Can you trap light in a box of mirrors

They start out nice and blue and energetic but wind up as red or even infrared or microwave in their old age, as observed by us, due to the red-shift caused by the expanding universe. Follow-up on this answer. Learn more physics! Related Questions. Still Curious? Why can't you trap light in a box? Presumably the photons are still around when you close the lid, but it goes dark. It might be possible to actually trap a beam observably for a short period of time. Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Can light be trapped theoretically? Ask Question. Asked 7 years, 4 months ago. Active 1 year ago. Viewed 12k times. Improve this question. Noel Braganza Noel Braganza 81 1 1 gold badge 1 1 silver badge 3 3 bronze badges. Unfortunately, there are no perfectly reflective things in nature. However, theoretically, you could trap light on a circular geodesic.

Practically that's near-impossible and probably not the best idea, though, since it would involve some serious manipulation of spacetime. And the related link. I'm still getting some interesting variations in answers and it's making me do more research. Which is a good thing. So if your initial photon is entangled with something after you put it in that parallel mirrors entanglement would be broken because it wont be the same photon to begin with.

Show 1 more comment. Active Oldest Votes. The time may be extended by increasing the distance between the great mirrors. Improve this answer. How is the light transmited for so long distances? Is better than two mirrors? Yes, the light obviously survives for much more time within optical fibers than for the millisecond quoted above.

There is no real loss in this so-called total internal reflection, see en. So it's in no way a "periodic system". You could keep the light in a "circle of an optical fiber" for quite some time, however. Of course you can. In fact, you likely have a device in your home right now that not only traps light and stores it—it keeps it cold, too!

They probably inject them at the factory, like Freon or something. Hold on. What will they think of next? Scientists have devised several ways to trap light and save it. But suppose you want to keep your pet light beam for ten seconds or a minute—an eternity in the light-storage game. In a vacuum, Harvard University physicist Lene Hau created a tiny cloud of sodium ions so cold that their movements synchronized.

She then shot a light beam into the cloud at the same time she fired a laser of a different frequency into the cloud from the side. This laser confused the electrons of the sodium atoms and kept them from absorbing the primary light beam. Hau showed that if you block the laser at the correct moment, the light beam stops, though its particulars are still there, encoded in the imprint of the electrons.