CERN on Wednesday is hosting a colloquium talk by Joseph Lykken, who supposedly will discuss Prospects for experimental quantum gravity. There’s by now a long tradition of string theorists dealing with criticism that their research program is inherently immune from experimental test by making bogus claims about experimental testability. Lykken has been at it for at least twenty years (see here), and this sort of misleading claim about testability is the latest in a long campaign.
If you read the abstract, it looks like what Lykken is actually talking about is numerical simulations of an SYK model with of order 100 Majorana fermions on a quantum computer. Ignoring the quantum computer hype (unclear how long it will really be before such simulations are feasible), keep in mind that the SYK model is a quantum mechanical toy model, not a model of quantum gravity in a physical dimension. The only thing a quantum computer could test would be the validity of certain approximations schemes in such a toy model. For comments by David E. Kaplan about similar testability claims, see the interview discussed in the previous posting, which includes:
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?”
Update: Lykken was giving Colloquium talks on Experimental String Theory nearly a quarter century ago. He was also one of the main sources for the embarrassing NYT 2000 article Physicists Finally Find a Way to Test String Theory.
“For the first 25 years, the thinking has been that superstring theory is so difficult to see experimentally that you have to figure it out by its own mathematical consistency and beauty,” Dr. Lykken said. “Now that’s completely changed. If this new picture is true, it makes everything we’ve been talking about testable.”
Hopefully science journalists have learned something and we won’t see a forthcoming NYT article on how “Physicists Finally Find a Way to Test Quantum Gravity”.
Update: Lykken’s slides are here. His proposal for an experimental test of quantum gravity is explicitly acknowledged as the same as one made by Lenny Susskind here in 2017. At the time that made no sense to me and I wrote about it here. It still makes no sense.