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Name: penn
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Question:
Does light bend or does it refract which is a different process? If it does "bend", what are the limits? Also, is there a evaporation point similar to absolute zero.



Replies:
Does light bend? From the point of view of general relativity and Einstein's Equivalence Principle, light bends as a result of the curvature of space-time caused by the presence of a mass. However, from the "point of view" of the photons that are moving through this curved space-time they are trying to move in a straight line but feeling forces. The latter is an interesting point of view as photons are massless. This give credence to Einstein's point of view. The limit of this bending is reached when the central mass is great enough to cause the curvature of space-time to be so great that the light bends back in a loop of limited height. When this limit is reached one has a black hole and the limited height is called an event horizon. For more info. check out Stephen Hawkings book "A brief History of Time" or Edward Teller's book "Dark Secrets of Physics". Both have excellent discussions on these matters. Does light refract? From a classical point of view light refracts as it moves from one medium to another that can slow the light down. The r refraction is limited bn the denser medium. as one approaches the critical angle the angle of refraction approaches 90 degrees. After this total internal reflection is achieved. This is easily demonstrated with Snell's law from any physics text. From a quantum mechanical point of view things get a bit dicy. Rather than try to address that in the limited space here let me suggest reading Richard Feynman's book "QED". His concrete e discussions are excellent. Also Teller's book has a nice discussion of Newton's particulate theory or refraction and momentum. Have fun studying! By the way, I wonder about the semantics here with respect to bending.

Nick P. Drozdoff



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