# Speed of light depending on gravitational constant?

• SpiderET
In summary, the question is whether or not there is a peer-reviewed theory that proposes a link between the speed of light in a vacuum and the gravitational constant. There is no such theory, for the same reason given in the summary.
SpiderET
I just wonder if there were any serious (and peer reviewed published, to be in line with guidelines) theory, which had proposed some link between speed of light in vacuum constant and between gravitational constant G. For example a calculation of speed of light based on G.
Tried google search but with no result, so I guess the answer is no, but maybe somebody here will know better.

Something similar to Maxwell approach calculating speed of light based on permittivity and permeability.

I don't think that concept would make sense at all. We use the speed of light to measure distances. How can the speed of light change in an objective way?
Only dimensionless constants are fundamental, all other constants can get arbitrary values without changing physics by redefinition of our units.

mfb said:
I don't think that concept would make sense at all. We use the speed of light to measure distances. How can the speed of light change in an objective way?
Only dimensionless constants are fundamental, all other constants can get arbitrary values without changing physics by redefinition of our units.

Under some circustances it would maybe make sense, but I can't write here about it, because it would be pure speculation, which would be agaist guidelines.
But thanks for reply anyway, it seems that the answer is no, there is no such peer reviewed theory.

There is no such theory, for the reason given. You can define your units of time and length to make c be anything you like, and your units of mass to do the same for G. You can even define funky units that change over time or across space to establish any relationship you like. There is simply no physical content to the idea.

SpiderET said:
Under some circustances it would maybe make sense, but I can't write here about it, because it would be pure speculation, which would be agaist guidelines.
But thanks for reply anyway, it seems that the answer is no, there is no such peer reviewed theory.

Even if wikipedia is not a recommended source here, you may be interested by the recently reviewed article: "http://en.wikipedia.org/wiki/Variable_speed_of_light" which I think is addressing for a part your questioning.
A by side interrogation seems to be: "With which speed does the gravitational interaction really move?" I know the theory and you can find professionally verified demonstrations proving that that speed theoretically is c, the same than the one of electromagnetic interactions (e.g.: Lichnerowicz, 1955). But on the other side of the reality you shall obviously discover that experiments confirming these theoretical demonstrations are, perhaps not missing, but rare and yet discussed. I hope it brings a positive and constructive contribution to your questioning.

## 1. What is the relationship between the speed of light and the gravitational constant?

The speed of light and the gravitational constant are both fundamental constants in physics. However, they are not directly related to each other. The speed of light, denoted by c, is a measure of how fast light travels in a vacuum. The gravitational constant, denoted by G, is a measure of the strength of the gravitational force between two objects.

## 2. Can the speed of light be affected by changes in the gravitational constant?

No, the speed of light is a universal constant and is not affected by changes in the gravitational constant. The speed of light is a fundamental property of the universe and cannot be altered by external factors.

## 3. How does the speed of light change in different gravitational fields?

The speed of light is constant in a vacuum, regardless of the gravitational field. However, in the presence of a strong gravitational field, such as near a black hole, the path of light can be affected, causing it to appear to bend or be redshifted.

## 4. Is the speed of light affected by the curvature of spacetime due to gravity?

Yes, the speed of light can be affected by the curvature of spacetime due to gravity. In Einstein's theory of general relativity, the presence of mass and energy causes spacetime to curve, and this curvature can affect the path of light, making it appear to travel at a slower or faster speed.

## 5. How does the speed of light relate to the theory of relativity?

The theory of relativity, proposed by Albert Einstein, states that the laws of physics are the same for all observers in uniform motion. This theory also includes the famous equation E=mc^2, where c represents the speed of light. The theory of relativity has been extensively tested and has been shown to accurately predict the behavior of objects moving at high speeds, including the speed of light.

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