(March 2, 2018 at 1:57 pm)Anomalocaris Wrote:(March 2, 2018 at 1:46 pm)Rhondazvous Wrote: This is the $50 million question
If gravity only affects objects that have mass and photons are massless, why does light curve around a planet or get trapped in a black hole?
Photons have energy, E=MC^2, hence photons have equivalent of mass.
Think of it this way, by E=MC^2, all forms of energy have equivalent of mass, and therefore are both affected by gravity, and exert their own gravity. If global warming heat the earth up, the gravity of the earth actually increase because the added kenetic energy of the molecules makes the earth slightly more massive.
One aspect of this that is a bit strange is that massless particles, like the photon, actually move along a different path (a null path) than a massive particle of going very close to the speed of light would. The deflection of the light is *double* what would be expected from a naive equivalence between the mass and energy. that was actually one of the distinguishing experiments differentiating special and general relativity when applied to gravity.
