By John Horgan

All science writers, especially those who delve into cosmology, particle physics, and other fields that purport to reveal ultimate reality, get letters from cranks. In the pre-e-mail era, I received envelopes stuffed with missives, sometimes hundreds of pages long, from people unaffiliated with any institution known to me. Some letters conformed to the etiquette of a peer-reviewed scientific paper, with an abstract and footnotes. Others were so baroque—the text handwritten in shifting scripts and colors, veering between technical and mystical arcana, and adorned with fantastical diagrams—that their authors had to be floridly psychotic. Either way, the letters' purpose was to inform me of a revolutionary new theory that would resolve the mystery of, well, everything. If I helped reveal this Truth to the world, I could share the glory!

In the early 1990s, when I was a staff writer for Scientific American, I made the mistake of writing an ironic response to what I thought was an ironic letter, sent via fax. The writer, whom I'll call Tachyon Tad, had "discovered" a new physics, one that allowed for faster-than-light travel, in prohibition of Einstein's special theory of relativity. In my faxed reply, I said that if Tad ever built a warp-drive spaceship, I'd love to hitch a ride. Dumb joke. For months, my fax machine churned out sheets covered with Tad's dense elaborations of his theory and plans for a superluminal machine.

After that, I simply tossed cranky letters. What else was I supposed to do? I had neither the time nor the scientific wherewithal (as a former English major) to find the flaws in their logic, any more than I could double-check the math that yields, say, quantum electrodynamics or some spiffy new variant thereof. As a mere journalist, I relied on experts to do that for me, especially ones at big-name institutions like the California Institute of Technology, the University of Cambridge, Harvard and Stanford Universities, and the Massachusetts Institute of Technology, who presumably had been thoroughly vetted. My job isn't to uncover scientific truth, I told myself, but to report on what professional scientists think the truth is.

But cranks have always haunted me. Who, I wondered, are these people, toiling in feverish obscurity over their wildly ambitious theories? And how could I be so sure that Tad, say, is not a loon but a genius? Couldn't he (almost all the cranks who write me are male) be the real deal? What is the difference, really, between cranks and experts? Just as experts are often wrong, can't cranks occasionally be right?

Margaret Wertheim, who has a degree in physics, couldn't set these questions aside either. In the early 1990s, this distinguished Australian-born science writer began collecting manuscripts from "outsiders," as she calls them, and even corresponding with them. In 1995, when she was in Tacoma, Wash., to give a talk, she drove 30 miles to a trailer park perched on the edge of the Green River Gorge. There she met Jim Carter, owner of the trailer park, whose lavishly illustrated manuscript on "circlon synchronicity" had captured Wertheim's imagination. Carter's theory, which began germinating in him when he was still a teenager in the early 1960s, explained all the "mysteries and paradoxes that have plagued physical science for centuries," as he put it, in terms of circlons, which are springs made of smaller springs.

Carter turned out to be not a reclusive schizophrenic, but a charming, ruggedly handsome husband and father. A self-taught jack of all trades, he was a former abalone diver, meteorite hunter, gold miner, and inventor. His most successful creation was the "lift bag," an inflatable device with which the Navy, Coast Guard, and salvage companies resurrect sunken objects. To provide experimental evidence of his circlon theory, Carter cobbled together three trash cans, rubber sheets, and a disco smoke machine into a contraption for blowing smoke rings. The experiment worked.

In her entertaining and philosophically provocative new book Physics on the Fringe: Smoke Rings, Circlons, and Alternative Theories of Everything (Walker & Company), Wertheim tells the tale of Carter, who became a close friend, and embeds it within a history of outsider physics. She traces the phenomenon back deep into the 19th century, when the British mathematician Augustus De Morgan collected hundreds of examples of "paradoxers," whom he defined as people who held views "apart from the general opinion" in science, mathematics, and other fields. Just as modern cranks often declare that Einstein was wrong, so did 19th-century paradoxers tout the superiority of their ideas to those of Newton.

De Morgan pointed out that some paradoxers were mainstream figures. "From the ridiculous to the sublime is but a step," De Morgan commented. "Which is the sublime, and which the ridiculous, every one must settle for himself." The 17th-century scholar John Wilkins, a master of Trinity College, Cambridge, and a founder of the Royal Society, speculated that wild geese were capable of flying to the moon. Newton—discoverer of gravity, inventor of calculus, modern optics, and mechanics, and the supreme embodiment of scientific reason—filled his notebooks with all manner of wacky theological and alchemical conjectures.

Unfair, you say, to judge past masters from our modern vantage point? Some giants of 20th-century science were famously cranky, too, even by standards of their time. The hard-nosed quantum theorist Wolfgang Pauli was fascinated by extrasensory perception and other paranormal phenomena. The chemist Linus Pauling spent his final decades insisting, in the face of strong counter-evidence, that massive doses of vitamin C could treat a wide range of disorders, from colds to cancer. (My mother, a Pauling devotee, doled out huge vitamin C pills to me and my siblings in the late 1960s.) With apologies to Alexander Solzhenitsyn: The line between brilliance and looniness runs through every great scientist's brain.

My favorite modern paradoxer was the British astronomer Fred Hoyle, who coined the term "big bang" (although he loathed the theory) and helped elucidate how light elements fuse into heavy ones in the cores of stars. He once tried to convince me that the AIDS virus was a U.S. military experiment that had gone awry and that flu viruses came from outer space. Great scientists are great, I've concluded, because they discern patterns in the flux of nature that elude us ordinary mortals; we should not be surprised when some patterns turn out to be illusory.

Indeed, whole fields can descend into crankiness. Wertheim serves up her philosophical punchline toward the end of her book when she turns her attention to mainstream physics and cosmology. She shares my sense that some popular suppositions—notably the notion that reality consists of extremely tiny strings wriggling in hyperspaces of a dozen or more dimensions, or that our universe is just one of an infinite number of universes—verge on pseudoscience, because they are even less experimentally testable than Carter's circlon theory.

Wertheim calls a 2003 conference on string theory and cosmology "by far the most surreal physics event I have ever been to." She likens it to "a sugar-fueled children's birthday party or the Mad Hatter's Tea Party," with each presenter spinning out speculations that everyone else considered to be "unsupported by evidence and based entirely on arbitrary assumptions." Far from fringe figures, the attendees included Stephen Hawking of Cambridge, Brian Greene of Columbia University, Lisa Randall of Harvard, and other stars of modern physics.

On the other hand, Wertheim is gent­ly, affectionately skeptical of the outsider physicists, too. In the 1990s, she notes, Carter and other outsiders formed an organization, the Natural Philosophy Alliance, or NPA, which hosts events and maintains a Web site where, as Wertheim puts it, outsiders "can publish their ideas without fear of censure." When Wertheim attended an NPA meeting in Grand Junction, Colo., it reminded her of the Three Christs of Ypsilante (Knopf, 1964), by the psychiatrist Milton Rokeach. The book describes an experiment in which three schizophrenic patients, each of whom believed he was Christ, were introduced to each other in a mental hospital in Ypsilante, Mich. Each concluded that the others were crazy.

Watching presenters at the NPA meeting, Wertheim comments drily, was like "watching 30 Jesus Christs. Everybody had the Answer. Everybody was the One." She nonetheless suggests that, given how far mainstream physics has drifted from a grounding in empirical evidence, perhaps we should judge all physics theories according to their beauty, elegance, and craftsmanship. And just as the art world occasionally embraces outsiders who lack formal training, so perhaps physics—and physics writers—should look more favorably upon the imaginings of autodidacts like Carter.

So what do I do with my crank—I mean, outsider—mail now? As it happens, one is sitting in my e-mail inbox. The author claims to have predicted the recent report (which I bet will not hold up) that neutrinos travel faster than light. Echoes of my old friend Tachyon Tad! I wish I could say I read these letters carefully, appreciating their unique aesthetic qualities, but I don't. I still delete them. I'm too busy working on my own fringe theories to help others with theirs.

John Horgan directs the Center for Science Writings at Stevens Institute of Technology. His next book, The End of War, will be published by McSweeney's Books in January.