Perpetual motion won’t stop

We all know you can’t get something for nothing. In particular, everyone knows that the Law of Conservation of Energy means you can’t get free power out of nowhere.

But that doesn’t seem to stop people thinking that law doesn’t apply to them, as every few years someone tries to invent a new perpetual motion machine.

The most notable attempt in recent years was an Irish company called Steorn, who in 2006 published a full page ad in The Economist announcing their discovery, and inviting scientists and engineers to evaluate it. Their invention, called Orbo, uses a clever arrangement of magnets that, so they claim, causes it to keep turning and generating more energy than is put in.

Five years later and, although Steorn is still going, you really have to conclude the proof is in the pudding: if it was real, we’d all be wallowing in free energy.

Beyond that though, it’s very hard to properly evaluate their claims; and not just because you have to pay them a licence fee to get any details. The trouble is that conservation of energy is pretty fundamental to the laws of physics you need to evaluate the theory behind their claims.

As an example, consider the classic overbalanced wheel:

Overbalanced wheel, using swinging weights around the rim
The overbalanced wheel, uses swinging weights around the rim to try and ensure there's always more torque on one side (the right hand), so it keeps turning.

At first glance it looks like it could work: the weights on the right-hand side swing out further, so they exert more torque on the wheel. But if you sit down and calculate the actual forces and torques that apply, you’ll find that the fact there are more weights on the left, they balance it out and the wheel won’t turn.

And of course this is entirely consistent with conservation of energy. The change in an object’s energy due to a force acting on it – called work – is equal to the force multiplied by the distance it acts over.

This means that force, motion and energy are all related, and the laws of dynamics that govern how things behave simply cannot violate conservation of energy.

So our Irish friends, no matter how they try to justify their claims with “magnetic interactions whose efficiency varies as a function of the time frame of the interaction”, are going to find the same thing. Energy conservation is as intrinsic to the laws of electromagnetism as it is to Newton’s laws of motion, gravitation, etc.

Now, it’s entirely possible Steorn are quite sincere in their beliefs, thinking they just have a few engineering problems to solve until they obtain unlimited free energy. But no matter how they try to bend the laws of physics, it’s going to remain impossible.

Sorry to disappoint, but I wouldn’t go holding your breath.

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