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Author Topic: What does science say is the difference between nuclear forces and gravity?  (Read 1481 times)

Offline Colin2B

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This question arises from a subsidiary question in a thread about gravity.
Contributions are welcome which explain the current scientific view (not pseudoscientific or crank theories) of the difference between the forces which bind the nucleons in the atom and the force of gravity which also acts between those nucleons.
In this I will take the part of the innocent questioner.


 

Offline PmbPhy

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Quote from: Colin2B
What does science say is the difference between nuclear forces and gravity?
One difference is in how these forces are mediated:

The strong force between nucleons is mediated by mesons whereas the strong force between quarks is mediated by gluons.

The gravitational force is mediated by gravitons.

If a gravitating body of mass M is held at rest and another uncharged test body is placed in its vicinity then the test body will accelerate towards the gravitating body with an acceleration which is independent of the properties of the test body.
 

Offline evan_au

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Another difference is in the masses of the force-carrying particles.
  • The photon is massless (some would say "zero rest mass"). This makes electromagnetism a long-range force, traveling at the speed of light. We can detect photons with our eyes.
  • Gravitons have never been directly detected, but they are also thought to be massless. This would make gravity a long-range force, traveling at the speed of light.
  • Mesons and Gluons have mass, and this means that they decay before the travel very far. This makes their corresponding forces short-range forces (mostly within the nucleus of an atom). 
Fixed a typo
« Last Edit: 15/05/2015 10:35:18 by evan_au »
 

Offline PmbPhy

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Quote from: evan_au
The photon is massless (some would say "zero rest ass").
I think you might want to check your spelling on that one my friend. Lol!

Quote from: evan_au
Mesons and Gluons have mass,...
Mesons have mass. Gluons have zero mass. See:
http://en.wikipedia.org/wiki/Massless_particle

I know. It's confusing. I was told the following from a particle physicist from SLAC
Quote
Quarks interact in QCD via the exchange of gluons.

It is possible that the net effect of many gluons leads to a confining potential for quarks. This is what happens in my work on light-front holography.
I don't know what that means myself.
« Last Edit: 15/05/2015 01:44:40 by PmbPhy »
 

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