Thought of the day

If light bends through a particular medium and has no mass, ultimately energy and momentum have more to do with gravity rather than the mass of a body. So while it is true that the gravitational force is the measure of attraction between two different bodies, it is not implied that mass is the cause of this, further leading to the orthodox understanding that force is not defined by a mathematical equation, rather than the unorthodox understanding that we can define forces mathematically.