Physics & Astronomy News

<p>Artist rendering<br />
New radiation source could be less harmful alternative to x-rays
A new source of intense terahertz (THz) radiation, which could offer a less harmful alternative to x-rays and has strong potential for use in industry, is being developed.
<p>Though Mercury may look drab to the human eye, different minerals appear in a rainbow of colors in this image from NASA's MESSENGER spacecraft. (Image credit: NASA/Johns Hopkins University APL/Carnegie Institution of Washington)</p>
Mercury May Have a Thinner Crust Than We Thought
Scientists used careful mathematical calculations to determine the density of Mercury’s crust, which is thinner than anyone thought.

<p>An artistic view of frequency conversion from near-infrared to mid-infrared through a nonlinear crystal. (Photo: Alexander Gelin)</p>
Molecules Brilliantly Illuminated
A new high-power laser system generates ultrashort pulses of light covering a large share of the mid-infrared spectrum.
<p>A cloud of atoms is held above a chip by electromagnetic fields. The EPR paradox was observed between the spatially separated regions A and B (Illustration: University of Basel, Department of Physics)</p>
EPR paradox observed in many-particle system for the first time
Physicists have observed the quantum mechanical Einstein-Podolsky-Rosen paradox in a system of several hundred interacting atoms for the first time.

Einstein’s “spooky action” goes massive!
The elusive quantum mechanical phenomenon called entanglement has now been made a reality in objects almost macroscopic in size.
Organic solar cells reach record efficiency
In an advance that makes a more flexible, inexpensive type of solar cell commercially viable, researchers have demonstrated organic solar cells that can achieve 15% efficiency.
New exotic phenomena seen in photonic crystals
Researchers observe, for the first time, topological effects unique to an 'open' system.

Science Facts

The Antennae

by NASA Marshall Space Flight Center and

A Chandra X-ray image of The Antennae revealing loops of hot gas spreading out into intergalactic space, huge multimillion degree clouds, and bright emissions from neutron stars and black holes. The image is color coded: low, medium and high energy X-rays are red, green and blue.: Image Courtesy NASA/CXC/SAO/G. Fabbiano et al. NASA's Chandra X-ray Observatory has discovered rich deposits of neon, magnesium, and silicon in a pair of colliding galaxies known as The Antennae. The deposits are located in vast clouds of hot gas. When the clouds cool, say scientists, a great number of stars and planets should form. These results may foreshadow the fate of our own Milky Way and its future collision with the Andromeda Galaxy. When galaxies collide, direct hits between stars are extremely rare, but collisions between huge gas clouds in the galaxies trigger a stellar baby boom. Massive newborn stars race through their evolution in a few million years and explode as supernovas. Heavy elements manufactured in these stars are blown away by the explosions and enrich the surrounding gas for thousands of light years.

The supernova rate in The Antennae is about 30 times that of the Milky Way. Supernova explosions heat the gas in these galaxies to millions of degrees Celsius--so hot that they emit X-rays. Such clouds are mostly invisible to optical telescopes, but they are easy targets for the Chandra X-ray Observatory. Chandra data reveal regions of high and varying enrichment. In one cloud, for instance, magnesium and silicon are 16 and 24 times as abundant as in the Sun. As the enriched gas cools, a new generation of stars will form, and with them new planets. A number of studies indicate that clouds enriched in heavy elements are more likely to form stars with planetary systems, so in the future an unusually high number of planets may form in The Antennae. At a distance of about 60 million light years, The Antennae system is the nearest example of a collision between two large galaxies.

The collision, which began a couple of hundred million years ago, has been so violent that gas and stars from the galaxies have been ejected into the two long arcs that give the system its name. The Antennae give a closeup view of the type of collisions that were common in the crowded early universe and likely led to the formation of many of the stars that exist in the universe today. They might also provide a glimpse of the future of our Milky Way galaxy, which is on a collision course with the Andromeda galaxy. At the present rate, a crash such as the one now occurring in the Antennae could happen in about 3 billion years. Tremendous gravitational forces will disrupt both galaxies and reform them, probably as a giant elliptical galaxy peppered with hundreds of millions of young Sun-like stars. And maybe hundreds of millions of habitable planets, too. These violent crashes aren't an end, after all. They're a new beginning.

Jumping Starlight

'Twinkle, twinkle, little star, how I wonder what you are,' says the song by Jane Taylor. But stars don’t really twinkle; their light reaches the earth in a steady way. Why then do we see them flicker ...
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Exercising In Space

What did astronaut Shannon Lucid like least about her six months on Space Station Mir? The daily exercise. 'It was just downright hard,' she wrote in Scientific American (May 1998). 'I had to put on a ...
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Double rainbow, note the color reversal in the faint, secondary rainbow.
Somewhere Over Which Rainbow?

How many rainbows are there really when we only see one during a rainstorm? The answer isn't as simple as you might think! Rainbows are formed when light enters a water droplet, reflects once inside ...
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Science Quote

'All of us, are truly and literally a little bit of stardust.'

William Fowler

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