Posted on 08/24/2005 6:02:52 PM PDT by Arkie2
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. If all the frequency components have the same phase velocity, then the overall pulse will also appear to move at that velocity.
However, if the components have different phase velocities, then the pulse’s overall velocity will depend on the relationships between the velocities of the separate components. If the velocities differ, the pulse is said to be moving at the group velocity.
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 area where such an advance could be enormously beneficial is in the telecommunications industry.
Although information can be channeled through fiber optics at the speed of light, it can’t be processed at this speed because with current technologies, light signals must be transformed into much slower electrical signals before they are useful.
hevenaz’s technique would essentially allow light to be processed with light without a costly electrical conversion.
The group’s research will be published in an August 22nd issue of the journal Applied Physics Letters.
It's an illusion. The article even says so, even thought the headline implies otherwise.
It's not really an illusion. Read the whole article and you'll see there's more to it than just an illusion, like improved telecoms.
Big deal! I want my flux capacitor!
photonic ping!
"....and even stopping it all together."
Cool, when can they pile it up and package it ? I'll buy a box, open the top and shine the super concentrated beam on photocells in my glove compartment to run my car !
Here's a great flash presentation that explains it all.
http://gregegan.customer.netspace.net.au/APPLETS/20/20.html
They'll sell it in a package deal along with dehydrated water.
I'm having trouble with this. For one, what if the light is all one frequency, as in a laser? For two, doesn't incoherent light all travel at C? Do different frequencies travel faster and slower? If so, then why don't the frequencies separate during regular transmission?
Superluminal illusion:
Quickly pass a lazer over something very far away (say, the moon). If you didn't know better, one might calculate that a little red dot is sweeping across the lunar surface faster than light! (Of course the dot is not a real unit, but many photons spread over a large distance...)
Neat! Good demo.
Go to this link.
http://gregegan.customer.netspace.net.au/APPLETS/20/20.html
Then read this.
http://gregegan.customer.netspace.net.au/APPLETS/20/SubluminalNotes.html
It is an illusion. No information travels faster than light. It just looks like it might.
I've noticed threads like this get a lot of response at night for some reason so I save them up and post them late. Keeps Freeper insomniacs amused!
It's not just a good idea. It's the law.
For those interested, this was predicted by quantum electrodynamics, one of the most impressive theories in all of science. I would recommend anyone read Feynman's book QED if you want to know more information.
Bet they get worse gas mileage, though.
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