Are Electromagnetic Waves Perpetual Motion?

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Discussion Overview

The discussion revolves around the nature of electromagnetic (EM) waves and whether their self-sustaining characteristics could be interpreted as a form of perpetual motion. Participants explore the implications of this idea in relation to physical laws and the concept of perpetual motion machines.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that if EM waves are self-sustaining, they could be considered perpetual motion, raising questions about the validity of such a concept in physics.
  • One participant argues that while perpetual motion is not allowed in the form of a machine that does work indefinitely, a process can continue indefinitely without an external energy source as long as no work is extracted from it.
  • Another participant mentions that light or EM waves can travel indefinitely in a vacuum, but extracting energy from them (e.g., using solar cells) would prevent their perpetual nature.
  • A hypothetical scenario is presented involving a superconducting ring where current could circulate indefinitely in an ideal, insulated environment, but this would also depend on not extracting work from the system.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of perpetual motion in relation to EM waves, with no consensus reached on whether EM waves can be classified as a form of perpetual motion.

Contextual Notes

The discussion includes assumptions about the nature of perpetual motion and the conditions under which processes can be considered self-sustaining. There are also considerations regarding the effects of external factors like friction and energy extraction on the behavior of EM waves.

wolram
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in all the articles i have read it is said that em waves are self sustaining, if this is corect then they are perpetual motion, i thought that was not allowed??
 
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Photons do not have mass. That means that they move
through space but not through time - that means they
always have the speed(of light) c according to relativity.

Live long and prosper.
 


Originally posted by wolram
in all the articles i have read it is said that em waves are self sustaining, if this is corect then they are perpetual motion, i thought that was not allowed??

I believe that perpetual motion is allowed in the sense that it does not violate any physical laws. What is not allowed is a "Perpetual Motion Machine" that runs forever and also does work.

You can have a process continue indefinitely without an external source of energy as long as you do not harness it or extract work from it. There must be no loss either--as for example due to friction or air resistance: which can be thought of as doing undesired work like heating something by rubbing or stirring up the air. To continue, the process must do no work.

Light or EM waves can travel indefinitely in a vacuum, but if one sticks solar cells in their path to extract electricity then their motion stops being perpetual

I suppose in an ideal superconducting ring you could start current flowing around the ring and then put the ring in an perfectly insulated box and the current would keep on circulating around the ring forever. Or until someone tried to get some work out of it.
 
how daft of me, thanks...
 

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