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?
Gravitational lensing is a phenomenon in which the gravitational force of a massive object, such as a galaxy or a black hole, bends the path of light from a distant object. This results in a distortion of the appearance of the distant object, making it appear larger, brighter, or even multiple images of the same object.
Gravitational lensing occurs due to the warping of space-time by massive objects. According to Einstein's theory of general relativity, massive objects create a curvature in space-time, and when light passes through this curved space-time, its path is bent, resulting in a lensing effect.
There are two main types of gravitational lensing: strong lensing and weak lensing. Strong lensing occurs when a massive object acts as a perfect lens, creating highly distorted and magnified images of the background object. Weak lensing occurs when the lensing effect is subtle and does not create multiple images, but instead causes a slight distortion in the appearance of the background object.
Gravitational lensing is significant in astronomy as it allows us to study and observe objects that are otherwise too distant or faint to be seen by traditional telescopes. It also helps us to understand the distribution of dark matter in the universe and the structure of galaxies.
Yes, gravitational lensing can be used to study black holes. As light passes near a black hole, its path is significantly bent, resulting in a strong lensing effect. This allows us to observe the effects of a black hole on the surrounding space and objects, providing valuable insights into their properties and behavior.