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I have been reading about gravitational lensing. All the models I have seen discuss light going around the outside of some gravitational source, like a black hole or something. Would it act more like a traditional lens if passing through the middle a source that was more donut shaped, instead of around a ball type shape? If so, could somethig like this be done experementally?
- Michael French
First of all gravitational lenses are not like the reading glasses you buy at WalMart. Ordinary optical lenses focus a point source into a point image. Gravitational lenses focus a point source into a circular line image. Sometimes you see only a small arc of the circle depending on the relative positions of the source and lens. As to whether or not a doughnut shaped lens would work, I haven't worked it out in detail but I suspect the answer is no. Could one perform an experiment? In principle yes, but there are not too many doughnut shaped galaxies out there.
I presume you have read the Wiki article: http://en.wikipedia.org/wiki/Gravitational_lens
(published on 08/11/10)
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