What Material can slow the light the most?

[Sashatheman]

From my understanding , the speed of light that we all talk about when saying, nothing can travel faster then that speed, is the speed of light in a vacuum. But if i read correctly, light slows down abit when ever it travels through any type of material ei Air, water, or a diamond.

 

So whats the material that can slow down light the most?

 

And is it possible to make something eg an electron to travel faster then light, under such a condition? Any effect?

[ecoli]

From my understanding , the speed of light that we all talk about when saying, nothing can travel faster then that speed, is the speed of light in a vacuum. But if i read correctly, light slows down abit when ever it travels through any type of material ei Air, water, or a diamond. So whats the material that can slow down light the most?

 

in 2003, Mikhail Lukin, at HArvard, slowed the speed of light down to 0 m/s

using rubidium gas.

 

 

 

And is it possible to make something eg an electron to travel faster then light, under such a condition? Any effect?

 

no

[YT2095]

Cerenkov Radiation, is that what you`re thinking of?

[sabbath]

I would guess, the denser the material, the slower c gets...somehow I feel I'm about to be rebutted:D

[YT2095]

c remains a constant no matter what.

[5614]

Indeed, but the light itself does travel slower.

 

c is defined as the speed of light in a vacuum, so does not chage when light is going through a medium.

 

And is it possible to make something eg an electron to travel faster then light, under such a condition? Any effect?

Yep, as pointed out by YT, when this occurs you get an effect known as Cerenkov Radiation. It gives off a light blue colour as seen here:

http://images.google.co.uk/images?q=Cerenkov+radiation&hl=en

[swansont]

in 2003' date=' Mikhail Lukin, at HArvard, slowed the speed of light down to 0 m/s

using rubidium gas.[/quote']

 

Not exactly. That makes for a catchy story title, but what's happening is that you are storing the light in an atomic state. The longer you store it, the slower the average propagation speed becomes.

 

From this

"The experiments don’t involve stopping the actual photons, or particles of light. Instead, information about the light wave is gradually transferred to specially prepared atoms trapped within a glass chamber, and then turned back into a replica of the original light wave. That’s the real trick."

 

A surprisingly accurate description in a popular-press medium. Maintaining the original properties (e.g. the coherence) is the hard part.

 

 

no

 

Yes. You get the Cerenkov radiation that YT mentioned. Remember that "faster than light" and "faster than c" are not the same thing. When light travels through a medium, the overall propagation speed slows to c/n, so it s possible to travel faster than the light propagation speed.

[swansont]

From my understanding ' date=' the speed of light that we all talk about when saying, nothing can travel faster then that speed, is the speed of light in a vacuum. But if i read correctly, light slows down abit when ever it travels through any type of material ei Air, water, or a diamond.

 

So whats the material that can slow down light the most?

[/quote']

 

You can prepare some materials so that the index of refraction is very large at some wavelength, making the speed of propagation very low at that wavelength in those materials. v = c/n would be very small. This tends to happen near a real absorption line.

 

For bulk materials, you would want something that has a large index. I recall some semiconductors used for laser diodes having indices around 3.5. Here is a list of indices of some more common materials.

[zking786]

You would need to search google for a table of refractive indeces. I think there are some materials with a refractive index of over 4, but am not sure of the names.

[bharatiyedu]

http://www.robinwood.com/Catalog/Technical/Gen3DTuts/Gen3DPages/RefractionIndexList.html

 

here is the link that has some values.

 

is this what u are talking about?