Skeptical Update Perpetual Motion

http://www.youtube.com/watch?v=PIvZJ9xGutI

Skeptical update. I’m Jon, current chair of the RIT skeptics. Since Ask a Skeptic is coming out only once a month, I thought that I’d help fill the gap with a short skeptical update of my own.

I’m going to talk about a youtube video called OC MPMM – Alsetaikin’s Video, link in the show notes, which is being billed on the internet as a perpetual motion machine. Now, the about this video section doesn’t say that it is a functional perpetual motion machine… Or at least not a final product

To me it just looks like a spinning disk. The first two laws of thermodynamics, which so far have tested true, do not permit perpetual motion machines.

The first can be paraphrased as saying that energy cannot be created nor destroyed, only transformed.  That means that the amount of energy in the universe is constant. Perpetual motion machines  supposedly produce more energy than they take in and use that energy to continue the motion of the machine.

The second law of thermo dynamics, which is often misunderstood can be paraphrased as saying that within a closed system entropy increases over time. We should be clear to what entropy refers to. Entropy is a physics term which is often sort of mischaracterized as meaning chaos. Really it refers to the availability of a system’s energy. So, the higher the entropy of a system, the less the system’s energy is available.

Classic example is a glass of water with ice cubes. Let’s pretend that this is an isolated system, so the glass doesn’t interact with it’s environment. To start out with the solid phase water will be colder than the liquid phase water. As time passes, and the ice melts, the temperatures will equalize. No energy has left the system, but the difference in energy levels which could have been used to do work disappears so that the final water is somewhere between the two temperatures you started out with.

So when you put energy into a machine, some of it becomes unavailable, dispersing perhaps through radiant heat or sound, and you get less energy out than you put in. The energy still exists; it is just in a less available form.

These laws of thermodynamics have been tested and shown to be true time and again, and shown to be descriptive of the universe. So what is going on here?  Looks to me like a spinning disk. If you watched the disk for long enough, it would eventually slow and stop. There are lots of ways to make a spinning disk, with slow friction ball bearings, with an electric motor attached to a gearbox, or even, yes, with magnets. At best the magnets extend the time for which the disk is spinning, but even permanent magnets eventually weaken. Yes that’s right the potential energy of the system becomes less available over time.

I’m Jon for the RIT skeptics. Keep on Rollin.