The model requirement has been discontinued, but the agency has remained skeptical of such applications.
"The patent office used to say that they didn't patent perpetual-motion machines, but it turned out that there really was no such rule," Park said.
A 1990 federal court ruling against inventor Joe Newman, who applied for a patent on a motor that he said could return more energy than it consumed, was interpreted as precluding patents for such devices.
But the verdict has not fully stemmed the tide of applications.
"The effect that [the court ruling] has had is that patent seekers no longer call them perpetual-motion machines," Park said. "Now it's called capturing zero-point energy."
Zero-point energy is a real type of energy produced by the miniscule movements of molecules at rest. Harnessing this energy is theoretically possible, but the task seems, at least for the moment, practically impossible.
When asked about Volfson's machine, a U.S. Patent and Trademark Office (USPTO) spokesperson said the agency does not discuss specific patents. But the spokesperson explained that qualified patent examiners review each application according to rigid criteria.
First the idea must be patentable by law, said Brigid Quinn of the USPTO, based in Alexandria, Virginia. "There is patent law that describes what is patentable subject matterfor example, the laws of nature aren't patentable."
If an idea passes legal muster it must then meet several specific criteria.
"Is it new?" Quinn asked. "Is it useful, which means does it work? Is it nonobvious? And is it described in such detail to enable someone skilled in that technology to make and use it based on the description that must accompany the application?"
Patent office scientists and engineers, skilled in particular technologies, make their determinations based on these criteria and the current state of the science involved.
But despite their best efforts, mistakes are inevitable and patents may be granted to unworkable ideas. Some 5,000 examiners must currently handle a load of 350,000 applications per year.
Meanwhile, no amount of nay-saying will stop inventors from dreaming of a legitimate perpetual-motion breakthrough. Park believes that these hopefuls far outweigh any ill-meaning scammers.
"The most curious aspect of this is that most of these people truly believe that they've made some new discovery that most people haven't thought of," he said. "It doesn't often work out."
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