There’s a long interview with David E. Kaplan (not the same person as David B. Kaplan…) by David Zierler at the AIP Oral Histories site. The whole thing is quite interesting and I recommend reading it, but I do want to point out that it shows that I’m a voice of moderation on the string theory issue. Some extracts follow:
About Ann Nelson and string theory in the 1990s:
She was extremely dismissive of string theory, and thought it was—you know, there was—my impression from her and from other people of that generation that weren’t doing string theory was that the string theorists were colluding in a sense, or were dismissing anything but string theory, and deciding that if you did string theory then you’re much smarter than the people who are not doing string theory. There was some unhappiness in the theoretical field. And the cancellation of the SSC probably added to that tension between the two.
But I don’t think she came of it from taking a side. I think she looked at the situation and said, “String theory is total bullshit.” In the mid-’80s, there were some realizations—there were some consistency checks that kind of worked in string theory, and people got super excited. Oh, my god, string—yeah, it could be the, you know, underlying thing to particle physics. But that was it.
The successes after that were few and far between. But there was an obsessive—like we’re studying the theory of quantum gravity. And it was deridingly called the theory of everything. And then they took that on, you know. We’re studying the theory of everything. And then the young people who want to do the greatest stuff would go to string theory. And there was a concern and some upset by the people not doing string theory that they’re absorbing a lot of people to do this crap, which is not very physics like. “It’s I believe the theory, and so I’m going to study all aspects of it, and maybe one day we’ll connect it with the physical world.” As opposed to I believe in the phenomenon, and I’m trying to explain that and more, and so I’m going to try out different theories and see what they’re consequences are.
And now I look back, and it’s obvious that string theory was bullshit in the sense of there were so many people working on it, and they were not manifesting any real progress externally. It was all internal consistency checks and things like that. And so at the time, you know, whenever it came up—and it didn’t come up much because there were no string theorists in Seattle—she was just very dismissive, like, you know, “What are those people doing? I don’t know what they’re doing.” [laugh]
About being a postdoc at SLAC:
There were a lot of string theorists at Stanford. I didn’t understand any of those talks. Or sometimes when the talks were not in strings, Lenny Susskind would yell at the speaker that this is bullshit or whatever, da, da, da, da—you know, abusive at some level. So Stanford was weird in that way.
About realizing what was going on in string theory, his evaluation of past (Strominger-Vafa) and current claims about string theory and black holes:
But—so I don’t—and it’s part of probably why I didn’t understand—I didn’t think of myself as a physicist because there’s a lot of physicists working very hard on what? I don’t know what they’re working on. It’s not—you know, I used to just think I’m too stupid to understand what they’re working on. And finally reading some of those papers, they’re not what—it’s stupid. There’s a lot of stupid stuff in there. String theory really is just stupid. It’s unbelievably stupid. There’s so many people who are working on it that don’t actually know physics that they can’t even describe a physical characteristic of the thing they’re calculating. They’re missing the whole thing.
So that’s when I realized string theory is like a video game. There are people just addicted to it. That’s all that’s happening. And it’s couched in the theory of everything and da, da, da, da.
So that’s all. I just kind of—I learned quite a bit about these things. And then I saw the people like Lenny Susskind, who was terrorizing people who work on regular physics, as just a plain asshole. That there are actual people who are deciding string theory’s important, wanting to do string theory, and they’re even protecting the field. And some of those people are talking about how entropy now of a black hole can be described as a geometric thing, an entanglement, and that Hawking’s paradox about evaporating black holes is really wormholes, virtual wormholes coming from the inside to the outside, and all kinds of language. And you could test information theory of black holes using atomic physics experiments. And it’s literally bullshit.
There are people—prominent people—in physics who say, “I’m applying for this money from the DOE, but I know it’s bullshit.” And then there are experimental atomic physicists who don’t know and are shocked to learn that “What? String theorists don’t have a Hamiltonian? They don’t actually have a [laugh] description? What am I testing?”
So I have converted a little bit to the opinions of my predecessors, only because I’ve actually done the work. I’ve actually tried to understand black holes of late, and I’ve gone back to those papers which are the breakthrough, celebrated, amazing papers about black holes, and there’s nothing in them. It’s really—it’s just a very simplistic picture where, look, if you take this hyper-simplistic picture, these numbers match these numbers, which means thinking about a black hole having entropy is correct, da, da, da, da, da.
No matter that the black hole they’re talking about is extremal. It doesn’t actually Hawking radiate. It’s a totally hyper-supersymmetric, multiple charges, free parameters. So now that I’ve finally dug into it, I realize that—not that all humanities fields are bad. But it’s much more like a humanities field where there are the prominent people in the field, and they decide what’s interesting. And that if you impress those people, you can get ahead. But that dictates then what research is done. And they’re not going to discover anything in that context. They’re not going to get anywhere. There’s not a lot of people doing—you know—thinking outside the box or just thinking diff…you know, doing different things, you know.
About the argument that string theory must be worthwhile because lots of people are doing it:
What is your response to a string theorist who would say, and I know this because one has said this to me, “Look, four people were doing this in 1968, 20 people were doing it in 1984, 1,000 people were doing it in 2000, and now there’s 6,000 people who are doing string theory all over the world. And that’s proof that there’s something here that’s worthwhile”? What is your response to that line of reasoning?
[laugh] Take those numbers, continue the exponential, and apply it to Christianity—
—and Islam and Judaism and Buddhism. Give me a fucking break. They’re describing a religion that can attract and addict people. That is exactly the kind of statement that shows it’s bullshit and non-scientific. They’ve proven it for me that they are not about discovering something. They’re about dominating the field for the purpose of what? That’s proof? Give me a break. Give me a fucking break. Slavery was very popular, and became widely used. Nazism. Come on. You can take extreme examples and show that that is so non-scientific and sick that the progress they have made is to get more people to work on something that isn’t producing anything. Oh, man, I wish you didn’t tell me that. [laugh]
About the current state of the field:
There are so many things to think about. I don’t know what narrowed our field. I don’t see it as we’re dying because we’re coming to the limits of what we can do, the limits of what we can calculate in string theory, and the limits of how big of a ring we can build. I think most people are just doing useless stuff.
And so that’s why I—the whole depression or whatever, that’s a product of the non-willingness to feel stupid by the majority of our field. Expertise is more important to them than discovery. And that’s what I think is happening. And so what we’re seeing is not the death of the field, but the death of a direction that is being committed to by 98% of them.