Southerly by David Haywood

Public Address Science (transcript): Why You Shouldn't Invest in Perpetual Motion Machines (Energy Special, Part 6 of 12)

In my former life as a university lecturer (of the most temporary and unimportant variety), I often had mad inventors arrive at my office door-step.

On one such occasion, a Canadian flew all the way from Vancouver to ask me a question about Stirling engines. It was a trivial problem, which I could easily have answered over the phone, but he was so appreciative of my solution that -- by way of reward, I suppose -- he removed his trousers to show me the scars where a grizzly bear had bitten him on the arse.

If I say that he was practically the sanest inventor that I ever encountered, then this will give you some idea of the high standard of madness in the inventing business.

Of course, the typical inventor that I dealt with (in the field of energy engineering) usually thought he had devised a system that extracted energy from nowhere. In the energy business such devices are called Perpetual Motion Machines of the First Kind. But, from time to time, I would occasionally deal with inventors who claimed to have produced a 100 per cent efficient heat engine -- known as a Perpetual Motion Machine of the Second Kind.

Naturally enough, neither type of inventor was pleased to hear that thermodynamicists had long known such machines to be impossible. And, on one occasion, neither were the friends and relatives of the inventor -- who had been cleverly persuaded to sink more than two million dollars of their own money into his little energy scheme.

In fact, the realization that there is such a thing as energy -- and the subsequent proof of the impossibility of perpetual motion machines -- was one of the great scientific advances of the nineteenth century. This week's episode of Public Address Science (actually, ahem... from mid-November last year) looks at the contribution to human civilization made by early work in the science of thermodynamics.

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