What Should We Be Worried About?

BIG EXPERIMENTS WON’T HAPPEN

LISA RANDALL

Theoretical physicist & cosmologist; Frank B. Baird, Jr., Professor of Science, Harvard University; author, Knocking on Heaven’s Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World

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 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. Relinquishing this for short-term ends would be a tragedy.

In my field of particle physics, everyone is worried. I don’t say that lightly. Recently I’ve been to three conferences where the future was a major topic of discussion. Many ideas were 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, where protons collide at very high energies—to turn to for new experimental results. In the summer of 2012, we learned that a Higgs boson exists. It was a major milestone, of which the LHC engineers and experimenters can be proud. With last year’s data, where the decays of many more Higgs bosons were 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 it has. The LHC also promises to answer this question when it’s turned back on in 2015 after having been shut down for two years to upgrade to higher energy.

But the energy gain will be less than a factor of 2. I can fairly confidently say that I expect answers implying the existence of new particles beyond the Higgs boson. But I can’t confidently say that I expect them to be less than a factor of 2 heavier than the energies we have already explored. This is worrisome. Not finding anything, ironically, would be the best argument that the LHC energy was simply not high enough and more energy is necessary. But discoveries are what usually egg us on. Not finding anything would be very bad indeed.

The Superconducting Super Collider, which was canceled by the U.S. Congress, 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, which 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’m 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. 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 represented 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.