Manipulating the Speed of Light?

Palomar · 2005-08-20 06:03:19

*This is groovy:

Scientists have recently succeeded in doing all sorts of fancy things with light, including slowing it down and even stopping it all together.

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.

Sheesh...what will they think of next? Or is some of this illusion?

Discusses phase velocity, relationships and group velocity. New to me.

Happy reading.

--Cindy

John Creighton · 2005-08-20 14:09:42

Read me
*This is groovy:
Scientists have recently succeeded in doing all sorts of fancy things with light, including slowing it down and even stopping it all together.

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.
Sheesh...what will they think of next? Or is some of this illusion?
Discusses phase velocity, relationships and group velocity. New to me.
Happy reading.
--Cindy

It must by some illusion otherwise they would talk about communication applications.

Palomar · 2005-08-20 14:26:52

It must by some illusion otherwise they would talk about communication applications.

*Is this what you're looking for?

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.
Thevenaz’s technique would essentially allow light to be processed with light without a costly electrical conversion.

--Cindy

John Creighton · 2005-08-20 15:02:10

It must by some illusion otherwise they would talk about communication applications.
*Is this what you're looking for?
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.
Thevenaz’s technique would essentially allow light to be processed with light without a costly electrical conversion.
--Cindy

This is nothing new. And doesn’t violate any laws of physics and can’t be used to transmit information faster then the speed of light. The articles kind of devoid of information because it says nothing about how light is used to process light. Also it is irrelevant how fast the electricity travels compared to how fast the light travels, what is relevant is how fast the information travels. So if the electricity travels half the speed but carries twice the information per distance then it doesn’t matter. However, over long distances speed matters not for information rate but time delay.

I think the author is wrong when he/she says, “if all the phase velocities are the same then the group velocity can be any speed”. I think that the group velocity only travels faster or slower then the phase velocity if the phase velocity changes with respect to frequency. I am going to have to dig out some text books here. But it is interesting that if they can make all the phase velocities the same it means that they will eliminate dispersion. Which means you can build fiber optic lines over larger distances without an equalizer and have the same bandwidth. There is an alternative nonlinear approach where nonlinear effects relating phase velocity to amplitude will counter act the effects of dispersion. For some reason I think it is called a solenoid but that name sounds wrong, so I’ll have to look it up.

Martian Republic · 2005-08-21 17:34:23

Good Post!

I just saw it and was going to post it.

Larry,

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#1 2005-08-20 06:03:19

Re: Manipulating the Speed of Light?

#2 2005-08-20 14:09:42

Re: Manipulating the Speed of Light?

#3 2005-08-20 14:26:52

Re: Manipulating the Speed of Light?

#4 2005-08-20 15:02:10

Re: Manipulating the Speed of Light?

#5 2005-08-21 17:34:23

Re: Manipulating the Speed of Light?

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