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....-- Vernon, Jul 26 2001 (?) CockroachesRus http://www.cco.calt...onj/text/roach.htmlIncludes Atmospheric Pressure and a Liquid Nitrogen Dunk [thumbwax, Jul 26 2001, last modified Oct 06 2004] For [nitehawk] http://www.npwrc.us...m/idguide/wood1.htmrana sylvatica (New England Wood Frog) [Klaatu, Oct 06 2004] Shameless plug http://www.halfbake...20By_20Ferroliquid!Another method of achieving suspended animation, using magnetic cooling. [spacemoggy, Oct 06 2004] [PS] *meow*
I think the idea is to freeze the subject extremely quickly. For reasons which elude my memory, this prevents the ice crystals expanding so much as to rupture the cells.-- -alx, Jul 26 2001 PeterSealy, concerning people getting turned into mush at 1500 atmospheres, what data do you have to support that claim. I didn't say that all that pressure was going to be applied at once, after all! Sure, it might take a few days to pump up the pressure slowly enough so that the subject acclimates, but the worst problem I see has to do with breathing very thick air. Increasing the oxygen partial pressure a little is not harmful, and may be necessary.
Also, I have read enough about cryonics to know that you have the name wrong...(it USED to be "cryogenics", but isn't these days).
-alx, I had read about the rapid freezing, but couldn't recall why it was considered important. As long as water becomes Ice-I, cells are in danger of rupturing, regardless of the size of the ice crystals -- unless you can get truly "amorphous" ice by rapid-enough freezing. And it is quite obvious that preventing large crystal formation is exactly what we need to deal with the self-purification issue I mentioned.-- Vernon, Jul 26 2001 Freeze a Cockroach - extremely low water. ReAnimate. Heck, you may not have to ReAnimate it at all. Of course, Liquid Nitrogen isn't the Medium of choice.-- thumbwax, Jul 26 2001 //freeze the subject extremely quickly//I believe that rapid type of freezing for the same reasons is called "Flash-freezing" - if my recollection of conversations with butchers-in-the-family is correct.-- thumbwax, Aug 09 2002 I like this. It should be testable, using champagne bottles (for high pressure chambers), normal freezers, and fruit flies. Fruit fly larvae have a very high tolerance for ethanol (also often in rotting fruit) and this could be added as extra antifreeze.
OK, maybe not champagne bottles. Not sure what sort of household items might be able to withstand 1500 atmospheres.-- bungston, Dec 02 2003 If we're considering true "suspended animation" as a mode of star travel, it does not necessarily have to include freezing.
The classical concept of "S.A." involves sleeping.
'Ah those little slices of death, how I loathe them' Edgar Allen Poe
The Russians and the U.S. after the Russians developed and have been using a device that induces sleep for long periods of time by inducing the brain to match the harmonic signal that is generated by the device.
This was called Electro-Sleep, although it is better known now as, Electro-Anesthesia.
A patient or in this case space traveler could be kept under for the duration of the flight. We can remove the worry about excess waste building up in the space travelers system, by installing a Gastrointestinal tube in our space travelers and feeding them a nutrient rich liquid food that leaves zero residue in the system.
Also during the duration of the flight they could be hooked up to a TENS Unit to keep muscles from atrophying.
We would need more sophisticated computer systems than we have currently. Those would include glitch free, shut down and freeze up free systems. These would be used to monitor the sleeping crew and if needed wake up those crew memebers that may be needed for various operations during the flight, i.e. repairs, course corrections, etc... I know sounds a little like HAL. Although that is what is needed. Does NOT need to be be an AI type system.
Let me know what you all think.
Mad Doc-- Mad Doc, Mar 26 2004 I did some accidental research in my freezer with ants. Their trail skirted the seal, and each time I opened it, a couple dozen more got in. After several cold, lifeless days, I finally decided to wipe them out with a warm sponge. Within seconds, they were crawling up my arm. It was so strange, I had to test it out again.-- oxen crossing, Mar 27 2004 "glitch free, shut down and freeze up free systems"
So you're saying that it'd have to be a Mac?-- Eugene, Mar 28 2004 (Bungston) Are you fluent in sleep technologies? Do you know what happens every night while you snooze?
In contrast to the waking state, sleep is characterized by a relative decrease of physiological functions(blood pressure drops, respiration rates decrease dramatically, heartrate goes from 70-90 BPM to 30-50 BPM). And a relatively low response to external stimuli.
You age at a lower rate while you sleep. Another reason to get a good 8 hours of sleep, you'll live longer.
Want to lower your heart rate and respirations even more, simply drop the temperature, all without affecting the body. Ever wonder why when it's cold outside you have a hard time waking up. Now you know.
Don't need to freeze the body, and thus take away the worries of defrosting, and the concurrent ice forming in the blodstream. Just drop the temperature of the sleeping body by 8.6 - 10 degrees.
This doesn't cause frostbite of the skin or freeze blood cells.
As far as taking "Decades" for interstellar travel, with the old technology that most are familiar with this would be true. But there already operating propulsion systems that can and will shave monstrous amounts of time off of interstellar travel.
Unfortunately due to budgetary constraints these will not be built en masse for some time. Also the technology for constructing the spaceframe necessary to hold up to the tremendous forces exerted by the powerful engines, is not up to speed yet.
There is a special metal in development(one cubic inch weighs one ton)which will be able to withstand those forces. Although the equipment needed to roll this metal out into sheets for building, is still in development also.
So while it is already possible to travel to the stars with our current technology, we could do it better and much faster with the next 10-20 years.
So no we wouldn't wake "Old" although we will have aged, although at a greatly diminshed rate, all with just a little sleep technology.
Now you know why they call me...-- Mad Doc, Apr 06 2004 [Mad Doc] /"Don't need to freeze the body, and thus take away the worries of defrosting, and the concurrent ice forming in the blodstream. Just drop the temperature of the sleeping body by 8.6 - 10 degrees."/
The reason our bodies go into hypothermia is because the chemical reactions that take place in our cells to keep our bodies alive require a certain temperature. Otherwise, there would be no reason for hypothermia.
Cold blooded animals don't depend on a constant temperature. That's probably why they have evolved to have the antifreeze...they could stand getting very cold in the first place.-- nomel, Jun 09 2004 This might actually work. I was pleasantly suprised--the only iffy thing is the 1500 atm of pressure, which I really wonder how the human body would react to.-- 5th Earth, Jun 11 2004 I did the exact same thing that [oxen crossing] did with the ants. Cool em, forget about them for two days, thaw em out. After 15 minutes, they're good as new. You can't leave them in the ice bin though. Freezing them for long periods of time seems to kill them. The frost probably makes a mess of their organs. For higher organisms, maybe we don't have to freeze them at all. Just cool them to near freezing. Problem is, the bacteria that operate at low temperature may cause flesh to spoil.-- mailtosalonga, Jul 13 2004 The big problem I've got with this is that, even if these people were revived, I can't imagine that their mental functions would remain intact.
I am of course making some assumptions, those being that the brain is a self-regulating/chaotic system that may be difficult to jump-start back into operation after being frozen for years.
The reason why ants and fish may be able to deal with being frozen is likely related to them having a simplified nervous system that is capable of restarting from scratch.
I doubt the human mind can work like that. Perhaps by using some form of brain-wave stimulator, you could re-animate the mind - but this is something we don't know anything about and...if it were possible would open the door to truely reviving people (or at least their brains) after they had died.
I do like some of the ideas of [Mad Doc] - Wet-wiring etc, though they do sound a tad un-ethical (and the notion that such a system would have //No glitches, shut downs, or freeze ups// is not one I share - the human machine being just as prone to failure than any other type of machine)
So yes, freezing as some sort of mummification process to preserve the human body in as perfect a manner as possible - but not as life-extension/hibernation device.-- zen_tom, Jul 14 2004 random, halfbakery