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Gravity on the Brane
March 6, 2010  |  by Michael Anft

(page 4 of 4)

Finding the Higgs boson could lead physicists to other new particles, as well as to discoveries about how the ones we know about—the relics of the Higgs, theoretically—attain mass, and generally how the whole stew pulls together. The Higgs figures mightily in Randall-Sundrum’s extra-dimensional schema, along with several other theories. “The whole raison d’être of RS-1’s fifth dimension is to resolve a puzzle of the Higgs,” Sundrum explains. “The force that separates ordinary discernible gravity from the Higgs boson is actually higher-dimensional gravity that pulls in the extra dimension. Discovering the Higgs might make the case for extra dimensions in nature.”

In short, the search for the Higgs particle will decide who’s right and who’s wrong on How It All Works—if they find anything at all.

Most scientists say there will be many more losers than winners—if there are any winners. Experimental physicists, under the eyes of the European Organization for Nuclear Research (known by its French acronym, CERN), have designed ways to possibly create the Higgs. The LHC, delayed for much of the past few years by construction glitches, electrical problems, and a pigeon that gummed up the works by dropping a bit of baguette into a vent, reopened its inquiry into the Higgs in earnest in November. Since then, Hopkins professors, postdocs, and students have been on hand to observe or perform experiments. “My guess is we see data in the next two or three years,” says Sundrum.

What signs of the God particle will theorists be looking to see?

“It’s possible we’ll discover the Higgs boson and nothing else, which would mean there are no deeper questions that would lead us on,” says Kaplan, who is making a documentary film on scientists taking part in LHC experiments (see “Subatomic Cinema”). “Mathematically, it’s possible that the Orioles will be in the Super Bowl, and that the parameters of the universe we live in have been tuned so carefully that the standard model is squared by the Higgs. That could mean we’ve reached the end of the study of fundamental physics. Or without the Higgs, we could find any other result, which would be mind-blowing, which is what the Raman types would expect.”

Others predict that the universe will continue to lob curves at theoretical physicists. “The most likely outcome of the LHC is something completely surprising,” says Jonathan Bagger, a Hopkins vice provost and a professor of physics who favors the ideas underpinning supersymmetry. “We theorists have our hubris, but there’s never any guarantee that nature will do anything we say.”

For Sundrum, LHC data will be parsed for deviations in the patterns energy particles carry off after protons kamikaze into one another. One particle might come out in our dimension, with the other heading into another dimension, as measured by the energy associated with its decay. In another scenario, the energy of an extra-dimensional particle would pull energy away from the particle in our dimension, creating an energy imbalance in the LHC’s detectors. One can measure this, although experimentalists have their work cut out for them when it comes to measurement. Competing theories also foresee some energy imbalances, so separating it all out might take some time.

But Sundrum is optimistic that the experiments will amount to something. “If there are extra dimensions, there will be certain frequencies on top of the usual boring ones we see,” he says. “You look for echoes when particles at high energies get dislodged from their resting places in the extra dimension. It’s like acoustics. We’ll hit different notes.” In essence, scientists working at CERN will use an exotic kind of quark to measure the levels of energy, record them, and analyze them.

Sundrum might join them. He’s familiar with the place, having traveled to CERN 10 times or so to give talks, check on progress, or simply soak up the atmosphere that only thousands of others who understand the way things work as deeply as he does can provide. The gang might be quarrelsome, but like a family, they understand where each other is coming from.

He might not get the results he’s looking for, but he’s not likely to lose his balance. “It’s high-risk, high-reward work that Raman does,” says Kaplan. “Chances are he won’t get there. But he’s relentless—he’s been working on this for 15 years. There’s a part of him that will not give up the fight, and it’s an honest fight.”

Sundrum’s self-description is a bit less martial. He likes to think a certain way. He usually starts with a guess on some arcane matter, uses his intuition to try things on and feel them out for a while. Only after a good bit of time marinating in his own guesswork does he switch on the physicist’s vicious critical faculties. If he can think his way to an answer before he actually writes down formulas, he’ll do it. “I love that—it’s a very physical thing,” Kaplan says. “He has that intuition beyond anyone else I’ve met who could do the math.”

As he awaits word from the LHC, he works on his forthcoming book, “Journey to the Fifth Dimension,” and moves the Randall-Sundrum models around in his head. He wonders what nuances he might be missing, what trick he hasn’t found, or what critical tweak he could make to shore up his and Randall’s original thinking. “The last paper I wrote in September had a good bit of RS in it,” he says. “There is a lot in RS that is elegant, valuable. But when you compare it to nature, how does it stand up? The last 10 years have been spent reworking particle physics to check whether we have a harmonious story or not. There are things in the margins that still worry me.”

With that, he’s off to steep in them amid the quiet of his office, where the calm and the emptiness mirror the vastness of a universe that resists facile explication.


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