#nasa #webb #universe #time
#gravity #lens
The gravitational lensing that appears in the Webb Telescope image released today is due to the collective gravity of the galaxy cluster SMACS 0723. It bends the light from objects behind it.
This is similar to the gravitational lensing of a black hole, but it's curved less. Think of it as a lens with a long focal length. In this case the focal length is billions of lightyears!
>"This is similar to the gravitational lensing of a black hole, but it's curved less. Think of it as a lens with a long focal length. In this case the focal length is billions of lightyears!"
That's not correct at all. I really screwed this up. It doesn't act like a glass lens at all (except that it bends light). It's much more complicated than that and it doesn't even have a focal point or a focal length. So...
nevermind. 
(The first paragraph is correct though.)
