Isolated in the middle of a desert valley known as Jornada del Muerto--the journey of the dead--the McDonald ranch house could be a testament to man's efforts to challenge and control nature's most unruly elements.

Even in the winter the sun shines here with the white-hot luminance of dry ice. Sandstorms boil out of the south. Only scrub grows, along with strange desert creatures. Buzzards hang in the pale sky.

But it is not the McDonalds' pioneering western grit that is honored here. The honor goes to other men who toyed successfully with a new element, one they created in an accomplishment of astounding proportions that left the world with a dilemma of equally astounding dimensions.

In a little green room adjoining the McDonalds' dining room, scientists assembled the active materials for the crude first atomic bomb. Using screwdrivers, they carefully moved the two hemispheres of man-made plutonium toward the point of critical mass. Then they took the device, which they called the gadget, a few miles away into the desert and exploded it.

Almost 37 years later the world has perhaps 50,000 such gadgets.

That array--methodically accumulated through Cold War and detente, through crises and arms-limitation treaties--represents a potential for self-destruction that numbs most human minds. Pyschic numbing, in fact, is the term the psychiatrists have given our ability to push out of mind all those devices and the world we have created to build, control and possibly use them.

Psychiatrists speculate that the Armageddon fears went underground, buried in the psyche, with the open-air test-ban treaty almost 20 years ago. They are reemerging now in a world in which some openly discuss limited nuclear wars while others try to peel back the veil of numbness and force the dilemma into the public mind.

The clash of the two forces already is sweeping Europe. In America it still is building toward the issue, perhaps the ultimate issue, of the '80s.

A few hundred miles from here, in Amarillo, Roberto drives out into a different desert to work every day, leaving behind his 6-month-old son and his wife in their modest Texas Panhandle home.

Roberto assembles and dismantles nuclear weapons--land mines for the Army, depth charges for the Navy, strategic city-killers for the Air Force. Sometimes he bolts them together. Sometimes he saws them apart, exposing the innards for someone else to fashion into more advanced models. Roberto's priest says the work is immoral. His government says it is patriotic. His government pays him $10 an hour, and he needs the job.

Far to the northeast, in Utica, N.Y., Dino Crenshaw goes to work every day, too. A sign asks him: Are You EWO Ready? That means, is Crenshaw ready to react to an Emergency War Order? Ready to climb aboard a B52, take Roberto's hydrogen bombs over the Soviet Union and use them?

In Huntsville, Ala., Carey Cooper dreams a lot, some of them hilarious, darkly funny Catch-22 dreams, others Kafkaesque nightmares. Cooper describes himself as a '60s draft dodger. He didn't run to Canada or to his doctor or to college. But he did hide.

Cooper volunteered for the Air Force, and spent four years in the underground world of a Minuteman command capsule near Minot, N.D.

Now, nine years after he last emerged from beneath the prairies, he is studying computer sciences, learning the language of computer pulses. Zero, one; zero, one; zero, one. His missiles were activated by combinations of computer pulses. Random pulses, which no one could explain, often invaded his command capsule. One of his dreams is about random pulses. Zero, one; zero, one; zero, one.

Crenshaw, Cooper and Roberto--he says using his real name would endanger his son's security and his job at America's only nuclear weapons assembly factory--live in a hidden American world. It is only subtly hidden, because it is too large and too pervasive to hide truly.

The scene at the McDonald ranch belies what has happened in the world since the scientists came, did their work and left.

The ranch, deep inside the Army's heavily guarded White Sands Missile Range, stands untended and etched by four decades of sandstorms. Its old windmill tilts precariously, dry skeletons of tumbleweed clinging to its ankles. The windowpanes have been ground by the relentless desert winds so that not even a shard remains. Inside, the ceiling rafters hang in cobweb shadows. The once-fine hardwood floors are a swamp of dry-rot traps beneath which rattlers curl up for the winter.

Jim Bryant, an Army guide, walks gingerly across the floorboards into the green room, known now as the assembly room.

Masking tape, which the scientists used to seal the room against desert sand, hangs like flypaper. Ancient packing crates, shipping instructions fading on their sides, sit where they were cracked open. It is as if the scientists left, forgot to pay the maid and no one has returned since. No one except G. J. and J. J.

On the far wall G. J. has scrawled that he loves J. J.

Bryant has no idea who G. J. and J. J. are or how they got past all the Army's guards, across the miles of desert, through the missile-testing areas and into the assembly room.

"Just random folks, I guess," Bryant said. "Life is full of random folks and random events."

The gadgets are in the hands now of a random group of nations--the Soviets as well as the Americans, the British, the French, the Chinese, probably the Israelis and perhaps the South Africans. India has successfully tested one. Before the end of the century they could be possessed by a dozen other nations, ranging from Brazil to Pakistan. Some fear that the possessors soon will include such random folks as Muammar Qaddafi or the Red Brigades.

America's nuclear-arms society has grown in a fashion that makes IBM and Xerox look like mom-and-pop grocery stores. It is a strange society.

It has produced pipe-smoking scientists who can reduce the active weapons package of a nuclear bomb to the size of a grapefruit or smaller, and strategists who argue that, just as partly cloudy can be partly sunny, 100 million dead means 140 million alive.

It has produced a cadre of truck drivers moving anonymously among the Bekins vans and Safeway carriers on American highways, their unmarked 18-wheelers filled with plutonium and triggers and other bomb parts, their taillights trailed closely by vans full of agents armed to the teeth.

It has produced its own language: CEP, EMP, TERCOM, Slickems, Counterforce, Countervailing and LNO nuclear strategies.

It has produced a world of hollowed mountains in which computers link to satellites that watch silos in faroff Plesetsk and warn of nasty activity in the steppes of Russia. Random pulses--zero, one; zero, one; zero, one--set off 147 false alarms in one recent 18-month period.

It has produced products which, if exploded at optimum altitude over the Washington Monument, would destroy the entire metropolitan area of the capital. The winds would blow cars off the Capital Beltway; the heat would start fires beyond.

It has produced missiles with a CEP--a circular error probable--of 90 feet. That means that a weapon fired at home plate in Yankee Stadium has a 50 percent chance of landing between home and first base, or between home and third base or within 90 feet behind the plate in the box seats.

It also has produced executive toys. Vulnerability Assessment Calculators and ICBM System Effectiveness and Survivability Slide Rules sit on the desks of strategists, courtesy of the companies that make Slickems and other modern products.

It has affected millions of Americans, some like Roberto and Crenshaw and Cooper, in quite direct ways, almost all others in some dark way that, as they say in the society, may never be quantified.

Thousands of "atomic veterans" are attempting to prove now that in the early days of open-air testing they were exposed unnecessarily to radiation effects.

In Nevada, Utah and Arizona, thousands of civilians are suing the government, claiming that they were never warned that their homes were in the fallout patterns from the Nevada tests in the '50s and '60s.

The majority of the young women on Rongelap, an obscure Pacific atoll over which a hydrogen bomb's fallout passed without any attempt to warn the people, now perform their festive South Seas dances with flower leis covering throat scars where their thyroid glands have been removed.

But some experts, particularly the nuclear-activist psychiatrist Robert Lifton of Yale, claim that the effects of the nuclear age are far more pervasive.

Carey Cooper sat in his silo for four years, his missiles training death on millions, and the dreams emerged almost a decade later. Lifton says that is classic pyschic numbing.

All of us, he says, hide from nuclear reality because the dilemma is too large for the mind to handle.

In 37 years the size of nuclear weapons has been reduced from the bulbous bathesphere shape of Fat Man to slender artillery projectiles. Their power has evolved to a sophistication that makes them more than 1,000 times the strength of the weapon that leveled Hiroshima.

The philosophies, the strategies for handling the dilemma, also have evolved, from elation over ending the Second World War, to awe of the incredible power, to fear of an inevitable arms race of a kind never imagined, to a futile attempt to keep the discovery secret, to the incredibly bleak rationalizations of mutually assured destruction to the even bleaker but perhaps inevitable fashion of the '80s: limited nuclear war.

It is not difficult to get a sense of the Darwinian nature of the evolution of the nuclear dilemma by visiting the place where it all started. The scene is as bleak and isolated as the Galapagos, where Darwin studied the creatures that gave him the theory that brought the world to critical mass almost as shockingly as the splitting of the atom.

Not far from the ranch are the remains of the crater of the Trinity Site, surrounded by cyclone fences.

It is a bit of a disappointment. When the gadget exploded at dawn on July 16, 1945, the heat was four times that of the sun. It dug a crater 1,200 feet wide, fusing the desert sands into a green glass the scientists dubbed trinitite.

Enrico Fermi, the wry Italian physicist who had taken bets the night before on whether the experiment would merely destroy New Mexico or incinerate the entire world's atmosphere, was one of the first to ride a lead-lined tank to ground zero.

Robert Oppenheimer, the scientific director of the project, watched the roiling purple clouds bubble toward the stratosphere and thought immediately of the words of an ancient Hindu philosopher: "If the radiance of a thousand suns were to burst into the sky, that would be like the splendor of the Mighty One." He was elated, then immediately depressed, recalling the next lines: "I am become death, the shatterer of worlds."

Only a few small instrument bunkers remain in the vicinity, weathered homes for rats and rabbits. The bunkers from which the observers watched, 10,000 yards away, were torn down long ago. In the late '40s some now-anonymous Army general ordered bulldozers to fill in the crater, as if psychic numbing were the best course then, too.

The general's camouflage has settled now, so that Trinity is a shallow, saucer-like depression. On the edges, a few stunted greasewood bushes grow, and bits of trinitite have worked their way up through the earth.

Bryant says the radiation level now is "less than you'd get from a chest X-ray." But the signs on the outer fence warn "Radiation--Keep Out," and the notice on the inner fence warns visitors to stay no longer than 90 minutes. The visitors who come here pick at the trinitite and take it home as souvenirs.

It is lonely here, the winds whispering softly and vacantly. Then, suddenly, over the deep purple of the Oscuro Mountains a vapor trail soars skyward, a low rumble reaches the crater and so does the memory of other signs along the dusty desert roads near here: "Danger--Missile Impact Area."

In Jornada del Muerto, the evolution goes on. Later this year the Pershing missiles that have inspired marches in Europe will land here, if up-range governors remove their objections to the overflights.

Other tests reveal even more about the evolution of the nuclear age as it nears its fifth decade. Last year ordnance experts stacked hundreds of tons of conventional explosives a few miles away in an attempt to simulate the overpressures from a nuclear explosion.

The test was designed to validate theories about "hardening" American industrial plants. Hardening industrial sites is part of the liturgy of the war-fighting, and war-surviving, doctrines becoming fashionable in the '80s.

Its leading advocate is T. K. Jones, a former Boeing engineer from Seattle who now is a deputy undersecretary of defense. Jones has a plan, about which he is passionate.

He would surround basic industrial machines with crushable aluminum chips, cover them with plastic tarps and bulldoze dirt over them. After the attack men would dig out the machines, the nation's industrial base would begin whirring again and the computers would revitalize what the Soviets had sought to destroy.

Jones uses aerial photographs of Hiroshima to reinforce his argument. Amid the general devastation he points to an occasional bridge and the concrete shells of a few buildings left standing.

"The photographs of Hiroshima are a kind of Rorschach test for the people who are in this business," said Larry Smith, a former staff aide to the Senate Armed Services Committee and one of Capitol Hill's more knowledgeable nuclear-arms experts.

Some people look at Hiroshima and see utter devastation, Smith said. Others see "targets" still standing, flowers blooming a few months later and a city rebuilt.

Smith once asked Jones where he would get the electrical power to restart the machines, presuming they survived and men wanted to dig them out. If all the automobile batteries in Seattle were strung together, Jones replied, they would produce enough power to run Boeing for a year.

"The problem with nuclear-war planning is that it has become so intricate, so arcane, that you can rationalize anything," Smith said.

The war-fighters, however, say they believe this also is pyschic numbing, a denial of the world's realities. If Lifton, the anti-nuclear psychiatrist, wants Americans to overcome the numbing to organize against nuclear weapons, the war-fighters want strategists and politicians to overcome it to become still better prepared.

The name of the nuclear game in the '80s is defense. President Reagan, when he spooked Europeans with his offhand comments about limiting a nuclear war to Europe, also said: " . . . All over the world . . . research is going on to try to find the defensive weapon. There never has been a weapon that someone hasn't come up with a defense."

The most significant part of Reagan's strategic arms proposals was not the limited go-ahead of offensive weapons such as the MX missile and the B1 bomber. It was the emphasis on defense: hardening and preserving command, control and communications facilities needed to carry on after an attack.

T. K. Jones wants to go further than the president's first proposals. Like Carey Cooper, the former Minuteman missileman, Jones also has a nightmare. His nightmare is about Soviet bombers, roaming at will over a devastated America because adequate air defenses were abandoned. About craters where Cooper's command capsule couldn't respond to an attack because the United States didn't build antiballistic missiles. About industries that could have been saved with crushed aluminum, metropolitan populations that could have been saved with evacuation plans.

It horrifies Jones that Americans will not take nuclear defense more seriously. "It makes more sense to me to spend a little bit of money to ensure that a lot more Americans survive instead of spending a lot more money trying to blow up a few more Russians," he said.

Carey Cooper recently listened to Jones speak at a strategic-arms seminar in Huntsville. "That guy's idea of disarmament," Cooper said afterward, "is for both sides to shoot everything they've got and then the world will be disarmed."

The talk of limited nuclear war has contributed greatly to the resurgence of the American nuclear-protest movement after more than a decade of quiescence.

One of these groups, the Boston-based Physicians for Social Responsibility, is attempting to give the Hiroshima Rorschach test to the American public.

The thought of an explosion of a single 20-megaton bomb in an air burst over the Washington Monument creates a nightmare that few minds can tolerate: a moonscape of destruction out four miles beyond RFK Stadium and Walter Reed Army Medical Center, near-destruction beyond the Beltway.

Shortly after the first bomb was dropped in 1945, Albert Einstein, who wrote the original letter encouraging President Franklin D. Roosevelt to begin its development and then was horrified by its implications, said mankind would need to develop a new kind of thinking to survive the gadget.

From the beginning, men have floundered in their attempts to develop that new way of thinking.

William Laurence of The New York Times was the only journalist present at Trinity. He wrote poetically of the experience: "One felt as if he had been privileged to witness the birth of the world, to be present at the moment of creation when the Lord said: Let there be light." But Laurence added that the "great symphony of the elements" was "full of great promise and foreboding."

Reports of strange sicknesses and deaths among survivors of Hiroshima and Nagasaki began seeping back to the United States. Army Gen. Leslie R. Groves, military director of the $2 billion Manhattan Engineering Project that built the first atomic bombs, tried to assure the world that America had not used a "horror" weapon to end World War II. Descriptions of the radiation deaths were exaggerated, Groves testified before Congress, and he had been assured that death by radiation was, in fact, "very pleasant."

In Los Alamos, N.M., where scientists already were beginning the relentless postwar development of more weapons, the physicists were furious. One of their colleagues, Harry Dagnian, 26, was dying slowly and painfully after a screwdriver slipped and his hand edged into a chain reaction. His hair fell out and his death took 26 unpleasant days.

The technology has evolved in the decades since Trinity; the thinking has not. The thinkers in the modern nuclear-arms society struggle for answers, but fatalism is the most clearly consistent theme.

George Kistiakowsky, a scientist who was present at Trinity and served as President Dwight D. Eisenhower's science adviser during development of the hydrogen bomb, said he expects to survive the bomb but that his grandchildren won't. Kistiakowsky is in his 80s.

Larry Smith, the former Senate aide, is frightened by the '80s, with its war-fighting mentality, and yearns for a "return to the awe" of nuclear weapons. But he said he doesn't think nuclear weapons can be wished away, and paraphrased John F. Kennedy in groping for an answer: "Eternal vigilance. A long twilight struggle. I fully expect a detonation in my lifetime."

Former defense secretary Harold Brown, after years of trying to deal with the Soviets, sounded almost despairing: "When we build, they build. When we don't build, they build."

Georgi Arbatov, a member of the Soviet Central Committee, said his country feels that the dropping of the Hiroshima bomb was aimed at the Soviets more than at the Japanese.

Albert Carnesale, an arms expert at Harvard, describes the mistrust this way: "We look at their forces through the telescope's small end toward the large and our own through the large to the small. They do the same. Equality, then, becomes not possible."

Paul Wagner, manager of the nuclear-arms assembly plant to which Roberto drives each day to secure his son's future, did not pause for thought when asked if he expects his grandchildren and their grandchildren to be grappling with the same problem he grapples with in Amarillo. "Sure," he said quickly. "We can't un-invent it, can we?"

Theodore B. Taylor, a brilliant theoretical physicist, dropped out of the world of the Los Alamos bomb designers more than a decade ago when he found himself designing weapons so small, as he put it, that they could be placed under the hood of a Volkswagen. Author John McPhee spent months with Taylor in the development of a book about the nuclear dilemma.

Toward the end, Taylor grew quite pensive. He assumed that more advanced civilizations existed in other parts of the universe. He also assumed that some were alive and some were not.

"Every civilization must go through this," Taylor said. "Those that don't make it destroy themselves. Those that do make it wind up cavorting all over the universe."

In Huntsville, where Wernher von Braun and the rocket scientists began this civilization's romp into space, Carey Cooper does not dream of cavorting through the universe. He dreams of a different kind of rocket, with megatons atop it and a simple key he has held in his hand often.

In Cooper's latest dream, the proper combination of computer signals pulse into his command capsule outside Minot. The Emergency War Order arrives, as it would for Dino Crenshaw in Utica. But, in his dream, Cooper is not EWO Ready. He rebels, holding the 10 rockets that he controls, rockets that could take out 10 Soviet cities with more firepower than was unleashed in both the world wars.

The pressures intensify, the orders grow more frantic. His fellow Minuteman officer, a young missileman also in his early 20s, nervously fingers his holstered sidearm, there in case his buddy goes mad.

Suddenly, as will happen only in dreams, a colonel materializes in the tight compartment 60 feet beneath the North Dakota prairie. "Turn . . . the . . . key," the colonel orders.

In his dream, Cooper still rebels. His chin juts out toward the colonel and he begins a speech: "For four years you have been telling me American policy is to deter nuclear war and that I am here to make sure war never happens. Your policy, colonel, appears to have failed . . . . "

At that point, Cooper wakes up to a world in which policies are changing. But he also awakes knowing that it was all a dream, that he would have turned the key. It is so easy, a simple twist to the right, like starting his car.

"Three, two, one . . . mark," Cooper would say.

On the computerized control board, which he still sees in front of him in the middle of the night, the green lights would start flicking rapidly.

Enable command. Flick. Launch command. Flick. Launch in progress. Flick. Missile away. Flick.