One of the more interesting memes to come out of 4chan are posts of rudimentary drawings of inventions or scenarios that, at first glance, seem to violate the laws of physics and allow for something supernatural to occur. One of the most common types of of these posts are ones related to “free energy” or perpetual motion. We’ve taken ten of these images and asked Steve Nelson, a Physics professor who holds a Ph. D. from Duke University in physics, to explain why these somewhat intuitive ideas fall flat in real life.
1. Free Energy Sail
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Why this wouldn’t work:
The force the fan puts on the air (Newton’s Laws, equal and opposite reactions) are put on the fan as well. Because of this, there is no net force on the sail-car, resulting in zero movement. Also, conservation of energy prevents you from recovering the energy of the wind for the fan.
2. Free Energy Flashlight
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Why this wouldn’t work:
Solar cells are only about 15% efficient. Light bulbs are even less efficient. Even if you could get a 100% efficient light bulb and a 100% efficient solar cell, you still wouldn’t ever be able to extract a net gain of energy from the system. Even the act of seeing light from the light bulb would necessarily mean that energy was being removed from the system, making the bulb increasingly dim until all the energy was dissipated.
3. Eternal Engine Magnet Car
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Why this wouldn’t work:
Similarly to the wind car, this vehicle would not move without violating Newton’s laws of motion. There is an equal force on the arm holding the magnet as on the truck, resulting in no net movement. The intuitive misconception here is that the magnet exerts a one-way force, when in fact there is an equal and opposite force on the magnet.
4. Free Energy Earth
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Why this wouldn’t work:
While likely impossible to dig a hole through the earth due to the intense pressures and temperatures involved, this system is subject to magnetic damping that will extract energy from the system over time. This pictured system would produce eddy currents in the conductor due to movements in the magnetic field. The flow of electrons in the conductor would create an opposing magnetic field which would result in the damping of the magnet and cause heat inside of the conductor. The loss of the energy used to heat up the conductor would be equal to the loss of kinetic energy of the magnet.
5. Free Energy Ferrofluid
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Why this wouldn’t work:
This one is intuitively difficult to find fault with, and comes the closest of any thus far. However, it will not work and will fail for more practical reasons. Capillary action will not work in the same way with this type of fluid, leading to problems with the ferrofluid moving up the tube. Additionally you would likely have problems with ferrofluid sticking to the magnet instead of falling as depicted in the image.
6. Free Floating Energy
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Why this wouldn’t work:
In order for the ball to make it through the valve while keeping the water in, it would be required to overcome friction, removing energy from the system. Additionally, the ball would not just “pop out” of the top and fall back down, additional energy would be required for this to work, leaving the system far from perpetual motion.
7. Free Energy Windmill
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Why this wouldn’t work:
This is another case of failing to account for the equal and opposite forces as stated in Newton’s laws of motion. The magnets exert an equal and opposite force on the blades as the blades do on the magnets, resulting in a windmill that does not move.
8. Free Energy Flashlight
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Why this wouldn’t work:
You would not be able to get more light to hit the solar panel than was emitted from the bulb. The number of photons doesn’t magically increase, they’re just packed more densely at shorter distances (meaning more intensity, but not more overall energy).
9. Free Energy Room
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Why this wouldn’t work:
Mirrors aren’t 100 percent reflective. If they were, it might be possible to create a chamber where light could bounce around indefinitely. Once something with less than 100% reflectivity entered the chamber, it would absorb all the light in a nanosecond. In order to see light, it is absorbed by our eyes, so such a theoretical room would be drained of the light by our process experiencing the light through our eyes.
10. Free Energy Pool
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Why this wouldn’t work:
This one is a simple matter of energy efficiency, you never get as much energy out of a system as you’d put in to move the water in your ring-shaped pool.
All Image Sources:
1. Reddit.com
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