When it comes to the weak nuclear force and why it is weak, there’s a strange story which floats around. It starts with a true but somewhat misleading statement:
- The weak nuclear force (which is weak because its effects only extend over a short range) has its short range because the particles which mediate the force, the W and Z bosons, have mass [specifically, they have “rest mass”.] This is in contrast to electromagnetic forces which can reach out over great distances; that’s because photons, the particles of light which mediate that force, have no rest mass.
This is misleading because fields mediate forces, not particles; it’s the W and Z fields that are the mediators for the weak nuclear force, just as the electromagnetic field is the mediator for the electromagnetic force. (When people speak of forces as due to exchange of “virtual particles” — which aren’t particles — they’re using fancy math language for a simple idea from first-year undergraduate physics.)
Then things get worse, because it is stated that
- The connection between the W and Z bosons’ rest mass and the short range of the weak nuclear force is that
- the force is created by the exchange of virtual W and Z bosons, and
- due to the quantum uncertainty principle, these virtual particles with mass can’t live as long and/or travel as far as virtual photons can, shortening their range.
This is completely off-base. In fact, quantum physics plays no role in why the weak nuclear force is weak and short-range. (It plays a big role in why the strong nuclear force is strong and short-range, but that’s a tale for another day.)
I’ve explained the real story in a new webpage that I’ve added to my site; it has a non-technical explanation, and then some first-year college math for those who want to see it. It’s gotten some preliminary comments that have helped me improve it, but I’m sure it could be even better, and I’d be happy to get your comments, suggestions, questions and critiques if you have any.
[P.S. — if you try but are unable to leave a comment on that page, please leave one here and tell me what went wrong; and if you try but are unable to leave a comment here too for some reason, please send me a message to let me know.]
3 Responses
Is the stiffness of the W and Z fields due to their interaction with the Higgs field?
I loved your statement that it is the field, not imaginary particles, that mediate force. I have never been able to wrap my head around the concept of imaginary particles mediating force. Can you point me to a bit more detailed explanation of the subject?
Well, make sure you read my article, because so far that is the clearest explanation that I know of in the literature that doesn’t just do it all in advanced math. Read all of the side comments in the mathy section.
The point is that a virtual particle in a diagram that shows a force between two real particles (the final figure of the new article) is nothing but what is known as a “Green function”. Green functions are used to calculate forces at an advanced undergraduate level, and they are proportional to the force laws that you are familiar with. So the mathematical connection is very direct. Maybe I’ll have to write this math out for people who want to follow it closely. I’m not sure what math level you have, though, so after you’ve read the article, let me know what questions you still have.