In the weeks after the folks at the Large Hadron Collider announced that they had found the Higgs, people I met would ask if I was excited. After all, the Higgs was what particle physicists were searching for, right?
As usual in this blog, the answer is “Not really.”
We were all pretty sure the Higgs had to exist; we just didn’t know what its mass would be. And while many people had predictions for what properties the Higgs might have (including some string theorists), fundamentally they were interested for other reasons.
Those reasons, for the most part, are supersymmetry. If the Higgs had different properties than we expected, it could be evidence for one or another proposed form of supersymmetry. Supersymmetry is still probably the best explanation for dark matter, and it’s necessary in some form or another for string theory. It also helps with other goals of particle physics, like unifying the fundamental forces and getting rid of fine-tuned parameters.
Fundamentally, though, the Higgs isn’t likely to answer these questions. To get enough useful information we’ll need to discover an actual superpartner particle. And so far…we haven’t.
That’s why we’re not all that excited about the Higgs anymore. And that’s why, increasingly, particle physics is falling into doom and gloom.
Sure, when physicists talk about the situation, they’re quick to claim that they’re just as hopeful as ever. We still may well see supersymmetry in later runs of the LHC, as it still has yet to reach its highest energies. But people are starting, quietly and behind closed doors, to ask: what if we don’t?
What happens if we don’t see any new particles in the LHC?
There are good mathematical reasons to think that some form of supersymmetry holds. Even if we don’t see supersymmetric particles in the LHC, they may still exist. We just won’t know anything new about them.
That’s a problem.
We’ve been spinning our wheels for too long, and it’s becoming more and more obvious. With no new information from experiments, it’s not clear what we can do anymore.
And while, yes, many theorists are studying theories that aren’t true, sometimes without even an inkling of a connection to the real world, we’re all part of the same zeitgeist. We may not be studying reality itself, but at least we’re studying parts of reality, rearranged in novel ways. Without the support of experiment the rest of the field starts to decay. And one by one, those who can are starting to leave.
Despite how it may seem, most of physics doesn’t depend on supersymmetry. If you’re investigating novel materials, or the coolest temperatures ever achieved, or doing other awesome things with lasers, then the LHC’s failure to find supersymmetry will mean absolutely nothing to you. It’s only a rather small area of physics that will progressively fall into self-doubt until the only people left are the insane or the desperate.
But those of us in that area? If there really is nothing new? Yeah, we’re screwed.