Is it possible to freeze and effective unfreezing of the human body?
The main problem is that the water in the cells of the human body freezes in the form of crystals. The crystals damage the cells and structures within cells. Cells burst. There is no method to prevent the precipitation of crystals of water so far. If the cells burst, our medicine does not know how to repair such damage. It will be so for a long time, unfortunately. If someone froze, then we can not go to defrost.
But I'm optimistic message. Just being in the cold if you do not freeze, causing the brain reduces the need for oxygen so that it is possible to restore to life, even after quite a long time. Longer than those famous three minutes, in which it is necessary to restore circulation to an unconscious person.
I hope that this knowledge will never be needed.