As this is my first posting please excuse me if my approach is wrong. The question I wish to ask was posted at another forum and I thought it a valid one. When experimenting with the idea of capturing light I have tried doing so using crystals and found that the only result was that the crystal "glowed" but the interesting thing was that when the laser light was switched off the crystal fell dark immediately. If as the above question suggests the beam of light is travelling and is constantly being refected within the crystal then I find the immediate extiguishing of the light in the crystal puzzling. Can any one help me with this as I find it a little confusing?