Would it be possible to create a perpetual motion machine in an environment without air, friction, or dissipation?

Question

Perpetual motion machines don't work because as it moves, the air molecules hit it and slow it down. Friction slows it down in a similar way. If there were no forces to slow it down, could it work?

BowlOfRed · Accepted Answer

This would be an example of what wikipedia calls a perpetual motion machine of the third kind, a machine that does not produce excess energy, but is able to move for a long time due to reduction of losses.  Losses do not have to be air resistance, so removing (as much as possible) air does not remove all loss.
Wikipedia has a list of some examples of low-loss systems.  No system is perfect and losses eventually accumulate, although it may require astronomical timescales before the losses become significant.  Basically the idea of "removing all forces" is an ideal, not practically reachable.  Even as such systems approach the ideal, they still contain a finite amount of extractable energy.  Any attempt to remove more energy than that finite amount will fail.

Bob D · Answer

Yes, if there are no energy dissipative forces perpetual motion would be possible. The thing is, there are always dissipative forces. Even the vacuum of outer space is not completely empty. To quote Wikipedia, "it contains a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays". Collision with the particles will eventually dissipate the energy of a moving object, albeit very very slowly.
Hope this helps.

NiRVANA · Answer

No, unless you throw quantum mechanics out of the way too.
This is because, even if there was no air drag or friction or whatever due to some reason, due to operators in the hamiltonian kf any system having a communication relation between them, one can see that even on very weak coupling to the environment, you have dissipation.
Now, you might say that you can remove the coupling altogether, but thats not possible since it means that the machine doesn't interact with electromagnetic waves or gravitational waves(has no mass basically) or any other field as such. That would simply mean the machine is not made lf any know matter and you can't really "see" it.

Would it be possible to create a perpetual motion machine in an environment without air, friction, or dissipation?

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