Go and take your place with the alchemists. Leonardo drew several variants of the wheel in his notebooks. In reality, there are too many physical forces working against the dream of perpetual motion. We're hoping to rely on our loyal readers rather than erratic ads. To support Open Culture's continued operation, please consider making a donation. We thank you! Perpetual motion is most definitely NOT possible. Losses to friction will always prevent a perpetual motion device from working as claimed: Continuing in motion without additional input of energy beyond an initial starting impetus.
I am not a physicist and I do not claim to know what is possible in theory. A few minutes on Google is really all it takes to see that every physicist who is qualified will tell you that the balance sheet is not going to ever add up to a profit, even if one discounts friction losses. And if you take the time, they will cheerfully explain to you WHY such a thing is impossible. And this is one of them.
A couple of things maybe related to this, maybe not. A pendulum will continue to swing forever as long as it gets a little kick from something every cycle. Unless there is perpetual motion involved? Final thought just hit me. What are the sources of the kick equivalent force that keeps moons and planets rotating on their axes and revolving in their orbits.
Will have to read up on this subject. I have a great idea on changing gravity into motion perpetually can not find anybody to help me build it.
Name required. Email required. Click here to cancel reply. Get the best cultural and educational resources on the web curated for you in a daily email. We never spam. Unsubscribe at any time. The energy in and out of the system balances at all times. The energy from sunlight, used to convert water and carbon dioxide into a fossil fuel is equal to what we get out from burning them completely back to water and carbon dioxide. The energy from a hydrogen fuel cell reaction is the same as the energy put into the electrolysis reaction to split the water molecule in the first place.
Perpetual motion, and most other forms of free energy theory , insist that this "energy" in stage either doesn't need to happen or that the in and out doesn't need to balance.
Perpetual Motion Machines: Working Against Physical Laws
More on-the-ball proponents who understand conservation of energy may attempt to replace it with some form of magic, either magnetic depolarisation, gravitational work, just plain handwaved as "unexplained" or something far more exotic involving nanotechnology or zero-point energy. Because the energy in and out of a system balances, a perpetual motion machine is possible in theory or as a thought experiment. This is providing that all of the energy it produces goes into feeding the machine again. Where the problem occurs is in attempting to get the machine to do any work.
Extracting this energy causes the machine to slow down, reducing the energy output, and so on until it draws to a complete stop. This is why it needs to be fed something in the form of fuel, whether that be unburned hydrocarbons, hydrogen and oxygen or nuclear energy or even light.
Even Heron's fountain  will eventually run out as the water level settles to an equilibrium at the lowest point, and it must be "recharged" by physically lifting the water back to a higher level. This gives the water the potential energy the energy gained by working against gravity to move again — the "perpetual" nature of Heron's fountain is just a short-term illusion. But remember that perpetual motion is in theory only, in practice there are always inefficiencies and energy is always going to be lost from the machine, either via friction or even air resistance.
This takes energy out of the system constantly, rendering it impossible.
Designs of alleged perpetual motion machines that can actually be built as opposed to ones that work only on paper tend to fall into one of two categories. For many devices this can be shown to be false very easily, but highly efficient devices or ones with a very convincing illusion of motion, very sensitive and observant measurements can be required. However, if the output genuinely exceeds the input, the question arises why their output can't be fed back in, eliminating the need for an outside energy source entirely. Sometimes, though, claims of "over unity" are simply based on blatantly faulty science, such as claiming that a machine that has an input of 5 amps and an output of 10 amps is "over unity".
The second type, ambient energy machines, do in fact continuously put out energy, but they do so by drawing on ambient energy sources: for instance, a clock might run off the daily fluctuations of air pressure. An alleged perpetual motion machine might have a purported design, but have a hidden energy source not disclosed, or at least not explicitly stated, in those plans.
These fall into a category known as "fraudulent". Proponents of perpetual motion are quick to respond with the fact that the Earth orbits around the sun and rotates seemingly forever. However, the Earth seems to orbit forever because space is near-frictionless and there is no counter-momentum that stops them from orbiting. If a planet of equivalent size crashed at an identical speed, then it would stop or change course depending on the angle of collision.
If you put a generator on a planet , it would start to slow down, although negligibly. Momentum machines in space can work, but cannot be harnessed for productive energy. Strictly speaking, planetary orbits are not perpetual motion. As the planets and their star rotate around their common center of gravity, they emit gravitational waves.
Those gravitational waves drain the orbital system of energy so the planet eventually gets closer and closer to its star. In other words, planets do slow down. Now this orbital decay due to gravitational waves emission is ridiculously small so it has only been measured for extreme systems like binary neutron stars or black holes which are heavy and may orbit each other within minutes, seconds or just a fraction of a second.
Our planet Earth is subject to gravitational wave emission as well, but the orbital decay is so small that it in practice won't affect Earth within the Sun 's lifetime; instead of Earth spiralling into and being devoured by our Sun, it will rather be our Sun turning into a red giant which extends beyond the current orbit of Earth and thus devours it. One highly desirable feature of a thruster for use in spacecraft is for it to use no reaction mass. Several ideas have been proposed, though few — if any — actually work in practice.
In many cases, these devices do consume energy, but like perpetual motion machines violate conservation of momentum and can create an illusion of working even when they don't. An oscillation thruster  consists of a drive which attempts to create motion by sliding a mass around at different speeds.
If you can imagine a mass being slowly drawn back then fired forward at speed, then the momentum from that would arise from this would transfer to the drive itself and motion will be created. However, this is a clear violation of the conservation of momentum and energy; the force required to draw this weight backwards is equal to what will be produced forwards, and both will cancel.
Also, the force to push the mass in a direction will have an equal and opposite force on the device trying to push it. Like many perpetual motion engines, this particular drive can create the illusion of motion by exploiting coefficients of friction. The force from the slow drawing back of weight is proportionally lower but over a longer period of time and is not great enough to overcome friction. The force from the faster motion going forward is strong enough to overcome friction and a net motion occurs.
This is actually a trivial and somewhat inefficient method of creating net motion and is known and exploited for certain tasks,  but would not apply in the frictionless environment where such devices are expected to work. While hooking up a generator to its own motor is a popular modern variant on perpetual motion which definitely doesn't work because of the horrendous inefficiencies in electricity generation , there are several classic examples made up over time.
Even today, people are trotting out only minor variations of these long disproved models. The capillary bowl, or Boyle's Flask after Robert Boyle makes use of a few " paradoxes " of hydrostatics. Particularly, it's related to Pascal's Vases, where water remains at the same level regardless of the shape of the flask, so an apparently small volume of water can resist a large volume of water — demonstrating that the level of a fluid is dependent on depth and doesn't act like a set of weighing scales. It is not powered by gravity, as might be suggested by a quick glance at the hypothetical apparatus.
However, the flask would fail to fill regardless as water tension related to the same force that causes capillary action would prevent the flow emerging from the capillary at the end. A droplet may form on the end of the capillary, but would be held in place by the surface tension of the fluid; you could shake the device, forcing it to drop and encourage the flow to start, but that would be adding in energy to the system and defy the point of perpetual motion.
In principle, Boyle's Flask will run perpetually using a superfluid as these have zero viscosity, and thus remove the main barrier that prevents the capillary action from flowing continuously in this setup.
We are all makers
Demonstrations of near perpetual motion have been achieved using superfluids because they are frictionless friction being the main barrier to producing real-world perpetual motion , although conditions required to keep something in a superfluidic state are very difficult to maintain. But don't all rush out to buy up the world's supply of helium -4 just yet; regardless of the perpetual nature of the motion in theory, it is still impossible to extract work from these devices and have them continue.
The Bhaskara's wheel, Also referred to as the Overbalanced wheel, consists of a cog and several spokes with weights on the ends. Hinges allow the weights and spokes to move, altering the center of gravity of the device and causing it to spin.
However, as it spins, the spokes at the top of the wheel flip down, adding to the momentum by keeping it off balance and cause the wheel to turn indefinitely. The hypothetical device should never come to an equilibrium position.