Technically, a galaxy could qualify as a perpetual motion machine… on a mortal timescale, at least.
On a mortal timescale? If it has appreciable gravity, it’s motion is perpetual, until it meets another body with appreciable gravity.
There’s no such thing as a perpetual motion machine on a human timescale. Either it runs forever or it runs for what amounts to only a very long time.
What definition of the word “machine” does a galaxy qualify for?
Nope. A teensy, tiny fraction of the gravitational force that keeps pulling the stars in the galaxy towards the center — i.e. what makes it spin in a circle — goes to various factors that end up letting the various bodies either drift outwards or spiral inwards, depending on various factors — and there’s no stable configuration where it will do neither. At some point, even if our galaxy doesn’t collide with another, each and every thing contained in it will either be absorbed by the black hole at the center — which will, in turn, evaporate due to Hawking radiation or some fancy physics thing — or be flung out into deep space, to slowly disintegrate as all matter eventually will, leaving the universe cold and dark and physically incapable of supporting any life whatsoever.
More like Dali in Millicent’s case
I had to google it to get the joke…”coach class” on an airplane.
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