Let's talk about methods. Methods in physics are often loaded with mathematics and the overall image of this science can be rather scary to persons who are not familiar with formal methods. The same holds for all engineering disciplines, as engineers frequently use mathematical models to find out about their constructions. But like other sciences, physics and engineering sciences are not applied witchcraft, but rather a mixture of wits and formulae when necessary.

A Simple Approach

We all know the disappointing feeling if we have a look into a university textbook. Loaded with formulae, the facts are buried in a bunch of fancy characters. What the whole thing is about, remains unclear. Here, I use a different approach; an approach which should be the natural one. This could be your checklist for analyzing a (perpetual motion) machine:

  1. Don't be gullible, be sceptical.
  2. Look at the known facts. Carefully look at geometry, sizes, weights, assumptions. Are the facts complete enough for further analysis?
  3. Check, if all these assumptions are plausible. Try to figure out if the data are consistent in themselves.
  4. Carefully check, if all assumptions made in the description fit into known facts. Are there any simplifications which might have influence onto the expected function of a concept?
  5. Check, if the claimed function makes correct usage of the known principles in physics. Are there any implicit assumptions made? Are assumptions made which could be intended to mislead you?
  6. In the first step, ignore friction, compressibilty of liquids, and relativistic effects if possible. The classical physical approach works in that way and produces fine results.
  7. Separate the whole construction into manageable parts. It's easier to analyze several small subsystems than a single large construction.
  8. Try to find the section which could be made responsible or which is claimed to produce the overunity behaviour. Ask yourself, why the rest of the construction or concept is necessary if the "magic portion" may be sufficient alone.
  9. Try to avoid math as long as possible. There is no need for mathematics if the principle of the construction is flawed and the flaw can be identified by an elementary approach. Calculations are totally useless if they are based on wrong assumptions.
  10. Use elementary methods to get a clear understanding about the indended operation of the device, e.g. use graphical methods for proportional relations or to sum up force vectors.
  11. Use the most simple mathematical model which seems appropriate. After having made your calculations, carefully check them. Lay them aside and cross-check them a few days later.
  12. Leave your heavy mathematical artillery at home unless you really need it. And if you need it, think twice before you chose the wrong gun in a hurry!
  13. Ask colleagues for advice if you get stuck in your analysis. Often an idea from another person can help solving the issue.
  14. Use libraries and good internet resources. Read. And learn, learn, learn!
  15. There will remain tasks which cannot be solved by the skills and knowledge you have. This is not because you are too stupid, it is simply because you can't know everything and you can't learn all sciences and methods in all your lifetime. Do not worry about that. Having no simple solution is the reason which makes science a research work and keeps engineers busy.
  16. Describe your results in an unambigous, simple way. Use illustrations to clarify your results. You will learn a lot about the methods you have used when you try to describe your results for others.
  17. For the sake of brevity and clarity do not hesitate to discard unneccessary calculations, needless drawings or superfluous facts.
  18. Let an independent researcher who works in that area check your results.

Don't be confused by all these suggestions. If you memorize the phrase "think simple", you are on the right way. Do not use more sophisticated methods than absolutely necessary! Sometimes a machine design will not work due to stunningly simple reasons. Look at this example.


This recirculation mill combines an overshot water wheel with a pump, whose type was commonly used in mining. The design looks plausible, but by knowing about the efficiency of the water wheel and gear, we can conclude that this machine won't work.
Remark: Ord-Hume attributes this design to Robert Fludd, but the style of machine elements makes it more plausible that it is a machine from the 19th century, inspired by Fludd's idea.
    But there is a much simpler reason, why the design is flawed. Look at the indicated directions of the rotating parts! The machine operates the pump in the wrong direction, thus pumping water down. We learn: when analysing mechansims, it is useful to check the kinematics first, before wasting any further effort.

Last update: 22 May 2004 /
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