# Thread: The speed of the force of nature?

1. We know that electromagnetism and gravity move with the speed of light , so the strong nucleon force also move with the speed of light, right?

2. Originally Posted by johnzxcv
We know that electromagnetism and gravity move with the speed of light , so the strong nucleon force also move with the speed of light, right?
No. The particle that mediates the electromagnetic force is the photon and that which mediates gravity is the graviton. Since each of these is an inverse square law these particles have zero mass. However the force that mediates the strong force is not an inverse square law. It drops off much faster (i.e. does not have the same functional form) than an inverse square law. The potential function for the strong force is the Yukawa potential. The particle which mediates this force therefore has mass and therefore the speed of the interaction should be less than the speed of light.

3. They are known as pi mesons or pions for short.
Pion - Wikipedia, the free encyclopedia

4. Originally Posted by Jilan
They are known as pi mesons or pions for short.
Pion - Wikipedia, the free encyclopedia
Thanks Jilan. I kept saying to myself Don't forget to tell them that this particle is a pion and yet I still forgot!

You're welcome! I don't know WTH is going on here...my "window of time" to reply is so short all I can anymore is "yes" "no" or "duh?" Every single time...what, does everyone on this site

type a complex reply in 57 seconds!!!! (this hasn't happened before, just the last couple days)

6. Particles make of quark,right? So what quark make graviton and photon

7. Originally Posted by johnzxcv
Particles make of quark,right?
No. Only a certain class of particles called hadrons are made of quarks. Hadrons come in two forms, baryons (such as protons and neutrons which are made of three quarks) and mesons (such as pions which are made of a quark and an antiquark). See Hadron - Wikipedia, the free encyclopedia

8. Originally Posted by Physicist
No. The particle that mediates the electromagnetic force is the photon and that which mediates gravity is the graviton. Since each of these is an inverse square law these particles have zero mass. However the force that mediates the strong force is not an inverse square law. It drops off much faster (i.e. does not have the same functional form) than an inverse square law. The potential function for the strong force is the Yukawa potential. The particle which mediates this force therefore has mass and therefore the speed of the interaction should be less than the speed of light.
Then how fast is the strong nuclear force?

9. Originally Posted by Jilan
They are known as pi mesons or pions for short.
Pion - Wikipedia, the free encyclopedia
The pions mediate the residual strong force, which is the force between nucleons. The real strong force between the quarks is mediated by gluons. These are massless so the force will propagate at c. I'm not sure about the residual nuclear force though.

10. Originally Posted by Jilan
The pions mediate the residual strong force, which is the force between nucleons. The real strong force between the quarks is mediated by gluons. These are massless so the force will propagate at c. I'm not sure about the residual nuclear force though.
Ooooo!! Great point. I never thought about that. Let me think about it and get back.

11. Originally Posted by Physicist
Ooooo!! Great point. I never thought about that. Let me think about it and get back.
So speed of strong force is c?

12. Originally Posted by Physicist
No. The particle that mediates the electromagnetic force is the photon and that which mediates gravity is the graviton. Since each of these is an inverse square law these particles have zero mass. However the force that mediates the strong force is not an inverse square law. It drops off much faster (i.e. does not have the same functional form) than an inverse square law. The potential function for the strong force is the Yukawa potential. The particle which mediates this force therefore has mass and therefore the speed of the interaction should be less than the speed of light.
You said particle that mediates the electromagnetic force is the photon.Than what particle mediates the force between charge?

13. The photon.

14. Originally Posted by Jilan
The photon.
You mean particle with charge fire photon.

15. That's sort of the picture, but the photons are virtual. Here is a good link that talks about virtual particles and forces.

16. Originally Posted by Jilan
That's sort of the picture, but the photons are virtual. Here is a good link that talks about virtual particles and forces.
Thanks.
I understand now.
How about the weak force. Does it's speed equal c?

17. That force is mediated by the W and Z bosons.
W and Z bosons - Wikipedia, the free encyclopedia
These are heavy particles so only act over a short range. They have mass so will not travel at c.

18. Originally Posted by Jilan
That force is mediated by the W and Z bosons.
W and Z bosons - Wikipedia, the free encyclopedia
These are heavy particles so only act over a short range. They have mass so will not travel at c.
I want to know how fast are they?

19. Since their half lives are 3×10−25 s, they don't travel fast or far.

20. Originally Posted by AlexG
Since their half lives are 3×10−25 s, they don't travel fast or far.
More to the point, it's not possible, neither in theory nor in practice, to measure the speed of such a particle. Velocity has no meaning at the quantum level. That's something a lot of people don't understand about quantum theory. There's really no such thing as a velocity operator. Some people like to think of the operator V = P/m where p is the momentum operator and m the particles mass as a velocity operator. However the problem with this is that P is conjugate momentum and not the mechanical momentum mv.

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