For three years, as part of a book project, I chased after aliens. I never found them. Instead I found a lot of concepts, like the Fermi Paradox and the Zoo Hypothesis and the Anthropic Principle. I toyed with the Drake Equation. I begrudged the Principle of Mediocrity. This is what happens on the ET beat: You get lost in the wilderness of philosophy. There's nothing to grab onto, nothing to sink your teeth into. There are no fragments of alien spaceships to examine under a microscope.

Many times I thought of the Duchovny Theory. This is not an official concept but just something I picked up from David Duchovny, who chases aliens professionally on "The X-Files." We were in Vancouver, it was raining interminably, I was giving him a ride home. I knew him in college, a fact that ensures fabulous name-dropping possibilities for the rest of my life (like right now!).We stopped for a quick drink, where fans shouted his name and literally tried to grab onto him, to feed off the magic. Finally I asked him to explain why so many people believe the central premise of his show, this idea of an alien invasion and a vast government conspiracy.

He said, "At the base of it, it gives a very easy answer. Which is that there's bad guys out there, they're all powerful, and they're making your life miserable. It's the Oliver Stone answer. There's a reason bad things happen to good people. We show why. It's not random. We're more religious than `Touched by an Angel.'"

Duchovny was using "religious" loosely, but he was on the right track. Time and again I found that larger philosophical and theological issues were shadowing the question of ETs. You couldn't engage the topic simply through the avenues of biology and chemistry and planetary geology. God kept showing up to join the debate. He'd clear His throat noisily to make sure someone paid Him attention.

(Or was that just thunder?)

It used to be that science and religion were like neighbors with a privacy fence in between. Perhaps there might be some occasional bantering out by the driveway.

But these days it's hard to investigate any scientific topic without dealing with religious issues. Suddenly, science and religion are in counseling together, working through their problems. The alleged convergence of science and religion is the subject of countless books and magazine stories. The American Association for the Advancement of Science has a program in science-and-religion, as does the John Templeton Foundation, started by a mutual fund tycoon. It has aggressively funded academic symposiums, including one earlier this year in Washington, "Cosmic Questions," which mulled whether the universe shows signs of intelligent design.

The rapprochement is not driven merely by institutional support. Many people are desperate for more spirituality in their lives, for a "marriage of sense and soul," to borrow the title of a book by the influential writer Ken Wilber. Wilber is a Buddhist, and his book has reportedly been read by both President Clinton and Vice President Gore. On the campaign trail, Gore is as likely to speak about spirituality as about science and technology and the environment.

During my book research I was conscious of being, in most situations, an unbeliever, unapologetically so. I'd gotten fairly good at understanding things like the structure of galaxies and the molecular constituents of interstellar dust clouds. Thrilling stuff! I could fake my way through a cocktail party conversation on DNA. But spirituality remained, for me, an esoteric topic. I realized that I couldn't just ignore or dismiss the beliefs of others, that it wasn't enough to stomp around in the role of The Invalidator. Anyone hoping to address the big unknowns in science (such as extraterrestrial life) needs to be prepared to speak the language of spirituality.

Let's face it: The question that really matters, that underlies everything else, is not whether you believe in aliens, or anomalies, or the new physics, or the vastness of the unknown. The important and timeless question is, Do you believe in God?

We need to deal for a moment with the question of whether science has found Him.

This seems to be a popular notion. The assertion is that God can be found in the details of nature, that He's right there in the equations, the physical laws, the constants of gravity, the chemistry of stellar fusion, and so on. If you change the weight of a proton ever so slightly, or make the most modest adjustment in the formula by which carbon is created at the center of a star, or if you make gravity a wee bit stronger or weaker, your universe won't work. Things will collapse or fall apart. The universe seems fine-tuned for life.

Joel Primack, a professor of physics at the University of California at Santa Cruz, and one of the organizers of the "Cosmic Questions" conference, says, "The universe seems to be incredibly finely constructed. It's very puzzling why that should be so. The obvious approaches to this are either to invoke an intelligent creator, or to say there's something there that we physicists need to keep working on."

Many people have taken this suggestive situation and drawn the dramatic conclusion. "Science Finds God," blared the headline on the cover of Newsweek magazine last year. Unfortunately the announcement was premature. Science is a clever enterprise, but it hasn't yet found a way to put God in a bottle.

Look at the laws of physics once again. Yes, they're just right for the emergence of intelligent life. But for several decades now there's been a common observation that only in a universe compatible with intelligent life will anyone stand around wondering why the universe is compatible with intelligent life. There could be other universes, perhaps an infinite number, most of them lifeless.

Physicist Paul Davies recently argued in Forbes ASAP magazine that the multiple-universes theory isn't any improvement, from the standpoint of science, over the intelligent-designer hypothesis. It violates, he thinks, the principle of Occam's razor, which states that one should choose the simplest of competing explanations. Multiple universes is hardly a simple idea. In a lovely irony, those other universes are also undetectable, according to the theorists who posit them. You have to take the existence of the multiverse on faith alone.

Which sounds familiar . . .

There is, as it happens, a third (if somewhat vague) explanation for the rules of nature. The rules could reflect fundamental principles of "complexity," in which orderly structures like galaxies and stars and planets inevitably emerged from the chaos of the universe's birth. In other words, maybe this is the only way a universe can be. (The question is sometimes asked: "Did God have any other choice?")

It's fair to ask whether it's even a good idea to attempt to prove God's existence through empirical means. There are those, like Ken Wilber, who think that's a risky proposition.

"If you hook your God to today's physics, then when that physics goes, your God goes with it," he says.

In John Updike's novel Roger's Version, a curmudgeonly professor of religion is confronted by a young computer wizard who thinks he's found, in the constants of nature, the proof of God's existence. The professor complains, "Even Aquinas, I think, didn't postulate a God who could be hauled kicking and screaming out from some laboratory closet, over behind the blackboard." When theology touches science, he argues, theology always gets burned.

"Only by placing God totally on the other side of the humanly understandable can any final safety for Him be secured."

Keep up the privacy fence, in other words.

In the movie "The Arrival," Charlie Sheen, looking even more beer-faced and burned-out than usual, thinks he's detected an alien signal. He goes to his boss, a NASA official (played by Ron Silver) who is a narrow-minded, persnickety, pencil-pushing bureaucrat. The official explains to Sheen that the suspicious signal does not meet the test of science, because it was not repeated. Without a repetition, it's like a nonevent. The official then tells Sheen that not only is his discovery meaningless, but that the entire search for signals is being terminated. Naturally Sheen is outraged. He can't believe that he has to make a second detection for his discovery to be valid. Who made up that rule? he asks. Can we fire him?

The NASA official who enforces the hateful rules of science turns out to be an alien himself, part of a subterranean hive of buglike extraterrestrials who only appear to be human. The aliens are causing global warming to make Earth more hospitable to their species.

The moral of the story: When someone starts talking about what's "scientific" and what's not, they're probably really worried about something else, like their plan to conquer the world.

Hollywood knows that science is not universally loved. Almost everyone has some level of reverence for what science has wrought, in the way of improved medicine, geographic discoveries, the moon landing and so forth. But science is also considered elitist and cynical. It questions the truth of people's deepest beliefs. It is usually incomprehensible. It uses a language that we do not speak. It is full of exclusions, prohibitions and negations. It's no fun.

My mystical friends say things like:

"When we make contact, it won't be with machines. We're not going to use the tools of science. It's going to be spiritual. We are going to travel through internal portals." They will say this while tapping their chest. (My own inner portal, I'm sad to report, is covered over with plywood.)

Many people want to achieve what they call "higher consciousness." What's remarkable is that they do not consider this a metaphor. For them, a higher consciousness is a literal, physical, vibrational condition. It has a reality to it that could theoretically be measured by careful utilization of a consciousness-ometer. People want their cherished narratives of reality to be viewed as every bit as "real" as the narratives of physicists and chemists and cosmologists. They want, in short, to have it both ways, to be free of the restrictions of science even while demanding that their beliefs be accorded the same level of respect as a scientific principle.

No one alive today can escape the fact that science is a foundation of our civilization. The most spiritual people still repair at some point to their computer to send e-mails. But science doesn't give us a comprehensive take on reality. It's more limited than that -- even a physicist or a chemist would say so. Science only describes the world to the extent that it is subject to the empirical investigation of science. For many people this means science provides only the technical version of reality. There has to be more!

There must surely be phenomena that science can't quite handle, because they're too exotic, too . . . vibrational. And so many people who accept the basic tenets of astronomy do not want to exclude from the realm of possibility the basic principles of astrology. All the achievements of reason, from Aristotle through Copernicus to Einstein, have been lovely, but people still want more. The temptation is to lean one's head out the car window, to try to peek around the corner, stretch the neck, catch a whiff of the unseen world.

Sure, scientists have discovered that we live in a galaxy with 100 billion-odd stars in a universe that contains, at the very least, tens of billions of such galaxies. But that's highly unsatisfactory. The most ambitious thinkers would prefer to have some other realms, some secret dimensions, and at least one parallel reality.

Science's explanation of the mind is also insufficiently amazing for many people. Science claims that a chunk of matter in the skull can manufacture the astonishing sensation of consciousness and give a person the ability to perceive the world subjectively, to love, to marvel, to look at a painting or a child's face and notice something beautiful. But people want more than that -- they want to have brains that can shape the world around them, that can bend spoons at a distance, that can change the universe with the amazing power of higher consciousness.

It isn't enough that science has discovered that humans are genetically related to every other living thing on the planet, from apes to squirrels to grasses to plankton to long-dead dinosaurs. No, people want to have something even more "holistic" than that, a connection among all life forms that is spiritual. They want the ability to channel the thoughts of dead people and aliens (though one never hears about anyone channeling a dead alien).

More. It's a wonderful concept. More of everything.

It may be that we're seeing a triangulation of world views rather than a simple dichotomy. There's religion, there's science, and there's pseudo-science. Advocates of pseudo-science lift much of the language of real science and combine it with a passionate desire to believe in the incredible. But no pseudo-scientist would ever want to be accused of engaging in religion. The wonderful thing about contemporary UFOlogy, astrology, New Age consciousness-raising and certain types of alternative medicine is that these belief systems can be defended as secular truths -- unlike the supernatural stuff taught in Sunday school. Best of all, UFOlogy, etc. are advocated by a groovier set of people than is traditional religion or traditional science. Religion is pushed by grandmas and deacons and camp counselors; science is pushed by bowel-blocked, middle-aged Caucasians who can't relax.

We live in a world of machines. We do not understand the machines, don't know what's inside, and sense that the machines don't understand us. The computer is a magic box. We yell at it. It has no soul. Naturally the last thing that anyone wants is to be a machine, to be one of them, another soulless entity, and that is the ultimate perceived slander of science, with its talk of neurons, brain chemistry, DNA, proteins, receptor cells, the geometry of life, a common origin in a warm tidal pool, everything descended from slime. Where's the spiritual dimension? People are offended. The mortal sin of science is that it does not take seriously the idea of mortal sins.

The universe as described by astronomers does not contain good or evil. In the scientific view, no one made us, no one cares about us, and when we die we disappear for all eternity and our bodies are devoured by worms and all that is left is a skeleton that eventually turns to dust and then the sun blows up and everything is destroyed and then other bad stuff happens. The driving force in the universe is not a Creator, but just some equations -- it's just mathematics and geometry taken to the extreme. The universe is a machine.

(All this is my impression -- thoughts of a generalizing nature, emerging from my brain in what feels like a random pattern, a synthesis after many interviews and much reading, and it doesn't feel like the product of neurotransmitters. If a machine had written these paragraphs they would be better organized.)

Bryan Appleyard's Understanding the Present is as articulate and thoughtful a review of the rise of science as anyone could wish to read, but he is also rather furious. He writes that science is widely promoted as "a triumphant human progress toward real knowledge of the real world. This is the official view of the schoolroom and the television spectacular. For me it is nonsensical propaganda which conceals all the important issues. In my version the story is a sad one, a long tale of decline and defeat, of a struggle to hold back the cruel pessimism of science."

He adds, "The struggle is to find a new basis for goodness, purpose and meaning."

What might that new basis be? He doesn't say. His book is essentially a complaint, not a prescription, and a serious indictment.

A kindred spirit of Appleyard's is the historian John Broomfield: "Classical science bore the seeds of its own destruction. A consciousness that conceives an indifferent, spiritless machine universe of which the basic constituents are senseless chunks of matter locked in interaction by random, purposeless energies is profoundly unhealthy for humans, critters, and the very Earth itself."

The accusation, simply put, is that science has devalued the universe by robbing it of its soul.

My initial reaction is to say tough luck. The great thing about science is that it is willing to provide unpopular answers. That's why it works so well. It's not a beauty contest. It's not a process for telling people what they want to hear, it's a process for finding out what's true.

That, however, shouldn't be where the defense of science ends. The promoters of scientific thinking need to make the case that we are not spiritually poorer for our gains in scientific knowledge. Skepticism hasn't ruined the universe. This remains a place where goodness, decency, beauty, love and timeless truth remain viable notions. I believe humans can find in their own nature -- the virtual miracle of being alive and conscious, of being able to think! -- a great deal of motivation to create a better and more ethical planet.

Supporters of the scientific method need to figure out how to communicate more passionately the dazzling beauty of scientific knowledge. Science has banished the idea of vitalism -- the life force -- but it must take the next step of showing that without a life force, life is actually all the more incredible. It's a stunning idea that through sheer organization, through information passed via a single amazing molecule, a hunk of matter can move through the world with the properties that in aggregate make something alive. A human being is composed of the same material, the same simple elements -- hydrogen and oxygen and carbon and nitrogen atoms, and so on -- as the lifeless objects around us. Life and nonlife are connected: At base we are the same stuff. (And frankly, it is better to be alive.)

A secular explorer of the world has to decide when to reduce an issue to its material constituents and when to remain metaphorical. Reductionism isn't all that useful, most of the time.

Love is a good example. Love may be a function of brain chemistry and hormones. Love may be, as the evolutionary psychologists would argue, an adaptation, a form of social behavior shaped by millions of years of animals competing for survival in a state of nature. Love may involve neurological and biological events driven by proteins making contact with receptor cells. But if you wanted to know about love, you probably should forget about talking to a biologist, and turn instead to a poet.

Or, if you're so inclined, God.

Joel Achenbach is a Post staff writer. This article was adapted from his new book, Captured by Aliens, published by Simon & Schuster.