As to politics, it can't be said with any confidence that anti-relativity types are registered Republicans either. For example, the editor of Beckmann's anti-relativity newsletter told me that her contributors cover the entire political spectrum.

On the other hand, Brad DeLong, professor of economics at the University of California at Berkeley, points out that for many conservatives, "The admission that measurements of time and space depend on the motion of the observer is in their minds somehow tied up with the erosion of traditional cultural 'absolutes,' and scientific truth should be sacrificed to cultural order whenever necessary." He cites the writings of Bethell as an example.

According to Smolin, cranks are just a fact of life for working physicists. "Several of us have speculated that there must be a particular psychosis that results in people believing that they have disproved relativity," he said. "Any of us who are in relativity and at all visible get several communications a month from such people, sometimes in the form of self-published books, sometimes letters, sometimes e-mail." He added, "Usually they are innocuous, but a few times I have been threatened."

Owen Gingerich, professor of astronomy and the history of science at Harvard, told me about a character who used to stalk around the Harvard physics department some years ago. "He was a giant hulk of a guy who really put the fear of physical harm into some of the folks over there. I wish I could remember his name, but he was really exercised about special relativity being wrong, and since he has left here he has organized several conferences that seem widely attended by anti-relativity nuts."

Gerald Holton, Gingerich's colleague and author of "Einstein, History and Other Passions," told me: "Yes, I recall the fellow, as described, but happily have suppressed the memory of his name, and not seen him for years."

Smolin describes another dissenter: "There is presently someone in San Francisco who sends me hate mail often, full of bizarre sexual innuendoes and threats, together with insulting messages about how I am not as smart as I claim to be ... but there is never a return address."

Still, he said, such examples are unusual. "In most cases it is a sad story; sometimes someone has been working for many years on an idea, and has clearly a huge investment in it. Sometimes it literally comes from someone living on a park bench in Rio or in a homeless shelter in New York.

"In all cases it is easy to distinguish them from other members of the public who are interested in science and even from the occasional layperson who has their own theory about physics ... Such people are not surprised when you tell them their idea is wrong, and are genuinely interested to have the reasons explained to them."

Not so with most cranks. Indeed, a perusal of Internet discussion groups reveals just how thin-skinned and obtuse many can be. Beckmann was a case in point. Disappointed when his self-published book "Einstein Plus Two" attracted no attention among physicists, he took to visiting the newsgroups on the Internet and starting "flame wars," baiting other physicists about shopworn "paradoxes" in relativity -- and always dodging specific challenges about his own work.

According to Robert Low, a physicist at Coventry University in England, "I did have some correspondence with Beckmann a few years back; [this] came to an abrupt end when he took exception to something I said ... I never once seemed to be able to get him to see the point of any objections to his work."

Carlip, John Baez of the University of California at Riverside, Tom Roberts at Lucent and other physicists who still visit the discussion groups to answer questions about relativity have had similar experiences. Cranks only want validation of their theories, and often plainly don't even respond to objections raised by the physicists they approach. Indeed, after perusing the various threads in the discussion group, one can only admire the patience physicists show in the face of the flagrantly insulting jibes and non sequiturs thrown at them. Van Flandern has been a regular visitor to the newsgroups, contending for years that the "speed" of gravity must exceed that of light -- in violation of relativity -- despite several patient, detailed refutations put to him by Carlip, Baez and Chris Hillman, a mathematician from the University of Washington.

In his book "Cranks, Quarks and the Cosmos," science writer and physicist Jeremy Bernstein points out that one of the criteria that always defines crank science is its lack of correspondence with the body of scientific knowledge that has gone before it. "I would insist that any proposal for a radically new theory in physics, or in any other science, contain a clear explanation of why the precedent science worked," he wrote. Einstein did this, as the first page of his paper on special relativity, "On the Electrodynamics of Moving Bodies," illustrates perfectly.

In contrast, "The crank," Bernstein wrote, "is a scientific solipsist who lives in his own little world. He has no understanding nor appreciation of the scientific matrix in which his work is embedded ... In my dealings with cranks, I have discovered that this kind of discussion is of no interest to them."

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