We have two questions on this site about perpetual motion machines.

Both questions were heavily downvoted (good for us!) but neither question was closed, apparently because the connection to energy is sufficient to be considered on-topic. Still, this question deserves only one kind of answer:

No, you cannot due to the second law of thermodynamics. No, you cannot get more energy out than you put in. No, you cannot invent a perpetual motion machine.

Do we want to preserve these questions, or should they be deleted from the site?

2 Answers 2


Good question. My proposal:

  • Vote to close. This reduces the prominence, doesn't allow for new answers, but keeps the good responses which explain why perpetual motion machines don't work.
  • Use a default/standard close reason. Right now we don't have one, but perhaps something like: "This question is about perpetual motion machines, which are off-topic for this site."
  • Mark all future questions on this topic as duplicates of these two.
  • If preservation is what we want then a historic lock might be more appropriate here than closure - it stops voting, comments and answers - basically making the question 'read only' to regular users (mods can still do some things including removing the lock). A closed question can still be voted on, commented, reopened or deleted by regular users. Historic locks can only be applied by mods though.
    – Robotnik Mod
    Mar 3, 2020 at 22:37
  • 3
    Personally I'm indifferent whether we close or lock such a question, either is fine with me (I closed one of them already, the other is still open). With 2 questions in 7 years I do think there is no need to make any special arrangements for this, like adding a default close reason, unless we start seeing much more questions like this.
    – THelper
    Mar 4, 2020 at 8:26

Another idea might be to create a generically written 'catch all' community wiki question and answer, which describes the general failings of a perpetual motion machine. This could then be used as a duplicate target for the current (and any future) perpetual motion questions. Something like the following:

Is it possible to generate unlimited energy?

I have an idea to generate potentially unlimited energy.

Is this possible? Will my contraption work?


What you are describing is a perpetual motion machine, and no, it won't work.

Energy can not be created nor destroyed; it can only be transformed or transferred from one form to another. This means, you cannot get more energy out than you put in....

What do you think?

  • I wasn't sure at first, but now I am warming up to this idea.
    – Nic
    Mar 4, 2020 at 5:41
  • I like it. Given the LED question (which to my surprise has 40K+ views!!) we probably also want to cover "recycling energy for ever" in such a question.
    – THelper
    Mar 4, 2020 at 8:30
  • @THelper yeah good idea. I didn't really expand on the answer too much in my example above but ultimately it can be as descriptive as we'd like - probably with multiple sections properly 'debunking' these sorts of "free energy!" myths
    – Robotnik Mod
    Mar 4, 2020 at 10:14

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