Question

Gravity exerts a force on everything around it,as a result of which the bodies or objects become closser to it or infact bound the central core or the point where there is maximum gravity.So gravity must exert a force on light too(although light cant be considered as a celesial body).Hence light should be bound to the earth(in case of earth) rather than escaping from it into the universe.Even if this does not happen due the very high speed of light...then atleast a fraction of light must not leave the planet and always stay around it.Therefore only very little fraction of light should escape the earth,thus making earth lesser bright when observed from other planets as very little light moves from the earth(in case if gravity was holding light to the core of the eath where gravitational force is maximum).Then why doesnt all of this happen????

Answer 1

Light is clearly affected by gravity, just think about a black hole, but light supposedly has no mass cause photons are mass less. On the other hand, if we take that light has a mass, then wouldn't mass become infinitely larger, the closer it travels to the speed of light. Now why doesn't your phenomenon work? That is because, photon will travel around the curve in space and time that gravity creates and black hole does that but not the earth because photon is mass less and it will travel in a straight path until and unless an external force creates a depression on its path and photon changes its direction.