Reinventing the Square Wheel
Why build an unworkable device? Every basement tinkerer has probably built at least one device that didn’t work as expected. One can learn a lot from such failures, because they teach us the pitfalls of design, the limitations of materials, and the restrictions imposed by nature’s laws. It’s easy to superficially examine a drawing or blueprint of a device, and glibly say, “That will never work.” It’s quite another thing to reason out exactly why it doesn’t work, and one can gain even deeper insight from hands-on manipulation of the recalcitrant mechanism.
PERPETUAL FUTILITY
When people say, “It’ll never work,” they may sometimes be right. Most new ideas turn out to be wrong and are swept under the rug of history. But even wrong ideas can be useful because they give us valuable information about what doesn’t work, and narrow the field of things we might try that could work. Unfortunately, some people never give up on a discredited idea. Such is the case with the perennial search for perpetual motion. Even today some “perpetual motionists” firmly believe it is possible, devoting considerable time and money to their attempts to achieve it.
Early Attempts at Perpetual Motion
A perpetual-motion device is easier to define than to make. It is a wheel that continues its motion — undiminished — forever, without input or output of energy. Even better would be a machine that continues its motion indefinitely while continually putting out additional useful power (output power greater than input power). Hopeful inventors call this an over-unity machine, because it would have a power efficiency greater than 1. If some of its output were used to power the input, it would require no fuel, but would simply continue doing useful work. Needless to say, no such machines have ever been successful, or we would not have an energy crisis.
Perpetually turning wheels were described in Sanskrit treatises in the fifth century, and later by the Indian mathematician Bhaskara (c. 1159). One such wheel had cylinders around its rim partly filled with mercury. As the wheel turned, the motion of mercury was supposed to keep the wheel heavier on one side of the axle, causing it to rotate perpetually. (If you build this model, use colored water. Mercury is an environmental hazard.)
Top illustration by Hans-Peter Gramatke
The production of useful work is strictly limited by the laws of nature. The production of useless work seems to be unlimited.
This idea reappears in Arabic manuscripts, one of which contained six perpetual motion devices. These designs later reached Europe. A wheel described by French architect Villard de Honnecourt in 1245 is identical to a design from Arabia — an overbalanced wheel with hinged hammers or mallets equally spaced around its rim. De Honnecourt insisted on an odd number of hammers. He claimed his device would be useful for sawing wood and raising weights.
Villard de Honnecourt’s Wheel
One reason these overbalanced wheels seem plausible to some people is because a static picture is used to represent a dynamic situation. People suppose that the falling hammer gives the wheel an extra impetus. But when the wheel moves clockwise (perhaps initiated by a push), the weight falling from A to B pushes the wheel backward (counterclockwise) during its fall, which probably isn’t what the inventor wanted. Casual inspection of the diagram wouldn’t lead you to expect this, but it’s easy to observe once you build one and try it.
Of course some of the forward motion of the wheel is recovered when the weighted arm hits the peg at position B, but there’s a net loss because all materials are somewhat elastic, converting kinetic energy to thermal energy when compressed. The hammers’ fall doesn’t generate additional energy but causes loss of energy. A simple flywheel without the hammers would work better.
All perpetual-motion machine designs, when carefully examined, can be proven unworkable for at least two reasons: (1) theoretical — they are based on incorrect assumptions about physics, or they apply physics incorrectly; and (2) experimental — if you build and test them, they don’t work.
Photography by Donald Simanek; illustration by Hans-Peter Gramatke
Simon Stevin’s Ball-Ramp and Woodward’s Wheel
Flemish mathematician and engineer Simon Stevin (or Stevinus, 1548-1629) analyzed a device consisting of a chain of balls on a frictionless double ramp. The chain was supposed to slide counterclockwise since there was more weight of chain to the left of the vertex. But Stevin’s analysis showed that the system had no inclination to move at all, because it was always in static balance. These results led Stevin to formulate a fundamental principle of mechanics, known as Stevin’s Principle of Virtual Work, which is found in textbooks even today.
Something about the notion of perpetual motion tantalizes those with restless minds, who think, “Perhaps there’s some principle of physics, as yet unknown, that we might discover if we just alter the design a bit.” So, through the centuries, these people tinkered with the designs, in a fantastic variety of ways, until the proposed machines became hopelessly complex. Such is the perversity of nature that none of them worked.
Some inventors were so confident of success that they included a brake in their designs to prevent the machine from turning so rapidly that it would tear itself apart. They needn’t have worried.
Some drawings included an arrow showing which direction the inventor supposed that the wheel would turn. This is especially helpful; without it, we physicists wouldn’t have the slightest idea which way the wheel should turn. If laws of physics allow the wheel to turn equally well in either direction, you can be quite sure the wheel won’t initiate motion by itself and won’t sustain motion forever when you give it a push.
By the 19th century, there was a refreshing return to simple basics. F. G. Woodward proposed a hoop wheel supported by two rollers. This is about as simple a design as you can imagine. Since the wheel always has more weight to the left of the rollers, that side should move down, as the arrow indicates. But the wheel stubbornly defies that “logic,” refusing to budge.
PERPETUAL OPTIMISM
Inventors before the 17th century had no physical laws of energy and momentum that would cause them to doubt the possibility of perpetual motion. But today we have a body of well-tested and accepted laws of mechanics that clearly tell us that certain things are impossible in nature, and no experimental evidence suggests otherwise. So how can anyone still expect to invent a perpetually moving mechanism? Well, many do, undeterred by a long history of total failure, contemptuous of the laws of physics, and oblivious to scientists who declare, “It’ll never work.”
Hans-Peter Gramatke has identified 1,800 perpetual-motion patents in the United States, England, France, and Germany between 1860 and 2000, and a dozen patents from other countries. From 2000 on, an average of about 50 patents per year were issued worldwide. Most were in the four countries named above, although Japan, China, and Korea show recent increases. These are patents that were “obviously” intended to be perpetual motion. There may be many more unworkable device patents in other categories.
Patent examiners do look for serious flaws in patent applications, but their primary criterion for patentability is that a device be a new idea; it doesn’t need to be workable or practical. That’s why unworkable devices get patented. Today, inventors avoid using words that would signal to an examiner that their device is supposed to get something for nothing, or that it is violating any well-established laws of nature.
Has all of this effort been a waste of time? Not entirely. Failed experiments give us a better understanding of the inherent limitations in nature’s operations. Science learns from its mistakes. Perpetual motionists’ mistakes get perpetually repeated.
PIXIE DUST
Perpetual motionists are especially attracted to those parts of physics they don’t understand. William Gilbert (1544-1603) summarized his experiments on magnetism in his book De Magnete (1600). The book was a sensation, widely read and widely misunderstood. It stimulated all sorts of incorrect, pseudoscientific notions about magnets, some of which still persist today. One fellow, heavily invested in a scam perpetual-motion device, wrote to me that every physicist should know that magnets contain infinite stored energy. As an example, he cited the lowly refrigerator magnet, which, he said, “can hold itself in place forever, working against the pull of gravity, so it obviously has unlimited stored energy.” Obvious to him, perhaps, but physicists know that work is the product of force and the distance that force moves something. A magnet does not move as it clings to the refrigerator, so it does no work and expends no energy.
Since simple mechanisms have been so well studied for so long, perpetual motionists today concentrate on elaborate and complex schemes, and then challenge skeptics to find the flaw. Science writer Bob Schadewald once observed, “A perpetual motionist typically concocts a scheme so complicated that he can’t see why it won’t work. He then assumes that it will work.” Some perpetual motionists pin their hopes on cutting-edge speculations of theoretical physics. Zero-point energy and dark energy are popular now. Perpetual motionists use these as the stage magician uses “magic pixie dust” — to justify apparent miracles. Some postulate as-yet undiscovered laws or hidden energy sources in nature, give them names, and then assume they have just those properties required for the success of their perpetual motion machine. They forget that these properties exist only in their imaginations.
Zero-point energy is a useful concept that has been experimentally confirmed in many ways. But this energy is “locked up” by constraining laws of physics that prevent it from producing useful work. There is not a shred of evidence, from experiment or established theory, that suggests any way to utilize zero-point energy as the driving energy for a cyclic machine. Dark energy is still a speculative hypothesis whose usefulness in physics theory remains to be seen. It, too, seems to be unavailable for conversion to useful work.
HOW CAN WE SAY THAT SOME THINGS ARE IMPOSSIBLE?
Of course, science has not yet discovered all of nature’s secrets. In the future we are sure to formulate new principles of physics. Even some of the laws we now know to be valid may need modification or reinterpretation as future discoveries are made. It is even possible that some basement inventor might stumble onto a useful device or even a new physical principle while trying to achieve perpetual motion.
Should we fund research into perpetual motion? I think not. A thing is not necessarily true just because we’d like it to be. It would be foolish to pursue this research because we haven’t a single indication, no evidence, no theory — nothing — that even suggests that a perpetual-motion machine is possible, and nothing to suggest how to go about achieving it even if it were possible. Research into antigravity devices, vehicles that travel faster than light, gravity shields, or ways to travel back in time would be just as promising. We haven’t a clue how to make them, either, and well-established laws predict that they aren’t possible.
Every law of nature that tells us how nature works also tells us how nature doesn’t work. The negative part is abhorrent to some people, who desire a magical universe where anything you can imagine is possible, if you tinker with things enough. Laws of nature express the constraints imposed by the geometry of the universe. You can imagine other geometries, but they are not recognized in our universe. For example, you may imagine a triangle in a perfectly flat plane that has exactly equal angles but very unequal sides. But that’s not achievable in our universe. Geometry is also the fundamental limitation on the performance of machines.
Illustration by Hans-Peter Gramatke
Simanek’s Silly Spring Device
Most perpetual-motion-machine designs that people send me are variations of old and discredited ideas. It gets boring after a while, so I decided to invent one of my own — to make a point. It uses a flexible, coiled spring looped over two pulleys. One side of the spring is kept compressed by a non-slipping belt running over smaller pulleys fixed to the larger ones. Clearly it is heavier on one side of the pulley axle, and this “unbalance” is maintained as you manually turn it. It can be rotated freely, in either direction. But it will not turn on its own, even if you could reduce friction to zero. Thanks to Hans-Peter Gramatke’s animation, you can see it in motion on my website (see References, below). It demonstrates that computer simulations can model unreality just as well as reality.
References
At these two sites, you can find pictures of many perpetual-motion devices you might want to build yourself. They are guaranteed to be unworkable.
Donald Simanek’s Museum of Unworkable Devices: www.lhup.edu/~dsimanek/museum/unwork.htm
Hans-Peter Gramatke’s pages: www.hp-gramatke.net/index.htm
Donald E. Simanek is emeritus professor of physics at Lock Haven University of Pennsylvania. Visit his pages of science, pseudoscience, and humor: www.lhup.edu/~dsimanek.