A Painter and His Paint Brushes in A Free Falling Lift, As Visualized by AI
The effects of gravity are locally indistinguishable from the effects of acceleration. The physical laws inside a small, closed system (like a laboratory or a spaceship) behave the same whether the system is in a uniform gravitational field or accelerating uniformly in the absence of gravity. This follows from the equivalence of gravitational and inertial masses of bodies.
More Succinctly:
A homogeneous gravitational field is completely equivalent to a uniformly accelerated reference frame.