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Theoretically speaking, I don't know of a reason why perpetual motion could not occur in an isolated system. We do know how to make a frictionless, or nearly frictionless liquid- one of the forms of liquid helium has no detectable friction, IIRC. If one could build a super insulated capsule with a pendulum lubricated with liquid helium, and shoot it off into deep intergalactic space, where gravity would drag on it and there's not much electromagnetic energy to heat the helium up, I expect we could keep the pendulum going for, say, a few billion years at least.
Of course, this is completely different from the popular notion of perpetual motion, which involves the machine involved performing work on some other object. This most certainly defies the laws of physics. Note, however, that laws of physics are merely descriptions of what we observe to be happening in nature. We devise theories to explain the observations contained in these laws, but if the laws are not valid because our observations are innaccurate, the theories are called into question. There is, however, no reason that I know of to expect that the laws in question will be disproved.
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"Apocalyptic thought is curiously pleasurable."
-Theodore Dalrymple
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