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Pushing The Frontiers Of High-Energy Physics Links Humanity

I spent last week at CERN, the high-energy physics laboratory near Geneva, Switzerland, where the Higgs boson particle was discovered in July 2012.

For those who are not yet familiar, CERN houses a giant particle accelerator — the Large Hadron Collider (LHC) — a machine designed to find the smallest constituents of matter.

To a physicist, going to CERN is a bit like a pilgrimage to a cathedral. We are visiting a holy place, metaphorically speaking, where we use our tools and creativity to expand our knowledge of the cosmos and our place in it. In the Middle Ages, different cities competed with one another for pilgrims, as they brought money for the local economy and religious credibility. Relics were displayed as magnets of attraction, rendering the visit meaningful to those seeking spiritual guidance and inspiration. A cathedral served many purposes, including being a place of beauty and networking among members of a religious community.

CERN has just finished the first run of the upgraded LHC, reaching energies that almost doubled those of the previous runs, the ones that found the Higgs. The machine works by colliding protons against protons head-on, after accelerating them clockwise and counterclockwise to speeds approaching the speed of light. The particles fly around a 17-mile circular tunnel, buried about 300 ft. underground. At some spots, within devices called detectors, the particles are made to collide with one another. A detector is essentially an amazingly sensitive camera, capable of recording the trajectories of the particles that fly off from the collision point.

A CERN engineer told me that to make beams of protons collide with beams of protons is like trying to shoot two needles, one from North America and another from Europe, and make them collide in mid-air over the North Atlantic. It takes tremendous skill and highly precise technology.

The current run was more of a calibration to show the feasibility of reaching such unprecedented energies. Now comes the hard work of tweaking the machine to do what people expect it to do. The LHC is testing knowledge at the fringes, opening windows to the unknown in the world of the very small. Physicists and engineers at CERN are under tremendous pressure to find something new. Our knowledge of particle physics is at a crossroads, where what we know is not enough to explain what we see.

We don't know if the Higgs boson is a single particle or a composite made of two or more. The proton, for example, is made of three particles called quarks, connected by other particles called gluons. It's a bit like looking at an orange and trying to find out what's inside without being able to cut it with a knife. We don't know if a hypothetical symmetry of nature known as supersymmetry exists or not. Supersymmetry (SUSY for the intimate) was proposed in the early 1970s as a possible solution to several questions in particle physics. After more than 40 years, the LHC has the capability of testing the hypothesis, as SUSY predicts that many new particles should exist. Whole careers have been built on the expectation that SUSY is a true symmetry of nature. To not find any trace of it at the LHC would be devastating to many people.

Finding something new — "new physics" — would give new impetus to high-energy particle physics. I had the opportunity to talk to Rolf Heuer, CERN's director general, about this. He joked that one major discovery was enough for his mandate (he was referring to the Higgs), as he is stepping down in January. But he also acknowledged that it will be hard to justify to the politicians and tax payers why it's important to keep on researching the structure of matter at higher and higher energies.

There are, I believe, many reasons why.

First, even if these machines cost a lot of money (in the billions of dollars), they are still cheap in comparison with certain weapons, such as B-2 bombers and nuclear aircraft carriers. Of course, the U.S. and Europe need to have a strong military defense. But one must question how many B-2 bombers, aircraft carriers and nuclear submarines are needed given the current geopolitical scene, where the threat is more intelligence-dependent.

Second, the search for the basic constituents of matter connects us to the distant past and to the distant future, intellectually and practically. Intellectually, because it is part of our search for meaning in a cosmos full of mystery, now as in the beginning of civilization. We want to know where we came from, our place in the cosmos, what we are made of. It is no wonder why cosmology and high-energy particle physics attract so much attention. They are providing answers to some of the deepest questions we can ask about ourselves and the world we live in. Few things can be more exciting than that.

Third, large scientific projects are spectacular models for international collaborations. Thousands of people from dozens of countries work together to advance knowledge. It doesn't matter what your political or religious beliefs are, your skin color or social class; when scientists collaborate they do so in an open, democratic exchange of ideas. A good example is the SESAME accelerator, operating in Jordan, bringing Israeli scientists into collaboration with colleagues from many Arabic countries.

Fourth, there are the countless technological spinoffs from this kind of research, applicable in all facets of our modern life. High-powered magnets, fast-control switches, huge data mining and storing capabilities, ultra-fast data transfer and computing power, etc. It's always good to remind people that the World Wide Web was born at CERN, as a way to facilitate the exchange of information among the thousands of scientists working together. Few inventions were more deeply transformative to the world. And it was all for particle physics, at least in the beginning.

Fifth, as Rolf Heuer reminded me, it's also about people training. Tens of thousands of technicians, engineers and scientists acquire life-long skills doing high-energy research that they will later employ elsewhere. Teachers come by for extension training, students get wowed everyday.

Like cathedrals, machines such as these are a testimony to what people can do when they get together to face a challenge. This is the greatest legacy of this kind of research, a reminder of what we can accomplish, even amid the darkest of times.

Marcelo Gleiser is a theoretical physicist and cosmologist — and professor of natural philosophy, physics and astronomy at Dartmouth College. He is the co-founder of 13.7, a prolific author of papers and essays, and active promoter of science to the general public. His latest book is The Island of Knowledge: The Limits of Science and the Search for Meaning. You can keep up with Marcelo on Facebook and Twitter: @mgleiser.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Marcelo Gleiser is a contributor to the NPR blog 13.7: Cosmos & Culture. He is the Appleton Professor of Natural Philosophy and a professor of physics and astronomy at Dartmouth College.