Is cryonics possible?

An early question you might ask upon first hearing about cryonics is:  "Is cryonics possible?"  After all, thus far, no one has even taken a large human organ (much less a person), frozen it, brought it back to normal temperatures and had it continue functioning (living) long term.  What makes people think this sort of thing is possible?

The first thing to consider here is that irrespective of what has or hasn't yet been accomplished, the idea of cryonics, so far as we know, does not violate any laws of physics.  So long as there is no violation of physical laws,  it is not unreasonable to think that future technology could accomplish the reanimation and repair process required to bring about reanimation.  But we have more evidence to support this idea than pure conjecture.

Clues to the idea that cryonics is possible come in part from what has been done with single human cells and in other organisms.  Human sperm, eggs, and embryos are now routinely frozen and then reheated and are viable.  The time between freezing and re-thawing can sometimes be years.  Previously frozen embryos are more or less routinely implanted into a woman's uterus and result in healthy babies.   There are people walking around today who, when they were but single cells in the past, were once frozen!

Then consider certain animals which routinely can survive being frozen.  Examples include the tardigrade, Alaskan wood frog, and the Upis beetle.  All of these animals seem to have a form of natural antifreeze which evolution has developed to prevent the formation of ice crystals in and between the cells, thereby preventing major structural damage.  (Appropriately, those organizations involved in human cryonics use a human-grade form of antifreeze for the same reasons).

A more complex example of freezing and rethawing success was performed with the rat kidney.    Human Biosystems, Inc. took a rat kidney, reduced its temperature to -80 degrees celsius, and then three months later, implanted it into a rat - having it function for about three hours.  Although this not a perfect result - it is certainly a proof of concept and getting closer to the kinds of success at revival we all hope to see in the future.

Still another proof of concept was the teaching of the C. Elegans organism.  C. Elegans is a small worm which can be taught various responses to stimuli.  A researcher (Natasha Vita-More) was able to teach worms certain responses, to freeze them, thaw them, and demonstrate that the worms retained the learning.  This shows that brains (neurons) can probably retain their structural information after being revived.

To summarize,  the logic of cryonics and the examples discussed,  show that cryonics seems tantalizingly plausible.