Two Reviews

Two reviews by physicists of my book and Lee Smolin’s have recently appeared.

The first is by David Lindley in the Wilson Quarterly. Lindley has written some excellent popular books about physics, including one about quantum mechanics entitled Where Does The Weirdness Go?, and he has a new one about the history of the uncertainty principle that I look forward to reading. He is also the author of The End of Physics: The Myth of a Unified Theory, which appeared back in 1993, and was the first popular book I know of that explained that the project of finding a unified theory of particle physics had started to run into trouble and was not making progress. In some ways Lindley’s book was a precursor to John Horgan’s later The End of Science, and Horgan acknowledges Lindley’s influence. Lindley notes that I say a bit about his book in mine, saying I misstate one of his arguments. He has to be right about this, so I’m rather curious to know what I got wrong (an internet search shows that he has been pretty successful at keeping his e-mail address non Google-accessible, so I haven’t yet contacted him to ask him about this). His description of the books is reasonably accurate and straight-forward, and he ends with the following observation:

As for string theory, it’s likely to unravel only when its practitioners begin to get bored with their lack of progress. Like the old Soviet Union, it will have to collapse from within. The publication of these two books is a hopeful sign that theoretical physics may have entered its Gorbachev ­era.

December’s Physics Today has a review of the same two books by Kannan Jagannathan, under the title Scrutinizing string theorists and their future. One unusual aspect of the review is the peculiar description of the reviewer, unlike any I’ve ever seen before in Physics Today:

Kannan Jagannathan is a professor of physics at Amherst College in Amherst, Massachusetts. Though his background is in high-energy theory, he has no strong stake or expertise in string theory.

It’s an indication of the highly partisan nature of the controversy these books have stirred up that Physics Today seems to have found it necessary to include this sort of unusual disclaimer. It appears true that Jagannathan is no partisan, but his disclaimer of expertise on the subject covered by the books is associated with a rather superficial take on the arguments these books are making. His only attempt to evaluate whether there is anything to the claims Smolin and I make about the problematic behavior of some string theorists is to have read Lisa Randall’s recent popular book Warped Passages, and found that she doesn’t seem to share our concerns.

While avoiding saying anything about the substance of my arguments, Jagannathan does take exception to the style of some of them, suggesting I should use more “temperate rhetoric”, and avoid “anecdotes and private communications.” Perhaps he’s right that tactically it would have been better for me to write a more impersonal book, bending over backwards to appear to not be expressing personal opinions. For better or worse, I chose to do something quite different; to write a very personal book, expressing precisely what I think, and describing experiences that have led me over the years to these opinions.

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47 Responses to Two Reviews

  1. Alejandro Rivero says:

    The comparision with the Soviet Union is interesting. Acording Lenin, or more properly according a reported talk of Lenin with one of the leaders of Spanish anarchist union CNT, the system was foreseen to allow “about 50 years” (this was 1927 or so), after which it would fall, expectedly towards anarcho-socialism. This bit or the prediction was a sort of failure, but except on this detail Lenin mechanism worked as a clockwork: not having internal renovation of leaderships, the system burnt out itself.
    Now, the hope with physics, or with string theory, is that science self-implemented destruction mechanisms, rooting a theory without experimental input, will work.

  2. Thomas Love says:

    Lindley’s new book: “Uncertainty: Einstein, Heisenberg, Bohr, and the Struggle for the Soul of Science” sounds like an interesting read, but I’ll bet he doesn’t mention that the uncertainty principle is classical physics, coming from any wave phenomenon. It is in the classical theory of light and the classical theory of acoustics.

  3. D R Lunsford says:

    Peter – you were entirely correct to write in the style you did – it reminds me of Klein’s highly personal and very instructive style and humanizes the whole thing. It’s an excellent book regardless of your point of view because the arguments are logical and the facts are clear.

    -drl

  4. Tony Smith says:

    An Amazon UK synopsis of Lindley’s 1993 book “The End of Physics: The Myth of a Unified Theory” says in part:
    “… the particle physicists …[in]… their attempts to reach … for a unifying theory … and unable to subject their findings and theories to experimental scrutiny … have moved into a world governed by mathematical and highly speculative theorizing,
    none of which can be empirically verified.
    David Lindsey argues that a theory of everything derived from particle physics will be full of untested – and untestable – assumptions.
    And if physicists yield to such speculation, the field will retreat from the high ground of science, becoming instead a modern mythology.
    This would surely be the end of physics as it is known today. …”.

    Since superstrings were dominant in high-energy physics theory in 1993, it is obvious that Lindley was referring to superstring theory as the “… modern mythology … the end of physics …”
    Now. over a decade later, Lindley says that superstring theory
    “… [i]s likely to unravel only when its practitioners begin to get bored with their lack of progress …”
    which indicates to me that Lindley disagrees with the hopeful view of Alejandro Rivero that
    “… science self-implemented destruction mechanisms, rooting a theory without experimental input, will work …”.

    Further, given such things as the videotaped reactions at KITP to Johnson’s first talk, the blogs of Lubos Motl and Clifford Johnson, etc, it seems to me that it is very unlikely that superstring “practitioners” will “get bored with their lack of progress” at any time in the foreseeable future,
    so
    it seems to me that Lindley’s view is that if you want to do high-energy theoretical physics in the forseeable future, your options are either:
    do superstring theory or;
    work in a relatively small niche field (tolerated as long as it stays in its place as a small niche) like LQG or;
    somehow make a living outside the established physics community, record your work for posterity as best you can, and hope that, if it is correct, somebody 100 years or so from now might stumble across it.

    In short,
    superstringers own the City Hall of high energy theory, and you can’t fight City Hall.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

  5. A says:

    Surely past years look like a Breznevian stagnation era. Since 1960 a failure seemed likely but not unavoidable, so a whole apparatus of people who got power thanks to communism, togheter with a few strong believers, could force everybody to keep going for 30 more years in doing something that almost nobody believed.

    And the end can take different forms.

    Susskind could be a Gorbachev, who destroyed communism in an attempt of changing it. Maybe Motl dreams to be a Kim, who still keeps pure communism in North Korea. More likely, the end could be something constructive like in China.

  6. Thomas Larsson says:

    according a reported talk of Lenin with one of the leaders of Spanish anarchist union CNT, the system was foreseen to allow “about 50 years” (this was 1927 or so)

    Nitpick: Lenin died in 1924.

  7. Alejandro Rivero says:

    Nitpicked. You forced me to check notes. Effectively, Angel Pestaña was sent to Moscu in 1920, while Nin was sent in 1921 (1922?). I think the note I remember was a comment from Buenacasa on the report of Pestaña back in Spain. Victor Serge explains he was with Pestaña when they first meet Lenin, but he does not mention this remark about the temporality of the dictatorship.

  8. D R Lunsford says:

    Tony – the entire thesis of the Lindley book is absurd, because we have working example from 1865 – Maxwell’s unification of electricity and magnetism. This introduced a new scaling constant called – let me think – oh yes, the speed of light.

    -drl

  9. King Ray says:

    I don’t think string theory will die until the funding is cut. I knew a guy in grad school who got several postdocs doing string theory who told me he didn’t even believe in it but he was getting all these great jobs doing it. I think it is wrong to work on something in science you don’t even believe in just to make money and get a job. Science is supposed to be a higher calling.

  10. L group says:

    Experimental input, although the ultimate source of the theory, is itself overhyped in the discussions of string theory and theory in general. If ultimately the only output of string theory is a more efficient formalism for QFT with no additional physical predictions, that is itself a major contribution. Such an existing or expected contribution may or may not justify the current levels of interest in string theory, but neither does harping on the lack of current relation to experiments.

  11. Carl Brannen says:

    On the topic of what will destroy string theory, a very interesting 800+ page book is Collins’ on gravity waves. I would never have picked up a book on physics by a “sociologist”, except that I took two graduate physics classes from Joe Weber who is the subject of a good bit of the book.

    The main subject of the book is how it is that communities of physicists reach agreement on subjects that are debated. The author’s well supported contention is that debate does not always change minds and that in the worst case debates both sides are supported by well respected physicists. Since 99.99% of what we know, we know not by direct experience but instead because we trust the judgement of others (for example, I’ve never measured the mass of an electron), the physics community has no way to decide the issue (think Einstein versus QM).

    Eventually, truth is decided when one side or the other gets an advantage at minting graduate students, and the other side dies off. My guess is that the advantage comes about partly by numbers, and partly by way of attractiveness of the calculational techniques, but the author does not discuss this. After one side or the other wins, history is then rewritten so as to make the side that died off look like idiots and old fogies. And a new generation is taught that science is 100% correct.

    One can argue that physics has done well with this technique of fighting over the truth — most physicists believe that the foundations of physics are solid. But from a sociological point of view, even if string theory is wrong, we can expect its proponents to go to their graves unrepentant, and to dominate theory until they retire.

  12. Peter Orland says:

    To Carl Brannen:

    There are examples of scientific controversies which were resolved by
    data and not by sociological forces (such as one side dying off). I don’t find Kuhn’s thesis especially convincing.

    People are naturally reluctant to abandon their theories and ideas for notions suggested by others. Thus science tends to stay a conservative enterprise, in which only the best thought out ideas eventually predominate. This may sound overly idealistic, but it’s often true.

    As an example, consider Harlow Shaply who refused to believe that
    spiral nebulae were galaxies external to our own. In spite of his
    heated arguments with Hubble and others, he eventually changed
    his mind (and wrote a popular book entitled “Galaxies”). The point
    is that Shaply didn’t have to die for the galaxy concept to win acceptance. There are other examples (Hoyle and the steady-state vs big-bang universe is one).

    Anyway, people really can be persuaded by evidence. observational
    or otherwise, if only to save their own reputations (or in some cases, to get a post-doc).

  13. Johny says:

    Peter Orland: let me add one more example to your list. Schroedinger refused for a long time to accept Einstein’s photon idea. He was convinced by Bohr that there was no other way to interpret the photoelectric effect. According to an account by Heisenberg, the discussions were long and difficult. So much so that Schrodinger fell ill, but still Bohr sat by his bed and went on discussing the issue. In the end, Schrodinger didn’t die and accepted the particle nature of light.

  14. Tony Smith says:

    King Ray said that he “.. . do[esn]’t think string theory will die until the funding is cut. …”
    and
    that he “… knew a guy in grad school who got several postdocs doing string theory who told me he didn’t even believe in it but he was getting all these great jobs doing it …”.

    As King ray went on to say, “… it is wrong to work on something in science you don’t even believe in just to make money and get a job …”.

    In light of King Ray’s comment, it seems to me that the most accurate USSR analogy for present-day superstring theory is Lysenkoism, which:
    got dominant government funding;
    viciously attacked competing approaches; and
    had worker/supporters who knew about the flaws in Lysenkoism but supported it anyway in order to continue getting funds and jobs, and to preserve positions of prestige and political/funding power.

    From a wikipedia entry at http://en.wikipedia.org/wiki/Lysenkoism on Lysenkoism:
    “… mass-media presented him [Lysenko] as a genius who had developed a new, revolutionary technique.
    … Lysenko … was … supported by the … propaganda machine, which overstated his successes and omitted mention of his failures.
    Instead of making controlled experiments, Lysenko relied upon questionnaires …”.

    To me, that sounds a lot like the present-day superstring cult of personalities, every one relying on praise from each other, similar to Lysenko’s “questionnaires” whose replies consited mostly of sycophantic praise.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

    PS -

  15. Tony Smith says:

    Sorry about the omitted PS –
    I was going to remark about how long Lysenkoism lasted and how difficult it was to bring down, but I found writing it to be too depressing if it is an indicator of how long the superstring cult is to last and how difficult it is to bring down, so I stopped writing after “PS -”.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

  16. Graduate says:

    I also though of Lysenkoism as a possible analogy to what is going on with string theory. I didn’t find it satisfying.

    1. For one thing, Lysenko was viewed as providing metaphorical evidence for the validity of certain national policies (As Lysenko sought to vernalize wheat, the soviet people where thought to be vernalized by the harsh policies of the Soviet Union, becoming stronger and hardier with more harsh treatment; or so the theory went). There is no such unholy alliance between string theory and politics.

    2. Another important distinction is that Lysenko ignored the results of actual experiments. In string theory, there are no experiements for the theorists to ignore.

    I have one question however. I have been wondering about the way theoretical physicists argue mathematics. I understand the mathematical way of proving statements. But I’ve been confused by the way physicists argue in mathematical sketches. How does one decide which of the debaters has ‘won’ ? It seems to me entirely possible to string together plausible conjectures and get several contradictory statements. And that indeed seems to happen often. I would appreciate some insight into this aspect of theoretical physics culture.

  17. Peter Woit says:

    TheGraduate,

    Physicists characterize all sorts of different things as a “proof at physicist’s level of rigor”. These range from cases where one has overwhelming evidence from numerical calculations that something is true and cases where something is true for sufficiently well-behaved functions (and the exact characterization of “well-behaved” has not been sorted out), to cases where the evidence is very fragmentary and far from convincing. Traditionally physicists haven’t worried too much about whether they really have a sold argument for a conjecture, since it has often been the most efficient tactic to just assume things will work, and go ahead and calculate under that assumption. If the calculations lead to inconsistencies or disagreement with experiment, that’s the time to go back and check assumptions.

    One big problem with string theory is that the lack of any experimental tests means that all you have to go on is the lack of inconsistency, and given the way the theory is built on a lot of unproved conjectures, this can get problematic.

  18. Tony Smith says:

    Graduate said
    “… Lysenko ignored the results of actual experiments.
    In string theory, there are no experiements for the theorists to ignore. …”.

    Actually (in my opinion) there are substantial experimental results that show absence of supersymmetry,
    and
    those results (in my opinion) have been effectively ignored by superstringers choosing successively heavier scales of supersymmetry breaking as successive experimental results failed to see supersymmetry.

    The superstringers (in my opinion) are acting in a way that Feynman considered unscientific in the book Feynman Lectures on Gravitation” (Addison-Wesley 1995) at pages 22 and 23, where Feynman said:

    “… a famous professor … asked “… how are you sure that the photon has no rest mass? …
    I [Feynman] answered … “… I would be glad to discuss the possibility that the mass is not of a certain definite size. The condition is that after I give you arguments against such mass, it should be against the rules to change the mass.”
    The professor then chose a mass of 10^(-6) of the electron mass.
    My [Feynman's] answer …[was given]…
    Then he [the professor] wanted to know what I would have said if he had said 10^(-12) electron masses …
    [again, Feynman's answer was given]…
    After this, the professor wanted to change the mass again, and make it 10^(-18) electron masses …
    [again, Feynman's answer was given]…”.

    Feynman went on to say
    “… We do not want to do similar things in attempting to construct a theory …
    we should be prepared to put forth definite theories … and be prepared to reject them if they are inadequate. “.

    I think that superstringers have been in violation of Feynman’s standards for some time,
    and
    that superstringers are, and have been for some time, effectively ignoring experimental results indicating that superstring-type supersymmetry does not exist.

    It also seems relevant that now, with indirect evidence indicating that even the LHC will not see superstring-type supersymmetry, superstringers such as Lubos Motl are attempting to move the goalposts yet again, exemplified by Lubos Motl saying on his blog, about superstring theory, such things as:

    “… we are confident that an answer to these questions exists in the non-supersymmetric case and it will be unique just like it was in the supersymmetric cases. …”.

    Contrast that statement
    with Lubos Motl’s past view of supersymmetry as a fundamental part of superstring theory, exemplified by his rejection (in 2004) of a non-supersymmetric string theory model by saying “… “String theory” is a shorthand for “superstring theory” …”.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

  19. King Ray says:

    Tony, very interesting analogy. I hadn’t heard of Lysenko before, but he definitely reminds me of some people I have known.

    I’m sure there are many people working on string theory that don’t really believe in it; the one person I mention was just the one honest enough to admit it.

    I think string theory is just a mutual admiration society; if you agree with everything they say you are a super genius, otherwise you are stupid and a crackpot. I don’t think many of them are actually that bright, and none of them have any aesthetic sense or physical intuition such as Einstein had. They are clearly not independent thinkers like Einstein either, but conformists.

  20. Thomas Larsson says:

    In string theory, there are no experiements for the theorists to ignore.

    String theory predicts supersymmetry – not seen.

    String theory predicts 496 gauge bosons – 12 seen.

    String theory predicts extra dimensions – not seen.

    String theory predicts a large and negative cosmological constant – the cc is small and positive.

    String theory predicts proton decay – not seen.

    Aether theory predicts aether wind – not seen.

    But then again, Lorentz and Poincare didn’t count negative experiments any more than Gross and Witten.

  21. TheGraduate says:

    “Between 1934 and 1940, under Lysenko’s admonitions and with Stalin’s blessings, many geneticists were executed (including Agol, Levit, and Nadson) or sent to labor camps. The famous Soviet geneticist Nikolai Vavilov, was arrested in 1940 and died in prison in 1943.”

    This is a quote from Wikipedia.

    Look, there is really no comparing Lysenkoism and string theorists. There are lots of historical examples of legitimate scientists who used their academic power to exclude people who disagreed with them. One of these incidents would be a more appropriate comparison.

  22. Peter Woit says:

    TheGraduate is right. Please stop with the highly exaggerated attacks on string theory and string theorists. These are off-topic, not enlightening, and kind of repetitive.

  23. Ludmilla says:

    >String theory predicts supersymmetry – not seen.

    The jury is still out on susy, extra dimensions, the Higgs boson, etc. At least until 2008-2010.

    Actually, it’s not so clear to me that string theory really predicts susy. One of the most disappointing features of string theory (or, should I say, of string theorists) is that no clear-cut predictions are made. That’s why some say it’s not even wrong.

    In my opinion, string theory is here to stay. Most likely not as a TOE, but as a math-phys framework. Personally, I don’t believe in TOEs, stringy or otherwise, I think it’s just a silly idea.

  24. anonymous says:

    Maybe the behavior of string theorists is more predictable than string theory: here are my testable clear-cut predictions (or maybe just my worries) about their official reaction to some possible future LHC results:

    if LHC sees supersymmetry, eureka we have up to N=8 of them.

    if LHC sees extra dimensions, eureka we have 6 or 7 of them.

    if LHC sees technicolor, eureka we have AdS/CFT.

    If LHC sees dark matter, eureka we have discrete gauge symmetries.

    if LHC sees nothing new, eureka eureka we have the anthropic landscape.

    Sorry for this non politically-correct comment, but I believe it’s true. Hopefully the next few years before LHC will allow to improve the physics and/or the sociology of string theory.

  25. Thomas Larsson says:

    The jury is still out on susy, extra dimensions, the Higgs boson, etc. At least until 2008-2010.

    Sure. Every experiment that does not see evidence for susy or extra-dimensions is irrelevant, such as muon g-2, B_s oscillations, permanent electric dipole moment, no deviations from Newton’s law, etc.

    H. A. Lorentz did not give up on aether theory that easily neither. For years he discovered increasingly complicated, Rube-Goldbergesque constructions, instead of accepting the obvious conclusion of the Michelson-Morley experiment. He never went as far as making anthropic arguments, though (a large aether wind might be incompatible with human life).

    Of course, he had his reasons. Aether theory was the only game in town – it follows from Newtonian mechanics and the Galilei group, which had passed every test for 200 years. And he certainly did not care about some crackpot patent clerk, who was ignored by everybody until Max Planck made him his assistent in 1910.

  26. dan says:

    Dear Thomas Larsson,

    “String theory predicts a large and negative cosmological constant – the cc is small and positive.”

    Hasn’t this been successfully addressed by the KKLT paper, which shows that string theory can account for a small positive cosmological constant?

  27. Ludmilla says:

    Sure. Every experiment that does not see
    evidence for susy or extra-dimensions is irrelevant, such as
    muon g-2, B_s oscillations, permanent electric dipole
    moment, no deviations from Newton’s law, etc.

    No, every experiment that does not see susy, extra
    dimensions, technicolor, preons, strings, whatever, is not
    irrelevant. It just puts tighter bounds on each of those
    possibilities. At some point those bounds can completely
    exclude one of the possibilities, or at least make it
    phenomenologically irrelevant.

    As far as I know, all known models of new physics are
    currently pushed into a rather uncomfortably tight region of
    their respective parameter spaces by experimental data. But
    we are not there yet. Ruling out susy (in its
    phenomenologically significant variants) will take LHC data.

    If you want to know my personal opinion, the MSSM and extra
    dimensions will not be seen at the LHC. But then, opinion
    is not fact. Also, that point of view does not solve any
    problems and, in fact, makes them worse. Without susy, how
    do you solve, for example, the LEP paradox and the dark
    matter problem? I don’t have an answer, do you?

  28. D R Lunsford says:

    TL – that was hysterical. I can see that paper,

    “Aether-Wind und Lebensmöglichkeit”

    Poor Lorentz, he really was very brilliant. Relativity was so much simpler than what he was doing.

    -drl

  29. Chris Oakley says:

    TL – that was hysterical. I can see that paper,

    “Aether-Wind und Lebensmöglichkeit”

    I cannot. I doubt that, even in his darkest dreams, he would have contemplated anything so ludicrous, and if he had, he would have being a laughing stock. Now some prominent physicists try to make a laughing stock of those who do not believe in the Anthropic Principle, which I suppose only shows how far we have fallen.

  30. anonymous says:

    http://www.kuro5hin.org/story/2006/10/31/161746/39

    “String Theory and the Crackpot Index

    “…Certainly, Dr. Greene has been been working for a long time (10) on a paradigm shift (10), towards which Einstein struggled on his deathbed (30). For his effort, his theory has no equations (10) and no tests (50). With the starting credit, that much makes 105 points.

    “Is Dr. Greene a crackpot? No. But is this how physics should be presented to the public?”

    Wonder why Woit doesn’t discuss this stuff?

  31. Peter Woit says:

    anonymous,

    I saw the story you mention, but the main answer to why I didn’t think it was worth discussing is embedded in what you quoted. I think there’s a lot wrong with string theory and how it is pursued, but Brian Greene is not a crackpot, and neither are most string theorists.

    I disagree with Brian about a scientific issue, the prospects for string-based unification, and, as a result, also don’t think the kind of public promotion of this idea he has engaged in is wise. But he’s a perfectly reasonable person, willing to admit that string theory may be wrong, just trying to promote and pursue ideas he believes in. I’ve known him for a long time, work in the same department, and talk to him regularly. I think both of us see our disagreements as scientific ones and want to avoid personalizing them. If you want to engage in Brian-bashing, do it elsewhere.

  32. Thomas Larsson says:

    Hasn’t this been successfully addressed by the KKLT paper, which shows that string theory can account for a small positive cosmological constant?

    With 10^500 parameters one can fit 2*10^499 tail-wriggling elephants. Or the value of the cosmological constant.

  33. Thomas Larsson says:

    No, every experiment that does not see susy, extra
    dimensions, technicolor, preons, strings, whatever, is not
    irrelevant.

    Ludmila, I was responding to Graduate’s claim that “In string theory, there are no experiements for the theorists to ignore.” So evidently he, as many other string theorists, thinks that none of these experiments is relevant.

  34. Ari Heikkinen says:

    Speaking of books..

    I’m soon ordering some books from amazon and just out of curiosity, was thinking of buying a book about string theory and another that points out problems with it.

    I’d basicly prefer something with actual equations for backing up any claims instead of merely philosophy (I already have Greene’s book about string theory, but it was, although excellent read, a bit too basic without any equations whatsoever), so while I’m leaning towards that Zwiebach’s “first course” book on strings (based on searching on amazon), which one should I pick for a rebuttal for it, Lee’s or Peter’s? What’s the difference? Wouldn’t want to end up buying another book with just claims and nothing to back them up, be it critics or advocates.

  35. Steve Myers says:

    I hope this isn’t entirely off topic, but I’ve been thinking about popular books and articles on science. How good are they? When I read one on something I know well I find they are too thin or skip the “hard” stuff that you need to understand to even know what’s going on. There is a good book by Longair on physics but would you classify it as popular? Scientific American, for example, is often too thin and can give a wrong impression of a field.

    When I think about explaining my own rather simple work in a popular way I find that I have to explain FFT and signal processing, etc. What bothers me that even a Dirac prize winner can make a mistake about entropy and the arrow of time, what kind of mistakes are in stuff that I’m not familiar with — like Biochemistry?

    This is a serious questions: can one even write a good popular book on a subject — like theoretical particle physics without simplifying too much. I’ve discussed this with my computer scientist son who says he knows of nothing in his field. I know of & enjoy as light reading books by Gamow, Pagels, Einstein, Feynman, etc., but to even have a vague idea of what’s going on in a field I don’t know of any better or easier way than reading the technical stuff and working on a problem.

  36. Peter Woit says:

    dan,

    The problem with KKLT is that it “accounts for” a small CC by using a very complicated Rube Goldberg setup (Susskind’s description), and if you believe this works, you can “account for” just about anything, your theory is unpredictive, and you’re not doing science. Thomas inaccurately characterizes KKLT as have 10^500 parameters, which is not right, it’s 10^500 solutions, but this doesn’t change the problem.

    Ari,

    My book has some more technical material than Smolin’s, but it is still written without using equations, and it was not possible in this format to explain in technical detail many things. I also included quite a few suggestions for more technical further reading. One problem with Zwiebach’s book is that it only covers a small part of the string theory story, not taking you very far at all into the issue of how to connect string theory to real physics.

    Steve,

    I think there’s a wide variety of “popular” books out there. Quite a few oversimplify and don’t even try and give a legitimate explanation of what is going on. But some do an excellent job of giving an accurate picture of a field, even if a true understanding of the subject requires spending a lot more time and working out some basics techical details for oneself. To my taste, the best books I’ve seen often take a historical point of view, showing how a scientific subject evolved to the point it is now. Knowing the history of a subject is often a good place to start when trying to learn the basics.

  37. King Ray says:

    I really enjoyed Abraham Pais’ Subtle is The Lord, a biography of Einstein with equations along the way to his discovery of GR.

    http://www.amazon.com/Subtle-Lord-Science-Albert-Einstein/dp/0192806726/sr=8-4/qid=1165253958/ref=sr_1_4/002-0203434-5813668?ie=UTF8&s=books

  38. A lot of things that string theorists talk about exist outside the context of string theory. Brian Greene might talk about ten spacetime dimensions for string theory but John Baez can talk about them outside string theory. Greene might talk about exceptional algebras for string theory but Baez can talk about them outside string theory. Green might talk about string theory worldsheets but Urs Schreiber says there’s a deep connection between a worldsheet and Feynman paths (Feynman was not a string theorist). Even the supersymmetry of superstrings exists outside string theory (and there are other types of supersymmetry too). The one nice thing about the anthropic landscape is that it has quite a few critics who are string theorists. Given the politics of physics, sometimes I think it might be easier just to pursuade string theorists to work on different things under the string theory umbrella than to get them to downsize their empire.

  39. Who says:

    I met a PhD student of Steve Giddings just in the past month—he was up from Santa Barbara to hear some talks. He mentioned what his thesis research was about: it wasn’t string theory though it was somewhat LIKE string theory—IIRC it didnt need extra dimensions, maybe it lived in 4D like normal people. This is, of course, vague gossip—but I remember getting a
    sense of drift, of a program morphing into something else. It wasnt quite cool
    anymore to be doing core string, so you emphasized the distance.

  40. Ludmilla says:

    Ludmila, I was responding to Graduate’s claim

    Thomas, you quoted from my message, so I thought
    reasonable to assume you were responding to me. I still
    think so.

    The jury is still out on susy, extra dimensions, the Higgs boson, etc. At least until 2008-2010.

    Sure. Every experiment that does not see evidence for susy or extra-dimensions is irrelevant, such as muon g-2, B_s oscillations, permanent electric dipole moment, no deviations

  41. King Ray says:

    Giddings is Witten’s student, isn’t he?

    I agree that we should explore 4D theories more fully. Higher dimensional theories have never been successful, going back to KK. I think by going to higher dimensions people are taking the easy way out. There should be a theory entropy statistic that is a measure of how complicated a theory is, and very complicated theories should be avoided.

  42. Thomas Larsson says:

    Ludmila, your first post was a response to my statement “String theory predicts supersymmetry – not seen.” Evidently you found this objectionable.

    String theory predictions have always been wrong in the past. Why should the LHC change this good old tradition?

  43. Ludmilla says:

    String theory predictions have always been wrong in the past. Why should the LHC change this good old tradition?

    :) That’s a good joke. But the same thing could be said of you and every other guy around. So, why should the LHC confirm any of your predictions, this one in particular?

  44. Thomas Larsson says:

    Why susy or extra-dimensions are unlikely to be seen at the LHC? Perhaps because other experiments put quite tight constraints on any deviation from the SM – unitarity triangles etc. Susy already requires fine-tuning at the percent level.

  45. Tony Smith says:

    Thomas Larsson said “String theory predictions have always been wrong in the past. “.
    Ludmilla replied “… the same thing could be said of you and every other guy around. …”.

    No.
    Some models do make predictions that have NOT always been wrong.
    Some aspects of my personal example can be found in the abstract at http://arXiv.org/abs/physics/0207095 and in that paper.
    My further work along those lines has been blacklisted by the Cornell arXiv,
    but can be found on my web site.

    I am not saying that my model is the only model that makes some correct predictions, only that it is one example and that the one example is all that is needed to refute Ludmilla’s allegation that predictions of “every other guy” have “always been wrong”.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

  46. Ludmilla says:

    one example is all that is needed to refute Ludmilla’s allegation

    Tony: “every other guy” means roughly “one out of every two”. I have always considered you as part of that privileged predictive half.

  47. Tony Smith says:

    Ludmilla, my apologies for misunderstanding what you meant by “every other guy”
    (half of the population,
    as opposed to all of the population except Thomas Larsson)
    and thanks for considering me to be part of the “predictive half”.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

    PS – My misunderstanding may have been an example of a linguistic version of the ambiguous image phenomenon illustrated by the images at http://www.questacon.edu.au/html/tg_p8a.htm
    The way the human brain works with respect to such things is interesting, but probably off-topic for discussion here.