# What is the nature of the force of gravitation?

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

Related Other Physics Topics News on Phys.org
CWatters
Homework Helper
Gold Member
Something else.

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

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:

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

PhysicoRaj
Gold Member
This is wrong. Gravity is the bending of space-time, not space.
Sorry, that was an unintended mistake. I forgot to add "time".
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.
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?

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.

but didn't know it heralds misconceptions.. can you throw some light on that?
See here:
http://en.wikipedia.org/wiki/Gravity_well#Gravity_wells_and_general_relativity

Here my summary from a previous thread:
- Rolling balls on a rubber sheet can be used as a qualitative analogy for the gravity well (gravitational potential). That's why it gives the correct qualitative result. But that has nothing to do with explaining General Relativity and curved space-time, because it applies equally to Newtonian Gravity.

- The indented rubber sheet can be used as a qualitative visualization of the space (not space-time) distortion in General Relativity (Flamm's paraboloid). But that has has nothing to do with explaining how masses attract each other in General Relativity, which requires including the time dimension (space-time distortion). Flamm's paraboloid represents a distortion of spatial distances between coordinates, and could just as well be shown with the funnel upwards, so the rolling balls would give a wrong result. Therefore rolling some balls on the curved surface representing Flamm's paraboloid makes no sense.

- The local intrinsic curvature of space-time you are asking about is primarily related to tidal-effects, or gravity gradient.

1 person
PhysicoRaj
Gold Member
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:
Both the rigid gravity well and the rubber-sheet model are frequently misidentified as models of general relativity, due to an accidental resemblance to general relativistic embedding diagrams and perhaps Einstein's employment of gravitational "curvature" bending the path of light, which he described as a prediction of general relativity.

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

At the moment, gravitons are entirely theoretical constructs that delicately walk the knife-edge precipice between the domains of scientific respectability and the shady world of hand waving.

Gravitational waves are a different phenomena...

Last edited:
A.T.