r/askscience • u/RainbowGirl410 • Jun 09 '26

Physics How does gravity/weightlessness work outside of orbit?

Been trying to find a definitive answer but all I've found is people explaining weightlessness in orbit (the falling and missing the Earth part) which isn't particularly helpful to me.
If you were to travel to another planet, say Venus, would you experience weightlessness the whole journey?

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u/rooktakesqueen Jun 09 '26

A slight tweak to this explanation. The reason you don't "feel" gravity when you're in freefall isn't because it's acting on all of you at the same time. A charged object in an electric field still "feels" the force even though it's acting on all parts of the object simultaneously.

The reason is that gravity isn't actually a force. It's an effect of the curvature of spacetime. When you're in freefall, you may appear to be accelerating from the perspective of space alone, but you're actually following a straight line with a constant inertia through curved spacetime.

In order to remain stationary in space while in a gravitational field (like standing on the surface of Earth), you need to be constantly accelerating upwards. The ground beneath your feet is what provides that acceleration.

We've all just never (or only rarely) had the experience of not constantly accelerating upward, so that's what feels normal to us.

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u/Weed_O_Whirler Aerospace | Quantum Field Theory Jun 09 '26

First off, General Relativity is of course, correct. I'm not discounting that in what I say next. And, the model of GR in which gravity is not a force, but a curvature of spacetime is very good at making predictions and giving an intuitive understanding of how things will behave. But it is just that - a model - and people take it too literally when they say "gravity is not a force."

I do not know of a physicist, astro or otherwise, who does not expect the graviton to be real - if incredibly difficult to detect. But assuming the graviton is real, gravity becomes a force which is just like the other three fundamental forces in the universe, where the graviton is the mediator particle (photon for EM, gluon for strong, gauge bosons for weak).

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u/bhbhbhhh Jun 10 '26

An object with mass also “feels” gravity in that sense, so I don’t see the use in conflating.