If gravity is a fictitious force, how is it responsible for the spherical shape of planet?

Question

If gravity isn’t acting directly on Earth’s mass how is it the cause of the Earth’s shape?

I often read that gravity "pulls" earth into its spherical shape, but if gravity is a fictitious force how can it "pull" on earth?

Answer 1

Fictitious forces are those that appear to arise as a consequence of the tendency of objects to move inertially. According to General Relativity, mass (and energy) bends spacetime, so that the paths of objects moving inertially are bent in a certain way. The bending effect has a spherical symmetry. The result is that the matter that makes up the Earth came together as a consequence of a local curvature in spacetime, the spherical symmetry of which caused the particles to form, and remain in, a roughly spherical shape. The Earth is slightly ellipsoid, bulging at the equator owing to the centrifugal effect of its rotation- ironically another fictitious force.