Spring 2006

Molecular Fingerprinting

Science sleuths have a new and powerful method for identifying (and investigating) atoms and molecules, thanks to Graduate Student Mike Thorpe, Research Associate Kevin Moll, Senior Research Associate Jason Jones, Undergraduate Student Assistant Ben Safdi, and Fellow Jun Ye. The new method allows them to study molecular vibrations, rotations, and collisions as well as temperature changes and chemical reactions. The technique can also detect trace amounts of chemicals with exquisite sensitivity because it can precisely identify their characteristic patterns of laser light absorption, or molecular fingerprints. What's so special about this method is that its broad spectral bandwidth makes it possible to detect millions of parallel light channels simultaneously in real time. Read more »

Flare Up!

Gamma-ray bursts signal the birth of a new black hole, whether it's created during the collapse of a massive star or via a merger between two compact objects such as neutron stars. Astrophysicists have determined that long gamma-ray bursts are associated with collapsing stars and short bursts are associated with binary mergers. In both cases, however, black-hole accretion powers the burst. Recently the Swift X-ray Telescope revealed another common feature: erratic X-ray flares in their afterglows. Swift has detected flare-ups in about half of the gamma-ray bursts it has observed so far. Read more »

Bubble Shock Trains

Black holes are pretty strange, sucking in not only nearby matter but also the space around it. These cosmic vacuum cleaners are powered by thin, gaseous accretion disks in orbit around them. Something drives the orbiting gas to spiral in toward the black hole, where all trace of it disappears forever into the singularity. One of the exciting challenges in astrophysics is to figure out the physics driving this process, which keeps black holes growing for billions of years after they're formed. Read more »

Heme Motions

Our lives depend on heme. As part of hemoglobin, it carries oxygen to our tissues. As part of cytochrome c, it helps transform the energy in food into the energy-rich molecule ATP (adenosine triphosphate) that powers biochemical reactions that keep us alive and moving. As part of cytochrome P450, it helps break down toxic chemicals in our bodies. Read more »

As the Sun Turns

Juri Toomre and his group concentrate their stellar research close to home – just 93 million miles away, to be precise. They want to answer the question: What dynamic processes occur deep within the Sun? To find out, they use a powerful combination of computer simulations and helioseismology (which analyzes sound waves produced by the Sun to probe its internal structure.) The researchers believe that working out the details of the Sun's internal structure should lead to explanations for the 22-year sunspot cycle and other regular surface features such as the Sun's consistent, but variable, rotation rate. Read more »

Fermi Sea

JILA physicists are collaborating to explore the link between superconductivity and Bose-Einstein condensation (BEC) of fermions at ultracold temperatures. Fermions have an odd number of total protons, neutrons, and electrons, giving them a half integer spin, which is either up or down. At ultracold temperatures, this means fermions can't just occupy the same energy level (like bosons, which have an even number of atomic constituents) and form one superatom in a BEC. Instead, they stack up in the lowest energy states, with two fermions in each state, one spin up and one spin down, forming a Fermi sea. Read more »

Partnership in Time

There's only one way to prove you've invented a better atomic clock: Come out on top of a comparison of your clock with one of the world's best atomic clocks: The NIST-F1 cesium fountain atomic clock, the nation's primary time and frequency standard. NIST-F1 is so accurate it won't gain or lose a second in more than 60 million years. Read more »

Body of Evidence

Artist's rendition of infrared radiation from a star passing through an interste

One fun thing theorists do is undertake creative projects that predict phenomena that haven't yet been observed experimentally. In fact, sometimes they even predict things no one has ever imagined before. In other cases, the goal is to unravel the mechanism behind an experimental result that initially seems to conflict with the known laws of quantum physics. Fellow Chris Greene's group enjoys self-driven, innovative work in both categories. Read more »

Bubbling Clusters of Galaxies

Galaxy clusters contain enormous clouds of gas whose cooling should result in the formation of a multitude of new stars. But that's not what NASA's Chandra X-ray Observatory is detecting. Instead there's a whole lot less gas cooling and new star formation than scientists had predicted. Perhaps the most mysterious discovery of all is that the clusters are humming – a low B-flat 57 octaves below middle C. The hum originates from ripples of sound waves washing through great galactic gas clouds surrounding supermassive black holes. Read more »