Perpetual Motion

In Our Time: Science

BBC

History

4.5 • 1.4K Ratings

🗓️ 24 September 2015

⏱️ 46 minutes

🔗️ Recording | iTunes | RSS

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Summary

Melvyn Bragg and guests discuss the rise of the idea of perpetual motion and its decline, in the 19th Century, with the Laws of Thermodynamics. For hundreds of years, some of the greatest names in science thought there might be machines that could power themselves endlessly. Leonardo Da Vinci tested the idea of a constantly-spinning wheel and Robert Boyle tried to recirculate water from a draining flask. Gottfried Leibniz supported a friend, Orffyreus, who claimed he had built an ever-rotating wheel. An increasing number of scientists voiced their doubts about perpetual motion, from the time of Galileo, but none could prove it was impossible. For scientists, the designs were a way of exploring the laws of nature. Others claimed their inventions actually worked, and promised a limitless supply of energy. It was not until the 19th Century that the picture became clearer, with the experiments of James Joule and Robert Mayer on the links between heat and work, and the establishment of the First and Second Laws of Thermodynamics. With Ruth Gregory Professor of Mathematics and Physics at Durham University Frank Close Professor Emeritus of Physics at the University of Oxford and Steven Bramwell Professor of Physics and former Professor of Chemistry at University College London Producer: Simon Tillotson.

Transcript

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0:00.0	Thank you for downloading this episode of In Our Time, for more details about in our time, and for our terms of use please go to BBC.co.uk.
0:08.0	Radio 4. I hope you enjoy the program.
0:11.0	Hello, Perpetual Motion has intrigued some of the greatest names in science as they try to invent machines that could power themselves endlessly.
0:18.0	Leonardo da Vinci sketched a wheel to keep on turning, Robert Boyle worked on an apparently never-ending fountain.
0:25.1	They were designed for windmills, pumping bellows to drive their own sails and water wheels
0:29.4	recirculating their own mill streams.
0:32.2	To scientists, the designs were a way of exploring the laws of
0:35.1	nature. There were others though who claimed their inventions actually worked
0:38.6	promising and for free, a limitless supply of energy, supposedly another scientific miracle in the ages of discovery.
0:46.2	Many doubt it, among them Galileo, but none could prove perpetual motion was impossible.
0:51.2	That had to wait for the 19th century and two of the most robust laws in
0:54.2	science, the first and second laws of thermodynamics. With me to discuss perpetual
0:59.1	motion R. Ruth Gregory, professor of mathematics and Physics at Durham University, Frank Close, Professor Emeritus of Physics at the University of Oxford, and Stephen Brownwell, Professor of Physics and former Professor of Chemistry at University College London.
1:14.0	Frank Close, what does scientists mean by perpetual motion?
1:17.0	Well, the idea that you could have a machine, that once it was operating, could continue to run forever without needing any power
1:25.9	to keep it going that's the idea of perpetual motion and if it was possible it would
1:31.0	be fantastic in all meanings of the word and to give an example of the
1:36.2	problem what's happening right now I mean people are listening to this moment me speaking and whatever the device they're using my voice is
1:46.3	the sound of my voice is propagating through the air to their ears the sound energy
1:50.4	coming out of their radio or their laptop and where's that energy coming from?
1:54.9	Well it's coming ultimately from the battery power in their radio or the electrical power
2:00.4	supply from the socket and the wall or maybe they've got a wind-up radio that
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