Some of you may be aware of the current fuss about the possibility of a perpetual motion machine (even better than that, in fact; a perpetual energy machine with a net power output) that a small Irish company claims to have developed. This reminded me of something.

A quick look through a pocket notebook from my school days and I find a design for a magnet-based perpetual motion machine, © me 1988, nestling among ideas for a self-levelling vehicle suspension mechanism, a 3D laser hologram TV, a 'music on demand' portable radio and various other inventions that I'm now beginning to wish I'd investigated further.

I showed the design for the perpetual motion machine to my university physics tutor a few years later and he couldn't explain why it wouldn't work, though we were both pretty convinced that it wouldn't. I reckoned that ultimately the energy needed to shield and/or move the magnets out of the way during rotation would equal or exceed the energy 'created' by the machine. But I never built it to test it.

I did wonder if you could slightly cheat the conservation of energy law by effectively using the geological energy that created the magnets in the first place, but then I discovered cars and girls and forgot about the whole thing.

I've seen the same invention in other places since, so I wasn't unique. Which isn't really surprising. Basically, if you understand how an electric motor works, the first thing any would-be inventor will think is "Hmm, what if I replace the electromagnets with permanent magnets? A-ha! Limitless energy! If only I can shield them somehow..."

But let's assume, for the sake of argument, that this new claim isn't a hoax, a mistake or a clever marketing ploy. Let's assume, against my intuition, that this company really has discovered the secret of free energy. What then? Call me mildly pessimistic, but I think it could lead to major conflict and unpleasantness, as any significant geo-political or economic shift generally does.

It seems unlikely that the super-power(s), OPEC, oil companies and anyone else with a vested interest in the status quo (i.e. pretty much everyone in the energy business) are going to sit idly by and watch their incomes disappear overnight, with much of it going instead, in the shape of patent licensing fees, to a private company on a small green island in the North Atlantic.

"Oh well, we had a good innings. Time to let someone else have a slice of the pie", is almost exactly what such people won't be thinking.

Commentators in the national press tend to look only at the scientific possibilities of free energy, but that's like talking about Prozac without mentioning the brain chemistry on which it acts. You have to look at the probable human reaction to such an invention. This is really all about psychology and national sociology, not merely physics.

The more I think about it, the more I think that free energy could be one of the worst things ever to hit humanity. One of the few restraints that keeps us from invading every part of the globe, or importing every kind of exotic, endangered product from every tiny country, is the cost of transport, the majority of which is accounted for by fuel. Take that away and it seems likely that ecological and social decline will accelerate rapidly.

More prosaically, can you begin to imagine the gridlock on our roads if nobody had to pay for petrol any more? It all seems rather a high price to pay for a mobile phone that never needs to be recharged. But I still suspect that the invention is either a fake or a mistake.