Prisms Make Colorful Light
Most recent answer: 10/22/2007
- chase gilbert (age 9)
Elbow Valley Elementary, Calgary Alberta Canada
Light going through lenses does the same thing a little bit, causing a problem called "chromatic aberration". The different colors focus at slightly different points because they bend different amounts.
Why do different colors bend different amounts? The amount the light bends depends on how much it slows down in the glass. How much it slows down depends on how much its electromagnetic field shakes the electrons in the glass. The electrons respond a little differently to different frequencies of shaking, and different frequencies of light means the same thing as different colors.
Mike
(published on 10/22/2007)
Follow-Up #1: Does gravitational lensing have aberrations?
- Anonymous
I'm not sure what the difference between Newtonian and relativistic gravitational lensing is. Perhaps you can elaborate on your thought experiments?
In nature, gravitational lensing does not contain chromatic aberration (like dispersion), since all wavelengths of light are bent by the same amount. This can be seen by the equivalence principle. I like to remember that gravitational fields are equivalent to accelerating reference frames, and use the elevator thought experiment:
As for the other aberrations, all I can say is that they must be very large (in general). The matter making up the "lens" is not smoothly distributed, so the lens will be far from perfect.
I know a fair amount about lens aberrations, but very little about gravitational lensing. I'm curious whether knowledge of optical aberrations is useful for calculating or understanding gravitational lensing (I'm guessing probably not)... maybe someone else can answer that question.
David Schmid
(published on 04/21/2013)