Whats "gravitational lensing".?

Question

And what happens to the light we ubsorb and don't reflect.

Answer 1

A normal lens works by bending light rays to focus them onto a screen, just like the one in your eye or a camera.

A gravitational lens performs a similar function, except that it's not shaped glass that bends the light rays, it's a very big gravitation field. Prime candidates are very large black holes, or sometimes whole galaxies.

They allow us to see things that are much farther away in greater detail than we could otherwise, and sometimes to see things that are so faint we could not have seen them at all.

Here's a very good diagram of how such a lens works:

http://en.wikipedia.org/wiki/Image:Gravi...

Answer 2

light being bent and focused by gravity, just like a lens does.

Answer 3

A gravitational lens is formed when the light from a very distant, bright source (such as a quasar) is "bent" around a massive object (such as a cluster of galaxies) between the source object and the observer. The process is known as gravitational lensing, and is one of the predictions of Albert Einstein's general theory of relativity.

The gravity from a massive object (such as a galaxy cluster or black hole) can warp space-time, bending everything in it - including the paths followed by light rays from a bright background source. This alters the time taken for the light to reach an observer, and can both magnify and distort the apparent image of the background source.

Unlike an optical lens, maximum 'bending' occurs closest to, and minimum 'bending' furthest from, the center of a gravitational lens. Consequently, a gravitational lens has no single focal point, but a focal line instead. If the source, massive lensing object, and observer lie in a straight line, the source will appear as a ring behind the massive object.

Imagine a bright object such as a star, a galaxy, or a quasar, that is very far away from Earth (say...10 billion light years). For our discussion, let us imagine we have a quasar. If there is nothing between it and us, we see one image of the quasar. Yet, if a massive galaxy (or cluster of galaxies) is blocking the direct view to the quasar, the light will be bent by the gravitational field around the galaxy [see figure below]. This is called "gravitational lensing," since the gravity of the intervening galaxy acts like a lens to redirect the light rays. But rather than creating a single image of the quasar, the gravitational lens creates multiple images. We follow the light rays from the Earth to the apparent locations of the quasar. If the galaxy were perfectly symmetric with respect to the line between the quasar and the Earth, then we would see a ring of quasars!

Now, if the massive galaxy is off-center (as might be expected) with respect to the line between the quasar and the Earth, then the two light paths would be different distances around the galaxy. This makes the twin images be formed at different distances away from the actual quasar.

Finally, since the distances between each of the objects is so great, the radius of the galaxy and the mass distribution of the galaxy are well approximated by point masses (the error is small). Thus, one can use simple geometry (knowing the mass of the galaxy, the distance of the galaxy and the two images) to estimate the distance to the actual quasar.

The light isn't absorbed or reflected, it is bent.

Answer 4

gravitational lensing is the effect that takes place when a massive object such as a galaxy,bends,distorts and magnifies the light of a more distant object because of its high mass the massive galaxy distorts the space around it,and sometimes acting as a lens,it was first proposed by Einsteins theory of relativity.and only happens if its lined up with our line of sight,there's a few examples,you should look it up on google,image.

Answer 5

suppose you are aiming your telescope to a point (Az,Al), that is azimuth, altitude

suppose there's a black hole in the direction you are watching

suppose theres a star or a galaxy behind the black hole

then, you are NOT suppose to see that star (or Galaxy)

but

it happens that you CAN already see the star or G, this is why

http://upload.wikimedia.org/wikipedia/co...

the fotons that were going not in your direction but upper or lower, are bent by the balck hole and redirected to you,

http://www.landsil.com/imagenes/fisica/L...

oftenly at both sides od the black hole

http://www.kalipedia.com/kalipediamedia/...

thats gravitational lensing,

http://upload.wikimedia.org/wikipedia/co...

the point is that the astronomers see the distant star, ina closer position, doing the corrections, they can have more information than before

Answer 6

Bending of light.