Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: katieHaylor on 07/09/2017 16:34:26

Title: Are light waves affected by gravity?
Post by: katieHaylor on 07/09/2017 16:34:26

Kooklan asks:

Are light waves affected by gravity? If so, does it change the wavelength or amplitude? How would light passing through a cluster be affected?

Can you help?

Title: Re: Are light waves affected by gravity?
Post by: Janus on 07/09/2017 18:10:54

Both the path and wavelength of light can be affected by gravity.   If light passes by a massive object, its path will be deflected. This can produce an effect known as gravitational lensing.
Light traveling from one gravitational potential to another will have its wavelength affected.  Moving from high to low potential (towards a massive object) causes its wavelength to decrease and going the other way causes it to decrease.

Light passing through a cluster will likely have its path bent to some degree due to gravitational lensing.  As light enters the cluster from one side it will have its wavelength decreased and as it leaves it will increase.  What an observer will see for the light leaving the cluster depends on what his potential with respect to the cluster is relative to the source of the light.

Title: Re: Are light waves affected by gravity?
Post by: evan_au on 07/09/2017 20:13:31

Bending of light by a gravitational field is predicted by Newton's theory of gravity; Einstein's General Theory of Relativity predicted a greater deflection. Arthur Eddington measured binding of light by the Sun during an eclipse of the Sun in 1919, and found it was closer to Einstein's theory.
See: https://en.wikipedia.org/wiki/Tests_of_general_relativity#Deflection_of_light_by_the_Sun

Astronomers use gravitational lensing to observe galaxies which would be too faint to see with unaided telescopes.

Astronomers have also used gravitational lensing to estimate the distribution of invisible "Dark Matter" surrounding visible galaxies.
See: https://en.wikipedia.org/wiki/Gravitational_lens

Change in the wavelength of light due to a difference in gravitational potential was also predicted by Einstein's General Theory of Relativity.
See: https://en.wikipedia.org/wiki/Gravitational_redshift

Title: Re: Are light waves affected by gravity?
Post by: chiralSPO on 08/09/2017 14:13:38

A new member added a few posts to this thread regarding some highly unorthodox views. I have split those posts off into a new thread, which I have placed in the "New Theories" section of the forum. Please use that new thread to continue discussion of those topics, and this thread to continue a discussion of generally accepted science. Thank you.

Title: Re: Are light waves affected by gravity?
Post by: F'dscience on 08/09/2017 16:39:55

First, you need to know what is light exactly.

Then, what is gravity exactly.

Then, how the 2 interact?

Title: Re: Are light waves affected by gravity?
Post by: chiralSPO on 08/09/2017 16:55:40

Quote from: fuckedscience on 08/09/2017 16:39:55

First, you need to know what is light exactly.

Then, what is gravity exactly.

Then, how the 2 interact?

We may never know "exactly" what anything is. But that doesn't mean we can't study how they interact and learn about that interaction.