Stopping Light

[hummingbird]

Stopping Light

 

I was searching here so wouldn't have to start a thread but there is nothing on here about this topic that I can find.

 

Does this mean that we have harnessed the ability to hold light immobile? If this is true does anyone know for how long?

[C1ay]

Stopping Light

 

I was searching here so wouldn't have to start a thread but there is nothing on here about this topic that I can find.

 

Does this mean that we have harnessed the ability to hold light immobile? If this is true does anyone know for how long?

 

Try browsing some of the articles at http://www.google.com/search?q=frozen+light...

[hummingbird]

They've stopped light for 1.5 seconds. Impressive! I'd thought it wouldn't be possible to freeze light.

[Qfwfq]

They've stopped light for 1.5 seconds. Impressive! I'd thought it wouldn't be possible to freeze light.

What they mean is that the medium has an extremely high index of refraction, which can be rapidly reduced to more ordinary values and then restored. Strictly speaking, the medium is not really opaque, as they put it, technically it is transparent.

 

In a vaguely similar manner, ordinary familiar glass is not technically a solid, it is a liquid with extremely high viscosity at room temperature; this is why very old windows often have glass panes that show signs of downward flow. A similar thing goes for thermoplastics (such as polyethylene or polystyrene). Technically, it isn't proper to talk about melting these materials it is more correct to say softening them. A spring loaded mechanical contraption could navigate through them when their viscosity is low enough and when it increases the mechanism would come practically to a halt, until it is again decreased.

 

I'm curious to know how much a low intensity particle beam would reduce the refractive index. If it doesn't, the beam ought to emit Cherenkov light at almost right angles, which would then propagate outward when the coupling beam is put on.

It would be a cool effect. :D

Edited September 7, 2010 by Qfwfq
typos

[C1ay]

In a vaguely similar manner, ordinary familiar glass is not technically a solid, it is a liquid with extremely high viscosity at room temperature; this is why very old windows often have glass panes that show signs of downward flow.

 

Urban legend :shrug:

[Qfwfq]

Urban legend :shrug:

That article mostly seems to discount the idea of downward flow in vertical glass panes with age being frequent, and maybe this is so (though I have memories of seeing window panes with runs that were not due to manufacturing unless the plates had been stored vertically before they had cooled quite enough). It also shows that, like in many topics that aren't simple and clear cut, there seems to be disagreement about terminology and of course new knowledge of details as time goes by, but it does not contradict the notion that amorphous solids can be described as highly viscous liquids; it says this is somewhat a choice of terms and before recent times (in the days of my physics courses and textbooks) it was mainstream to consider these as two ways of saying the same thing. There are also some details in that argument I could raise objections to, if it were the topic

 

The analogy remains in any case, a spring loaded mechanism would slow down with increasing viscosity until you would call it "stopped" and then resume when viscosity is again decreased. The same goes for the refractive index and light propagation. I found it a misnomer for that article to say the medium changes between opaque and transparent; a sufficiently high index simply has an effect like opacity but it clearly isn't due to the light being absorbed by or diffused from the surface.