Physics on the Brink

Not only are these vixens titillating for their rarity, but they also have the power to tear down the theories of the day. Theoretical physics is brimming with different possible models of the universe, all of which predict slightly different phenomena at high energies. The way a new particle looks and behaves will invariably go against the predictions of some current theories. Physicists can then either rule these out or tweak them to fit the observations—either way, inching closer to the ultimate goal of understanding the fundamental nature of the universe.

It’s because of this power that these sirens have such a compelling call, necessitating a multi-billion-dollar machine to capture their images. The LHC will, for the first time in decades, reach energies high enough to potentially create new particles—and the physics community is waiting with bated breath.

But even after the LHC begins operations next summer, waiting will still be the name of the game. “I’d say it will be a long time before we get to the stage where we will be comfortable telling theorists what we’re seeing,” says Mincer. Any strange phenomena will have to be checked and rechecked until the experimentalists are sure they are seeing something real—there are many ways that flaws in the machinery or computer programs could trick the scientists into thinking something is there when it really isn’t.

Even just knowing what to look for is a challenge. Every second there will be forty million particle explosions in the LHC, yielding enough data to fill a 200-gigabyte hard drive. Even if it were possible to record data this fast (it’s not) there would be no way to analyze it all. So the physicists must decide in advance what is interesting enough to keep, and they must choose wisely, because at the end of the day only one in a million events can be recorded.

This is where Mincer comes in. He and his team are designing a trigger—a computer program that will decide in a millisecond which data will be saved for later analysis. And in order to tell the computer what to look for, he needs the input of theorists. They can tell him what a strange new particle might look like, but of course there’s always the possibility that something will appear that nobody predicted at all.

And the thought of that—something completely unexpected—elicits an identical grin from both the experimentalist and the theorist.

A Dream or a Nightmare

“The coolest thing would be if all the tools that we’ve developed and that have been successful for the last 50 years just stopped working,” says Weiner, remarkably casual for someone who has just wished for the work of his mentors and predecessors to be rendered obsolete. Of course, in science, proving a theory wrong is a valuable step forward, so his irreverence would likely be forgiven.

He describes the physics scene in the mid-twentieth century, when the first particle accelerators were developed and scientists suddenly realized that there existed a whole slew of particles beyond the protons, neutrons and electrons that make up the girl next door. They already had complete, working models of the universe based on the particles they knew existed. Nobody needed to find any new particles—all it did was confuse things.

But scientists, especially theoretical physicists, love to be confused. In the years after the new particle bonanza they reworked their theories until they arrived at the Standard Model, which incorporates all the strange particles they discovered in the sixties and has successfully withstood the observations of the subsequent three decades. But physicists like Weiner hope the LHC might finally break its winning streak.

“I think we’re going to see a lot of new things,” says Weiner. He gleefully self-identifies as a “weaselly theorist”—when unexpected results arise, he and his colleagues bend and twist their existing models until they agree with the experimental data. Theorists can math their way out of all but the stickiest situations, and they have a lot of fun doing it.

For the experimentalists, however, discovering totally unexpected phenomena would necessitate a complete change in tactics. Allen Mincer compares this possible near-future to the early days of electricity when there was no theoretical guidance whatsoever. People simply played with electricity, observing its properties, and testing it in every way they could imagine. “It’s a very different way of thinking about things. It would sort of just be exploring at random instead of directed in some way.” He pauses, and gives a nervous laugh. “I’m not sure whether I’d consider that a dream or a nightmare, though!”