The History of perpetual motion machines reference article from the English Wikipedia on 24-Jul-2004
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History of perpetual motion machines

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The history of perpetual motion machines dates as far back as the 13th century, and probably further. Perpetual motion machines (Latin perpetuum mobile) are a class of hypothetical machines which produce useful energy "from nowhere" - that is, without requiring additional energy input.

Table of contents
1 Overview
2 Patents
3 Timeline
4 References
5 External links
6 Further reading


For millenia it was not clear whether such devices were possible, but the development of modern thermodynamics has led virtually all engineers and scientists to agree that they are impossible. In spite of this, thousands of people have attempted to construct the holy grail of energy production.

Some are developed with elaborate machines in the style of Rube Goldberg or Heath Robinson. Some designs may appear to work on paper at first glance, but have various flaws or obfuscated external power sources that render them useless in practice; others remain untested.

Proponents of perpetual motion machines often use other terms to describe their inventions, including "free energy" and "over unity" machines.


This sort of "invention" has become common enough that the United States Patent and Trademark Office (USPTO) has made an official policy of refusing to grant patents for perpetual motion machines without a working model.

The USPTO granted a few patents for motors that are claimed to run without net energy input. These patents were issued because it was not obvious from the patent that a perpetual motion machine was being claimed. These are:




1900 to 1950

1951 to 1980

1981 to 1999



External links

Further reading