The discussion centers on the examination of the spectrum of gravitationally lensed light, particularly focusing on potential red or blue shifts observed in different parts of an Einstein ring. Participants clarify that, according to General Relativity (GTR), light bending does not depend on frequency. However, Rudi Van Nieuwenhove raises the possibility of frequency shifts due to strong frame-dragging effects around massive rotating bodies, such as black holes or galaxies. The conversation references Chandrasekhar's "Mathematical Theory of Black Holes" for further exploration of these concepts.
PREREQUISITESAstronomers, astrophysicists, and students interested in gravitational lensing, black hole physics, and the implications of General Relativity on light propagation.
notknowing said:I was wondering whether one has examined the spectrum of gravitational lensed light (nice description on wikipedia : http://en.wikipedia.org/wiki/Gravitational_lensing ). Have there been indications on some red or blue shifts in the light from different parts of the observed ring? Does anyone know?
Rudi Van Nieuwenhove
Chris Hillman said:Well, in gtr, light bending certainly does not depend on frequency (in the geometrical optics approximation), but it's not clear to me what he has in mind.
Chris Hillman said:Rudi, sorry, but I don't yet understand your question. Did you take the point (already mentioned by meopemuk) that according to gtr, "light bending" (e.g. in "gravitational lensing") does not depend on the frequency of the light being bent?