# What is the nature of the force of gravitation?

1. Jul 7, 2014

### Syed Ammar

What is the nature of the force of gravitation? Is it electrostatic,magnetic or something else?
According to the law of gravity.. gravity exists between atoms to planets and planets to supernovae, How does gravitation occur?

If possible, dont paste links of references....just quote them..
Ill be much obliged..
Regards,
Ammar

2. Jul 7, 2014

### CWatters

Something else.

Truth is we don't know for sure what causes gravity yet.

3. Jul 7, 2014

### Bandersnatch

Gravity is one of the four fundamental forces, it's got nothing to do with electromagnetic force, just as electromagnetic force has got nothing to do with the strong force. That's why they're called fundamental - although some people hope to find a way to unify them all into different expression of one, even more fundamental force.

It's hard to tell what you mean by "nature" of the force. If it's a question about what it involves, just look at the equations.
By looking at Newton's law of gravity $F=GMm/R^2$- it's acting between masses, is proportional to some constant(G), and falls down with the square of distance.
In the more accurate theory of General Relativity, gravity is the effect of the curvature of space-time, which in turn is caused by energy.
The difference between the two is well presented in the following clip:

4. Jul 7, 2014

### PhysicoRaj

There are four fundamental forces in nature: Gravity, Electromagnetic, Weak force and strong force.
There is more to this: the weak and electro forces emerge as 'one' at a specific temp. etc.
So gravity is a unique type of force. It's nature is attractive. Conservative.
Gravity is the force due to the virtue of masses between the two attracting bodies.
The origin of gravity is somewhat complex for me to explain. You can look up relativity for that. Just for an understanding, it's like when you keep two balls on a stretched membrane, they create a depression around them and they tend two move towards each other. For the real gravity this occurs in a 3 dimensional space - bending of space.
Here's a way to visualise it:

There are gravitational waves and associated gravitons that are linked to the origin of this force, best is to study the relativity.

Last edited by a moderator: Sep 25, 2014
5. Jul 7, 2014

### Bandersnatch

This is wrong. Gravity is the bending of space-time, not space. The membrane analogy, while very flashy and tempting, is breeding more misconceptions than it mangages to explain.
I can understand the pedagogical rationale for using the membrane - better to give students some, even if faulty, understanding, than none at all, and hope they'll get interested enough to get motivated to learn the proper thing - but I heartily disagree with this approach.

6. Jul 7, 2014

### PhysicoRaj

Sorry, that was an unintended mistake. I forgot to add "time".
I just got the very first understanding of gravity this way and I liked it. I thought this would be a better way to understand gravity, but didn't know it heralds misconceptions.. can you throw some light on that?

7. Jul 7, 2014

### A.T.

That is exactly the problem with the analogy. There is no time-dimension on the rubber-sheet, which represents just two spatial dimensions.

See here:
http://en.wikipedia.org/wiki/Gravity_well#Gravity_wells_and_general_relativity

Here my summary from a previous thread:

8. Jul 7, 2014

### PhysicoRaj

Thanks a lot A.T., the man in my video specifies 'space-time' but mentions the membrane analogy is Einstein's picture of gravity, much opposite to what is in the wiki link of yours:

9. Jul 7, 2014

### A.T.

10. Jul 7, 2014

### PhysicoRaj

11. Jul 7, 2014

### OCR

Gravitational waves are a different phenomena...

Last edited: Jul 7, 2014
12. Jul 8, 2014

### A.T.

You're welcome. The video in post #3 above is an animated version of that top illustration.

13. Jul 8, 2014

### PhysicoRaj

Yes, I realised it as soon as I saw it. This was a completely new viewpoint of gravity for me.