Physics in the LHC Era

It was in 1900 that mathematician David Hilbert created a list of the most significant unsolved problems for mathematics at a conference in Paris. The list would eventually be fleshed out to reach a total of 23 problems. Hilbert’s Paris talk, “The Problem of Mathematics,” began this way:

Who among us would not be happy to lift the veil behind which is hidden the future; to gaze at the coming developments of our science and at the secrets of its development in the centuries to come? What will be the ends toward which the spirit of future generations of mathematicians will tend? What methods, what new facts will the new century reveal in the vast and rich field of mathematical thought?

The Wikipedia entry on Hilbert notes that the 23 problems, fewer than half of which were presented at the meeting, have gone on to be discussed throughout the following century, with some remaining unresolved to this day. I look at Hilbert’s introduction and think about how apropos the idea of gazing at ‘coming developments of our science’ is to what we do here. Maria Spiropulu, a senior scientist at CERN near Geneva, used Hilbert when talking to the New York Times‘ Dennis Overbye about a weekend conference that recently concluded in Los Angeles. The Physics of the Universe Summit had a grand title, and Spiropulu hoped to use it to “…set out the questions for the next nine decades.”

Now, of course, we have the Large Hadron Collider, which offers the chance to create conditions similar to those existing in the earliest moments of the universe. The trick is in making sense out of what it may show us. Lisa Randall (Harvard) pointed to Galileo’s maxim that physics progresses more when working on small problems than talking about large ones, which could be taken as a way of saying that no matter how elegant a theory may be, it often runs into problems when we get into the details. Supersymmetry, for example, could explain things like dark matter, but Randall points out that no supersymmetric effects have turned up yet as deviations in the Standard Model of physics. Randall believes they should have.

Overbye’s article on the Summit lays out its interesting methodology:

Organized into “duels” of world views, round tables and “diatribes and polemics,” the conference was billed as a place where the physicists could let down their hair about what might come, avoid “groupthink” and “be daring (even at the expense of being wrong),” according to Dr. Spiropulu’s e-mailed instructions. “Tell us what is bugging you and what is inspiring you,” she added. Adding to the air of looseness, the participants were housed in a Hollywood hotel known long ago as the ‘Riot Hyatt,’ for the antics of rock stars who stayed there. The eclectic cast included Larry Page, a co-founder of Google, who was handing out new Google phones to his friends; Elon Musk, the PayPal electric-car entrepreneur, who hosted the first day of the meeting at his SpaceX factory, where he is building rockets to ferry supplies and, perhaps, astronauts to the space station; and the filmmaker Jesse Dylan, who showed a new film about the collider. One afternoon, the magician David Blaine was sitting around the SpaceX cafeteria doing card tricks for the physicists.

Wish I were a friend of Page’s — I could use a Nexus One! This is a lively bunch and ideas must have been flying. Gordon Kane (University of Michigan) opined that the Large Hadron Collider would indeed discover supersymmetry but offered no explanations that would point to a theory of dark energy. One big question at a time. Overbye quotes Lawrence Krauss (Arizona State) on the matter of theories and their application, and this, too, is entertaining:

“We get the notions they are right because we keep talking about them,” he said. Not only are most theories wrong, he said, but most data are also wrong — at first — subject to glaring uncertainties. The recent history of physics, he said, is full of promising discoveries that disappeared because they could not be repeated.

Physics can take us from optimism to pessimism in a heartbeat. Are we on the verge of discovering a true ‘theory of everything?’ Or are we likely to be more confounded with each new assault on the secrets of the universe? We haven’t a clue how to explain dark energy, and dark matter remains undetected. For that matter, as Overbye notes, we’ve assumed that dark matter is a kind of particle. What if, instead, it is an ‘entire spectrum of dark behaviors’? Are there forces as well as particles on what these physicists are calling the ‘dark side’?

No answers here, but plenty of questions, in keeping with Dr. Spiropulu’s wish to emulate Hilbert. As a series of investigative doors wide open to the 21st Century, the topics discussed here lead to both exhilaration and confusion. We’ve seen much the same thing occurring in the exoplanet hunt, where we hardly thought we’d find anything as outrageous as planets orbiting a pulsar, or ‘hot Jupiters’ existing breathtakingly close to their stars. The trick seems to be to build the tools that let us push farther and deeper into nature, without prejudging what we will find. ‘Prepare to be surprised’ is as good a motto for today as any.