Around the time of the Higgs discovery announcement last month I was contacted by someone from the Italian left-wing newspaper Il Manifesto, who asked if I’d write something for them about the Higgs. I told them that it would be much better if they could get an experimentalist to write about that topic, since the discovery was really an experimental achievement. They managed to get Tommaso Dorigo to write that piece for them (see here), but I agreed to write something for them a bit later, about the significance of other results from the LHC. That piece appeared in the newspaper today in Italian translation, an English version follows here.
This was written last week, under the combined influence of watching some of the Strings 2012 talks and thinking about the possible impact of the new $3 million Fundamental Physics Prizes, which largely went to string theorists. For this venue, I was unable to resist channeling my inner leftist (normally the only newspaper that wants me to write for them is the Wall Street Journal…) and making Russian financier Yuri Milner to a large extent the bogeyman of the piece.
A very serious concern that I wanted to raise is that of the long-term danger that fundamental physics faces in the combination of string theory ideology and the possible “nightmare scenario” of the LHC finding nothing that disagrees with the Standard Model. For decades now the theoretical side of the subject has been dominated by one specific set of not very compelling ideas: 10d superstrings at the Planck scale, with a SUSY GUT at slightly lower scale, and low-energy SUSY explaining the supposed “hierarchy problem” created by the vast difference between those scales and the scale of electroweak symmetry breaking (of order 100 GeV). The force most likely to challenge the hegemony of this ideology has always been the LHC, which was supposed to see superpartners responsible for stabilizing the electroweak scale. Watching the speakers at Strings 2012 made clear that the failure of this experimental prediction would not cause them to give up on this ideology, but instead to redouble efforts to prop it up at all costs.
The fundamental problem is the deeply entrenched nature of string theory ideology in the power centers of the academy and among the most talented theorists. Milner’s choice to provide out-scale rewards to such talented people is not the main problem, although he provided a convenient target for me in the piece. If we really do end up with the “nightmare scenario” of experiment not coming to rescue, it’s now all too clear where we end up: the textbooks of string theory and supersymmetry have already been written, and that will be codified as humanity’s best understanding of fundamental physical reality for the indefinite future.
Maybe some new theoretical ideas will somehow bloom, but otherwise our best hope to get out of this will be the efforts and innovations of talented experimentalists, likely requiring expensive equipment. It will be a challenge to continue to find public resources to fund this. Maybe if the trends of recent decades continue, it will be up to the financiers to decide whether humanity continues down the experimental path. Luckily, a lot of them seem to be interested in physics.
The article follows, you might want to skip it if you’re a regular blog reader here, since you won’t hear anything new and it’s a bit of a rant…
Last month came an announcement from Geneva that physicists of my generation had been anxiously awaiting since our student days nearly
forty years ago. Experimentalist Tommaso Dorigo wrote in this newspaper about the great achievement of the Large Hadron Collider at CERN and his 6000 or so colleagues, who came together to produce and make the first measurements of a new fundamental element of nature: the Higgs particle.
For theorists like myself, this was a bittersweet victory for our subject. The Higgs particle showed up more or less exactly in the manner predicted by the so-called Standard Model, a wildly successful fundamental quantum theory developed between 1967 and 1973. This theory had passed critical tests time and time again, but until last month the trickiest part of the theory had not been tested by direct observation. Perhaps we were missing something important, and the real world would slap us in the face with results contradicting the theory, and giving us clues about how to find a better one. Instead, we saw the equations of our textbooks dramatically confirmed. We now await a long process of detailed investigation of this new phenomenon, a process which will keep Tommaso and his colleagues busy for many years to come.
The Higgs discovery emerged as a single sudden announcement, but over the last two years an equally important discovery has slowly come into focus, one small piece of data from the LHC at a time. Unlike the case of the Higgs, this discovery has been a vigorous slap in the face to the theoretical particle physics community, telling us in no uncertain terms that we’ve been wasting most of our time for the past thirty years. For these three decades, the subject has been dominated by research into an elaborate speculative scenario which has been investigated in exhaustive detail.
This scenario goes under the name of “superstring theory”, referring to a set of ideas that form not exactly a well-defined theory, but rather a conjecture that a theory with certain properties should exist. This theory would unify the Standard Model with Einstein’s theory of gravity known as General Relativity, embedding both in a complicated structure involving six extra dimensions of space. The possibility that these new dimensions would put in an appearance at the LHC has often been used to impress the public with flashy claims about the dramatic things that CERN’s new machine could find, things that sounded like (and were) science-fiction. Whatever they told the public, few physicists were expecting such dimensions to be observable in the data, since the conventional speculative scenario put their size at far too small a value to be seen at the LHC. No one has been surprised at all by the failure of any sign of extra dimensions to show up at CERN, despite a careful search for any possible evidence.
The “super” in “superstring” though is a different story. This indicates a crucial property of the conjectural unifying theory: each fundamental particle should come paired with another one of very specific properties, the particle’s “superpartner”. The electron should be paired with a new particle named the “selectron”, each quark with a “squark”, etc. Over the years an increasingly rigid ideology explaining the supposedly wondrous properties of this “supersymmetry” which would dramatically improve upon the Standard Model. That supersymmetry provided none of the powerful explanations of past observations we have come to expect from new symmetry principles was an inconvenient issue best ignored. As each new generation of accelerators came to life at CERN and at Fermilab in the United States, superpartners were looked for, but never found.
Supersymmetry entered the textbooks anyway and has now been taught to generations of graduate students. Always part of the story being told was the claim that superpartners should have masses roughly similar to the mass of the Higgs particle. When the Higgs was found, the superpartners had to be there too. Consistency of the Standard Model demanded that the Higgs could not be too massive, so long before the LHC was turned on, it was a sure thing that if the Higgs particle was there the LHC would find it. That part of the story worked out perfectly, but it has been accompanied by a huge embarrassment: no sign of any superpartners at all. Not only were they supposed to be not too much heavier than the Higgs, but many of them were supposed to be much produced much more copiously, and thus be much easier to see. By now the LHC experiments have shown that such expected particles are absent, unless they are made inaccessible by pushing their masses up to more than an order of magnitude higher than that of the Higgs, a value far beyond what had been advertised as reasonable.
The implications of this attack on theorists by the reality principle are just beginning to sink in. The big yearly conference of superstring theorists was held this past week in Munich, with different speakers taking different approaches to dealing with the problem. One speaker advocated not doing anything until next year, hoping against hope that newer data would give better results. Others took the attitude that it had been clear for quite a while that superstring theory wasn’t going to show signs of existence at the LHC, so best to just work on finding other uses for it. In the conference final “Outlook and Vision” talk, the illustrious speaker announced that all was well, and didn’t mention the LHC results at all. The ostrich-like tactic of burying one’s head in the sand seems to be on the agenda for now, but this will become increasingly difficult to maintain as time goes on and more and more conclusive negative experimental results arrive.
As a physicist, one problem with having an experiment tell you that your ideas are wrong is that it means you are ineligible for a Nobel Prize. Your hopes for a right to a part share in $1.2 million have been dashed, and, no matter how famous and well-paid an academic star you may be, you will have to content yourself with living on your salary, supplemented perhaps by smaller, less well-known consolation prizes.
Around the time of the end of the superstring theory conference though, dramatic news came from billionaire Russian financier Yuri Milner. Known for building the most expensive house in the United States, he decided to help support physics by depositing $3 million dollars per person in the bank accounts of 8 prominent physicists and one mathematician, rewarding 6 of them for their work in superstring theory. He has modeled himself after Alfred Nobel, announcing a new foundation that will give out Fundamental Physics Prizes each year. Unlike the Nobel, these prizes can go to work for which there is no experimental evidence. What he’s looking for are “transformative advances” like superstring theory, which have gotten the seal of approval of popularity among high-status academics. Even if experiment shows the ideas to be wrong, as in the case of the latest data about supersymmetry, that doesn’t matter. What does matter is that the recipients should reflect the conventional wisdom in the academy. The choice of who to give the Prizes to included giving them to every single professor of particle physics at the world’s most prestigious academic institution, the Institute for Advanced Study in Princeton. The question of competition with the Nobel prize was dealt with by setting the value of the prize far above that of the Nobel, at a level significantly higher than any other academic prize in the world.
The slap in the face by experimental data and its threat to impose the reality principle on the most powerful figures in the world of theoretical physics has thus been met by a riposte from another powerful force. This is another reality, that of entrenched academic interests, funded by the billions of dollars available to financiers who want to impose their will upon the world, or at least the small part of it that will write the textbooks of the future. Which of these forces will carry the day? Will the budget cuts imposed on physics research in Italy and elsewhere cripple the ability of the LHC experiments to continue to reveal the structure of nature, leaving our future fundamental science in the hands of powerful interests who will decide which version of reality they like best?
In the longer term, the physics community now faces difficult choices. Any machine more powerful than the LHC will be expensive and require multiple decades to design, finance, build and operate. The temptation will be there to again promise discovery of exotic new dimensions and supersymmetries in order to convince governments to provide funding. Instead of such empty promises, physicists should just make the case that humanity deserves the chance to continue the experimental investigation of the fundamentals of physical reality. The alternative is all too clear: the lack of public money to fund experimental investigation will put those with private money in charge of deciding what our scientific reality will be.
Last Updated on