Final answer:
Gravity is the bending of spacetime caused by the presence of mass, according to Einstein's general theory of relativity. This curvature affects the path of objects and light, demonstrating that it is true gravity bends a beam of light via spacetime distortion.
Step-by-step explanation:
Gravity is indeed the bending of spacetime around massive objects, which is a core principle of Einstein's general theory of relativity. This bending is not just a simple warp in space but includes time as well, creating what we call the spacetime continuum. When matter such as a planet or star is present, it distorts this fabric of spacetime, and this curvature is what we perceive as the gravitational force.
A beam of light, despite having no rest mass, will have its path altered when passing near a massive object, but not because the light itself is being pulled by gravity in the traditional Newtonian sense. Instead, light follows the curvature of spacetime created by the mass, which is often visually represented like a trampoline deformed by a heavy ball. To answer the initial question, it is true that gravity is the bending of spacetime around massive objects, affecting not just matter but also light.