All Questions
6
questions
8
votes
2
answers
336
views
Why a gravitational lense makes multiple distinct pictures of a distant object rather than making a symmetric ring?
I cannot imagine how a group of galaxies may produce pictures of a distant object on a ring-like region that is not symmetric. Why there are empty parts of that ring where there are no pictures of the ...
- 1,815
1
vote
0
answers
35
views
Plausibillity of using a black hole as a telescope?
I recently learned about the proposed FOCAL telescope, which would use the Sun's gravity as a lens to observe exoplanets (or whatever it's aimed at) with incredibly high resolution. Obviously, the Sun ...
2
votes
1
answer
282
views
Do gravitational lenses act as prisms?
Light creates gravity, and the greater the light's frequency, the greater this gravitational effect is. It stands to reason then that light of different colors would react slightly differently to ...
- 804
1
vote
1
answer
808
views
Treating gravitational lensing as index of refraction
In Einstein's theory of gravity, an electromagnetic wave passing near a massive object is bent from its rectilinear path. We may regard this bending equivalently as due to a medium of refractive index ...
- 1,116
11
votes
3
answers
2k
views
Liouville's theorem and gravitationally deflected lightpaths
It is customary in gravitational lensing problems, to project both the background source and the deflecting mass (e.g. a background quasar, and a foreground galaxy acting as a lens) in a plane.
Then, ...
- 3,755
43
votes
5
answers
15k
views
How does gravitational lensing account for Einstein's Cross?
Einstein's Cross has been attributed to gravitational lensing. However, most examples of gravitational lensing are crescents known as Einstein's rings. I can easily understand the rings and crescents, ...
- 6,044