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F R E N D Z of martian
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Okay, off the top of my head - and I could be wrong here...
The photons of light entering the chamber excite the gas which in turn fires
off photons which of course creates other photons and so on...which then
reach the other side of the chamber before the original photon. So it
doesn't actually breach the laws of thermodynamics of or relativity.
R.
Robert Clayton - European IT Manager - Circle.com
12 Alfred Place, London, WC1E 7EB, UK
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-Original Message-
From: Martin Cosgrave [mailto:[EMAIL PROTECTED]]
Sent: Thursday, June 08, 2000 19:39
To: multiple recipients of
Subject: Fw: GeeK: FWD: Light Exceeds Its Own Speed Limit, or Does It?
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F R E N D Z of martian
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This looks really interesting but I'm too busy/tired to get into it. If
anyone can be bothered to read it and post a summary, I'd really appreciate
it. This physics stuff is hard work ... :-)
- Original Message -
From: Rohit Khare [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Wednesday, May 31, 2000 4:56 AM
Subject: GeeK: FWD: Light Exceeds Its Own Speed Limit, or Does It?
[SERIOUSLY -- the "easily unnerved" should NOT read this piece. PG-13
physics, in deed Rohit]
May 30, 2000
http://www.nytimes.com/library/national/science/053000sci-physics-light.html
Light Exceeds Its Own Speed Limit, or Does It?
By JAMES GLANZ
The speed at which light travels through a vacuum, about 186,000 miles
per second, is enshrined in physics lore as a universal speed limit.
Nothing can travel faster than that speed, according freshman
textbooks and conversation at sophisticated wine bars; Einstein's
theory of relativity would crumble, theoretical physics would fall
into disarray, if anything could.
Two new experiments have demonstrated how wrong that comfortable
wisdom is. Einstein's theory survives, physicists say, but the results
of the experiments are so mind-bending and weird that the easily
unnerved are advised--in all seriousness--not to read beyond this
point.
In the most striking of the new experiments a pulse of light that
enters a transparent chamber filled with specially prepared cesium gas
is pushed to speeds of 300 times the normal speed of light. That is so
fast that, under these peculiar circumstances, the main part of the
pulse exits the far side of the chamber even before it enters at the
near side.
It is as if someone looking through a window from home were to see a
man slip and fall on a patch of ice while crossing the street well
before witnesses on the sidewalk saw the mishap occur--a preview of
the future. But Einstein's theory, and at least a shred of common
sense, seem to survive because the effect could never be used to
signal back in time to change the past--avert the accident, in the
example.
A paper on the experiment, by Lijun Wang of the NEC Research Institute
in Princeton, N.J., has been submitted to Nature and is currently
undergoing peer review. It is only the most spectacular example of
work by a wide range of researchers recently who have produced
superluminal speeds of propagation in various materials, in hopes of
finding a chink in Einstein's armor and using the effect in practical
applications like speeding up electrical circuits.
"It looks like a beautiful experiment," said Raymond Chiao, a
professor of physics at the University of California in Berkeley, who,
like a number of physicists in the close-knit community of optics
research, is knowledgeable about Dr. Wang's work.
Dr. Chiao, whose own research laid some of the groundwork for the
experiment, added that "there's been a lot of controversy" over
whether the finding means that actual information--like the news of an
impending accident--could be sent faster than c, the velocity of
light. But he said that he and most other physicists agreed that it
could not.
Though declining to provide details of his paper because it is under
review, Dr. Wang said: "Our light pulses can indeed be made to travel
faster than c. This is a special property of light itself, which is
different from a familiar object like a brick," since light is a wave
with no mass. A brick could not travel so fast without creating truly
big problems for physics, not to mention humanity as a whole.
A paper on the second new experiment, by Daniela Mugnai, Anedio
Ranfagni and Rocco Ruggeri of the Italian National Research Council,
described what appeared to be slightly faster-than-c propagation of
microwaves through ordinary air, and was published in the May 22 issue
of Physical Review Letters.
The kind of chamber in Dr. Wang's experiment is normally used to
amplify waves of laser light, not speed them up, said Aephraim M.
Steinberg, a physicist at the University of Toronto. In the usual
arrangement, one beam of light is shone on the chamber, exciting t
