I've always been confused by the typical analogies I see when gravity as a space-time curvature is explained.(adsbygoogle = window.adsbygoogle || []).push({});

In 2-D it is usually a plane with field lines, and the surface of the plane is curved around an object. And so we are told a mass placed in this curvature will "fall" down the curve and that's how objects are moved in gravity. Its also given in the analogy of a funnel with a coin rolled down the funnel.

Then the more exact 3-D and 4-D models are given, but its still the idea that an object will "fall" along the curve towards the mass causing the curve.

My confusion is why do the objects move along the curvature? Say you took a stationary mass and placed it on the curved surface. Why would that mass want to move down the curve if its at rest? In the analogies, its actually gravity that is implied to move the object along the curve so they're using gravity to explain gravity which doesn't make sense.

So to sum it up, can someone answer or explain this question:

Take a stationary particle, of very low mass. Place it in the "curved" area of space-time around a large mass. What is making the particle accelerate on that curvature? Why isn't it happy staying in the spot its placed even though the spot might be curved in towards the larger mass?

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# Confusion with curved space analogies

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