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

What is Dark Energy?

by NASA Goddard Space Flight Center and

: Image Courtesy Beyond Einstein Because he originally thought the Universe was static, Einstein conjectured that even the emptiest possible space, devoid of matter and radiation, might still have a dark energy, which he called a 'Cosmological Constant.' When Edwin Hubble discovered the expansion of the Universe, Einstein rejected his own idea, calling it his greatest blunder. As Richard Feynman and others developed the quantum theory of matter, they realized that 'empty space' was full of temporary ('virtual') particles continually forming and destroying themselves. Physicists began to suspect that indeed the vacuum ought to have a dark form of energy, but they could not predict its magnitude.

Through recent measurements of the expansion of the Universe, astronomers have discovered that Einstein's 'blunder' was not a blunder: some form of dark energy does indeed appear to dominate the total mass-energy content of the Universe, and its weird repulsive gravity is pulling the Universe apart. We still do not know whether or how the highly accelerated expansion in the early Universe (inflation) and the current accelerated expansion (due to dark energy) are related.

A Beyond Einstein mission will measure the expansion accurately enough to learn whether this energy is a constant property of empty space (as Einstein conjectured), or whether it shows signs of the richer structure that is possible in modern unified theories of the forces of nature.

A composite Chandra X-ray (blue) and Palomar infrared (red and green) image of the supernova remnant W49B.
New Evidence Points to a Gamma-Ray Burst... In Our Own Backyard

Only 35,000 light years away lies W49B, the supernova remnant left over from the cataclysmic burst. New evidence pointing to a gamma ray burst origin for this remnant was discovered by X-ray data from ...
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Color image of the Antennae galaxies (NGC 4038/4039)
The First Starlight

Imagine being able to see our Universe 14 billion years ago when it was just a baby. If we had a time machine, we could go back and watch how its infant features emerged after the Big Bang. There are ...
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Hubble Space Telescope in orbit as seen from the Space Shuttle.
Big Fish

The phrase 'big fish eat little fish' may hold true when it comes to planets and stars. Perhaps as many as 100 million of the sun-like stars in our galaxy harbor close-orbiting gas giant planets like ...
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Science Quote

'The atomic bomb ... made the prospect of future war unendurable. It has led us up those last few steps to the mountain pass; and beyond there is different country.'

J. Robert Oppenheimer

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