predictions there, just mainly a discussion of the idea that many-worlds and the eternal inflation multiverse are somehow the same, an idea I continue to find unfathomable. Nomura doesn’t mention that he actually did have a prediction from the Multiverse (and someone made a movie about it…). The prediction was for a Higgs mass of 140 GeV, but of course when you’re in the multiverse business, wrong predictions are not a problem, they’re always true somewhere.

    Update: For more on the multiverse front, Edward Frenkel has a review of the Tegmark book in this Sunday’s New York Times. He does a great job of explaining the problems with the way Tegmark is trying to use mathematics. John Preskill tweets in agreement (positive and negative).

    Update: Nomura, when asked about experimental evidence for the multiverse, responded that the experimental situation is

    not much different from some other situations—e.g. in the big-bang theory, inflationary cosmology, and Darwinism in biology

    So, the scientific evidence for the multiverse is “not much different” than the evidence for evolution? And Tegmark thinks I’m the one in league with creationists…

    Posted in Book Reviews, Multiverse Mania | 62 Comments

    More Links, Interesting and Tedious

    First some links to interesting things:

    In the category of things that have gotten tedious, first there’s the ongoing hullabaloo about “firewalls” and Hawking (with the bottom line as far as I can tell just that, yes, there is an information paradox, might have something to do with the fact that we don’t understand quantum gravity…). If this interests you, you can take a look at

    In the multiverse-mania category, I’m forcing myself to read the Rubenstein book I’ve mentioned, will report on this when done, in the meantime there’s

  • In the London Review of Books, David Kaiser has a review of Lee Smolin’s book from last year Time Reborn. The review is mostly about the string theory landscape case for the multiverse, a bit about Smolin’s take on it.
  • Tom Banks has a new paper out surveying the issue of Supersymmetry Breaking and the Cosmological Constant. He surveys the anthropic string theory landscape argument and concludes that

    It is therefore fair to say, that much of the standard model, and certainly the peculiar values of many of the parameters in the standard model, cannot have an anthropic explanation. In string theory, extra generations of matter correspond to more tuning of moduli, small parameters do not appear to arise without a symmetry explanation, and symmetries are rare on moduli space.

    One cannot escape the implication that, on the basis of current theoretical knowledge, the String Landscape is ruled out by experiment.

    Besides being experimentally ruled out, the whole Landscape thing doesn’t work anyway

    My personal conclusion from all of this analysis, is that the theory of CDL tunneling provides no positive support for, and lots of negative evidence against, the proposal of a String Landscape…

    When combined with the phenomenological challenges I presented in Section 2, I conclude that the String Landscape is an hypothesis of dubious validity.

    This is a subject in which solid predictions are hard to come by, but I’ll make one here: string theory partisans will just ignore this, with the “String Landscape” now an hypothesis which has achieved some sort of new extra-scientific status. It’s an ideology you sign up for to justify not giving up on string theory (or as a foundation for your multiverse-mania), and as such, arguments like those from Banks are irrelevant.

  • Also in the category of serious scientific arguments against the anthropic landscape that will just be ignored, see Sesh Nadathur who explains why Weinberg’s original argument for the CC implies one that is 103 times too big. This is part of some arguments with Shaun Hotchkiss you might want to have a look at, see other blog postings here and here.
  • Finally, Max Tegmark is on tour promoting multiverse-mania and his Level IV version of it. The latest from him is here at Scientific American, where he’s claiming that his Level IV multiverse is science because it could be falsified by finding “some physical phenomenon that has no mathematical description.” I’ve tried arguing the absurdity of this with him in the comment section, so far no luck getting anything other than a dismissal of me as “emotional”.

    I was interested to see that his perception of what has been going on for the past decade as endless popular books promoting the multiverse have appeared is that

    whenever a physicist writes a book about them [multiverse ideas], the Web erupts with claims that they are unscientific nonsense.

    Curious to know what part of “the Web” he is referring to other than my blog…

  • Posted in Multiverse Mania, Uncategorized | 44 Comments

    The Perfect Wave

    Sometimes when I have come across claims of exotic phenomena at the far-out edge of the field of BSM physics based on branes and string theory (like time travel, or brane-world explanations of the bad OPERA result), my initial reaction has been “Are these people on drugs?” A new book out from Harvard University Press, The Perfect Wave, by theorist Heinrich Päs explains that yes, some of this particle theory activity has its intellectual roots in psychedelic drug consumption.

    The book opens with a short chapter about surfing in Hawaii, but then turns to a long chapter about LSD, the author’s experience with magic mushrooms, and the cult of Eleusis in ancient Greece. Supposedly this cult revolved around consumption of a psychedelic brew called “kykeon”, and we’re told that this was of great influence on Plato. The discovery of atoms is also attributed to a drug trip:

    Moreover, the perception of smallest details during a drug trip may have affected the atomism of Democritus, who first assumed that the world should be built up of indivisible elements.

    The next chapter goes on to discuss quantum mechanics from this point of view. Starting with Heisenberg’s claims of inspiration from Plato’s Timaeus, Päs moves on to Heisenberg’s student von Weizsäcker and his ideas about quantum mechanics and Plato’s Parmenides:

    In summary, Weizsäcker arrives at an amazing conclusion, that the notion of complementarity has its source in ancient Greece: “We find … the foundation of complementarity already foretold in Plato’s Parmenides.” We actually can recover the feel of what the ancient Greeks experienced in their mystery cults in modern twentieth-century physics!

    From there the book moves to the multiverse and Everett’s many-worlds interpretation of QM, telling us that:

    It is actually possible to recognize the multiverse — the collection of all of Everett’s parallel universes — directly as Parmenides’s primeval One: the unity of the world the ancient Greeks felt thay had lost in the charted modern world, and for whose reunification with the individualized ego they looked in the ecstasy of their mystery cults, in their Dionysian arts, or in the flush induced by psychedelic drugs.

    The main part of the book then begins with chapter four, which starts out:

    Physics is like surfing. Or like an LSD trip.

    The final chapter closes with an invocation of Nietzsche and a return to the multiverse of the many-worlds interpretation, with this now providing the Dionysian vision of science that he desired:

    For Nietzsche, science thus was the original cause for the ancient Greek’s suffering from the separation of subject and object. And for modern humanity being torn from the integral unity of nature.

    Only if science were reconciled with the Dionysian tragedy, with art and music, only if Socrates would start to make music, only then could science grant humanity with a deep metaphysical benefit, could establish a true meaning of life.

    In view of this, it is probably most amazing that science itself, with the many-worlds interpretation of quantum mechanics, leaves some room for an entire multiverse of alternative realities beyond our immediate experience — a multiverse mirroring the unity of Parmenides’s philosophy, as well as the egolessness of Aldous Huxley under the influence of psychoactive drugs, and a Dionysian creative moment bursting open all boundaries.

    In betwen the first few chapters and the last one, there’s a short 200 page book about neutrinos. This is the field of the author’s expertise, where he started out as a theory student working with the Heidelberg-Moscow double beta decay experiment. Claims from this group that they see a signal have been challenged by recent (too recent to be in the book) results from GERDA. The GERDA results are here, Heidelberg-Moscow’s response here. Neutrino physics is a complicated and fascinating subject, and one can certainly make a good argument that it’s now the part of HEP where there are things we don’t understand and promising avenues to explore using existing technologies (you don’t need TeV-scale accelerators).

    Unfortunately what most interests Päs is the far-out part of the subject, specifically ideas like using neutrinos to travel in time by hopping between branes. In the foreword to the book he does give a warning:

    Warning up front! The book deals with established scientific insights and with wild speculations… I highly recommend that the reader be alert to this difference.

    and then briefly notes which topics he will cover are extremely speculative, but then ends with an inspirational quote from Glashow:

    The wild ideas of yesterday quickly become today’s dogma.

    These warnings are quickly left behind, and it requires a careful and well-informed reader to sort through which of the material on neutrinos has some sort of relation to reality, and which is just baseless and wild speculation.

    When I bought this recently released book in the local bookstore (Book Culture, if you’re interested…), at the same time I acquired another very recently released book, which I’ll write more about here soon. The odd thing is that both of these books come from Ivy League university presses, and both end with a stirring and enthusiastic invocation of the multiverse as providing a Neitzschean answer to rationalistic Western science. There’s definitely a trend here… For the Päs book in particular, I’m rather mystified why Harvard University Press decided this was something they should publish.

    In the next to last chapter, Päs shows some awareness of why rationalistic science is so important:

    But useful application is not the point of neutrino physics. Rather it is a quest for a better basic understanding of the universe, thereby ultimately contributing to a solid foundation for the an incorruptible, rational world view. At times when intolerance, religious fanaticism, gut instincts, and irrational esotericism are flourishing, this is an effort whose importance should not be underestimated.

    I’m not sure that “irrational esotericism” is any more of a widespread problem in the culture at large now than it has ever been. If it is though, I don’t see how promoting over-the-top groundless speculation, the multiverse, and the idea (attractive as it may be) that fundamental physics should be a Dionysian activity based on psychedelic drug consumption is really going to help…

    Update: Heinrich Päs sent me the following. It addresses a few things in the review that could easily be misunderstood, providing very helpful clarifications and some of his point of view.

    Dear Peter,

    thanks for your extensive review of my book. If you allow, I would like to comment on a few points though which might be misunderstood:

    Your review may give the impression that the wild speculations in this book are not clearly identified. However, the preface you are citing identifies GUTs, supersymmetry and cosmic inflation as speculations which nevertheless represent “the present hopes… of most of the scientists working actively in these fields”, marks string theory and extra dimensions as “wilder” speculations, admits that shortcuts in extra dimensions are “speculations squared” and that time travel in extra dimensions may be considered as “speculation to the power of 1,000″. Also later on in the book I put some effort into saying clearly when I talk about textbook science and when I discuss scientific (and other) speculations, and I always motivate these speculations. For example, I mention your very own criticism of string theory as being “not even wrong” and I actually agree with you that scientific theories should make testable predictions. Of course this is one important difference of science and religion (or esotericism). However – and I hope you didn’t take that personal – I continue by arguing that it is more useful and pragmatic to try to find out whether some ideas of string theory could actually lead to testable predictions – what people like Antoniadis, Arkani-Hamed, Dvali, Dimopoulos, Randall and Sundrum have started – than to condemn it.
    And this is another important difference of science and religion: textbook theories can be questioned. Without speculation there would be no relativity and quantum mechanics, there would actually be no science at all.

    You also mention the controversial result of the Heidelberg-Moscow group and the wrong OPERA result. Let me clarify that I’m not an author or advocate of the Heidelberg-Moscow result, and that I always have emphasized that the OPERA result is most probably due to a mistake in the experiment. The results are mentioned in the book as what they are: controversial and wrong, respectively. And while the GERDA result is not in the book, the somewhat earlier result by EXO which also challenged the Heidelberg-Moscow result with a comparable sensitivity is discussed.

    Having said this, I actually like your review. It transmits the correct idea that this book takes you on the wild trip through neutrino physics, and may some of your more intellectually adventurous readers actually motivate to buy it.

    Kind regards, Heinrich

    Posted in Book Reviews, Multiverse Mania | 23 Comments

    The Perfect Theory

    Cosmologist Pedro Ferreira has a new book about to come out, entitled The Perfect Theory. The author accurately describes the book as a “biography of general relativity”, and it’s quite a good one, of the short and breezy variety (as opposed to the detailed and exhaustive sort).

    The theory’s parentage (Einstein), conception and birth are covered, in particular the way in which mathematics played a crucial role, with Einstein getting important help on this from his friend Marcel Grossman, as well as David Hilbert, who found the right dynamical equations at the same time. This material goes by fairly quickly though compared to many other sources for this history, in order to get to the main topic: the life story of the theory so far, nearly 100 years on. After the birth of the theory, it soon started to get wide acceptance, with Eddington helping to provide both the experimental confirmation in 1919 of the theory’s distinctive prediction about deflection of light by the sun, as well as ensuing publicity.

    Some implications of GR were found immediately (e.g. the Schwarzschild solution in 1916), and the 1920s saw early work on applying the theory to cosmology (de Sitter, Friedmann, Lemaitre). By 1929 Hubble’s observations of an expanding universe had shown the way forward in this area. Ferreira goes on to follow several different strands of how the theory has developed. These include: black holes (Oppenheimer, Wheeler, singularity theorems from Penrose, Hawking, the information paradox), cosmology (Hoyle and steady state models, the CMB, Peebles and the now standard model, with dark matter and dark energy), relation to quantum theory (DeWitt, supergravity), gravitational waves (Weber, LIGO, proposals like LISA), and quite a few others. A wealth of different topics and interesting pieces of the history of the subject are covered, although none in great detail. The emphasis is on this history, along with the present state and prospects of the subject, with not much attempt to try and explain the intricacies of the physics (which would take a much longer book).

    On the hot-button issues of string theory and the multiverse, Ferreira does a good job of giving an even-handed description of the arguments. For instance, he counsels reader to pay attention to George Ellis as well as multiverse proponents.

    For more about the book, there’s a very good review by Graham Farmelo here. Oddly though, just like with his excellent biography of Dirac, which ended with a weird attempt to claim Dirac as a string theorist, here Farmelo ends by trying to enlist Ferreira and GR in the cause of string theory:

    50 years later, the mathematical aesthetic of relativity has been enhanced by the beautiful demonstrations of its veracity that Ferreira describes. These would probably have made Born ponder why he and his peers did not spend more time developing a deeper appreciation of the theory soon after Einstein first presented it. Maybe there’s a lesson here for some of today’s string-theory sceptics?

    I’ve never seen anyone else try and claim that the history of GR is analogous to the history of string theory. As Ferreira’s book explains, unlike string theory, GR is a classic example of a testable scientific theory, coming with one impressive post-diction (precession of the perihelion of Mercury) and followed up by an impressive test of a distinctive prediction (bending of light at the 1919 eclipse). As for mathematical aesthetics, GR uses beautiful mathematics (Riemannian geometry) and its dynamics is determined by the simplest possible Lagrangian density (the scalar curvature and nothing else). Whatever the equations of string theory might be, they remain unknown. Rather than a lesson for string theory sceptics, this book provides some good lessons about what a successful fundamental theory looks like, ones that string theory proponents would be well-advised to ponder.

    “The Perfect Theory” is a good title for the book, with GR remaining our best example of a beautiful, powerful fundamental physical theory, based on the deepest mathematical ideas, with almost no free parameters. Ferreira does a great job of leading readers through the story so far of this amazing theory.

    Update: For another review of the book, see Ashutosh Jogalekar at The Curious Wavefunction.

    Update
    : Nature now has a podcast with an interview of Ferreira.

    Posted in Book Reviews | 21 Comments

    Quick Links

    • I’ve always thought more philosophers of science should be weighing in on the debate over “falsifiability” and the “demarcation problem” surrounding string theory and the multiverse (i.e. are these really science?). This is a complex and tricky subject that they have a long tradition of exploring, and it would be great to have this inform some of the debate instead of the often very naive arguments that dominate the discussion. Massimo Pigliucci does a nice job here, responding to Sean Carroll’s attack on falsifiability (see here, more discussion here). Pigliucci’s posting is great, giving a concise explanation of the way philosophers of science have found to think about these issues. It does though show that much of what needs to be examined are technical scientific issues (what exactly does “string theory” say or not say? What exactly are the conceivable things one could expect to measure and compare to theoretical predictions? What exactly is the state of efforts by string theorists to make predictions: how deadly are the obstructions they have run into?). In any case, here’s Pigliucci’s conclusion:

      But at some point the fundamental physics community might want to ask itself whether it has crossed into territory that begins to look a lot more like metaphysics than physics. And this comes from someone who doesn’t think metaphysics is a dirty word…

    • This evening at ASU there will be a program on Parallel Realities: Probing Fundamental Physics, you may be able to watch it live here. With David Gross there, at least it won’t be the usual “Isn’t the Multiverse cool?”-fest that this sort of thing recently often has turned into. Yesterday on Science Friday, Krauss, Wilczek and Brian Schmidt discussed Could There be a Crisis in Physics?
    • In case you’re wondering why there’s been no discussion here of Hawking’s recent claims about black holes, the reason is that I’m in agreement with Wilczek’s wise characterization of this on the Science Friday program:

      I think the kind thing to do is to pass this over in silence.

      If you really need some Hawking material, there’s The Top 10 Science Jokes, As Told by Stephen Hawking. Warning: safe for work, but not very funny…

    • Quite a bit funnier (although some might say, also kind of tired and sad..) is this “debate” between Bousso and Rovelli at the latest FQXi conference: String theory vs. loop quantum gravity.

    Update: Video of the ASU talks can be found here. Wilczek is still sticking with SUSY, but says “no more excuses… these particles have to materialize [at the full LHC energy]“. According to Twitter, this really was a rock-star event, with the local ladies “getting dolled up” and ready “to throw our panties onstage.”

    Posted in Multiverse Mania | 17 Comments