The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World

by Sean Carroll

  Physics paparazzi

  Giant particle accelerators aren’t the only way to look for new physics. Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics, or PAMELA for short, is an Italian cosmic-ray experiment that lives in low earth orbit, piggybacking on a Russian (nonmilitary) reconnaissance satellite. One of its main goals is to look for antimatter in cosmic rays, primarily positrons and antiprotons. It’s not surprising that we see some antimatter; there are high-energy processes in outer space that occasionally produce antiparticles, just as there are at the LHC. What was surprising is that PAMELA observed substantially more positrons than they expected. This could be evidence for some astrophysical process that we don’t currently understand, such as novel phenomena in neutron-star atmospheres; or it could be evidence for physics beyond the Standard Model, such as dark-matter particles annihilating and creating an excess of positrons. Various options are being investigated, although as time goes on the astrophysical options seem to be more promising.

  Even more surprising, perhaps, is how the word of PAMELA’s intriguing result got out. It often happens that a collaboration has preliminary results, not quite ready to be published or distributed, but enough to show to colleagues at a conference. That was the case with PAMELA at the International Conference on High Energy Physics in Philadelphia, in September 2008. PAMELA physicist Mirko Boezio briefly flashed a plot that showed an excess of positrons—a result that hadn’t yet been incorporated into any publications.

  Not briefly enough. While the plot was displayed, a young theorist named Marco Cirelli, sitting in the audience, quickly snapped a photo of it with his digital camera. Back home, he and collaborator Alessandro Strumia wrote a paper that proposed a new model of dark matter that could explain the excess, and sent it to the physics archive server http://arxiv.org, where it was distributed around the world. In their paper, they created plots in which they compare the theoretical prediction from their model with the data they extracted from their photo of the conference talk, with a footnote: “In order to comply with the publication policy, the preliminary data points for positron and antiproton fluxes plotted in our figures have been extracted from a photo of the slides taken during the talk.”

  Welcome to the new world. There is clearly something of a gray area here. A member of the collaboration might say that data that is not yet ready for publication should never be used in a theoretical analysis. But a member of the audience might reply that data that isn’t ready shouldn’t be shown in public talks, either. Piergiorgio Picozza, an Italian physicist and leader of PAMELA, was “very, very upset” that their data was acquired and used in this way. But Cirelli insists that he obtained permission from the PAMELA physicists who were at the conference: “We asked the PAMELA people [there], and they said it was not a problem.”

  As many teenagers have learned in the age of Facebook, anything you share with some people in the modern world you might as well share with everyone. Technology has made it effortless to distribute information, no matter how official or reliable that information may be. As Joe Lykken said in reference to yet another rumor, “Pre-blog, this sort of rumor would have circulated among perhaps a few dozen physicists. Now with blogs even string theorists who can’t spell Higgs became immediately aware of inside information about [these] data.”

  Whispers

  Rumors aren’t always benign. In April 2011, an anonymous commenter on Peter Woit’s blog Not Even Wrong leaked an internal ATLAS memo from Sau Lan Wu’s team at Wisconsin. The contents were explosive, if true: strong evidence for a Higgs-like boson decaying into two photons. But it was too good to be true; to get that strong a signal with the relatively tiny amount of data they had at the time, the rate of Higgs decays would have had to be thirty times larger than the Standard Model prediction. Not impossible, but not something anyone was expecting, either. Unsurprisingly, once ATLAS did come out with an approved measurement, the signal had gone away.

  This incident shows a downside of blogs. Internal memos such as this are the lifeblood of a large collaboration; they are written all the time, as part of the process described above for how an analysis matures into an approved result. Even the people who write the memos don’t necessarily believe the result is real; they are simply pointing something out that deserves closer scrutiny. That’s fine, as long as it is kept within the collaboration. If it goes public well before it’s been vetted, there is a serious danger of misunderstanding, which can ultimately serve to undermine the public’s confidence in the results that we do stand behind. Wu herself was furious: “Such a leak was totally unethical and irresponsible by the person who did it . . . The leak has damaged the freedom of conveying internal studies in written form to the collaborators. To me, this is an extremely sad affair.”

  In June 2012, CMS and ATLAS began to look carefully at the data they were able to collect so far that year. Everyone knew from the December 2011 seminars that there was a hint of Higgs at 125 GeV, so curiosity was understandably at a peak. As soon as the analysis began, rumors began to fly. There was a long-standing plan to present updates on the Higgs search in July at the ICHEP, scheduled for Melbourne. Chatter heated up when CERN announced that they weren’t going to wait for Melbourne, but would instead have special seminars immediately beforehand in Geneva. Why would they do that if they weren’t going to announce something big?

  Things got so bad that Fabiola Gianotti, in an email to reporter Dennis Overbye at the New York Times, pleaded, “Please do not believe the blogs.” But bloggers come in all stripes, and some tried to stem the tide rather than add to it. Michael Schmitt, a physicist at Northwestern and a member of CMS, wrote at his own at Collider Blog:

  My loyalty remains with my collaboration, especially the people who are working right now to carry out the analysis and verify the results, as well as to the people at the top who have to chart strategy and make difficult decisions. A little splash in a blog is not worth the bother it would cause all these people.

  The undeniable truth is that, with six thousand people on the inside, someone is going to give in to the temptation to spill the beans—even before the beans have actually been collected and counted. One of the most frequent anti-blog complaints was not that results were being distributed ahead of time, but that the results didn’t even yet exist; analysis takes time and often proceeds feverishly right up to the moment that a talk is given or a paper submitted for publication.

  Meanwhile, others took the excitement and turned it into an opportunity to have a little fun. On June 20, various users of Twitter started passing back and forth satirical tweets about the Higgs. The hashtag #HiggsRumors even briefly became a “trending topic” on Twitter, an honor usually reserved for news involving Jersey Shore or Lady Gaga. Jennifer Ouellette, a science writer and blogger (who is also my wife), collected some of the best tweets in a blog post.

  @drskyskull: I hear the Higgs boson once shot a man just to watch him die. #HiggsRumors

  @StephenSerjeant: ATLAS and CMS both beaten to Higgs detection by Chuck Norris. #HiggsRumors

  @treelobsters: On the Summer Solstice, you can balance a Higgs Boson on end. #HiggsRumors

  @tomroud: The God Particle actually is an atheist. #HiggsRumors

  The best I could muster at the time was “Little Mikey from the LIFE cereal commercials died after eating Higgs bosons and drinking soda at the same time. #HiggsRumors.” Probably this reveals more about my comedy skills (and my age) than anything else.

  Hollywood squares

  Los Angeles is an industry town, and the industry is entertainment. In early 2007, not long after I had first moved here, I got an unusual phone call. It was from Imagine Entertainment, the production company run by Ron Howard and Brian Grazer (Apollo 13, A Beautiful Mind, The Da Vinci Code). The filmmakers were in the planning stages for Angels & Demons, based on the Dan Brown book, which featured important scenes set at CERN. They wondered whether I’d be willing to drop by their Beverly Hills offices to chat about particle p
hysics?

  I admitted that I could probably fit it into my schedule. This was my first introduction to a little-known fact: Hollywood loves science.

  It’s the opposite of the usual stereotype, which is that movies and TV shows regularly serve up atrocious scientific mistakes, and typically portray scientists as either antisocial dweebs or mad geniuses bent on ruling the world. There certainly is a lot of that, but among many writers and directors there is a genuine interest in using honest science to improve the stories they want to tell. Howard and Grazer were sincerely interested in cosmology, antimatter, and the Higgs boson, and we shared an enjoyable lunch brainstorming ways to work physics into the film. Later, my wife, Jennifer, would become the first director of the Science and Entertainment Exchange, an effort from the National Academy of Sciences that works to improve interactions between scientists and Hollywood. Through the Exchange I was able to meet filmmakers like Ridley Scott, Michael Mann, and Kenneth Branagh, each of whom wanted to hear more about extra dimensions, time travel, and the Big Bang. Big-budget Hollywood movies are not meant to be documentaries or public service announcements for science; the storytelling always comes first, and suggestions from the scientists don’t always make it into the final product. But many respected professionals who spin fairy tales on the silver screen appreciate the underlying wonder of scientific discovery.

  For its own part, science isn’t averse to going Hollywood to help its own cause. Science writer Kate McAlpine, who spent time at CERN working with ATLAS, in 2008, released a YouTube video entitled “Large Hadron Rap.” The performance featured physicists dancing in front of LHC experiments while McAlpine rapped physics-themed lyrics over background beats:

  Twenty-seven kilometers of tunnel underground

  Designed with mind to send protons around

  A circle that crosses through Switzerland and France

  Sixty nations contribute to scientific advance

  Two beams of protons swing round, through the ring they ride

  ’Til in the hearts of the detectors, they’re made to collide

  And all that energy packed in such a tiny bit of room

  Becomes mass, particles created from the vacuum

  And then . . .

  Seven million views later, it is clear that the video struck a chord. There is no dearth of goofy YouTube videos on every subject under the sun; for some reason, this one stood out above the crowd. It serves as a reminder of how interested people can be in esoteric scientific questions when they are presented in a fun way.

  The most ambitious project along these lines has been masterminded by David Kaplan, a particle theorist at Johns Hopkins University. Kaplan’s day job is constructing models that can be tested at the LHC and in other experiments, but he has a long-standing interest in filmmaking. As a high school student, he remembers being academically unmotivated and didn’t even apply to go to college. His sister, without telling him, sent an application in his name to Chapman University in California. To everyone’s surprise he was accepted and spent a year there as a film major. It wasn’t to his taste, and he ultimately ended up transferring to UC Berkeley and majoring in physics. He didn’t go to graduate school immediately, partly because his Berkeley grades were so bad that he didn’t think anyone would write him a letter of recommendation. Instead Kaplan moved to Seattle and earned money on the side by tutoring physics students at the University of Washington. After enough of the students compared him favorably to the graduate students at UW, he finally entered the PhD program there. All’s well that ends well; he is now one of the leaders of a new generation of young particle theorists trying to push physics beyond the Standard Model.

  As the LHC era crept up on us, Kaplan was struck by the unique nature of the moment in time. He would share with friends his impression that this was a make-or-break point in the history of science, if not the history of human intellectual development. If the LHC finds something interesting, it will launch us on a new path of discovery. If it doesn’t, the prohibitive cost of modern particle physics might mean that this is the last major accelerator ever built. Kaplan became convinced that this high-stakes drama should be carefully documented. He would conduct interviews with particle physicists—both senior ones who have built careers on certain ideas about how nature works and would see them verified or thrown away, and younger ones who would have to cope with whatever the LHC did or did not reveal—and turn them into a book.

  The problem was that even when it comes to scientific papers, Kaplan is a terribly laborious writer. The solution was obvious: Rather than write a book, he would make a movie. Particle Fever (the film’s tentative title) was born.

  As a new faculty member, Kaplan had been awarded a small fellowship from the Alfred P. Sloan Foundation. Usually such fellowships are used to fund computers or travel or some amount of support for graduate students. Instead, Kaplan got a TV director interested in his idea, and the two used the money to make a five-minute clip that could then be used to raise the serious money required to create a feature-length documentary film. Their original budget was $750,000 (since increased), and the real work began: raising money, hiring editors and writers, raising money, interviewing physicists, and raising money. They handed out small high-definition cameras to physicists at CERN who were able to record crucial events like the 2008 startup and the accident soon thereafter. Kaplan himself has devoted a substantial amount of time to the project. He gets no salary, and at one point his family had to give him a $50,000 loan to keep it afloat.

  But interest has been immense. The development office at Johns Hopkins showed a clip to the university’s board of directors, one of whom made an investment on the spot. The National Science Foundation, which supports much of the basic research in the United States and is constantly haranguing scientists to get more involved in public outreach, was thrilled to find out that one of their researchers was taking outreach seriously, and offered substantial support. Walter Murch, a highly respected Hollywood editor who has worked with George Lucas and Francis Ford Coppola and won multiple Academy Awards, became fascinated by the film and offered his services at well below his usual fee.

  Throughout the process, Kaplan’s goal has been to capture some of the quixotic fervor that pushes scientists to understand the universe just a tiny bit better than anyone has understood it before. The emotional stakes are high; physics is an experimental science, and the most brilliant theorists in the world get little credit if the theory they propose turns out not to be the path nature has chosen. In Kaplan’s words,

  In the end, it’s an incredibly heroic exercise. And it is filled with different egos, and intensity, and overconfidence maybe. But what you understand is that people fool themselves. Scientists create a world in their brain, in order to get themselves to work as hard as they do and to keep going, knowing that it could be a complete failure. Their entire career could just be in the toilet as totally irrelevant.

  As of mid-2012, Particle Fever is nearing completion, and the team is hoping to get chosen for the Sundance Film Festival in January 2013. Fittingly, they are wildly ambitious, hoping for an eventual wide theatrical release that will truly bring the LHC to the masses. Whether that succeeds, they will certainly have created a singular document that will stand as a testament to both the excitement and the nervousness of physicists at the dawn of the LHC era.

  And David Kaplan will be able to devote himself to physics full-time once again. As interesting and novel as the process was, there’s no danger he will be changing jobs anytime soon:

  Making a movie is just a terrible experience. It’s so illogical, and there’s ego, and people making arguments in ways that just don’t make any sense. I hate it . . . I love physics.

  ELEVEN

  NOBEL DREAMS

  In which we relate the fascinating tale of how the “Higgs” mechanism was invented and think about how history will remember it.

  It was 1940, and Germany had just invaded Denmark. Niels Bohr, one of the founders o
f quantum mechanics and director of the Institute for Theoretical Physics in Copenhagen, was in possession of valuable pieces of contraband he needed to keep hidden from the Nazis at all costs: two gold medals that accompanied winning the Nobel Prize. How could he keep them away from the approaching army?

  Bohr had won the Nobel in 1922, but neither of the medals belonged to him; he had previously auctioned off his prize medal to help support resistance forces in Finland. They belonged to Max von Laue and James Franck, two German physicists, who had illegally smuggled their medals (which were engraved with their names) out of the country to keep them away from the Nazis. Bohr turned to his friend, the chemist George de Hevesy, who hit upon a brilliant idea: They would dissolve the medals in acid. Gold doesn’t dissolve easily, so the scientists turned to aqua regia, a highly corrosive mixture of nitric acid and hydrochloric acid, renowned for its ability to tear down “noble” metals. Placed in the aqua regia, over the course of an afternoon, the Nobel medals gradually dissociated into their individual atoms, which remained suspended in the solution. Any soldiers that would come poking around looking for suspicious hidden treasure would find nothing but a couple of innocuous flasks of chemicals hidden among hundreds of similar-looking containers.