Saturday, August 27, 2005

Space radiation may select amino acids for life

Space radiation may select amino acids for life

Space radiation preferentially destroys specific forms of amino acids, the most realistic laboratory simulation to date has found. The work suggests the molecular building blocks that form the "left-handed" proteins used by life on Earth took shape in space, bolstering the case that they could have seeded life on other planets. Amino acids are molecules that come in mirror-image right- and left-handed forms. But all the naturally occurring proteins in organisms on Earth use the left-handed forms - a puzzle dubbed the "chirality problem". "A key question is when this chirality came into play," says Uwe Meierhenrich, a chemist at the University of Nice-Sophia Antipolis in France. One theory is that proteins made of both types of amino acids existed on the early Earth but "somehow only the proteins of left-handed amino acids survived", says Meierhenrich. Meierhenrich and colleagues have a different theory. "We say the molecular building blocks of life were already created in interstellar conditions," he told New Scientist. The team believes a special type of "handed" space radiation destroyed more right-handed amino acids on the icy dust from which the solar system formed. This dust, along with the comets it condensed into, then crashed into Earth and other planets, providing them with an overabundance of left-handed amino acids that went on to form proteins.

Scientists Mess with the Speed of Light

Researchers in Switzerland have succeeded in breaking the cosmic speed limit by getting light to go faster than, well, light. Or is it all an illusion? Scientists have recently succeeded in doing all sorts of fancy things with light, including slowing it down and even stopping it all together. Now a team at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland is controlling the speed of light using simple off-the-shelf optical fibers, without the aid of special media such as cold gases or crystalline solids like in other experiments. “This has the enormous advantage of being a simple, inexpensive procedure that works at any wavelength,” said Luc Thévenaz, lead author of the study detailing the research. Using a technique called Stimulated Brillouin Scattering, the researchers were able to slow down or ratchet up the speed of light like the gas pedal on a car. They succeeded in reducing the speed of light by almost a factor of 4 (although that’s still plenty fast at 46,500 miles per second), but even more dramatically, the team was also able to speed up the speed of light. Light in a vacuum travels at approximately 186,000 miles per second, but a popular misconception is that, according to Einstein’s special theory of relativity, nothing in the universe can travel faster than this speed. This seeming paradox can be resolved because a pulse of light is actually made up of many separate frequency components, each of which moves at their own velocities. This is known as the pulse’s phase velocity.


At August 27, 2005 11:01 PM, Blogger PD111 said...

From the linked article By tweaking the relationship between phase velocities, it’s possible to adjust the group velocity and create the illusion that parts of the pulse are traveling faster than the speed of light.

One has to be extremely sceptical of any such claims.

What the scientists have done, is speeded up or slowed down some frequency components, such that the net effect is that the pulse has no distortion. They have not speeded up any frequency component such that it is travelling at a velocity faster then in free space.


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