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Perpetual Motion

May 17, 2013

Novel energy sources are always welcome, especially those that don't cause carbon emission or other environmental consequences. One interesting fictional energy source that seems to satisfy these conditions is the Zero Point Module (ZPM) of the various Stargate television series. As are most science fiction devices, the Zero Point Modules are associated with an established scientific principle that offers credibility. In this case, it's the zero-point energy of the vacuum.

Zero-point energy is the ground state energy, the lowest energy state, of a quantum mechanical system. This energy is not zero, so everything in our universe sits atop a baseline energy reservoir. Perhaps I shouldn't use the term, "reservoir," since it doesn't appear possible to tap into this energy, ZPMs notwithstanding, although the Casimir effect might cause you to think otherwise.

The Casimir Effect is named after Dutch physicist, Hendrik Casimir. In 1948, Casimir predicted that conductors spaced less than a micrometer apart will attract each other in a perfect vacuum, since the region between the conductors form an electromagnetic resonator that will only support a subset of the frequency modes of the vacuum state, the zero-point state. The vacuum outside this region, which supports all modes, will exert a pressure on the conductors. Casimir effect illustration

Illustration of the Casimir effect.

The vacuum region outside parallel conducting plates supports all modes, whereas the number of modes allowed between the plates is restricted. There is a net exterior pressure that acts to push the plates together.

(Via Wikimedia Commons))

Ten years after his prediction, Casimir's effect was roughly demonstrated by one of Casimir's colleagues at the Philips Research Laboratories, and an experiment in 1997 demonstrated the Casimir Effect to 95% accuracy.[1] Atomic force microscopy experiments, for which separations can be very small, has brought the agreement to 99%. The Casimir effect has implications for MEMS devices, since it's been shown to change the resonance frequency of a MEMS oscillator.[2] A review article about the Casimir effect is available on arXiv.[3]

It's no wonder that the Casimir effect has people dreaming about free energy (free, as in beer, not this free energy). If it were possible to achieve a separation of just ten nanometers for square centimeter parallel plate conductors, the attractive force from the Casimir effect would be 10 newtons, or one kilogram of force! The problem, however, is how to convert that force to useful work, since separating the plates requires the same force, and you would need to do that in a work cycle in any machine. Some schemes for separating the plates make the analysis a little complicated, but careful calculations will give the same prognosis.

This brings us to our topic of perpetual motion machines, which has a long history. I wrote about such machines in a previous article (Second Law of Thermodynamics, February 7, 2011). Although inventors have been fascinated by the idea of perpetual motion for hundreds of years, perpetual motion is disallowed by the first and second law of thermodynamics.

The first law of thermodynamics is the conservation of energy law. The second law essentially says that thermal systems will equilibrate after sufficient time and natural processes are irreversible. Physicists have been developing and validating thermodynamics for hundreds of years, so they're naturally skeptical about perpetual motion. The American Physical Society issued the following statement in 2003:
"The American Physical Society deplores attempts to mislead and defraud the public based on claims of perpetual motion machines or sources of unlimited useful energy, unsubstantiated by experimentally tested established physical principles."
The US Patent and Trademark Office does not grant patents for perpetual motion machines, as explained in its Manual of Patent Examining Procedure (MPEP).
"A rejection on the ground of lack of utility is appropriate when (1) it is not apparent why the invention is “useful” because applicant has failed to identify any specific and substantial utility and there is no well established utility, or (2) an assertion of specific and substantial utility for the invention is not credible. Such a rejection can include the more specific grounds of inoperativeness, such as inventions involving perpetual motion."(Section 706.03a)
Figure caption

The overbalanced wheel is a popular object in perpetual motion lore. The idea, which dates back to the Indian astronomer, Bhaskara II, in the twelfth century, is that the extended pendula on one side should exert a greater driving force to push the wheel around. What's not realized is that there is more mass on the opposite side of the wheel, so the forces equilibrate. Source images, left, a fifteenth century drawing by Taccola, and right, a Norman Rockwell illustration from the October, 1920, issue of Popular Science, via Wikimedia Commons)

The Casimir effect is not the only microscopic machine that at first appears to give a perpetual motion, but in fact will not. Richard Feynman invented the Brownian ratchet, a ratchet that moves just one direction when excited by randomly moving molecules. The ratchet in his thought experiment seems as if it should extract work from thermal fluctuations, but a detailed analysis shows that it will work only as long as the ratchet is cooler than its environment.

An arXiv article, posted earlier this year by Alejandro Jenkins of Florida State University, reviews the life of perpetual motion entrepreneur, Johann Bessler, also known as Councillor Orffyreus, who flourished about three hundred years ago.[4] According to Bessler's Wikipedia page, his latinized pseudonym, Orffyreus, was devised by his doing a ROT13 transform of his name.

This was a time before Sadi Carnot, Count Rumford, Rudolf Clausius, Lord Kelvin and Constantin Carathéodory, so thermodynamics had not been developed. That's why it's probably not surprising that Gottfried Leibniz and Johann Bernoulli thought Bessler's perpetual motion machine, called "Bessler's Wheel," to be real.[4]

Bessler became intrigued by perpetual motion after a visit to a monastery at which he saw a rotisserie that appeared to turn on its own.[4] I speculate that the inventive monks may have used something like Hero's engine. After a fortunate marriage boosted his social and financial standing, Bessler built a series of huge perpetual motion wheels. Although these were fabricated to appear to operate as overbalanced wheels, the works were always hidden, with Bessler asking for a huge reward to reveal the miraculous mechanism.[4]

Johann Bessler (Orffyreus)

Bessler and the title page of one of his pamphlets. A human skull always adds an air of authenticity. (Source images, left and right, via Wikimedia Commons.)

Bessler published pamphlets, such as in the above figure, advertising his perpetual motion wheel, but there were skeptics who counterbalanced the opinions of the believers I mentioned earlier. Finally, Bessler's maid revealed that the wheels had always been turned from an adjacent room, and that she had sometimes done the turning.[4]

Although some questioned the statements of a house servant, Bessler's wife also told of the deception. As interest in his wheel declined, Bessler concocted other miraculous inventions in his later years, until he died in a fall in 1745 while constructing a windmill in Fürstenberg.[4]

Jenkins finishes his article with his observation on why men of intellect in Bessler's time could have believed his claims. Scientists are not trained to spot deliberate deceptions, as our culture is one of open and honest discourse.[4] Many lessons can be learned from the Schön scandal.


  1. S. K. Lamoreaux, "Demonstration of the Casimir Force in the 0.6 to 6 μm Range," Phys. Rev. Lett. vol. 78, no. 1 (January 6, 1997), pp. 5-8.
  2. H. B. Chan, V. A. Aksyuk, R. N. Kleiman, D. J. Bishop, and Federico Capasso, "Nonlinear Micromechanical Casimir Oscillator," Phys. Rev. Lett., vol. 87, no. 21 (November 19, 2001), 211801.
  3. M. Bordag, U. Mohideen, V.M. Mostepanenko, "New Developments in the Casimir Effect," arXiv Preprint Server, June 8, 2001.
  4. Alejandro Jenkins, "The Mechanical Career of Councillor Orffyreus, Confidence Man," arXiv Preprint Server, January 14, 2013. Also appears as Alejandro Jenkins, "The mechanical career of Councillor Orffyreus, confidence man," American Journal of Physics, vol. 81, no. 6 (June, 2013), pp. 421-427.
  5. Perpetual Motion Page on Wikipedia.
  6. History of Perpetual Motion Page on Wikipedia.

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