Brian Greene has a new video out today, of himself talking to Edward Witten, mainly about string theory. Pretty much the usual decades-old hype, with nothing even slightly different than what a similar conversation would have consisted of 20 years ago.
Of historical and psychological interest, Witten explains that when the anthropic landscape nonsense arrived, it made him uncomfortable and unhappy:
I was very upset. It really got me disturbed. First of all, well, as a physicist, I wanted to explain the masses and lifetimes of the elementary particles and other properties, rather than accepting the fact that they depended upon the choice of a classical solution. Literally, it made me very unhappy for years. I made my peace with it because I had no alternative. So I made my peace with it by accepting the fact that the universe wasn’t created for our convenience and understanding it…
So I accepted that. I came to accept that, I would say, by now almost 20 years ago, roughly 20 years ago. And I’ve had a more peaceful life since then…
At the time I saw the “landscape” as something that would finally cause leaders of the field like Witten to admit that string theory wasn’t working and to hopefully move on to something else more promising. Surely he would not follow Susskind and some others down this obviously unscientific path. He explains here that facing the failure of his dreams “made me very unhappy for years”. He could have admitted failure, but that would lead to ongoing unhappiness. If he wanted to avoid admitting failure, he had no alternative.
String theory and string theorists like Greene and Witten more than 20 years ago reached a dead end. They were much younger then and one could have imagined a new beginning of a more promising direction. At this point though, any hope of that is long gone. They’ve long ago decided that they had “no alternative” but to spend the rest of their days repeating the same hype that had inspired them in their youth.
Greene does at one point refer to critiques of string theory, while dismissing these with the rather nasty ad hominem characterization of “the chatter of people who may have other agendas”. Unfortunately this conversation is largely the chatter of two people with a shared agenda, that of continuing to prop up a failed idea they are heavily invested in.
As it usually happens in fundamental physics the key point was simple, but it required thinking along unconventional lines. Weinberg and a few other physicists did it while string theorists were dreaming an elegant universe.
Alessandro Strumia,
Weinberg had already jumped on the string theory bandwagon, in 1984, before the string theorists like Brian Greene started “dreaming an elegant universe.” In fact, he brought Polchinski to UT Austin around that time, before Polchinski found greener pastures in Santa Barbara.
Dear Prof. Woit,
If students are free to choose their research interests, what is your concern here? The world is full of competing interests, in all endeavours and forms of being. You are surely free to pursue your research agenda. If someone finds it compelling, they will join you, will they not? I’m no physicist nor a mathematical physicist, but surely you all must be aware at some level that at the scale of our existence in this universe it is possible that there are some questions we will never have satisfactory answers to. Given that reality, what does it matter how someone chooses to pursue their inquiry, as long as you are free to pursue your own? Perhaps you’ve satisfactorily addressed this concern previously, and if so, I apologize and would appreciate being pointed in the right direction.
Polchinski was a very good theorist. He reduced the hope of getting physics out of strings by discovering that one can complicate complicated compactifications by adding branes. Maybe hope remains in non-supersymmetric constructions.
Anonymous,
You seem to be missing the point. This is not about telling people what research agenda to pursue. In this video (and in many other places over the past 20 years) Greene and Witten argue for a failed research program, on the grounds that not predicting anything about particle physics is not failure, since things about particle physics can’t be predicted (they are “environmental”). I’m just (as I have been doing repeatedly for the past 20 years) pointing out that this is not science, that it is nothing more than a bad argument designed to avoid admitting failure.
This is astounding. I have discussed it now with colleagues from 20 t0 55 years of age in the field. They are just astounded. These men have clearly considered their options late in the game and have chosen to end their careers in an alternate physics reality in which things all kinda worked out pretty well as evidenced by the fact that we are still forced to be talking about their failed movement which reordered the field and made it permanently unrecognizable.
Anonymous,
around 2000, theoretical physics students who aimed at being hired had to jump from quantum mechanics to string theory, skipping established physics. They had to start doing research on formal string problems, without knowing why. Later, progress on strings stalled. Many of such students lacked the preparation to move to more active research areas.
I thought this was a rather charming interview with Witten. He seemed relaxed and at least a bit realistic about string theory’s pluses and minuses. He was right to be upset by the anthropic stuff. I think it made him dig in his heels on string theory looking for a way out for a few decades past where he should have. He’s the best inside pitchman for the project (however poorly defined) at this point. Alessandro is correct that we have lost a generation of students who really understand standard model building in the way it was done in the 1970s-1990s.
Peter,
Thank you for sharing that link. I found the interview very interesting in the sense that it gave me a completely different perspective from yours. Your criticism of the old leaders of string theory is based on your belief that they act like hypocrites since they know that their research program has failed and yet they still promote it to the general public as a promising one. In the interview, we learn that one of the main leaders is evoking the old argument that the incapacity of string theory to predict the SM’s parameters is simply like GR’s incapacity to predict the size of the solar system and the masses of its sun and planets. Since this is a categorical error, it plainly shows that string theory leaders do not act like hypocrites by selling bad ideas to the general public, but they are rather like AI even in their professional lives: Their thinking consists of ruminating widely used ideas within their community. I don’t thus find them guilty of anything, they just follow their core beliefs. I just feel bad for that generation (and for the younger ones they keep recruiting and keep training) for having missed the real deal about Nature.
I send you and all your commenters my best wishes for a Happy New Year!
Commenter,
I don’t think that Witten is a hypocrite. There is a category of people, in physics as in politics, that just doesn’t care whether what they say is true of not (or, worse, will say things they are well aware are untrue). Witten is not at all in that category, but is always very careful and measured in what he has to say.
The reason I said this interview was interesting in terms of psychology is that Witten explains what it felt like to adopt the “landscape” excuse for why his theory wasn’t working. He says the problem upset him a lot for quite a while, then he found that adopting the excuse would stop the unhappiness and let him have psychological peace again.
If you read Joe Polchinski’s memoir
https://arxiv.org/abs/1708.09093
in section 10.7 he describes the same sort of difficult psychological period, experiencing anxiety and depression because of the problems of string theory, in his case finding solace in medication.
Polchinski and Witten were not followers and were extremely aware of exactly what the technical status of string theory was. In addition, there was a lot of public debate going on (partly because of my book/blog and Lee Smolin’s book), which made the more usual psychological tactic of just ignoring a problem and pretending it doesn’t exist harder to carry out.