# Coloumb's constant and the Gravitational constant

1. Jun 1, 2010

### diagopod

I'm trying to learn more about the differences and similarities b/w electrostatics and gravitation. Ke and G seem structurally similar, but while Ke can be broken down into 1 / 4 pi Epsilon0, I was wondering if there is a similar sub-structure for G? Is there any unit in gravitation analogous to Epsilon0 such that it makes sense to write 1/ 4 pi (constant here) = G?

2. Jun 1, 2010

### Gordianus

Factoring Ke as 17(4 pi epsilon0) is matter of convenience. This way Gauss' law takes a simple form. However the physical meaning is the same. On the other hand, there's no need to break down G to simplify some equation

3. Jun 1, 2010

### Creator

Seems like we just answered this a few days ago with no response from the poster...
...are you the same poster?

...

4. Jun 1, 2010

### diagopod

Nope, but thanks for the link. It looks like that particular poster seems to think that G can be derived. I'm aware that G is an empirical constant. What I was curious about was whether there was a more fundamental (albeit still empirical) constant inside of G that had the same relation to G that Epsilon0 has to Ke. But either way, the thread you're pointing me to clarifies that pretty well, and it does seem like there's a special case in GR where there is an "Epsilon (g)" as you point out. And in that case it seems it's reversed, where G has the same relationship to another constant e(g) that Epsilon0 has to Ke. Anyway, learning...

5. Jun 1, 2010

### Creator

Hi diagopod;
Historically, there have been a number of attempts at analytic expressions for G which usually reflect an attempt to unify EM and gravitation.
Here's a good review of some... http://www.konfluence.org/CalculatingG.pdf

Personally, if forced to choose, I favor Sakharov.

Creator

Last edited: Jun 1, 2010