From submarines to robots, much of the technology we take for granted today was originally conceived, not by scientists or inventors, but by that biggest of dreamers: the science fiction writer. Once thought wildly impossible, cryonics—the freezing of the recently dead, to be revived and repaired in the future when technology allows—seems to be following that same path.

In 1931, Neil R. Jones published the story “The Jameson Satellite” in Amazing Stories about a professor who, obsessed with immortality, launches his body into space and is eventually picked up, forty million years later, and revived by alien science. The story was quite popular at the time, eventually becoming a series and influencing future writers like Isaac Asimov as well as thinkers such as the young Dr. Robert Ettinger who, in 1964, wrote the nonfiction book The Prospect of Immortality, which explored cryonics in detail and eventually earned Ettinger the title The Father of Cryonics.

Since then, cryonics has become, if not yet a fully respected science, certainly a seasoned science fictional notion, employed in stories such as Clifford Simak’s “Why Call Them Back From Heaven?” and Fred Pohl’s “The Age of the Pussyfoot,” as well as in innumerable space adventure stories such as 2001: A Space Odyssey and Aliens where the crew is turned into corpsicles (thank you, Larry Niven) for long term storage during flight.

However, as cryonics’ determined subculture—clustered around a few companies such as Alcor—labors to make the theoretical into a reality, how close are we to actually making cryonics a real path to immortality?

Well, in large measure, cryonics is real right here and now.

Today, about a hundred people—including baseball legend Ted Williams who was frozen in 2003—lie in liquid nitrogen baths awaiting resurrection and the cure for what ailed them.

Reviving these pioneers with today’s technology, however, would be impossible as scientists are still missing the second, more crucial, half to the cryonics puzzle: how to repair brain cells damaged by shear stresses in their decent to the temperature at which patients are stored, seventy-seven Kelvin.  Especially since, when you reheat them, the cells are damaged even more.

There is, however, a promising future solution to this problem: nanotechnology.

Still in its nascency, nanotech, in fact, seems promising for a whole host of medical applications, theoretically being able to treat disease and decay at their fundamental levels.  Combining that technology with cryonics, however, will allow doctors to create the ultimate cure: the extension of life beyond death.  And, as cryonicists interpret “death” as having one’s identity destroyed beyond the limits of any conceivable future technology to recover, perhaps even redefining the end of life itself.

Exciting, yes. The bad news?  It will take approximately fifty years, if not a century, to develop nanotech to the point that it is able to repair the damage freezing and thawing does to human cells. Good thing about being frozen, though: you aren’t going anywhere. What’s another hundred years or so?

So barring the development of functioning nanotechnology, is cryonics still as fantastically implausible as even many thoughtful people consider it? (Even science fiction writers who were fascinated by the idea—Simak, Clarke, Heinlein, Sheffield—never made arrangements to be “suspended.”) Could there be some other, biological answer to the problem?

Well, consider that the Canadian painted turtle and several species of frogs, fish, and insects routinely make it through the winter by freezing and reviving and emerge in spring seemingly no worse for wear. Responding to the low temperatures of autumn, these creatures are able to move water out of their cells so that ice crystals form outside delicate membranes. They also produce a cocktail of glucose, amino acids, and glycerol (a kind of natural antifreeze). And while, yes, they do have special adaptations, their body chemistries are, from a human point of view, not so bizarre.

Preventing ice crystal formation is, of course, the crucial element in a successful revival from cryonic suspension, and the key to that is the use of those cryoprotectant glycerols. The only stumbling block here is that in animals, such refined physiological adjustments are the product of thousands of generations of evolution.  As warm-blooded mammals, our bodies have not developed the many fine adaptations to our physiology that would be required to ensure efficient uptake, use, and, later, flushing of the cryoprotectants. Rest assured, however, that biotechnologists are avidly working on extending these abilities to humans.

But aside from the questioning of its actual scientific and medical feasibility, the idea of cryonics has also suffered from a rather unfair charge: that it’s pointless. And creepy.

Well, as far as creepy goes, the practice of being frozen actually seems rather less so than, say, becoming food for worms or being consumed by fire. In fact, when cremation started out commercially, bodies were burned during the religious services.  Cremation businesses, however, quickly had to add organ music to cover the sudden, loud bang that frequently interrupted the funeral as the deceased’s skull exploded. Now that’s creepy.

So if we rule out creepy, what about the charge of cryonics being pointless? Or, to be more precise, a pointless outlay of money. Are cryonicists making a reasonable bet? Why do even so many of those intrigued by the prospect of life extension not take the gamble?

To wax numerical a bit more, suppose you look at cryonics purely as an investment. Does it yield a good return?

Well, what’s a person worth? Most Americans will work about fifty years at a salary in the range of around $30,000 to $40,000 per year—the national average today. In other words, they will make somewhere between one and two million dollars in their lifetime.

So one crude way to size up an investment is to take the probability of success (say, 10%—a guess) and multiply it by the expected return (two million dollars, earned by the revived person). Your expected return is then 10% of 2 million or $200,000. This is more than what cryonics costs today (about $50,000 to $100,000.) So, it’s a rational gamble, especially when you consider that cryonicists buy life insurance policies which pay their organization upon their death; it doesn’t have to be plunked down all at once.

The goal of cryonics, however, is not money but time—a future life. So another way to see if cryonics is a rational strategy is to take a person’s expected life span (about 75 years) and divide it by the expected gain in years if they are revived in the future—which would be, perhaps another 75 years—or possibly even centuries. In that case, the ratio of gained years to present life span is, say, 150 years divided by 75 years, or a factor of 2. (It could be higher, of course.)

Then, even if the probability of success is only 1%, say, the probable yield from the investment of your time would be 2 x 1% = 2%. And when viewed from that perspective, it makes sense to invest 2% of your lifetime earnings (say, $20,000 to $40,000) or of your lifetime—a year or so of effort.

But two percent is a conservative estimate, and the real realm of plausible probabilities seems to lie, actually, between one and, for the real optimists in the crowd, thirty percent. (And what are people who bet on science finding a cure for death itself if not the ultimate optimists?)

Ray Bradbury once told me he was interested in any chance of seeing the future, but when he thought over cryonics, he realized that he would be torn away from everything he loved. What would the future be worth, he asked, without his wife, his children, his friends? No, he told me, wouldn’t take the option at any price.

This is an example of the “neighborhood” argument, which says that mature people are so entwined with their surroundings, people and habits of mind, that to yank them out is a trauma worse than death. One is fond of one’s own era, certainly. But it seems to me that ordinary immigrants from every era have faced similar challenges and managed to adjust and make freer, better lives in their new homes. Just ask your grandparents.

So it must be with any way of thinking quantitatively about our future. We cannot see the range of possibilities without imposing our own values and views, mired in our time, culture, and place. Often, these are the things we value most—our idiosyncratic angles on the world.

But despite that, there is one clear advantage to cryonics: it does allow one to die with hope.