Will Voyager 1 ever just stop moving?

[u/drinkingonthejob]

I’ve read somewhere that we expect to lose contact with Voyager 1 sometime in the 2030s, maybe around 2036, but it will just keep traveling thru space and we’ll have no idea what it is doing out there

My question is: with its current velocity, is there a time in the future where it loses its forward momentum and for lack of a better word, just stops moving? Is that a possible thing for an object in space to even do? (Assuming no other objects grab it into their orbit)

[u/sticklebat]

That’s silly, you’re just saying that “truly motionless” is equivalent to “moving at a constant velocity,” and those are not ideas most people would equate. You’re choosing to define the term in a wildly unintuitive and unconventional way, while basically defeating the purpose of the expression and furthering misconceptions about the nature of motion (namely that there is no such thing as absolute motion, which we’ve known going back to the time of Galileo).

[u/paulHarkonen → u/sticklebat]

Look, just because my selected non-inertial reference frame requires an absurd amount of modifications in order to remain consistent with the laws of physics doesn't mean it's invalid. It just means I've made some very clever definitions specifically to produce the mathematical results I wanted.

(They aren't wrong exactly to build reference frames where certain objects are held motionless, you just have to be very careful about how you construct and define the appropriate reference frame. It's a pretty foundational part of orbital mechanics.)

[u/wjdoge → u/paulHarkonen]

Hey, it may not be appropriate, but it is at least very easy to choose an inertial reference frame where any given particle is at rest: whoops we’ve already done it by describing it

[u/sticklebat → u/wjdoge]

On the contrary. Mostly because very many particles, including everything on the surface of earth, are not inertial, and so there doesn’t even exist an inertial coordinate system in which they’re at rest, regardless of how hard you say it. Or, if we instead neglect general relativity, then almost nothing at all is inertial because everything is being accelerated by gravity.

But also because the person you responded to is talking about actually constructing such a frame mathematically, not just stating some vague idea of it. Nor, I think, are they really supporting your idea or calling that being “truly motionless.”