Gravitational Lensing and Frequency-Dependent Light Travel Time

In summary, the discussion was about the behavior of light that has traveled millions of years and is lensed around a body. The question was whether any frequency-dependent light travel time would cause the light to appear split when lensed, or if the various frequencies would recombine. The answer is that the path-bending of null geodesics in general relativity is not affected by color. However, there are other arguments to consider, such as the recent possible observation of high energy photons moving at different speeds due to the "vacuum" refractive index. The concept of a vacuum refractive index was also briefly discussed.
  • #1
wolram
Gold Member
Dearly Missed
4,446
558
Light that has traveled millions of years is gravitationaly (lensed) around a body,
if there is any frequency dependant light travel time ,would it not show up as if it
had been split by a prism when it was lensed around said body, or would the various frequencies recombine?
 
Astronomy news on Phys.org
  • #2
Basically no, the path-bending of null geodesics in GR is independent of colour (indeed, colour is relative).

There are other arguments to consider, the most significant being the recent possible observation that high energy photons move at slightly different speeds (think "vacuum" refractive-index).
 
  • #3
cesiumfrog said:
Basically no, the path-bending of null geodesics in GR is independent of colour (indeed, colour is relative).

There are other arguments to consider, the most significant being the recent possible observation that high energy photons move at slightly different speeds (think "vacuum" refractive-index).

Thanks cf, i do not know what , "vacuum" refractive-index is, i will look it up, i have an idea but could be way out.
 
  • #4
The only papers i can find with (vacuum refractive index ) are sub only.
 

What is gravitational lensing?

Gravitational lensing is a phenomenon in which the path of light is bent by the gravitational pull of a massive object, such as a galaxy or a black hole. This bending of light can create distorted or magnified images of objects that lie behind the lensing object.

How does gravitational lensing affect the frequency of light?

Gravitational lensing does not affect the frequency of light. The frequency, or color, of light remains the same as it travels through the lensing object's gravitational field. However, the path of the light may be altered, resulting in a longer or shorter travel time.

What is frequency-dependent light travel time?

Frequency-dependent light travel time refers to the fact that different frequencies of light can travel at different speeds through a gravitational field. This is due to the way that the gravitational field affects the path of the light, causing some frequencies to take longer to travel through the field than others.

How does frequency-dependent light travel time relate to gravitational lensing?

Gravitational lensing can cause frequency-dependent light travel time because the path of light is affected by the gravitational field. This means that different frequencies of light may take different amounts of time to travel through the lensing object's gravitational field, resulting in a delay or advance in the arrival of the light at the observer.

What are some practical applications of studying gravitational lensing and frequency-dependent light travel time?

Studying gravitational lensing and frequency-dependent light travel time can help scientists better understand the properties of massive objects, such as galaxies and black holes. It can also aid in the search for exoplanets and the study of the expansion of the universe. Additionally, these phenomena can be used to magnify and study distant objects that would otherwise be too faint to observe directly.

Similar threads

  • Astronomy and Astrophysics
Replies
4
Views
1K
  • Astronomy and Astrophysics
Replies
1
Views
1K
  • Astronomy and Astrophysics
Replies
1
Views
5K
  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Astronomy and Astrophysics
Replies
6
Views
2K
  • Beyond the Standard Models
Replies
6
Views
367
Replies
10
Views
2K
  • Astronomy and Astrophysics
Replies
8
Views
1K
Replies
9
Views
2K
  • Special and General Relativity
Replies
4
Views
1K
Back
Top