The Gravitational Curvature Of Light Reconstrued Through Systemic Functional Linguistics

Davies & Gribbin (1992: 81):

If the acceleration of a falling elevator, plunging downwards at an ever increasing speed,  can precisely cancel the force of gravity, thereby producing weightlessness, then the gravitational force and the inertial force produced by the acceleration are equivalent to one another. …

Imagine being in that falling elevator and watching the path of a light pulse crossing the elevator. In the reference frame of the falling observer the light travels in a straight line; but this means that from the point of view of an observer standing on the ground the light path must curve downwards [i.e. falling with the elevator]. The latter observer would attribute the curvature of the light beam to the effect of gravity, so Einstein made the prediction that gravity bends light.

Blogger Comments:

To be clear, it is the geodesic that gravity curves: the shortest trajectory that light takes through space. Physicists routinely confuse this curvature with a curvature of space-time. The reason why the geodesic is curved is that spatial intervals are contracted in the direction of the centre of mass, relative to other directions, so the shortest distance between two points is towards that centre of mass.