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I agree with mrexroad. Falling implies downward velocity. Free-fall is a different term that implies downward acceleration. For example, a ballistic projectile fired up that then falls back down first climbs, then falls, but it is in free-fall the whole time.


> Falling implies downward velocity. Free-fall is a different term that implies downward acceleration.

The GGP didn't say zero-g "is" falling. They said it's "the same as" falling. Which, for purposes of this discussion, it is, for the reason I gave--the key common property is being weightless, i.e., free falling.

Note, btw, that "free-fall" does not necessarily imply "downward acceleration". It just means "weightless". You could be weightless, in free fall, far out in deep space well away from all gravitating bodies, so that there is no well-defined notion of "downward acceleration" in your vicinity.


Fair enough.

Regarding your second point, I think everywhere in the universe has some direction of the gravity field, however weak it is, and that would be the downward direction. But yea in some ideal place with exactly zero gravity, there's that special case.




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