In 1954 the renowned physicist Enrico Fermi did a simple but depressing calculation about future particle accelerators. To create particles with an energy of 3 teraelectron-volts, he estimated, you’d have to build a ring 8,000 kilometers round at a cost of $170 billion. It was a rare instance of Fermi being wrong. The Large Hadron Collider achieved that energy level in 2010 with a 27-km ring for $10 billion. In large part, its success was brought to you by the letter ‘C’: the LHC collides particles with one another rather than smash them against a stationary target, as Fermi had envisioned. It also helped that magnets these days are stronger than Fermi dared dream. For Fabiola Gianotti, the LHC physicist who co-announced the Higgs boson two years ago, it’s an instructive tale for those who worry her field is reaching its limits. “The correct attitude is not to give up and say it’s impossible,” she says. “The correct attitude is to innovate.”
Last week she and her colleagues gathered at Columbia University to review LHC discoveries and talk about the future. Physicist/blogger Matt Strassler summarized some of the Higgs findings on his blog. Being personally engrossed by all things apocalyptic, I was fascinated when theorist John Ellis confirmed that the masses of the Higgs and of the heaviest known elementary particle, the top quark, place the universe on the brink of a catastrophic instability. At any moment, the vacuum could decay to a lower energy state, changing the laws of physics that govern our universe—an existential calamity that would wipe out every form of matter. To which your reaction should be: great news! The fact that we live on the edge of chaos is probably telling us something deep about the way the world is put together, as physicist Joe Butterworth blogged yesterday. (Besides, physicists might as well put a good spin on the vacuum instability, because if self-destruction is wired into the very laws of nature, there’s not a thing we could do to save ourselves.)
For now, the Higgs remains the LHC’s main output. No exotic particles or new forces have turned up—a null result that has disquieted not a few physicists. The speakers I saw at the meeting acknowledged their colleagues’ worries, but argued that these are still early days. When the LHC starts up again next year, it’ll have twice the energy. And if that’s still not enough to shake new particles loose, well, physicists are laying plans for even greater machines.
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