Suspended Animation

One of the main suggested uses for suspended animation relates to travel to the stars. At the speeds we can reach today, it could easily take thousands of years for a spaceship to get to the NEAREST stars. So, take the crew and put their lives into suspension, and start 'em up again when they arrive.

Thinking up that idea turned out to be far simpler than finding a way to make it work. Barring invention of some way to literally make the flow of Time stop inside a container (see the SF writings of Larry Niven about "stasis boxes"), the primary method pursued has involved freezing temperatures.

For some creatures, such as goldfish (according to something I once read, that is), we actually can freeze them solid, wait some significant period of time, thaw 'em out again, and observe them to apparently suffer no ill effects. But we can't do this with humans, alas.

As you know, the human body is mostly water; when water freezes, it becomes ice; and ice occupies more volume than the original water. This causes frozen cells to rupture -- think "frostbite". Not cool! (The critters that can survive freezing apparently have some kind of cellular anti-freeze, and/or more flexible cell walls than do humans.)

Nevertheless, we humans haven't run out of tricks yet, mostly because Science marches on, learning things that can be used in tricks. I should mention that the particular trick described here HAS been independently dreamed up by at least one other person (SF author Charles Sheffield, if I recall right), but the description that I had read about is not as detailed as the description that I thought up by myself, and am presenting here.

Start with a very strong pressure chamber. We seal the victim, er, volunteer, in, and start pumping in various gasses. At the start we want to cycle the air in the chamber, to remove nitrogen, and replace it with helium. When the subject's body has purged itself of all nitrogen gas in the bloodstream, then we begin raising the pressure. This has to be done much more carefully than a deep-sea scuba-diver, because we want something like 1500 atmospheres of pressure in the chamber, before we quit. Make that a VERY strong pressure chamber!. MOSTLY we just pump in helium, and try to keep the "partial pressure" of oxygen constant (naturally, a subsystem has to remove carbon dioxide). The reason we can't just increase the oxygen pressure along with the helium is that at high pressure, oxygen will start corroding the lungs. It IS a highly reactive gas, after all.

Next, at some point we also have to start pumping hydrogen gas into the pressure chamber. While this sounds like a recipe for disaster, it is both a necessity and a proven technology. It is necessary because of how blood chemistry is affected by various gasses at high pressure. Some gasses cause the blood to become more acidic, some cause the blood to become more alkaline. Since the acidity/alkalinity of blood MUST stay within a certain range for someone to survive, it is necessary to use a mixture of gasses that cancel out each other's effects. Helium and hydrogen constitute an appropriate pair of gasses to use. And, as mentioned, it is a proven technology; the very deepest divers use just such an oxygen/helium/hydrogen mixture, and as far as I know, none have exploded yet.

Arriving at the desired pressure, NOW we freeze the subject solid. It is a fact of Physics that when water is placed under sufficient pressure, it doesn't turn into ordinary ice when it freezes. Instead it turns into something that has been labeled Ice-II. (Increase the pressure even more, and we can make Ice-III, Ice-IV, and some others). Well, it happens that ONLY Ice-I, ordinary ice, is less dense than water, and so expands when it freezes, rupturing cells. Ice-II won't do that!

That's the main idea. There is a secondary issue that may need to be addressed, but I lack data to say how important it is. See, when ordinary water, containing various dissolved substances, freezes, it manages to "push out" impurities. That ice could be removed, melted, and be observed to be significantly improved in quality. The problem is, this self-purification during ice-formation is not beneficial to a cell. Water is a dilutant preventing certain detrimental reactions from occurring rapidly (or at all), so if the water clumps together during Ice-II formation, the cells could still be in trouble, as undiluted reactants encounter each other. But, as I said, I don't know enough about this aspect of the situation. Experimentation is in order!

Who wants to volunteer?

P.S. I do know that the frozen subject will have to be KEPT under pressure, for the duration of the experiment. Take away the pressure, and Ice-II will revert to Ice-I....