10th July 2012
The last week must have been a bit of a rollercoaster ride for you. Did the announcement at CERN of what looks like the Higgs boson take you by surprise?
The week before all this started happening, 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, rumours 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.
How were you feeling at that point?
I was getting excited. The final confirmation that the 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.
The teams on both ATLAS and CMS, the experiments looking for the Higgs particle, were 99.99994 per cent sure [a 5-sigma result, the “gold standard” for such work] that what they were seeing wasn’t a fluke. Were you surprised that the evidence was so strong?
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 time of last week’s Melbourne conference on high energy physics.
It was obviously an emotional moment when the announcement was made at the seminar last Wednesday.
I was asked by a journalist at the seminar 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 had won. There was a standing ovation for the people who gave the presentation, cheers and stamping. It was like being knocked over by a wave.
How did you celebrate?
With a can of London Pride ale on the flight back to London.
It was 48 years ago that you came up with a mechanism to account for the existence of mass, predicting the Higgs boson in the process. But one of your first papers on the subject was rejected, many of your peers thought your ideas were wrong at first, and Stephen Hawking bet against the discovery of the boson. Do you feel vindicated?
Yes, well, it’s nice to be right sometimes. I didn’t expect it to happen in my lifetime, at the beginning. Things began to change when the big colliders were built – LEP [the Large Electron Positron Collider, which was the predecessor of the Large Hadron Collider], 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.
Did you ever doubt that the particle existed?
No, I didn’t really. It is so crucial for the consistency of the mechanism. You can remove the particle as a theoretical exercise, but then it 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.
At the moment, they are calling it a “particle consistent with the Higgs”. The next step is to find out for sure that is what it is.
Yes. 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.
Several types of Higgs particle have been proposed, fitting various theories of particle physics. Which do you favour?
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 even enough, but it’s a way forward to get gravity involved. If you have supersymmetry, then there are more of these particles. That would be my favourite outcome.
You have always been a rather reluctant science celebrity. Is there a sense of relief and a hope that maybe now the attention will die down?
Relief is certainly part of it. It is still too recent for me to have come out of the upheavals of the last few days. The best I can hope for, I think, is some spells of quiet. At the moment, that’s not looking likely. My inbox and doormat are full with emails and letters 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 microbrewery in Barcelona which wants to know what my favourite beer is so they can brew a similar one in my honour. It is quite mad.
What with your peers calling for you to get a knighthood and the Nobel prize, there’s no sign of a return to a quiet life just yet. Do you think much about what might happen next?
Well, come October when the prize is announced I shall probably suffer from what Nobel winner Sheldon Glashow called Nobelitis. You get jittery.
With all this attention, have you come up with a snappy one-liner to explain the Higgs mechanism yet?
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.
The trouble is that when I try to explain it in the way I would prefer, there are so many people that don’t know the 18th-century physics that is 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 particle properties, and vice versa].
Because several people came up with the mechanism at almost the same time, knowing what to call the particle has been a minefield. What are you calling it these days?
I can’t see how it can continue to be called the Higgs boson, I reckon it will become just 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 as it has been recently. I keep having to tell people that it’s someone else’s joke, not mine.
That label has made the particle sound very accessible, though.
That’s true, but it has connotations that are simply misleading. It causes some people who don’t know how the phrase arose to say rather foolish things. I’ve heard some people who have a background in theology try to make sense of it in terms of that. They don’t understand it was just a joke, it was never meant to be taken seriously.