The world was set alight by the discovery of what looks like the Higgs boson earlier this month. For Peter Higgs, who proposed the particle's existence 48 years ago, it was a week to remember. He came up with the mechanism for how matter gets its mass at around the same time as other groups and predicted the particle that bears his name. He is professor emeritus at the University of Edinburgh, United Kingdom, where a new center for theoretical physics will be opened in his honor.
Jessica Griggs: This chapter in the Higgs boson story must have been a bit of a roller-coaster ride. Did the announcement by the European Center for Nuclear Research, or CERN, on July 4 take you by surprise?
Peter Higgs: The week before, I was at a physics summer school in Sicily. I didn't take any Swiss francs with me, and my travel insurance policy expired the day I was supposed to fly back to Edinburgh. As the week went on, rumors began to fly, but it wasn't until the Saturday before the announcement that we knew for certain that something was up. We got a phone call from John Ellis, the former head of theoretical physics at CERN, saying, "Tell Peter that if he doesn't come to CERN on Wednesday, he will very probably regret it." I said, very well then, I'll go.
JG: How were you feeling at that point?
PH: I was getting excited. The final confirmation that good news was coming came the evening before the CERN seminar. We had dinner at John Ellis's house, and he cracked open a bottle of champagne.
JG: The teams on ATLAS and CMS, the experiments at CERN looking for the Higgs boson, were 99.99994 percent sure that what they were seeing wasn't a fluke—a 5-sigma result, the gold standard for such work. Were you surprised that the evidence was so strong?
PH: That was amazing, especially as in the weeks before I had been visiting various high-energy physics groups working on ATLAS or CMS, and everywhere the researchers were sure that CERN would not get to 5-sigma by the start of the conference on high-energy physics in Melbourne, due to begin on the day of the announcement.
JG: It was obviously an emotional moment when the announcement was made.
PH: I was asked why I burst into tears after the presentation. During the talks I was still distancing myself from it all, but when the seminar ended, it was like being at a football match when the home team wins. There was a standing ovation for the people who gave the presentation, cheers and stamping. It was like being knocked over by a wave.
JG: How did you celebrate?
PH: With a can of London Pride on the flight back to London.
JG: You came up with a mechanism to account for the existence of mass, predicting the Higgs boson in the process. But there was opposition to your ideas at first. Do you feel vindicated?
PH: Yes, well, it's nice to be right sometimes. I didn't expect it to happen in my lifetime at the beginning. This changed when the big colliders were built: LEP (the predecessor of the Large Hadron Collider, or LHC, at CERN), the Tevatron, and now the LHC. At the beginning, no one knew what the mass of the Higgs would be, so it could have been too high for it to be discovered by these colliders.
JG: There were those who doubted the existence of the particle. Did you ever think that way?
PH: No, I didn't really. The Higgs is so crucial for the consistency of the mechanism. You can remove the particle as a theoretical exercise, but then the mechanism becomes nonsense. I had faith in the theory behind the mechanism, as other features of it were being verified in great detail at successive colliders. It would have been very surprising if the remaining piece of the jigsaw wasn't there.
JG: Your peers are calling for you to get a knighthood and the Nobel Prize in physics. Do you think about what might happen next?
PH: Well, come October when the prize is announced I shall probably suffer from what Nobel winner Sheldon Glashow called Nobelitis. You get jittery.
JG: You have always been a rather reluctant science celebrity. Is there a sense of relief and a hope that the attention might now die down?
PH: Relief is certainly part of it. The best I can hope for, I think, is some spells of quiet. At the moment, that's not looking likely. My inbox is full with emails, and letters are piling up on my doormat from people who want me to endorse their Higgs board game or to inaugurate the walkway of their new office atrium. There's even a Spanish microbrewery in Barcelona that wants to know what my favorite beer is so they can brew a similar one in my honor. It is quite mad.
JG: At the moment they are calling the find "a particle consistent with the Higgs." If it turns out to be the elusive particle, what comes next?
PH: In one sense it is the end of the road, in that it's the last piece of the standard model to be discovered. But in another, it's the beginning of where machines like the LHC go next. The next stage of exploration will include measuring all the properties they haven't seen. Hopefully this will provide clues for things like supersymmetry, which could be a comprehensive way to go beyond the standard model because it provides a framework for things like dark matter.
JG: Several types of the Higgs particle have been proposed, fitting various theories of particle physics. Which do you favor?
PH: I'm a fan of supersymmetry, largely because it seems to be the only route by which gravity can be brought into the scheme. It's probably not enough, but getting gravity involved is a way forward. If you have supersymmetry then there are more of these particles.
JG: Have you come up with a snappy one-liner to explain the Higgs mechanism yet?
PH: No, I spend more time telling people that explanations by physicists who should know better are nonsense. The one that I object to is that the acquisition of mass by a particle is like dragging it through treacle. That is a process where you are losing energy. When I try to explain how it works in the way I prefer, there are many people who don't know the 18th-century physics needed. I explain it as being somewhat like the refraction of light through a medium. The model I came up with in 1964 is just the invention of a rather strange sort of medium that looks the same in all directions and produces a kind of refraction that is a little bit more complicated than that of light in glass or water. This is a wave phenomenon, but you can translate it into the language of particles by waving your hands and muttering the magical names of Einstein and de Broglie, who formulated the idea that waves could have the properties of particles, and vice versa.
JG: As several people came up with the mechanism at almost the same time, naming the particle has been a minefield. What do you call it now?
PH: I can't see how it can continue to be called the Higgs boson. I reckon it will become the H boson. Hopefully in a particle-physics context it shouldn't get confused with hydrogen. I do sometimes still call it the Higgs boson so people know what I'm talking about. I don't call it "the God particle." I hope that phrase won't be used as much. I keep telling people that it's someone else's joke, not mine.
JG: It has made the particle sound very accessible.
PH: That's true, but it has connotations that are misleading. It causes some people who don't know how the phrase arose to say foolish things. I've heard some with a background in theology try to make sense of it in terms of that. They don't understand it was a joke and wasn't meant to be taken seriously.
This article originally ran in New Scientist.