Because all masses accelerate at equal rates in a gravitational field either:
1) Inertial mass and gravitational mass are exactly equal without an explanation why
or
2) The acceleration is just an effect of a curvature of space.
Imagine two bodies thrown exactly Northward on a sphere. Although their paths are parallel they would approach each other, as if there was an acceleration. This acceleration would be the same whatever their mass is.
1) Inertial mass and gravitational mass are exactly equal without an explanation why
or
2) The acceleration is just an effect of a curvature of space.
Imagine two bodies thrown exactly Northward on a sphere. Although their paths are parallel they would approach each other, as if there was an acceleration. This acceleration would be the same whatever their mass is.