Friday, 6 July 2007

How to build a real perpetual motion machine :-)

It's now the start of day 2 of Steorn's 10 day demonstration, and no sign of the promised Steorn perpetual motion machine demonstration. The museum is empty, there's just an empty(?) perspex box. The lights are out, and nobody's home. Given that Steorn were (last anyone heard) blaming the heat of the lights, I thought I would contribute a quick guide to how to build a real 'perpetual motion machine'.

You start with a Crookes radiometer. It's a very cool demonstration of some very complicated physics, but essentially a weather vane type arrangement will rotate in a near vacuum, if one side of the vanes are made much darker than the other side.

Though the physics is quite complicated, it's entirely real. It's covered quite well by Wikipedia I like the fact that some heavyweight physicists (including Maxwell and Einstein) were needed to finally explain it.

The energy that makes the vane rotate actually comes from the energy carried by light. There's a certain irony to the idea that the lights which Steorn are blaming for their failure would actually cause the success of this little prank!

So you take one of these, dress it up in a fancy box, add some complicated looking apparatus with plenty of high-tech monitoring equipment, and you're bound to fool a few people. Maybe put some heavy objects around it and claim it's due to gravity waves - they're still pretty poorly understood (comparatively), so that's bound to cause some attention-boosting controversy. Make sure there's nothing radioactive or anything else that wears out over time (like - say - a magnet), or people will be sure to pick on that.

Wikipedia points out that infa-red works as well, so you could even have a fantastic demonstration - point your powerful lights at it, wait until someone calls you on it and says 'but the energy's coming from the light, isn't it?', then kill the lights and switch on an infa-red light at the same time :-)

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