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Speed of light shattered?


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From the New York Times:

 

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 the

 

cesium atoms, and then a second beam passing thorugh the chamber

 

soaks up some of that energy and gets amplified when it passes through

 

them.

 

But the amplification occurs only if the second beam is tuned to a certain

 

precise wavelength, Dr. Steinberg said. By cleverly choosing a slightly

 

different wavelength, Dr. Wang induced the cesium to speed up a light

 

pulse without distorting it in any way. "If you look at the total pulse that

 

comes out, it doesn't actually get amplified," Dr. Steinberg said.

 

There is a further twist in the experiment, since only a particularly strange

 

type of wave can propagate through the cesium. Waves Light signals,

 

consisting of packets of waves, actually have two important speeds: the

 

speed of the individual peaks and troughs of the light waves themselves,

 

and the speed of the pulse or packet into which they are bunched. A

 

pulse may contain billions or trillions of tiny peaks and troughs. In air the

 

two speeds are the same, but in the excited cesium they are not only

 

different, but the pulses and the waves of which they are composed can

 

travel in opposite directions, like a pocket of congestion on a highway,

 

which can propagate back from a toll booth as rush hour begins, even as

 

all the cars are still moving forward.

 

These so-called backward modes are not new in themselves, having

 

been routinely measured in other media like plasmas, or ionized gases.

 

But in the cesium experiment, the outcome is particularly strange because

 

backward light waves can, in effect, borrow energy from the excited

 

cesium atoms before giving it back a short time later. The overall result is

 

an outgoing wave exactly the same in shape and intensity as the incoming

 

wave; the outgoing wave just leaves early, before the peak of the

 

incoming wave even arrives.

 

As most physicists interpret the experiment, it is a low-intensity precursor

 

(sometimes called a tail, even when it comes first) of the incoming wave

 

that clues the cesium chamber to the imminent arrival of a pulse. In a

 

process whose details are poorly understood, but whose effect in Dr.

 

Wang's experiment is striking, the cesium chamber reconstructs the entire

 

pulse solely from information contained in the shape and size of the tail,

 

and spits the pulse out early.

 

If the side of the chamber facing the incoming wave is called the near

 

side, and the other the far side, the sequence of events is something like

 

the following. The incoming wave, its tail extending ahead of it,

 

approaches the chamber. Before the incoming wave's peak gets to the

 

near side of the chamber, a complete pulse is emitted from the far side,

 

along with a backward wave inside the chamber that moves from the far

 

to the near side.

 

The backward wave, traveling at 300 times c, arrives at the near side of

 

the chamber just in time to meet the incoming wave. The peaks of one

 

wave overlap the troughs of the other, so they cancel each other out and

 

nothing remains. What has really happened is that the incoming wave has

 

"paid back" the cesium atoms that lent energy on the other side of the

 

chamber.

 

Someone who looked only at the beginning and end of the experiment

 

would see only a pulse of light that somehow jumped forward in time by

 

moving faster than c.

 

"The effect is really quite dramatic," Dr. Steinberg said. "For a first

 

demonstration, I think this is beautiful."

 

In Dr. Wang's experiment, the outgoing pulse had already traveled about

 

60 feet from the chamber before the incoming pulse had reached the

 

chamber's near side. That distance corresponds to 60 billionths of a

 

second of light travel time. But it really wouldn't allow anyone to send

 

information faster than c, said Peter W. Milonni, a physicist at Los

 

Alamos National Laboratory. While the peak of the pulse does get

 

pushed forward by that amount, an early "nose" or faint precursor of the

 

pulse has probably given a hint to the cesium of the pulse to come.

 

"The information is already there in the leading edge of the pulse," Dr.

 

Milonni said. "You can get the impression of sending information

 

superluminally even though you're not sending information."

 

The cesium chamberhas reconstructed the entire pulse shape, using only

 

the shape of the precursor. So for most physicists, no fundamental

 

principles have been smashed in the new work.

 

Not all physicists agree that the question has been settled, though. "This

 

problem is still open," said Dr. Ranfagni of the Italian group, which used

 

an ingenious set of reflecting optics to create microwave pulses that

 

seemed to travel as much as 25% faster than c over short distances.

 

At least one physicist, Dr. Guenter Nimtz <[umlaut over u>] of the

 

University of Cologne, holds the opinion that a number of experiments,

 

including those of the Italian group, have in fact sent information

 

superluminally. But not even Dr. Nimtz believes that this trick would

 

allow one to reach back in time. He says, in essence, that the time it

 

takes to read any incoming information would fritter away any temporal

 

advantage, making it impossible to signal back and change events in the

 

past.

 

However those debates end, however, Dr. Steinberg said that techniques

 

closely related to Dr. Wang's might someday be used to speed up signals

 

that normally get slowed down by passing through all sorts of ordinary

 

materials in circuits. A miniaturized version of Dr. Wang's setup "is

 

exactly the kind of system you'd want for that application, Dr. Steinberg

 

said.

 

Sadly for those who would like to see a computer chip without a speed

 

limit, the trick would help the signals travel closer to the speed of light,

 

but not beyond it, he said.

 

 

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As the article states, "Two new experiments have demonstrated how wrong that comfortable wisdom is."

 

It just makes me wonder, how much do we really understand about the environment we exist in, let alone what may exist outside of our comfortable surroundings.

 

I wonder how many others will wake up & realize that they were not only wrong themselves about how they perceived the world to exist around them, but more importantly, how wrong they were to follow like sheep to believe in the misconceptions of incorrect mainstream beliefs, without attempting to explore beyond that which has come to be accepted.

 

There are many things greater in heaven & earth, which do not apply to the calculations of modern science.

 

"Look for what seems out of place"

 

------------------

 

"Everything you know,...is Wrong!

 

soon we shall all discover the truth."

 

p)'i4q4

 

 

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