Perpetual motion or “Motion that continues indefinitely without any external source of energy”1 is a wonderful idea that many would love to see come to life. The possibilities of their use are endless. We could live off of the energy produced by a perpetual motion machine forever, however they are not very practical in application.

As much as physicist love to simplify and take the extra complicated stuff from the equation in the case of perpetual motion, the laws of thermodynamics, and friction cannot be ignored. The first law of thermodynamics that we must talk about is, well, the first law of thermodynamics. This law is usually called the law of conservation of energy and is stated as, “the internal energy of a closed system is equal to the amount of heat supplied to the system minus the amount of work performed by the system on its surroundings.”2 The second law of thermodynamics states that any physical system over time, differences in pressure, temperature, and chemical potential will result in the natural entropic dissolution of the physical system.3

All of that stuff above means two things. The first is that energy cannot come from nowhere. Energy cannot be created or destroyed, just converted from one form to another. In addition, the energy of a system must remain constant, which is not necessarily the case when discussing perpetual motion. The second is that no matter what a system will always break down. It is much like the case of your favorite sneakers. You cannot wear them forever and expect them to stay good as new. They will always eventually wear out.

Despite all of the reasons that perpetual motion machines cannot exist we’ve gotten really close to the idea in many applications. Check out the Youtube video below that shows up some awesome example of perpetual motion machines.

  1. http://www.websters-online-dictionary.org/definitions/perpetual+motion
  2. http://en.wikipedia.org/wiki/First_law_of_thermodynamics
  3. http://en.wikipedia.org/wiki/Second_law_of_thermodynamics


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