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Written by xScience.Info
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Wednesday, 13 December 2006 |
In 1670 Isaac Newton demonstrated the composite
nature of sunlight when he sent a carefully collimated sunbeam
through a prism, which spread out the light into a rainbow of
colors; by sending a beam of single color through a second prism
(with no further spreading) Newton showed that the color was not
being imposed by the prism but was intrinsic to the light itself.
Now physicists using the Advanced Photon Source at Argonne National
Lab, in Illinois, have spread out a beam of X-rays (which are, after all, just a
more energetic version of visible light) into a rainbow of colors.
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Written by xScience.Info
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Tuesday, 05 December 2006 |
The brain and heart both
generate weak magnetic fields which, in ways different from electric
fields, can reveal subtle clues about such maladies as epilepsy and
arrhythmias. Sensitive magnetometers, based on superconducting
quantum interference devices (SQUIDs), have been used to prepare
detailed magnetoencephalograms (MEGs). Unfortunately, these devices
require liquid helium and all its associated cryogenic equipment.
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Written by xScience.Info
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Monday, 30 October 2006 |
The waves are the fastest matter waves ever photographed,
clocking in at about 99.997% of the speed of light, close to 1 billion
miles per hour! But their speed is not their only interesting feature.
These waves, known as wakefields because they are generated in
the wake of an ultra-intense laser pulse, are traveling oscillations in
a sea of electrons known as a plasma, and give rise to enormous
electric fields, reaching voltages higher than 100 gigaelectron
volts/meter (GeV/m). To understand how strong this is, consider a test
electron experiencing one of these electric fields. The electron
“surfs” on the electric-field that accompanies the plasma wave, and
accelerates almost instantaneously to near-light-speed at a rate of
about 2 x 1022 m/s2, which is like going from 0 to 60 mph in one
zeptosecond. For those not in the know, that’s a billionth of a
trillionth of a second, or 1/1,000,000,000,000,000,000,000 of a second!
At this rate of acceleration, the electron would outrun any ordinary
matter-wave, but the light-speed wakefields keep up, accelerating the
electron to relativistic energies.
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Written by xScience.Info
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Friday, 29 September 2006 |
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 The composition of lipid membranes, similar to those that surround
living cells, can now be mapped at the nanometer scale. The work, by
researchers at Stanford University, the Lawrence Livermore National
Laboratory and UC Davis, is published in the Sept. 29 issue of the
journal Science.
All living cells are wrapped in a
double-layered membrane of fatty lipid molecules. Components of the
membrane can move sideways and organize into patches or other
structures. This organization can affect, for example, important cell
functions and vulnerability to viruses.
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Written by xScience.Info
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Sunday, 24 September 2006 |
 In the submicroscopic world -- the domain of elementary particles and
individual atoms -- things behave in the strange, counter-intuitive
fashion governed by the principles of quantum mechanics. Nothing (or so
it seems) like our macroscopic world -- or even the microscopic world
of cells or bacteria or dust particles -- where Newton's much more
reasonable laws keep things sensibly ordered.
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