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In this issue:
Darwin's Dinobird Fossil Analyzed at SLAC National Accelerator Laboratory
Symmetry Explains it in 60 Seconds: Dark Energy
Science Today: Antimatter: What is It and Where Did It Go?
It's the Season for Giving

SLAC Today

Thursday - December 11, 2008

Darwin's Dinobird Fossil Analyzed at SLAC National Accelerator Laboratory

(Photo - archeopteryx)
The Thermopolis Archaeopteryx Fossil. (Photo by Brad Plummer. Click for larger image.)

A keystone of evolutionary history, the Thermopolis Archaeopteryx fossil, has come to the U.S. Department of Energy's SLAC National Accelerator Laboratory to undergo a revolutionary type of analysis. Using intense X-ray beams, scientists will search for characteristics of the "dinobird" that have eluded all previous scientific analyses.

Researchers at SLAC's Stanford Synchrotron Radiation Lightsource are attempting to uncover secrets of the Archaeopteryx hidden from view since the creature sank to the bottom of a shallow lagoon and became entombed in limestone some 150 million years ago. To do this, they are using light source technology developed by DOE and primarily utilized for advanced energy-related research in materials science, biology and other fields. Only ten Archaeopteryx fossils have been found and studied. These specimens have undergone extensive visual analyses and even CT scans in the past, but never anything as comprehensive as the X-ray imaging researchers are utilizing at SSRL. Here, researchers are making the first maps of the chemical elements hidden within one of the best preserved specimens, possibly including remnants of soft tissue—not just bone. Approximately 16 by 16 inches (40 by 40 centimeters) in size, the Thermopolis specimen was originally discovered near Solnhofen, Germany, and is now owned by the Wyoming Dinosaur Center, located in Thermopolis, Wyoming.

Archaeopteryx holds a unique place in history. A century and a half ago, just a year after Charles Darwin published On the Origin of Species, the discovery of this fossilized half-dinosaur/half-bird species provided the strongest evidence yet for the theory of evolution.

For more information, see the full news release and photo gallery.

Symmetry Explains it in 60 Seconds: Dark Energy

Dark energy is the weirdest and most abundant stuff in the universe. It is causing the expansion of the universe to speed up, and the destiny of our universe rests in its hands. However, not much is known about dark energy.

Dark energy is everywhere and is extremely diffuse—a cubic meter of dark energy contains only as much energy as a hydrogen atom—and it is not made of particles. Dark energy is like a continuous, extraordinarily elastic medium. Its elasticity leads to its defining and most spectacular feature: its gravity repels rather than attracts. For the first nine billion years after the big bang, the attractive gravity of matter caused the expansion of the universe to slow down. Five billion years ago, dark energy's repulsive gravity overcame matter's attractive gravity, leading to the accelerating universe.

Figuring out dark energy is high on the to-do lists of both astronomers and physicists. During the next 20 years, ground- and space-based telescopes will shed new light on dark energy and perhaps bring a few surprises too. I, for one, believe that dark energy is the most profound mystery in all of science and that cracking the dark-energy puzzle will lead to advances elsewhere, from understanding the birth of the universe to illuminating string theory.

This story first appeared in Symmetry magazine.

(Daily Column - Science Today)

Antimatter: What is It and Where Did It Go?

Lessons from the SLAC B Factory and This Year's Nobel Prize

All elementary particles, such as electrons, protons and neutrons, have an antimatter version. For example, the anti-electron is exactly the same as the electron, but it has the opposite electric charge; likewise the anti-proton is just like the proton, again with opposite charge. But the Universe is just made up of matter, with virtually no anti-matter. If there were antimatter galaxies or stars there would be regions of space where antimatter and matter are annihilating each other, but this has not been observed. Why is there no antimatter in the universe?

Theory predicts that just after the Big Bang there must have been equal amounts of matter and antimatter. Early in the Universe there must have been some interaction between elementary particles that differed between matter and antimatter, and that produced a small excess of matter over antimatter. Then all the antimatter annihilated with most of the matter, leaving a small excess of matter and lots of energy. That small excess of matter is all the galaxies, stars, planets in the universe—it is us.  Read more...

It's the Season for Giving

(Photo - coat drive 2007)
The 2007 coat and blanket drive filled many boxes with warm items for people in need. (Photo courtesy of Thanh Ly. Click for larger image.)

In the final days before the holiday break, three charitable drives run by SLAC volunteers provide different ways to help those in need this winter.

Family Giving Trees placed around the lab are decorated with Wish Cards that you can use to provide a gift to a child who would otherwise go without. If you wish, volunteers Debbie Tryforos (x8764) and Diana Viera (x2244) will even do the shopping for you. But please act soon; this Friday, December 12 is the final day to participate in the Family Giving Tree drive.

You may also notice large barrels in SLAC lobbies and breezeways, filling with non-perishable goods. They're part of the Second Harvest Food drive, running December 5 through 19. Both foods and direct donations are welcome. Please see the announcement or contact Barbara Mason (x4757) for details.

In addition, you can help to provide coats and blankets directly to the needy and homeless. The lobbies of Buildings 40, 41, 48, 50 and 51 contain separate boxes for coats and blankets, now through December 17. See the announcement or contact Thanh Ly (x4496) for more information.


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