Imagine a device that could supply an unlimited amount of energy. It would solve many of the world’s problems in one fell swoop.
Unfortunately, such a device is impossible to build, but that hasn’t stopped people throughout history from trying.
In fact, to this very day, people still claim that they have created perpetual motion machines, and they keep getting proven wrong.
Learn more about perpetual motion machines, or the lack thereof, on this episode of Everything Everywhere Daily.
The idea of a perpetual motion machine is a tempting one, and if you know just enough physics to be dangerous, it is easy to think that such a device might be possible.
A perpetual motion machine is, as the name would suggest, a device that can continuously operate forever without any external energy.
As we’ll see in a bit, such a device is physically impossible, but for almost a thousand years, people have been trying, usually creating similar devices over and over.
The first known attempt at a perpetual motion device dates back to the 12th century in India. The Indian mathematician Bh?skara II created a device that became known as the Bh?skara wheel.
The Bh?skara wheel consists of a series of containers or compartments arranged in a circular fashion around a central axis. Each compartment is filled with a weighted ball or a liquid, and the weight of the balls or the liquid is carefully balanced to produce a continuous rotation of the wheel.
The best way I can describe it would be if you had a bicycle wheel with heavy weights around the spokes. As the wheel turns, the weights near the center of the wheel fall down the spoke to the edge providing momentum to move the wheel.
As the wheel turns, weights on the spokes near the edge would fall back down toward the axis due to gravity.
In theory, the falling, moving weights would be able to make the wheel turn indefinitely. One weight falls to provide momentum, which allows another weight to get into position.
This design could also be done with water or other substances.
I’ve done episodes in the past on a variety of inventions. In almost every case, I can point to some very early, crudely designed version of the invention and then a series of improvements made over time which developed the invention into what we know today.
However, in the case of perpetual motion machines, it seems that most people who have claimed to have created such machines have just reinvented the Bh?skara wheel in a literal or modified form.
They are generally called overbalanced wheels.
Bh?skara might have been the first, but he certainly wasn’t the last.
A similar device was designed by the 13th-century French architect Vilard de Honnecourt, but he never built it.
Leonardo da Vinci made drawings of a similar device. In Leonardo’s drawings, instead of straight spokes, there were curved spokes that looked like the lines in a nautilus shell. A ball bearing would then roll down each curved ramp from the axis to the edge, just like with a Bh?skara wheel.
There is no indication that he ever actually built such a device.
In the 17th century, there were a host of attempts at making perpetual motion machines.
In 1607 the Dutch inventor Cornelius Drebbel, who you might remember from my episode on the submarine, created a device that was a clock that never needed winding.
He demonstrated the device at the court of King James I of England, who was amazed at what he created. It was cleverly designed, but it wasn’t a perpetual motion machine. It ran on atmospheric pressure changes.
In 1618, the English physician Robert Fludd created something called the closed-cycle water mill. This machine was water which fell over a waterwheel. The turning of the waterwheel then powered an Archimedes screw which brought water up to a higher level to fall over the water wheel again.
The chemist Robert Boyle, the creator of Boyle’s Law, created something called the “perpetual vase.” This was nothing more than a container with a tube that looped around and emptied into it. It used the siphoning effect to refill the container that it came from.
In the early 18th century, German entrepreneur Johann Bessler claimed to have built over 300 perpetual motion machines. His machines garnered a great deal of interest among some of the greatest minds of his era, including Gottfried Leibniz and Johann Bernoulli.
He would often give public demonstrations of his devices, always making sure to hide the internal mechanism so no one could steal his ideas.
He did allow his devices to be inspected by several scientists who could find no fraud in his demonstrations.
In one demonstration, his giant perpetual motion was locked in a room in a castle where no one could touch it. It remained locked in a room for almost two months, and when the door was opened, it was still rotating at 26 revolutions per minute.
He demanded £20,000 in return for the secret of his invention.
It is now believed that Bessler was conducting some sort of fraud, although the exact mechanism of how it did it wasn’t known.
In the 19th century, there was a greater understanding that perpetual machines were impossible and that they violated the rules of physics.
However, that didn’t stop more claims of perpetual motion from being made.
In 1868, the US Patent office actually gave a patent to a perpetual motion device that was a type of rotary engine, which it was claimed could power a vehicle.
In 1900, Nicola Tesla made a rather vague claim about “self-acting” engine able to power a machine. He never explained the concept and never built a prototype.
Perpetual motion claims kept coming every few years, almost always from backyard tinkerers who claimed to have discovered a new type of physics.
In 1977, the US Patent Office issued U.S. Patent 4,215,330 titled “Permanent magnet propulsion system.”
Two years later, they issued another patent, U.S. Patent 4,151,431, for a permanent magnetic motor that didn’t require any flow of electrons.
Eventually, the US Patent office issued a decree that they would no longer grant patents on perpetual motion machines unless a working model of the device could be provided. According to their policy,
With the exception of cases involving perpetual motion, a model is not ordinarily required by the Office to demonstrate the operability of a device. If operability of a device is questioned, the applicant must establish it to the satisfaction of the examiner, but he or she may choose his or her own way of so doing.
Despite centuries of failed attempts a creating perpetual motion machines, people are still making claims of having created them today.
They almost always come from people who haven’t formally studied science, and claim that there is some sort of conspiracy to hide the truth that they have discovered.
So why exactly are perpetual motion machines impossible?
It has to do with the Laws of Thermodynamics.
The first law of thermodynamics is also known as the law of conservation of energy. Energy cannot be created or destroyed, it can only be transferred from one type to another.
This means that you can’t have a device that “makes” energy.
Many of the devices which appear actually to exhibit perpetual motion really are just getting energy from some outside source.
For example, at the University of Otago in New Zealand is a device known as the Beverly Clock. It has been running since 1864, and it has never been wound.
It is an incredibly clever device in a similar vein to the clock built by Cornelius Drebbel in 1607. However, it isn’t exhibiting perpetual motion, it actually runs on changes in atmospheric pressure. There have been several times over the last 160 years when it has stopped running during periods when atmospheric pressure was stable.
The second law of thermodynamics is the reason why devices like unbalanced wheels or the closed-cycle water mill can’t work. Entropy.
Let’s suppose you have an unbalanced wheel or some other sort of device that you think will keep turning forever.
There are going to be losses somewhere in the system.
In the case of an unbalanced wheel, as it turns, it is going to encounter some air resistance. It might be small, but it will exist.
Likewise, there will be friction on the axle of the wheel as it rotates. That friction will create a minor amount of heat which, according to the first law of thermodynamics, is just being converted from the mechanical energy of the turning wheel.
It is entirely possible to make such a device more efficient. You could place it inside a vacuum chamber to remove air resistance. You could create magnetic bearings to reduce the friction on the axle. You could make all the other moving parts out of some low-friction material like Teflon.
All of these sorts of changes could indeed make a very efficient wheel, and it is possible that such a wheel could turn for an incredibly long time. Ultimately, however, the piper of entropy has to be paid.
You cannot create a perfect vacuum, so there will always be a minor amount of resistance.
You can reduce friction, but you can’t eliminate it completely.
These laws of physics are why no perpetual motion device has ever and will never work.
They either are fraudulent in that there is some sort of external source of power, thereby putting energy into the system, or they will eventually stop due to entropy in the form of resistance or friction.
Despite the fact that this is one of the most cut-and-dry laws of nature, there probably will always be people who claim to have created perpetual motion machines.
So, if you ever hear claims from someone who says they’ve built a device that will solve the world’s energy problems, just remember that you can’t get around the laws of thermodynamics.