Why the dark side of the universe matters

Luminous matter accounts for only about 4 percent of the universe.

The world we see, including ourselves, barely makes a dent in the universe or our understanding of it. The 4 percent of the universe that is visible matter fails to shine a light on how the universe evolved or why galaxies spin the way they do. Those answers lie instead just out of reach of our understanding in the dark patches of the cosmos: the so called dark matter.

But year by year during the last decade scientists have inched their flashlights closer to this dark matter threatening to uncover its constitutes and how it works.

"Most of the matter in our universe, about 85 percent, is not explained. It is not stars or planets or dust or gas," said Fermilab physicist Mike Crisler at the 2009 meeting of the American Association for the Advancement of Science in Chicago. "It is not made from atoms or molecules, protons, neutrons, or electrons. It does not absorb or emit light. We use the phrase "dark matter" in much the same way that ancient cartographers used the phrase 'terra incognita.' We do not know its nature."

Even though we can't "see" dark matter, we infer its presence because of its gravitational pull, affecting the rotation speed of stars and galaxies. Stars are moving faster than they would if they were only influenced by the gravitational pull of the galaxy core, so the galaxy itself must be embedded in large clouds of dark matter exerting another pull.

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-- Tona Kunz, with additional reporting by Kristine Crane

Extreme Beam lecture series begins tomorrow

The first lecture of the Extreme Beam lecture series will take place at 4 p.m. on Thursday, Feb. 26, in One West. Junji Hisano, from the University of Tokyo's Institute for Cosmic Ray Research, will give a talk titled "Charged Lepton Flavor Violation."

The lecture series, which will feature talks at Fermilab throughout 2009, will give in-depth information about the science and accelerator and detector technologies that will create a world-leading physics program at the Intensity Frontier.

Visit the Extreme Beam Web site for more information.

Leader in bubble chambers, Pierre Auger died

Lou Voyvodic

Former Fermilab employee Lou Voyvodic, who made significant contributions to high-energy physics and astrophysics, passed away on Feb. 5, 2009.

From humble beginnings as a member of an impoverished immigrant family from Croatia, Voyvodic to become a role model and leader in the particle physics community, most recently at Fermilab.

Voyvodic was a group leader of the 30-inch bubble chamber section at Argonne and brought that technology to Fermilab in 1971. He directed the reactivating operations at Fermilab, and participated in the first experiments using the redeployed chamber. It was a success, and during its first two years of operation, the chamber produced more than two million pictures of p-p and pi-p interactions.

Voyvodic went on to coordinate nuclear emulsion experiments at the Meson Lab in 1972. The emulsion technique proved very useful in the measurement of charmed particle lifetimes, which he reported on at the 1979 Lepton-Photon Symposium.

In the 1980s, Voyvodic was a member of the LEBC high-resolution bubble chamber experiment at the Fermilab MPS, which measured inclusive charm cross sections. In 1994, Voyvodic gave a talk on leading particles, beam and target fragmentation at a conference to mark the 40th anniversary of the bubble chamber.

About 1990, Voyvodic became interested once again in cosmic ray physics, and became a founding member of the Pierre Auger Observatory. He was a source of insight and guidance to many students and postdocs on Auger. Although he had been officially retired from the laboratory, he was often seen coming in to work at the Fermilab Center for Particle Astrophysics.

He leaves behind four sons and one daughter, numerous grandchildren and a great-grandchild. He was a role model for his family and a wellspring of stories with characters ranging from foreign ambassadors to famous artists to Nobel Prize winners.

Force known as dark energy, will stretch the universe beyond detection

From MSNBC, Feb. 23, 2009

When astronomers in the distant future cast their eyes around the cosmos, they will come to the conclusion that our galaxy is alone in the universe.

Even with the most sensitive detectors, future scientists will not be able to observe the leftover radiation from the Big Bang explosion, study the motion of distant galaxies to conclude that space is expanding or even see distant objects.

In the future, the force astronomers now know as dark energy, will stretch the universe beyond detection, with objects receding faster than the speed of light.

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