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Visions of Future Physics


Get Nima Arkani-Hamed going on the subject of the universe—not difficult—and he’ll talk for as many minutes or hours as it takes to transport you to the edge of human understanding, and then he’ll talk you past the edge, beyond Einstein, beyond space-time and quantum mechanics and all those tired tropes of 20th-century physics, to a spectacular new vision of how everything works. It will seem so simple, so lucid. He’ll remind you that, in 2015, it’s still speculative. But he’s convinced that, someday, the vision will come true.
Quanta Magazine.

Original story reprinted with permission from Quanta Magazine, an editorially independent division of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences

On the strength of the torrent of ideas he has produced over the past 20 years—he won the inaugural $3 million Fundamental Physics Prize in 2012 “for original approaches to outstanding problems in particle physics, including the proposal of large extra dimensions, new theories for the Higgs boson, novel realizations of supersymmetry, theories for dark matter, and the exploration of new mathematical structures in gauge theory scattering amplitudes”—Arkani-Hamed, 43, a professor at the Institute for Advanced Study (IAS) in Princeton, N.J., is widely considered one of the best theoretical physicists working today. Colleagues point to his knack for simplifying impossibly complex problems, as well as his exceptional mathematical ability, creativity, instincts and vast knowledge of physics. “Nima is amazing in every component of talent space,” said Savas Dimopoulos, a theoretical particle physicist at Stanford University.

But while many top physicists shy away from stagecraft, Arkani-Hamed functions, colleagues say, as a “messiah,” a “Pied Piper,” an “impresario.” Arms in motion and dark hair spilling to his shoulders, he weaves together calculations, thought experiments and historical precedents into narratives, confidently outlining chapters to come. His listeners range from graduate students to Nobel Prize winners. “He keeps coming up with the goods, and his persuasiveness is hypnotic,” said Raman Sundrum, a theoretical physicist at the University of Maryland in College Park, “so a lot of people follow where he leads.”

Arkani-Hamed’s mission—simple to state, but so all-consuming that he barely sleeps—is to understand the universe. “I don’t feel I have any time to lollygag, at all,” he said this summer in Princeton. This obsession takes him in several directions, but in recent years one question about the universe has come to preoccupy him, along with the field as a whole. Particle physicists seek to know whether the properties of the universe are inevitable, predictable, “natural,” as they say, locking together into a sensible pattern, or whether the universe is extremely unnatural, a peculiar permutation among countless other, more mundane possibilities, observed for no other reason than that its special conditions allow life to arise. A natural universe is, in principle, a knowable one. But if the universe is unnatural and fine-tuned for life, the lucky outcome of a cosmic roulette wheel, then it stands to reason that a vast and diverse “multiverse” of universes must exist beyond our reach—the lifeless products of less serendipitous spins. This multiverse renders our universe impossible to fully understand on its own terms.

As things stand, the known elementary particles, codified in a 40-year-old set of equations called the “Standard Model,” lack a sensible pattern and seem astonishingly fine-tuned for life. Arkani-Hamed and other particle physicists, guided by their belief in naturalness, have spent decades devising clever ways to fit the Standard Model into a larger, natural pattern. But time and again, ever-more-powerful particle colliders have failed to turn up proof of their proposals in the form of new particles and phenomena, increasingly pointing toward the bleak and radical prospect that naturalness is dead.

Still, many physicists, Arkani-Hamed chief among them, seek a more definitive answer. And right now, his quest to answer the naturalness question leads through China. Two years ago, he agreed to become the inaugural director of the new Center for Future High Energy Physics in Beijing. He has since visited China 18 times, campaigning for the construction of a machine of unprecedented scale: a circular particle collider up to 60 miles in circumference, or nearly four times as big around as Europe’s Large Hadron Collider (LHC). Nicknamed the “Great Collider,” and estimated to cost roughly $10 billion over 30 years, it would succeed the LHC as the new center of the physics universe. According to Arkani-Hamed and those who agree with him, this 100-trillion-electron-volt (TeV) collider would slam subatomic particles together hard enough to either find the particles that the LHC could not muster or rule them out, rescuing or killing the naturalness principle and propelling physicists toward one of two radically different pictures: that of a knowable universe, or an unknowable multiverse.

The Chinese collider campaign has the support and involvement of many prominent researchers aside from Arkani-Hamed, including Yifang Wang, the Nobel Prize winner David Gross, and the Fields medalist S.T. Yau, as well as legions of experimentalists and engineers working behind the scenes, yet the project is controversial. Experts disagree about what the machine would achieve. They also wonder if China is ready to take the helm in particle physics, questioning whether its small particle physics community can grow quickly enough over the next two decades to run a project so enormous and complex, even with the help of thousands of physicists in Europe and the United States. As Tao Han, a particle physicist who supports the campaign, expressed the concerns of some of his Chinese colleagues, “Are we going to jump too far and fall hard?”

Now it is decision time. The Chinese government will release its five-year budgetary plan by the end of the year, revealing whether it plans to invest in research and development for the collider project.

“This 100-TeV collider program in China is brilliant; it’s challenging; it’s risky. And that’s precisely why nothing like this, I think, could really have had as much traction without Nima,” said Sundrum, who has visited Beijing to aid the campaign. “It has taken enormous persuasion for him to take this from a total fantasy, a losing fantasy, to something which has a fighting chance.”

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