August 09, 2013 | Daily Galaxy–Despite the discovery of the existence of the Higgs Boson on July 4, 2012 at the Large Hadron Collider in Geneva, puzzling questions about the nature of the universe remain unanswered. For example, the essential properties of neutrinos are still a mystery. And dark matter and dark energy, which together constitute 95 percent of the universe, are today still astonishing enigmas. The Higgs particle is unlike any other particle we have ever encountered. Why is it different? Are there more?Neutrinos are very light, elusive particles that change their identity as they travel. How do they fit into our understanding of nature? Are there new hidden dimensions of space and time? Known particles constitute 1/6 of all the matter in the universe. The rest we call dark matter. But what is it? Can we detect these particles in our labs? Are there other undiscovered particles in nature? There are four known forces in nature. Are these manifestations of a single unified force? Are there unexpected new forces? Both matter and anti-matter were produced in the Big Bang, but today our world is composed only of matter. Why? Why is the expansion of the universe accelerating?

Scientists debated those and other questions July 28-Aug. 6 at the University of Minnesota during the 2013 Snowmass Community Summer Study, the capstone in a series of meetings held last year. They wrapped up their work by identifying the most exciting and vital questions facing particle physics and by providing a 20-year outlook for the investigative work needed to address them. The final report of the Summer Study, to be published this fall, will detail the scientific importance of each question and the scientific instruments required to probe them.

“There’s a great deal of energy and a host of ideas in the field of particle physics,” said Jonathan Rosner, chair of the American Physical Society’s Division of Particles and Fields. “In the last 12 months, we’ve discovered the Higgs boson and made important discoveries about the behavior of neutrinos. It’s clear that there is much more to discover. We understand less than 5 percent of the matter and energy in our universe. What experiments can help expand our knowledge in the next 20 years?”

Significantly, the final report of the Summer Study will reflect the ideas of the next generation of scientists who will become the stewards of particle physics. It will include the results of a survey of graduate students, postdoctoral researchers and young staff scientists in the field.

“The Snowmass process is about planning the next generation of experiments, many of which have decade-long lead times,” said Jonathan Asaadi, a researcher at Syracuse University. “Decisions made today will shape the careers of the young scientists who will run these experiments many years from now.”

The ghostly blue clouds in the center of the Abell 1689 galaxy cluster above show where astronomers think dark matter is hiding. Abell 1689 is home to about 1,000 galaxies and trillions of stars. Both the visible galaxies and dark matter add to the gravitational pull in a cluster. These gravitational forces act like a lens, and when light passes through a cluster like Abell 1689, it bends. (Think of how light changes when it passes through an empty glass or a pool of water.)

The Daily Galaxy via American Physical Society

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