WHEN JACKSON ZINN DIES, IT'S OFF WITH HIS HEAD. WHICH WILL THEN BE submerged in a nine-foot-tall, stainless-steel capsule filled with 850 liters of liquid nitrogen -- at a chilly 320 degrees below zero. There it will remain, chemically frozen, for 100 years, give or take a few decades, in a warehouse on the wrong side of the tracks in Oakland.

Zinn, a bright man, a lawyer, is far from alone. He is president of the American Cryonics Society, which has 81 members who have contracted to be frozen at death. They have pledged $22 million in life insurance and trusts to maintain -- until scientists figure out how to revive them -- their frozen bodies.

Or in Zinn's case, his head. The rest of him will be cremated. Zinn doesn't like to call this head-freezing. He calls it a "neural job."

"Economy is a major factor," he says.

To be frozen from head to toe, you set up a $125,000 trust; the interest pays for $4,100 a year in maintenance costs, with money left over for research and the eventual thawing operation. The neural is much cheaper, requiring only $50,000.

Of course, you can sign up for the full-body treatment, and if your estate runs low on cash, you can be "converted," as one customer already has been. All it takes is a bluntly simple operation. And there's no need to worry about life without a body if you're revived in the future. Cryonics buffs believe that by the time scientists figure out how to revive frozen heads, they will have mastered cloning, and you'll get a body back in top form.

Freezing bodies is not something out of "Lost in Space." There are actual, live, mainstream scientists who work on ways to freeze human beings, or at least their organs. There are federally funded researchers who try to freeze human tumor cells and brain samples without damage. This is cryobiology, also known as low-temperature science.

But mention cryonics, the science of freezing bodies, or heads, to most establishment scientists and you get snide remarks about arrested adolescence and science fiction dreams. Mainstream scientists will not fund cryonics experiments. They will not publish cryonics reports in their journals. The military and the federal health bureaucracy turn down grant applications from cryonicists, who scrape together money from individuals and an occasional foundation.

Cryonicists will tell you that establishment scientists aren't as hostile as they seem. Some are even closet cryonicists. "We even have some of them signed up to be frozen," Zinn says. "They're just afraid that being associated with us will lose them their funding because they'll be thought of as crazy."

Zinn, who once went to theology school, isn't sure what happens when you die, and he doesn't care to find out. Quite possibly, he says, there is nothing after death. He does not like that, doesn't like even the idea of aging. "What's good about it? What is wrong with living forever?"

When Jackson Zinn dies, the death squad at that Oakland warehouse, the men of Trans Time, will do the neural job and preserve Zinn's head for . . . well, for who knows how long?

ACROSS THE STREET from a die-casting plant and an ironworks in a scruffy section of Oakland, hard by a row of sad little shacks some folks call home, there is a single, cluttered room behind a white concrete wall. This is not where you expect to find the cutting edge of science. Galileo had better digs.

This is Trans Time, one of four companies in the United States storing a total of about 15 frozen people; others are in Southern California, Michigan and Florida.

Zinn's head will be stored side by side with the others in stainless-steel capsules, known as dewars, originally designed to store bull sperm. The capsules are hooked up to a homemade electronic monitor and filled with liquid nitrogen. Right now, Trans Time is harboring the frozen bodies of two people and the heads of three others. And the bodies of somebody's pet dog and cat.

One woman has been on ice since 1974, though no one is quite sure how well she is preserved. Her preservation was rather primitive. Trans Time had no surgeon in those days, so a mortician did the operation.

The woman is not alone. Her husband, who died in 1980, now shares a capsule with his wife. They stand side by side. On their heads. That's in case of disaster: If no one can get to the capsules to refill the liquid nitrogen as it boils off, the brain would be preserved the longest.

The place looks like a barn converted into a storage room. Over there, shelves are packed with old filing boxes and jars of chemicals used in the operation to freeze a dead person. Here, under wraps, an ancient surgical gurney, an old heart-lung machine and other bulky equipment await the death of a customer.

Although there is little work to be done on the bodies once they're frozen, cryonics supporters hang out at Trans Time to read journals, trade ideas or simply be among fellow believers.

Art Quaife, president of Trans Time, is there almost all the time. He is not your typical corporate executive. He wears white socks. He is a mathematician. He has a simple guiding philosophy: "It is just not a good idea to grow old and die. I realized the enjoyment I'd get out of life was finite. That is not nearly enough. This is the most ambitious project in the history of man. It is hard to understand why we don't have 5 billion customers."

The warehouse is a clubhouse of sorts, a place where folks feel at home and stories get told. As I was about to leave, three Trans Timers pulled me aside. There was one more thing. Disney.

For decades, the rumor has been a commonplace of American folklore. The great imagineer is not dead, but frozen, waiting to be revived in the genuine Epcot of the 21st century. The Trans Timers knew how to find the truth. It was an elaborate plan, involving tracking shipments of nitrogen to a mountain in Utah. If I could prove that Walt Disney is frozen, imagine the publicity, imagine the credibility it would bring to cryonics.

"People always worry that we're a bunch of frauds," Jack Zinn says. This is a crucial point to cryonicists. The field has had its share of fly-by-night operations. One California group went out of business in the late '70s and let a bunch of bodies thaw out. That episode ended up in court and fouled up "the whole field for years," Zinn says.

So credibility is very important. These guys are extremely solicitous for reporters. They publish annual reports and open their books to the curious.

AN AUTUMN AFTERNOON IN 1960: PAUL Segall is 18, a precocious student from Flushing, N.Y., sitting inside a geodesic dome in an art class at the State University of New York at Stony Brook.

The professor is going on about the Neanderthal cave drawing of a bison projected on the wall. Segall, a science fiction buff all his life, remembers the scene in the movie "When Worlds Collide" where the guys come out of the flying saucer after learning to control the aging process and they look decades younger than their age. The young student stares at the caveman's art and decides he does not want to die.

"Here's the work of a man from 20,000 years ago, and where is he? I mean, he is dust," Segall recalls thinking. "He's not even dust. Well, what about me? I was going to college to be an engineer like my father, maybe go for rockets. But I knew I'd be afraid to go up in a rocket. What I really wanted was to be young forever. My father told me the human body was the greatest machine because it could repair itself. He repaired power plants and was frustrated by the way machines corrode. But humans, we have the ability to repair ourselves."

It's 28 years later, and Paul Segall, research director of Trans Time, is rushing. He doesn't have time for clothes that match. He's wearing those black tennis shoes with the gummy soles and brown cords and a white corduroy jacket and, yes, he's even got a pen pack in his shirt pocket. Square horn rims. Salad bowl haircut. Ultimate nerd look. These days, he is also a visiting scientist at Berkeley, where a sympathetic professor gave him some space in a lab. Segall is scrambling to find a certain journal article in the piles on his little desk in a corner of a tiny office in a sad old laboratory building on the Berkeley campus. Hurrying to finish one experiment so he can start another. This is a race against time. Science against the calendar. One inexorable force against another.

He must move the research forward, get the money to pay for more experiments, win the credibility that gets the money. And he must do it fast. Because the awful, horrible truth is that Segall is 45 now, a good-looking, healthy 45, but 28 years older than he was that day under the dome at Stony Brook, and people are still getting older and dying.

This must stop. Not because he fears death. "I never liked death, but I figured poof, I'm gone, I'm gone. I made my peace with it. But I have to figure out how to end the aging process. There's got to be a way."

Young Segall read a story in Playboy that told of early DNA research, of new ideas about genetic information that could be stored in deep freeze. He saw a scientist on Johnny Carson talking about something called cryonics. Segall, then studying gerontology, joined a New York cryonics group and, in 1968, helped freeze a young engineering student who had died.

In years to come, while Segall snapped up advanced degrees in biology and physiology from Hofstra, NYU and Berkeley, he worked on cryonics on the side. He developed his "seven-fold path to the conquest of death and aging": treating the aging, suspended animation, cloning, reversing the dying process (actually reviving the dead), regenerating tissue, developing artificial organs and transplanting body parts.

At first, the seven-fold path sounded a little crazy. Today, these are legitimate avenues of research, areas in which scientists are making steady progress.

He does his work wherever he can. He has done experiments on hamsters in his garage. More recently, he has worked on the sly in a borrowed lab at a secret location.

And then there is the dog.

SOMETIMES SCIENCE CALLS. PERSONAL frailties must be set aside. I do not particularly care for dogs. But I am on my way to Paul Segall's house in Berkeley to spend a perfectly lovely afternoon not with the scientist, but with his dog, Miles.

Miles is a beagle who got a second chance at life after a pretty sad start. Miles was born to be a lab animal, the kind of critter whose forlorn face stares out at you from the anti-animal-research ads. He was raised at a secret location, to keep him safe from the anti-vivisectionists and their terror tactics.

Fate was on Miles' side. He reached middle age having never been in an experiment. Too old to be used at the lab, he could have been killed. But a technician asked Segall if he needed an extra animal. Segall jumped at the offer; lab animals are expensive.

He took Miles home, where his daughter Tina adopted the beagle. Then, last year, when he was ready to test his new blood substitute, Segall carried Miles to a lab where he had been offered some time. He put Miles under and extracted all his blood, replacing it with a substitute designed to avoid the big problem with frozen liquid: It cracks, damaging cells.

Next, Segall froze Miles. The dog, named after Miles Monroe, the cryopreserved Woody Allen character in the movie "Sleeper," was chilled for about an hour, and only to 37 degrees Fahrenheit. But that was long enough to stop his heartbeat, circulation and brain activity. The beagle was in suspended animation.

Segall thawed Miles, drained the blood substitute and returned the dog's own blood. Within hours, Miles, a bit groggy, was up and about. Segall says Miles escaped the respiratory problems or infections researchers expected to find in a thawed animal.

Now, months later, I have come to check out the long-term effects. I meet Tina in the side yard, where she and the other children are engaged in a friendly episode of Torture the Dog.

Miles and I are introduced. He shakes hands and stands on his legs. He responds to his name. Tina gets him to jump through a hula hoop. He wags his tail. He seems happy.

This makes Segall happy. He has trumpeted the results of his experiment on talk shows, in interviews, to whoever will listen. But despite Segall's 35 publications, all those degrees and his triumph with Miles, the mainstream scientists criticize his work.

First, they say, Miles is not the first creature to be frozen and brought back to life. In 1956, British researchers did it with hamsters. The critters were on ice for three hours. They lived for only a few hours after they were revived, mostly because much of the liquid in their bodies had turned to ice.

And J.A. Panuska, a Jesuit priest and former Georgetown University cryobiologist who is now president of the University of Scranton, says Miles was never really frozen. Rather, the dog was in a deep state of hypothermia.

"No one has successfully frozen a whole mammal and defrosted it," Panuska says. Cryobiologists have moral and ethical problems with the very concept of freezing people. They praise Segall's mind, but they do not accept his work as science and they won't let him into their professional society.

"I'm one of the few living heretics," Segall says. "I'm not allowed to join because I freeze people when they die."

SO THE CRYONICISTS FORMED THEIR own club, housed in a tiny room behind a frosted glass door in a grand old San Francisco office building.

The rolls of the American Cryonics Society show the average member is highly educated. None of them believes belonging to the society bestows immortality, but in 15 years, only one member of the group has died. Then again, the average age is 39. Nevertheless, this is one of those strange little facts cryonicists like to mention and then just smile.

There are a disproportionate number of mathematicians, physicists and computer types. A bunch of them belong to Mensa, the folks who get together to crow about their high IQs. About half the members are Californians. And about half are libertarians.

"They don't like death and taxes, I guess," Zinn says.

Most cryonicists are atheists or agnostics, but the group includes a couple of ministers and observers of some major religions. The overwhelming majority of those signed up to be frozen are men. Maybe it's because women fear dead bodies, Zinn says. Or maybe it's because men are more likely to be scientists and most early cryonicists came from science backgrounds.

To be a cryonicist, you must have a stellar imagination. You must be the kind of person who simply nods when told that the society, ever searching for economical ways to preserve bodies for the Wonderful World of Tomorrow, is considering burying bodies in the Antarctic, using dynamite to blast holes in the permafrost, where the deceased could be stored maintenance-free.

To be a cryonicist, you must be able to take one look at a frozen body and envision a burgeoning industry of storage tanks, insurance sales, cryonics lawyers -- you must be able to imagine the world on ice.

Irving Rand had carved out a nice little niche for himself, selling insurance to Wall Streeters from his Long Island office. He was what is known as a Million Dollar Producer, which means he sold a lot of insurance. But he was in his late forties, getting a bit grumpy about, well, about life and death.

Then he saw the movie "Iceman," in which a caveman who was frozen in permafrost 40,000 years ago emerges alive and kicking. And Rand, who is a very practical man, told himself, "There must be some organization in the United States that does this."

Two years later, Rand runs Cryonics Coordinators of America, which is pleased to offer a new form of life insurance, a trust that will pay, after your death, for your freezing, maintenance and thawing and -- since you will come back to a society where you have no career or useful skills -- provide some spending money for a future century.

Rand himself has an insurance policy that will pay $500,000, $125,000 of it to cover his cryopreservation, the rest to get a good start in the next life.

"We're all passengers on the Titanic," he says. "What person would refuse to get on a lifeboat just because that may sink, too? Cryonics can be considered a leaky lifeboat."

Insurance in hand, you can sign up to be frozen -- but first you need a special will and legal instructions for your survivors.

Back to Jack Zinn. The president of the cryonics society also happens to be the guy who wrote the book on cryonics law. (He also does divorce and immigration work.)

Whoever is to be frozen, Zinn is betting he or she will need legal help. He has written forms protecting cryonicists and their money from relatives who don't understand why all that dough, which could be theirs, is going instead to care for Uncle Joe's head in a canister in Oakland. The forms put coroners, undertakers and families on notice that this dead body is not to be sliced up or burned or otherwise deterred from the search for eternal life.

But these contracts don't always work. When Althea Flynt, wife of Larry, publisher of Hustler magazine, died, her body never made it to the Alcor cryonics facility in Southern California. It's not clear whether her autopsy did too much damage or her grieving husband just forgot about it, but Althea Flynt's cryonics contract went unfulfilled.

Cryonics law is a new field. There is much to be done. Zinn is fighting for changes that would allow bodies to be frozen while they are still alive, leaving scientists of the future more living cells to work with. For now, bodies must be declared dead before cryonicists can freeze them. If the donor isn't quite dead, this can cause a problem for the cryonics society. It is called murder.

VENTURE CAPITALISTS, rich folks who look for speculative projects to fund, are snooping around, taking scientists out to fancy dinners.

Both cryobiologists and cryonicists, their renegade cousins, are racing to create the perfect blood substitute -- basically, a form of antifreeze to replace blood and prevent body fluids from becoming ice. The substitute could make it easier to harvest bodies for donor organs. It could produce an era of bloodless surgery -- why risk all that bleeding if you could put the blood aside until after the operation? Suddenly, this icy area of research has become a hot prospect.

So far, Trans Time, a company for profit, has actually made money exactly once in its 16 years of business. That said, the Trans Timers are salivating over the money that could flow if they perfect bloodless surgery or if freezing makes headway. The profits could be fantastic. If 1 percent of the Americans who die each year were frozen, and Trans Time made a $10,000 profit on each of them, that would be $200 million a year. Plus a tidy profit on insurance policies, on wills -- the possibilities are splendid.

The stakes are stupendous: A commonly used blood substitute could make the company that markets it unfathomably rich. Segall means to get there first. "That is the only way we can get the dividends that will allow additional research," he says. "That's where the money is to create an entire industry of low-temperature science."

But it must happen soon. There is so little time. He is 45 years old. Even now, after decades of argument, he is genuinely shocked by opposition to cryonics. He is amazed to find himself in a world full of Bernies, the character in the movie "Cocoon" who refuses to seek eternal life, preferring to play the hand God dealt him.

Segall has no time for Bernies such as Panuska, the Jesuit cryobiologist. Cryonics, the priest says, "is based on a hope, not a theory, and so it is not science. To freeze bodies today in the hope that somebody, someday will figure out how to unfreeze them is not science. It is an adventure.

"Cryonics people say why not freeze bodies just in case the science develops? I have to say, well, why? Why invest resources in this most remote chance? Who is going to pay for this? Who will decide who is to be frozen, and then who will be unfrozen? In a world struggling with hunger and homelessness, is this a proper use of resources?

"Everyone wants to live forever, but not particularly in this body and in this world. In my faith, death is a beautiful event. It is not to be feared. In all traditions, death is a part of life. Death affects moral judgments and concern for children. There is a cycle of life, and death is part of it. Cryonics to me seems a bit selfish."

Cryonicists have answers to those arguments, and for those people who say eliminating death will cause new problems, such as overpopulation. If no one dies, we are in for some heavy-duty crowds. People will tell nostalgic stories about luxuriating in rush hour on the Beltway.

"That's such a dumb point," says Quaife, the Trans Time president. "Why don't you commit suicide to help the population problem? Yes, in the long run, cryonics will contribute to population. But we are not limited to planet Earth." Quaife's solution: colonize space. Asteroid suburbs. Lovely developments on icy rocks flying through the universe.

I asked every cryonicist I met the same question. You are so certain this will eventually work. And even if it doesn't work, you say nothing but money is lost. So why don't more people sign up?

Fear of ridicule, Zinn says. "I had a lady tell me dying is natural. Of course, polio is also natural. We use our minds to extend our lives. You don't see people condemning braces, crutches or artificial hearts. What's natural is for man to be alive and happy."

Gerald Gruman, a physician and historian in Silver Spring, has written a book on the history of ideas about prolonging life. He neither supports nor opposes cryonics but is fascinated by it because it challenges the way we think about death.

Whether cryonics will succeed is hard to know, Gruman says. Freezing seems less fantastic all the time. But cryonics troubles doctors who find that the longer we extend life, the more we run into people so ill that they are sometimes better off dying.

"This has become almost a religion for the cryonics supporters, a sect that believes," Gruman says. "And then they just talk to each other. And they miss the ethical problems. Such as, why should this generation be saved? Why should Americans and affluent people have this instead of people in India? But cryonicists are still fascinating. In a way, they're kind of courageous." ::