Super-smasher targets massive mystery

A competitive twist
Fifteen years ago, when Leon Lederman wrote "The God Particle," he thought the Higgs boson would be found in the Superconducting Super Collider, a project that was just getting started in Texas. That machine would have been four times as powerful as the LHC — but when the costs started running far beyond the initial estimates, Congress killed the program.

Over the decade that followed, U.S. scientists weren't just waiting for the LHC to be built: The focus shifted to the Tevatron collider at Fermilab in Illinois, which theorists figured might have just enough punch to pick up the Higgs' trail.

Last year, researchers at Fermilab passed the word that they had found some interesting data — readings that hinted at the presence of the Higgs but weren't yet solid enough to publish. That added a competitive twist to the grail quest.

"The longer we wait, the higher the probability that Fermilab discovers something that we wouldn't mind discovering ourselves here," Jos Engelen, CERN's chief scientific officer and deputy director general, said last year.

Beyond the God Particle
What if physicists don't find the God Particle they are expecting to see? Ellis acknowledged that was a possibility. "This might be a little bit difficult to explain to our politicians, that here they gave us 10 billion of whatever, your favorite currency unit, and we didn't find the Higgs boson," he said.

But Ellis has faith that even then, there'd be something to discover — maybe something even weirder and more wonderful than the Higgs boson.

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"Probably the most likely option then might be extra dimensions," Ellis said. "And there are some ideas where if you have some additional dimensions of space, you could somehow do the job that the Higgs does in the Standard Model."

For years, string theorists have noted that their equations come out better if they assume that the universe has nine or 10 spatial dimensions instead of the three we can perceive. The LHC could provide the first evidence of those extra dimensions: Some theorists say the collisions could produce anomalously heavy particles, suggesting that part of their momentum was going into the extradimensional realm. Harvard physicist Lisa Randall estimates that the LHC could nail down the evidence for extra dimensions in five years.

Other theorists have focused on the idea that every subatomic particle should have an as-yet-undetected "supersymmetric" partner that mirrors many of the characteristics of the particles we know, but is dramatically different in other respects. The partners would have greater masses and a different spin, for example.

To date, no actual evidence of supersymmetry has been found. But if supersymmetric particles don't exist, then a lot of the theories that look beyond the Standard Model would have to be thrown out.

If supersymmetric particles do exist, they could account for a large part of the universe's dark matter. That's the 90 percent of all matter that scientists can detect only by its gravitational effect — a puzzle that has bedeviled astronomers for decades. "There are good reasons to think that these dark matter particles, if they exist, will be observable in the LHC," Ellis said.

Exploring the big-bang frontier
One of the LHC's detectors, known as ALICE, is devoted to studying the stuff that the universe was made of less than a billionth of a second after the big bang. Earlier experiments have hinted that the stuff was a super-hot liquid consisting of subatomic particles known as quarks and gluons.

For one month out of every year, the LHC will switch from smashing protons to smashing heavy lead ions, in an effort to re-create that quark-gluon soup and let ALICE analyze the recipe.

Yet another detector, LHCb, will study the tracks of particles containing specific types of quarks and antiquarks. The Standard Model predicts that equal amounts of matter and antimatter should have been produced in the big bang — but today, we see hardly any antimatter in nature. That's a good thing, because matter and antimatter annihilate each other when they come in contact, leaving pure energy behind.

LHCb will follow up on earlier experiments that suggest matter won out over antimatter because they somehow decay in different ways.

And then there are the wild cards in the deck: Could the LHC really create black holes or exotic forms of matter? What about all these claims that the world is in peril?

Chapter 2: Doomsday fears and futuristic dreams

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