[lee bolger]

lee bolger asked the Naked Scientists:
   
is it possible to trap light, for example using one-way mirrors formed into a sphere?

Lee Bolger, Bolton, Lancashire.

What do you think?

[Mr. Scientist]

Sure, but it could be more easily imagined by a box with mirrors inside. Careful though that the mirrors are smooth and cold enough or the photon will escape.

[JP]

One way mirrors don't reflect 100% of the light, but they do reflect a lot of it.  If you set up highly reflective surfaces facing each other, you could trap light in the cavity between them for a while.  (The actual time would be fairly short, though, since light travels so fast it bounces back and forth amazingly fast.)  Eventually, the light will escape.  Trapping light in a cavity can be useful, since its a technique that's used in making lasers.  Fiber optics uses a similar idea, trapping light inside a fiber as it travels rather than inside a sphere.

[syhprum]

It is also possible to trap lower frequency radiation in a box (cavity), cavities made of high temperature super conductors are used on the mobile phone network.
Does not the transmission of light in a fibre optic cable depend on the higher refractive index of the cable sheathing to redirect the radiation back into the fibre or is this system now obsolete ? 

[Mr. Scientist]

I don't know. I've never studied fibre optics, or know of any obsolete machine which you describe. Sorry.

[Mr. Scientist]

there is a fact my friend.no matter what, you can't trap energy.
because light is form of energy.so, it always transforms into other forms of energy.

Energy is something that we still could not understand.

What?

[Mr. Scientist]

We can trap energy - but not for very long - trapping energy was a concept of relativity when considered by th box experiment. What is not for sure is whether such an experiment can deduct you will get the same energy from the box due to the uncertainty principle in relation to time.

[yor_on]

It is also possible to trap lower frequency radiation in a box (cavity), cavities made of high temperature super conductors are used on the mobile phone network.
Does not the transmission of light in a fiber optic cable depend on the higher refractive index of the cable sheathing to redirect the radiation back into the fiber or is this system now obsolete ? 

Nope syhprum, you're perfectly correct. It's what makes it possible for us to communicate. http://en.wikipedia.org/wiki/Optical_fiber

Reminds me also of long transmission cables. When they first were tested it was found almost impossible to talk, like England - USA due to the interference, distorting the electromagnetic Waves so that the voices disappeared. It was first when a 'crackpot' suggested feeding the same distortion back into the cables one more time that the voices 'magically' came back. ( This is my recollection of it, there are people here that knows it much better than me, and can explain it too

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As for 'trapping' light. JP says it, you can do it 'for a time' but not perpetually, after all, light have a wave particle duality and as soon it is 'interacting' something happens. And seen as a particle it will 'bounce' losing momentum. Seen as a wave it will 'downshift' losing 'energy' ( As far  as I can see

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Furthermore. If seen as a particle it will be 'exchanged' into a new photon each time it 'bounces'.