Horgan Interview With Witten

Back in 1996 John Horgan’s The End of Science appeared, which included material from a fascinating 1991 interview of Edward Witten. I had mixed feelings when reading this. On the one hand, Horgan was doing something truly remarkable, challenging Witten in a way that no one else dared. This was 7 years after the “First Superstring Revolution”, and it was starting to become clear that string theory was not working out as hoped. No journalist other than Horgan though was talking about this, or willing to confront someone of Witten’s stature with difficult questions. Pretty much every other story in the press stuck to the simple narrative that Witten was a genius, and superstring theory a great success. On the other hand, Horgan did use his author’s freedom to edit and frame the interview to make Witten look bad (today he admits the Witten profile was “pretty snarky”), so he was landing some low blows, against a rather gracious opponent.

This year Witten won the Kyoto Prize, and I was shocked to hear that Horgan was the person chosen to interview him. Witten rarely gives interviews and I would have thought that Horgan would be the last person in the world he’d agree to an interview with, given his past experience. The interview is now available here.

This time around Horgan avoids the snark, and asks some straightforward questions about whether Witten’s views have changed since 1991, and what he now thinks about string theory, the multiverse, anthropics, etc. I have to admit that I find Witten’s answers depressing, in contrast to Witten’s advisor David Gross’s current take on these issues (discussed here). About anthropics, Witten’s “I don’t like it, but may be the way to go” contrasts with Gross’s “cop-out”, and his insistence on string theory as the way forward contrasts to Gross’s emphasis on the fertility of quantum field theory.

Back in 1996, after the appearance of Horgan’s book, Gross and Witten wrote in to the Wall Street Journal (reproduced here) to argue that Horgan was wrong, since string theory would be tested by finding SUSY at the Tevatron, or, failing that, definitely at the LHC. We all know how well that has worked out, and Gross seems to have learned a lesson from this. Witten on the other hand has moved on to even more dubious testability claims (e.g. that the string theory landscape can be tested by “seeing a signature of a prior phase transition in the CMB”). From the 1996 claim that vindication would come “in the next decade”, he now is talking about “200 years from now”. His one point of close agreement with Gross is that both agree that not knowing what string theory is when time-dependent effects are large is a big problem, one that has seen no progress.

By a couple years from now, the idea of making progress in our lifetime by seeing SUSY at the LHC, then going on to use this to learn about string theory should be finally finished off. Already Gross seems to have evolved from the 1991 point of view to a more promising one, perhaps Witten at some point will start to do the same.

: The AMS has something similar, a Mathematical Moment with Witten. Pretty much everything said about string theory is exactly the same as thirty years ago, only change is that the story used to be that string theory would get some vindication at the LHC, now it’s:

The verification of superstring theory is probably a long way off, but could be found here on Earth, using particle accelerators (possibly much more powerful than those of today)

consistent with the “200 years” estimate from the Horgan interview.

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27 Responses to Horgan Interview With Witten

  1. RM says:

    I am not sure why John Horgan’s views on science deserve publicity. Prior to his assertions about physics, he wrote a book claiming that mathematics was coming yo an end because proofs were becoming too hard. In the 20 years since the publication of his opinions, there is little doubt that major breakthroughs have occurred in mathematics. Similarly, we have gained hard data in physics on many fronts. We have not been as successful theoretically. Still, these are matters that should be judged by professional scientists rather than a journalist.

  2. Peter Woit says:

    You’re referring not to a book, but to an article he wrote for Scientific American (“The Death of Proof”). I haven’t looked at that in years, but I do remember that I disagreed significantly with what he had to say there. How mathematics keeps making progress despite getting harder and harder is an interesting question. I’m not so convinced though that in the long term math may also not find itself having reached a sort of end-point, with all of its fundamental structures and their relations discovered and laid bare. We’re still quite a ways away though…

    I think if you read Horgan’s take on the state of physics in the mid-nineties in the End of Physics, it stands up very well now. He’s not a physicist and didn’t always get things right, but he saw the problems fundamental physics was running into, in a way that most professional theorists either didn’t see, or if they did, refused to admit publicly. Like any science journalist he operates not as an expert, but as someone who talks to experts, asks questions, tries to get a handle on what is going on, and then communicate it to others. He has often been much more willing to challenge experts than is common among journalists. Experts don’t necessarily like this, but it sometimes is really needed.

  3. RM says:

    Yes, it “Death of Proof” was an article and not a book. My apologies. I think my point remains – his book “The End of Science” was a sweeping generalization to *all* of science. Not just particle physics. But also every other kind of physics, chemistry and biology. Do you really believe these claims are justified for *all* science?

    For example, major advancements in biology seem possible with the advent of techniques to image the interior of the human body. In the late 1990s, we also discovered that there was a non-zero cosmological constant which has obviously influenced the way we think about physics.

    Even in particle physics, ideas such as supersymmetry could have been discovered. I am not aware of any argument that could have proven that the predicted supersymmetric particles would not be discovered at colliders. When Horgan wrote his book, he could not have possibly known that these discoveries would not have happened.

  4. Peter Woit says:

    I agree that there’s a criticism to be made of the book that he’s sometimes trying too hard to fit different sciences in very different states into the same framework.

    As for supersymmetry, it was clear by the 1990s that this wasn’t an idea that was answering many questions that we didn’t understand about the standard model. Many people were highly skeptical of it for very good reason. If you had the choice to get your news from the many journalists who talked to Gross and Witten, took down uncritically what they said, then wrote articles about what glorious ideas susy and string theory were, or from Horgan who approached them skeptically, you’d have done a lot better in terms of understanding the real state of particle theory to go with Horgan.

    Sure, his skepticism could have been mistaken, SUSY and string theory could have turned into great successes. But his skepticism turned out to be justified, to his credit. Sometimes the world really does need skeptics…

  5. Dave Miller in Sacramento says:


    I doubt that anyone, including Horgan himself, thinks that he has gotten everything right in everything that he has written. But, as illustrated in the discussion here, he has managed to get a lot of people thinking and talking about significant issues. Isn’t that good enough? After all, no one takes him as an expert, he does not control funding, etc.

    There is a place for a gadfly, so long as a the gadfly does not have pretensions of divinity. Horgan does not seem full of himself.

    After all, even many of us who do not agree with Peter on everything feel he is provided a real service to physics by raising questions that needed to be raised about string theory but that were just being ignored.


  6. RM says:

    I am all in favor of reasoned skepticism. Horgan did not have the evidence back in the 1990s to make the strong claims that he did – in many cases, he failed spectacularly. In one particular instance, his poorly reasoned skepticism happened to be right about one particular theory. I don’t think that one example does much to restore his credibility.

    In the early 1990s, there were many reasons to think supersymmetry was the right path – starting with the fact that the gauge coupling measurements suggested unification. It is only after the discovery of the cosmological constant and the strong constraints on SUSY from LEP that the motivations for SUSY began slipping. But these occurred after Horgan’s book was published in 1996. If he had expressed skepticism about SUSY in 2001, I would not have complained.

    To sum up, poorly reasoned skepticism is about as valuable as war hawks braying for a fight at every opportunity.

  7. PAC says:

    Gross was much more bullish on string theory during his recent lecture at the Kavli Institute than he was at NYU. (Starting around 1:01:00.)


  8. Peter Woit says:

    Thanks. I think though that that’s also at NYU a few days ago, but a talk for the public as opposed to a talk for physicists like the colloquium talk a day earlier. To the public, Gross is giving much the same story as always, it seems to be when speaking to physicists that he’s evolving, perhaps realizing that the old arguments for string theory are no longer going over so well among his peers.

  9. Hanna says:


    Thank you for the post. I was wondering for some time what Witten was thinking, now that experiment and theory speak loud and clear against supersymmetry. He did not publish for a while on arxiv. I was hoping that he changed his mind, or that at least he developed some doubts. Now we know that he did not. Reading the interview, he reminded me of an old dictum:

    Errare humanum est, perseverare diabolicum.

  10. chris says:


    your reasoning is very peculiar. you say that in the mid ’90s a sober inspection of the evidence should have led a person to believing in SUSY. and that skepticism was not reasonable at that moment.

    i think you do not quite grasp what skepticism means. as i understand it, it means not believing in any phenomenon that is not established by firm evidence. and there was as little firm evidence back in the mid ’90s than there is now.

    now that the skeptics of back then turn out to be right (although some of them out of academia while some of the uncritical minds of the time hold professorships now) you suddenly say that they were mislead back then into holding the correct opinion?

    that is a very queer take on history.

  11. S. Molnar says:

    So, is it fair to say that when addressing the public Gross and Witten give much the same take as always, but when addressing physicists Gross is not so sanguine? If so, is there really a difference between the two? What, if anything, is Witten saying to physicists about the project?

  12. Dom says:

    RM, I’ll second the point about your take on scepticism, there is no onus of proof on the sceptic, the sceptic is the spokesperson for the Null Hypothesis.

  13. Shantanu says:

    Peter or anyone else: do you know if there was an upsurge in hype about string theory
    when evidence for non-0 neutrino mass was found in 1998. This was before pre-blogging days, don’t remember too well.

  14. Peter Woit says:

    I don’t recall ever seeing much in the way of claims that non-zero neutrino masses had any significance for string theory one way or another.

  15. imho says:

    Perhaps the larger issue is that public/private versions of this story exists at all. Everyone understands the need to preserve funding, and in every other field on earth, it’s almost mandatory that people “bend the truth” to protect their interests or create the appropriate public image… Unfortunately, that’s just the way the world works… But hard science is different. One of the core strengths of science is that it’s correct. No superstition, no opinions, just fact. The public trusts us because we’re impartial and we don’t lie to them… so why do some continue to obfuscate the truth???

    There are fields like Medicine, or Chemistry, or Cond Matt that can probably afford to falsely hype results. These fields produce concrete real-world results that directly benefit society. Yet at times, it seems these fields are the most subdued. So why is it that Fundamental Physics, which is mostly disconnected from society, feels the need to exaggerate results…. or maybe I just answered my own question?

  16. Als says:

    “There are fields like Medicine, or Chemistry, or Cond Matt that can probably afford to falsely hype results. These fields produce concrete real-world results that directly benefit society. Yet at times, it seems these fields are the most subdued.”

    The situation in medical science is far worse than physics. False claims, outright fraud and massive overhyping are depressingly common.

  17. Guido says:

    Slightly, but just slightly off-topic:

    “Brian Cox: ‘Multiverse’ makes sense”
    at http://www.bbc.com/news/science-environment-29321771

  18. AdamT says:

    FYI, the context of that article above is Many World’s interpretation of quantum mechanics measurement problem. As opposed to the string theory landscape or eternal inflation’s multiverse.

  19. RandomName says:

    I am very disappointed Horgan got the interview as he is just not a good interviewer for this kind of thing. And a *science* journalist claiming that we have come to the end of science/math is pathetic and sad.

  20. As I had said on my blog relatively recently, I think Horgan is a provocateur who carefully defines his terms to suit his agenda: http://nanoscale.blogspot.com/2014/04/john-horgan-same-old-same-old.html

  21. Roger says:

    According to Horgan, Bill Thurston sandbagged him on “The Death of Proof”.

  22. Raisonator says:

    Apropos Witten interview, there is an old one on the web which may not be so well known:

  23. NonaMe says:

    “string theory would be tested by finding SUSY at the Tevatron, or, failing that, definitely at the LHC. We all know how well that has worked out” Well, no we don’t. As far as I know the LHC is not over yet: it is barely starting to scratch the surface.

  24. HL-LHC or HE-LHC says:

    “His one point of close agreement with Gross is that both agree that not knowing what string theory is when time-dependent effects are large is a big problem, one that has seen no progress.”

    Can someone explain what are time-dependent effects on string theory and why is it a big problem? Does string theory have problems reproducing gravitational time dilation in GR?

  25. Eduardo Lira says:

    Dave Miller in Sacramento: “Horgan does not seem full of himself.”

    Not full of himself? The following statement by Horgan paints a different picture to me: “I don’t accept that the evidence for inflation is “vastly greater” now than in 1996.”

    Ed Witten may be wrong at the end concerning ST, but taking on him the way Horgan does reminds me of Salieri and Mozart. Except that Salieri was a music composer himself.

  26. Peter Woit says:

    Eduardo Lira,
    An interesting question is whether Witten is right or wrong about the evidence for inflation being “vastly greater now than in 1996”. I suspect Paul Steinhardt might disagree with him about this. Of the lists of evidence for inflation I’ve seen, the most convincing to me are pre-1996. But, I’m no expert, and I’d love to hear from an expert what they think of this.

    Horgan now has a good track record in his skepticism about Witten’s claims. Witten’s 1991 story that string theory would be vindicated at the Tevatron or LHC has not worked out, and in general Horgan’s 1991 skeptical point of view has held up a lot better than Witten’s.

    What do you suggest science journalists do when reporting comments from someone like Witten that they are skeptical about? Should they ever even have any skepticism about what someone like Witten has to say?

  27. Tim Howells says:

    > Roger says:
    > According to Horgan, Bill Thurston sandbagged him on “The Death of Proof”.
    > http://blogs.scientificamerican.com/cross-check/2012/08/24/how-william-thurston-rip-helped-bring-about-the-death-of-proof/

    Thanks for that very interesting and relevant link. Also note that in a postscript to that article Horgan links to this blog.

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