The discussion centers on the relationship between massless photons and mass-energy atoms in the context of gravity. It concludes that massless photons exert gravitational effects due to their pressure, which is distinct from the mass-energy equivalence described by Einstein's equation E=mc². The concept of "equivalent gravitational mass" is defined as ρ + 3p for homogeneous, isotropic sources, emphasizing the importance of the stress-energy tensor in understanding gravitational interactions.
PREREQUISITESPhysicists, students of general relativity, and anyone interested in the interplay between mass, energy, and gravity.
No, the photons would gravitate more due to their pressure.would massless photons and an equivalent number of mass-energy atoms have the same effects on gravity?
Neither do. You need the full http://en.wikipedia.org/wiki/Stress-energy_tensor" as a source term.Does mass play any special role in gravity or only energy?