# Is there a link between the "refraction" of light and the "gravity lensing" of light  ?

Both phenomenon involve the bending of light -- and its "acceleration"

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• neb
Lv 7
1 month ago

No. Refraction of light in a medium is due to a change in propagation speed of the light due to the permittivity and permeability of the medium.

Gravity is not known to change the permittivity and permeability of space and therefore the speed doesn’t change (as measured locally). So, no, they are not related.

Light follows the ‘null’ path in free space. Gravity defines the ‘null’ path.

• Who
Lv 7
1 month ago

light itself is not "bent" in gravity lensing

It STILL goes in a straight line

Its just that gravity has distorted space - so  IT becomes curved

so now light, even though going in a straight line, follows curved space

(I suggest you read up on "gravity" cos gravity is not a "thing" - its the name we give to the effect mass has on space - gravitational lensing being one of the effects

- draw a straight line across a piece of paper,

Now roll the paper into a tube so the 2 ends of the line are touching

so NOW  you still got the straight line BUT if you look through the tube it looks curved

THATS cos the line was drawn on a 2D sheet of paper But the paper is now a 3D tube

If that line was light then it would STILL be going in a straight line But to you it would be following a curved path in 3D

• 1 month ago

Both are quite similar only refraction is man made as in a lens

• 1 month ago

"Both phenomenon involve the bending of light -- and its "acceleration""

No, they don't.  Refraction is caused by the way the light's electric field behaves in the different media - gravitational lensing is caused by light following geodesics in curved space.  There's no acceleration involved.

• 1 month ago

Refraction is the fact or phenomenon of light, radio waves, etc. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density.

Gravitational lensing produces a similar effect, although the reason for it is quite different - a gravitational source curves space such that the light passing through it has an altered trajectory - much like light being refracted.

• ANDY
Lv 5
1 month ago

Refraction of light is different from gravitational lensing. When a ray of light enters a denser medium, light speed "seems" to slow down then speed up again as it goes out of the medium. (When we have two substances adjacent to one another, each is called a medium. Example: air over water, or oil over water).

You have to know that light does not change speed inside a denser substance like water. It is always going at 300,00 km /sec. The photons, however, encounter many particles where they will bounce from one to the other. And this will make the ray take a longer period of time to go through the substance. But if it should come out on the other side of the dense substance, you will see now that the speed is "normal" (no more dense substance to obstacle the light).

Now, a refraction occurs when you place, say, a pencil halfway inside a glass with water inside, the first rays entering the water "at an angle" will encounter the particles of water and will take a longer path to move through the water, as I said before, that the light will seem to go slower than when it was in the air. The rest of the ray of light will go into the water and the same will happen till all the beam goes into the water. This will cause a refraction: you will see the pencil as if it were bent in the water.

A gravitational lensing is the warping of space because of gravity alongside a celestial object. And light is involved too and it bends, but this has nothing to do with refraction of light.

• 1 month ago

Yes, a very definite link. . Gravitational lensing of light requires a LOT of mass, an entire large galaxy or galaxy cluster closer too us than the galaxy cluster that the light is coming from that gets refracted to form an Einstein ring arcs. Without all that mass the light would not be refracted by gravity.

The light is NOT being accelerated by the gravity or the mass. The mass is acting like a gravitational magnifying glass refracting and focusing the light. It is NOT speeding up or accelerating the light. It may be slowing it down because the refracted  light has a longer path.