# Newtons Constant Help

1. Apr 27, 2010

### Kainaan

Hello my name is Kainaan i just joined this forum, im 14 and i love every related to physics, i study quantum hysics and general relativity. I have a question about newtons constant, i have been reading on the Schwarzchild radius and came across the equation for it, in the eqaution it has the variable G wich stands for newtons constant, i understand all of the other stuff in the equation and i know what newtons constant is (6.7 x 10 to the -11), but i dont understand what it means like what it is.

if you could please explain it to me that would be awesome, i hope to talk to you all about other physics topics in the near future.

2. Apr 27, 2010

### George Jones

Staff Emeritus
Welcome to Physics Forums!

In some sense, G is a measure of the strength of gravity. If G were larger, gravity would be stronger; if G were smaller, gravity would be weaker.

3. Apr 27, 2010

### Kainaan

but isnt G a constant and therefor always the same, so i can not be larger or smaller its just always the same thing.

Last edited: Apr 27, 2010
4. Apr 27, 2010

### JesseM

Yeah, but you can imagine a different universe where the constant takes a different value, and figure out how the behavior of matter and energy would be different in that universe. Although, there are problems with talking about changes to values of non-dimensionless constants like G or the speed of light...see the discussion here, and see here for a list of dimensionless constants (all particle masses can be made dimensionless by dividing by the Planck mass).

5. Apr 27, 2010

### George Jones

Staff Emeritus
Right. The idea is to imagine universes that have different values of G than the value of G that we measure in reality.

If in an imaginary universe G is larger than what we really measure, gravity in the imagined universe would be stronger that it is in our universe; if in an imaginary universe G is smaller than what we really measure, gravity in the imagined universe would be weaker that it is in our universe.

Edit: JesseM was faster.

6. Apr 28, 2010

### Kainaan

ok now i understand thanks for the help