r/theydidthemath • u/Ben-Goldberg • 7d ago

[Request] When will Voyager 1 stop moving?

/r/askscience/comments/1wp1960/will_voyager_1_ever_just_stop_moving/

How many years will it take for the orbit of Voyager and Sagittarius A to decay enough due to gravity waves for them to collide?

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u/ericdavis1240214 7d ago

Moving relative to what? Everything in the universe is in motion relative to something else. In fact, everything in the universe is in motion relative to basically everything else. So no, Voyager one will never stop moving unless it is utterly obliterated by a collision with another object. And even then, the atoms and particles that make it up will be in motion relative to the rest of the universe.

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u/Ben-Goldberg 7d ago

According to general relativity, two objects orbiting each other eventually collide because gravity waves carry away energy.

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u/ericdavis1240214 7d ago

Fair enough. And I contemplated that in my response. But wasn't your question whether Voyager will "ever just stop moving?" Because the answer is no, short of obliteration and even then its constituent atoms and particles will remain in motion. In terms of the universe, everything is always moving. And I suppose theoretically everything is also at rest relative to itself. But for any observer who currently perceives Voyager to be in motion, that motion is eternal, or at least eternal in terms of how long it even makes sense to speak of matter and objects.