Just time for three quick items:
- There’s a wonderful book out now published by the Simons Center at Stony Brook, with the title Crossings. It tells the story of the center and of various people involved with it through a large number of interesting pieces written by these people. The book is published by the center, available here.
- Symmetry magazine has an article out today, with the title Can a theory ever die?. It’s largely about supersymmetry, with “No” the answer to the title question. There’s a story about Bruno Zumino I’d never heard before:
In 1996 theorist Jonathan Feng attended a seminar about searches for new particles predicted by the mathematically elegant theory of Supersymmetry. The speaker was optimistic that researchers would find the particles at massive colliders such as the Tevatron, then in operation at the US Department of Energy’s Fermi National Accelerator Laboratory, or the Large Hadron Collider, then under construction at CERN.
Feng noticed Bruno Zumino, one of the founders of Supersymmetry, in the audience. Zumino’s reaction to the talk confused Feng.
“He left the seminar shaking his head,” says Feng, who is now a professor at the University of California, Irvine. “I thought he would be happy that an army of people were looking for his theory. So why was he shaking his head?”
Feng caught up with the distinguished theorist during the coffee break. He still remembers what Zumino told him: “I never thought it would be this hard. If it’s this hard, then they’re never going to find it.”
So, twenty-six years ago one of the leaders of the field thought the idea was going nowhere and likely doomed. In the years after that LEP and the Tevatron put much stronger limits on SUSY before closing down in 2000 and 2011 respectively.
From 2010 to the present day, the LHC has again put far stronger limits on SUSY particles. Most now agree it is overwhelmingly unlikely that the rest of the LHC or HL-LHC runs will change the situation. And, prospects for a higher energy collider are very uncertain and many decades away. You’d think that would be the end of it.
But the article quotes theorists determined to keep at it (no quotes from anyone who thinks SUSY is over) and there’s still an active community of people pursuing what Zumino thought was doomed multiple decades and accelerator generations ago. Large conferences continue to be scheduled, for example SUSY 22 this summer, which will be preceded by a pre-SUSY school designed to train a new generation to work on the failed ideas for many decades to come.
- I’m leaving soon to spend a couple days in Texas, giving a colloquium talk at the University of Texas at Dallas math department.
Update: The slides from the talk at UT Dallas are here.
“take care when you travel through [Texas] Germany with the truth under your coat!”
I don’t agree with that interpretation of Zumino’s response. You may be attributing beliefs to him that he did not hold.
He doesn’t say that SUSY is “going nowhere” or “doomed,” he says that we’re “never” going to find direct empirical evidence for it at a particle collider. (Here I understand “never” in the colloquial sense of, “not in a reasonable amount of time.”) This is not really surprising, since there’s a lot of room between the LHC and the Planck scale, and no reason to believe superpartners should exist at energy scales accessible by 2000s-era technology (assuming they exist at all).
You might object and claim that an idea is doomed/going nowhere if there’s no hope of it being empirically verified or rejected in a “reasonable” amount of time (say roughly 100 years). But that’s not an obviously true claim, and it’s not clear that Zumino held it.
Sure, it’s possible Zumino thought that SUSY extensions of the SM broken at inaccessibly high energy scales were a promising idea, but I don’t see any good argument for that (as opposed to the electroweak scale, with the “naturalness” motivation).
Feng and Tanedo in the Symmetry article give the impression that it no longer matters whether prospects for experimental vindication of an idea have vanished. I suspect Zumino was of a very different generation which did not think this way.
Just a typo: Can a theory ever die?
I did some quick research, which indicates that, at least publicly, Zumino was more optimistic about SUSY than Feng indicates. In a 2008 review article
with Mary Gaillard, they write
“We are very optimistic that the MSSM, or some extension of it … will correctly describe the particle and superparticle spectrum that will be produced at LHC energies.”
and note that if there is no SUSY at LHC energies it could be at higher energies. If Zumino had lived, it’s an interesting question how he would have reacted to beliefs he was “very optimistic” about being disconfirmed experimentally. Maybe he would have reverted to his 1996 pessimism.