Recent content by njinear

im with you on this. it is one of the issues that seem pretty gnarly once we allow photons generate gravitational fields. so in a certain sense it is a bit of a paradox. but from the external inertial frame observer outside the field, momentum must have been transferred to the gravitating...

inflector good question. i am thinking that in the far field (away from significant gravitational fields) if the photon is moving in a different direction then the momentum difference between inbound and outbound directions has to be balanced against a comeasurate change in momentum from the...

vanadium is right, in the far field the change in momentum for the photon must be balanced against a very small change in the velocity of the body it bends around, so free photons have gravitational fields. however it is very poor form to assume that since others didnt see something it must not...

really hard to measure. but it has much wider philosophical and cosmological implications: since significant amounts of mass are evaporating from the universe, the gravity would be decreasing. and the fundamental energy-mass tensor is not right.

no, the deflection of light does not mean photons generate gravity. same as iron is attracted to a magnet but in itself is not particularly magnetic. weak but instructive metaphor. but light gets deflected because the star warps space. the photon, as far as it is concerned, just travels in a...

cragar you are right that generally any mass/energy should bend space time. but i am questioning if this is right. for example it is not clear what the gravitational field from a light speed particle would be like. also, imagine a 2 slit interference experiment where the photon could go...

i have a problem with the 1931 paper that it assumes what it is trying to prove, that is, that the mass energy tensor applies to photons. and really, it doesn't deal with photons, it deals with a "beam", which to say the least is not descriptive of what is really going on. the proof would have...

i have some questions about this, maybe you folks can educate me. einstein says energy carries gravity, but he makes the exception for gravity itself, that the tensor has an entry of zero for gravity's gravity. since gravity does not have gravity itself and it can carry energy away (seems...