2013 : WHAT *SHOULD* WE BE WORRIED ABOUT?

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Physicist, Harvard University; Author, Warped Passages; Knocking On Heaven's Door
Big Experiments Won't Happen

I worry that people will gradually stop the major long-term investments in research that are essential if we are to answer difficult (and often quite abstract) scientific questions. Important fundamental experimental science will always be at the edge of what is technologically feasible and moving forward requires commitment to advances. The applications are not obvious so there has to be an underlying belief that finding the answers to deep and significant questions about how the universe evolved, how we evolved, what we are made of, what space is made of, and how things work is important. The ability to find answers to these questions is one of the characteristics that makes human beings unique and gives meaning to our lives. Giving this up for short-term ends would ultimately be a tragedy.

In my specific field of particle physics, everyone is worried. I don't say that lightly. I've been to two conferences within the last week where the future was a major topic of discussion and I'm at another one where it's on the agenda. Many ideas are presented but my colleagues and I certainly worry whether experiments will happen.

At the moment, we have the Large Hadron Collider—the giant accelerator near Geneva that collides together protons at very high energies—to turn to for new experimental results. Last summer we learned that a Higgs boson exists. It was a major milestone of which the LHC engineers and experimenters can be proud. With this year's data, where the decays of many more Higgs bosons have been recorded, we will understand more about the particle's properties.

But we also want to know what lies beyond the Higgs particle—what is it that explains how the Higgs boson ended up with the mass that it has. The LHC also promises to answer this question when the LHC turns back on after shutting down for two years to upgrade to higher energy.

 But the energy gain will be less than a factor of two. I can fairly confidently say that I expect answers that imply new particles beyond the Higgs boson to exist. But I can't confidently state that I expect them to be less than a factor of two heavier than the energies we have already explored. This is very worrisome. Not finding anything, ironically, would be the best argument that the LHC energy was simply not quite high enough and more energy is necessary. But discoveries are what usually egg us on. Not finding anything would be very bad indeed.

In fact, the Superconducting Supercollider that was cancelled in the US would have had about three times the energy. It was designed with the ultimate physics goals in mind, which argued for a more powerful machine. The LHC—though designed to answer similar questions—was built in a pre-existing tunnel that constrained the maximum energy that could be achieved. If we had three times the energy, I'd be a lot less worried. But we don't.

So I am worried. I'm worried I won't know the answer to questions I care deeply about. Theoretical research (what I do) can of course be done more cheaply. A pencil and paper and even a computer are pretty cheap. But without experiments, or the hope of experiments, theoretical science can't truly advance either. Happily, advances wouldn't cease altogether as we would still get new results from astronomical observations and smaller scale experiments on Earth. And there would be many ideas to play around with But we wouldn't know which of them represent what is really going on in the world.

On top of that, the universe often has more imagination than we do. We need to know what the universe is telling us. Some of the best new ideas come from trying to explain mysterious phenomena. I hope the future presents us with some answers—but also more mysteries to explain.