[ALBSA-Info] I vetmi ligj i Einstein-it qe do ti resistoje kohes eshte : " asgje nuk eshte absolute"

[Artin Spahiu]

Ky artikull nuk ka te beje me ceshtjen
shqiptaro-greke-nderkombatare, eshte vetem per ata qe
jane kurioze ne evolucionin teknniko-social. (cdo
paralelizem qe mund te behet me relativitetin e
mendimit rreth ceshtjeve nevralgjike eshte krejt
rastesor) 


Wednesday July 19 8:03 PM ET

Light May Break Its Own Speed Limit
(Laser exceeds speed of light in lab test) 

By ALEX DOMINGUEZ, Associated Press Writer 

Scientists have apparently broken the universe's speed
limit.

For generations, physicists believed there is nothing
faster than light moving through a vacuum - a speed of
186,000 miles per second.

But in an experiment in Princeton, N.J., physicists
sent a pulse of laser light through cesium vapor so
quickly that it left the chamber before it had even
finished entering.

The pulse traveled 310 times the distance it would
have covered if the chamber had contained a vacuum.

Researchers say it is the most convincing
demonstration yet that the speed of light - supposedly
an ironclad rule of nature - can be pushed beyond
known boundaries, at least under certain laboratory
circumstances.

``This effect cannot be used to send information back
in time,'' said Lijun Wang, a researcher with the
private NEC Institute. ``However, our experiment does
show that the generally held misconception that
`nothing can travel faster than the speed of light' is
wrong.''

The results of the work by Wang, Alexander Kuzmich and
Arthur Dogariu were published in Thursday's issue of
the journal Nature.

The achievement has no practical application right
now, but experiments like this have generated
considerable excitement in the small international
community of theoretical and optical physicists.

``This is a breakthrough in the sense that people have
thought that was impossible,'' said Raymond Chiao, a
physicist at the University of California at Berkeley
who was not involved in the work. Chiao has performed
similar experiments using electric fields.

In the latest experiment, researchers at NEC developed
a device that fired a laser pulse into a glass chamber
filled with a vapor of cesium atoms. The researchers
say the device is sort of a light amplifier that can
push the pulse ahead.

Previously, experiments have been done in which light
also appeared to achieve such so-called superluminal
speeds, but the light was distorted, raising doubts as
to whether scientists had really accomplished such a
feat.

The laser pulse in the NEC experiment exits the
chamber with almost exactly the same shape, but with
less intensity, Wang said.

The pulse may look like a straight beam but actually
behaves like waves of light particles. The light can
leave the chamber before it has finished entering
because the cesium atoms change the properties of the
light, allowing it to exit more quickly than in a
vacuum.

The leading edge of the light pulse has all the
information needed to produce the pulse on the other
end of the chamber, so the entire pulse does not need
to reach the chamber for it to exit the other side.

The experiment produces an almost identical light
pulse that exits the chamber and travels about 60 feet
before the main part of the laser pulse finishes
entering the chamber, Wang said.

Wang said the effect is possible only because light
has no mass; the same thing cannot be done with
physical objects.

The Princeton experiment and others like it test the
limits of the theory of relativity that Albert
Einstein developed nearly a century ago.

According to the special theory of relativity, the
speed of particles of light in a vacuum, such as outer
space, is the only absolute measurement in the
universe. The speed of everything else - rockets or
inchworms - is relative to the observer, Einstein and
others explained.

In everyday circumstances, an object cannot travel
faster than light.

The Princeton experiment and others change these
circumstances by using devices such as the cesium
chamber rather than a vacuum.

Ultimately, the work may contribute to the development
of faster computers that carry information in light
particles.

Not everyone agrees on the implications of the NEC
experiment.

Aephraim Steinberg, a physicist at the University of
Toronto, said the light particles coming out of the
cesium chamber may not have been the same ones that
entered, so he questions whether the speed of light
was broken.

Still, the work is important, he said: ``The
interesting thing is how did they manage to produce
light that looks exactly like something that didn't
get there yet?'' 



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