The New York Times
JAN. 12, 2015
The Compact Muon Solenoid Experiment, among others, has helped CERN become a leader in particle physics once again. Credit Denis Balibouse/Reuters
Rolf-Dieter Heuer, a crinkly-eyed German with a snowy goatee, showed up at the Four Seasons, the perennial Manhattan power lunch spot, dressed like the physicist he is — in a sweater and baggy jeans for the red-eye to Geneva — rather than the diplomat he had just been playing.
The United Nations was in session, and Dr. Heuer, the director-general of the European Organization of Nuclear Research, or CERN, had a featured role in events celebrating the laboratory’s 60th anniversary.
In 2009, when he took over, dark clouds were hanging over CERN, the world’s largest physics lab.
A few months before, the lab’s new Large Hadron Collider, the most expensive particle accelerator ever built, had blown up, indefinitely delaying the hunt for new particles, new forces and even perhaps new dimensions of nature. Some scientists were taking their research to a competing collider at the Fermi National Accelerator Laboratory in the United States. The worldwide economy was collapsing, as if into the black hole some alarmists had predicted the collider would make.
LHC at CERN
Tevatron at FNAL
Under Rolf-Dieter Heuer, who is in his last year at the helm, CERN has been revived as a leader in particle research. Credit Gerard Julien/Agence France-Presse — Getty Images
Now he looks fondly on those days. “If you start with such a low point, you can show your team was able to bring everything out of a low point up to a high point,” he said.
Dr. Heuer, 66, is entering the last year of his term; in 2016, Fabiola Gianotti, an Italian particle physicist, will take over as the director. Dr. Heuer will become the director of the German Physical Society.
If he rode in under dark clouds, he will ride out on a white horse. It was Dr. Heuer who stood up on the morning of July 4, 2012, in front of the world’s physicists and said, “I think we have it,” declaring an end to the half-century chase for the Higgs boson, a keystone of modern physics that explains why elementary particles have mass.
CERN, formed after World War II to rekindle European science, now has 21 member states. The newest, and the only one outside Europe, is Israel. The United States, which has observer status at CERN, is not a member but played a big role in building and operating the Large Hadron Collider.
In December, Dr. Heuer went to Islamabad to sign up Pakistan as an associate member. He said his long-term dream was a network of international labs, “islands where people can work together independently of the political situation in their home country.”
Dr. Heuer, born in Bad Boll in southern Germany in 1948, has spent his career in the trenches of particle physics, in which scientists emulate 3-year-olds by smashing bits of matter together to see what comes out.
He has no heroes, but said he had learned the ropes from his teachers. One indelible moment came when his Ph.D. supervisor at the University of Heidelberg, Joachim Heintze, tore up the first draft of his dissertation, saying it was too detailed. “It was amazing,” Dr. Heuer said. “A clear string of logic was missing. And that was the last time it was missing.”
He went on: “It was a memorable meeting. Since then, I propagate that message: When you have a problem, make sure you speak it out, and then it is forgotten.”
He had an opportunity to put that philosophy to the test early in his term at CERN, when physicists reported in a seminar there that they had measured subatomic particles known as neutrinos streaming from Geneva to their detector in Italy faster than the speed of light, contrary to the laws of physics then known.
Dr. Heuer was criticized for letting CERN be used as a platform for a result everybody believed was probably wrong. (The researchers later realized they had plugged their equipment together wrong.) In the end, Dr. Heuer said, nobody was fooled and the kerfuffle was fun, an example of the scientific process. Given the choice now, he said, he would do it again.
“I don’t think it’s up to the director-general to act like a censor if the result is against what everyone believes,” he said.
The neutrino controversy helped set a sort of dubious stage for the main event in particle physics so far this century: the Higgs boson.
Energy is the coin of the particle physics realm. The more energy with which two particles can be collided and transformed, the more intimately nature can be studied. The Large Hadron Collider was designed to be powerful enough to shake loose the Higgs boson.
“I think everybody was surprised it went so fast,” Dr. Heuer said of the Higgs hunt, especially because the collider had to be operated at only half its capability to avoid straining its circuits after the 2009 explosion.
It will start up again in March, running close to full strength for the first time, with proton bullets of 6.5 trillion electron volts — enough energy, scientists hope, to break into new ground.
The Higgs boson completed the Standard Model, a suite of equations that agrees with all the experiments that have been done on earth. But that model is not the end of physics. It does not explain dark matter or dark energy, the two major constituents of the cosmos, for example, or why the universe is made of matter instead of antimatter.
The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.
For decades, theorists have flirted with a concept called supersymmetry that would address some of these issues and produce a bounty of new particles for CERN’s collider.
“At the beginning, everyone was assuming supersymmetry was around the corner,” Dr. Heuer said, “and it would be the first thing to be detected.” It was not, nor has any deviation from the Standard Model predictions for the Higgs yet been recorded, disgruntling many theorists who hoped for a clue to the next great theory.
Standard MOdel of supersymmetry
Dr. Heuer is not among them — yet. “It’s not up to us to be disappointed by something nature has given us,” he said.
“On the one hand, it is fantastic how well the Standard Model works,” he said. “On the other hand, it’s frustrating how it holds against all precision tests.”
“If nothing shows up in the next runs, then one has to scratch the head,” he said.
The CERN collider has years yet to run, but the world’s physicists are already pondering even bigger colliders. Last summer, Chinese physicists announced a proposal to build a pair of colliders 32 miles around, twice as big as CERN’s. With international support, they said, the machines could be scaled up to reach energies of 100 trillion electron volts. Not to be outdone, CERN scientists have suggested tunneling under Lake Geneva to build a supercollider. Japan is also interested in having a Higgs factory built there.
It takes more than national pride and curiosity to build a multibillion-dollar particle accelerator. The Large Hadron Collider, Dr. Heuer said, had a natural justification: It would be powerful enough to find the Higgs boson, or whatever else made particles have mass.
“It was a no-lose theorem,” he said.
Without a clearer theory about how nature works at higher energies, however, there is no specific prediction for bigger machines to test. The energy value of 100 trillion electron volts, he conceded, is just a nice round number.
“This no-lose scenario does not exist for 100 TeV,” he said. To propose a new machine without such a killer app, he said, “you have to have a very good argument you can explain in a relatively clear-cut way.”
Can that be done? Do taxpayers and everybody else have a hope of understanding what the physicists are doing?
“That depends on your effort, sir,” he answered.
“The math behind it — forget it, even for me,” said Dr. Heuer, admitting that he is not fluent in quantum field theory, the body of math from which the Higgs springs. “I’m not a theorist.”
But he went on, “The answer is yes: You should be able to understand at least the logic behind it. You can explain to interested laymen.”
“Of course,” he said, “they will forget it two hours later. I know how it is when I learn something new.”
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