Re: forces

[LUDWIK KOWALSKI <KOWALSKIL@alpha.montclair.edu>]

Strong forces between quarks are mediated by eitht gluons and weak 
forces are mediated by three bosons. WEAK FORCES BETWEEN WHOM?

Is the term "Pauli force" acceptable? Where does it fit our system
of "only four forces"? Does it have the same nature as an attractive 
force between the non-overlaping nucleons?

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On 13 Nov 1997 15:05:48 Leigh Palmer <palmer@sfu.ca> wrote:

> Along this line I've always added a nontraditional force to the
> conceptual toolbox with which I equip my students. I call it the
> Pauli force, and it is always repulsive. It is the force exerted
> by the 1s electrons in lithium which repels the next electron to
> join the party. It is quite a natural extension of the force
> concept to the realm in which we all know it is not entirely
> appropriate, but it seems to aid their conceptual grasp.

Leigh (see below) was pointing to page 359 in Evans book..where the 
"Pauli force" is introduced. I would be very happy to accept that 
"a weak force is a repulsive force due to the Pauli exclusion principle."
This would allow me to say that by strong forces nuclei attract each
other at longer distances and by weak forces they repel each other at 
shorter distances. 

In fact, short-range repulsive forces are essential when nucleons
are treated as fundamental particles. Without repulsion the radia
of atomic nuclei would not be proportional to A^0.333. And neutron
stars would be point-like (?).

Shoul we accept that a weak force=(repulsive force between fermions 
when they "try to overlap")? I do not think that this would agree
what is usually stated when the weak force is introduced to students.

The idea of a force which is not a push or pull of some kind is
difficult to accept. Forces are identified by acceleration, not 
by turning something into something else. They say that a week force
is responsible for beta decay. This is too vague for my taste. 
A force turning a neutron into a proton? A force turning a down-quark 
into an up-quark? A force turning a frog into a prince?  A force of
moral charcter? A persuasive force of an argument? .... These are
different things and the same name, force, should be avoided, at least
in physics. 

Why do the authors of so many introductory textbooks impose this idea
of "only four forces of nature" on us? 

By the way,
"Pauli" forces between neutrons inside a neutron star must be as large 
as "strong" attractive forces, unless the system is not in equilibrium. 

> .... I have a 42 year old textbook which refers to "The Weak-interaction 
> paradox for Low-lying States." It uses the language I can readily 
> understand. I won't quote it here, but those among you fortunate enough 
> to own "The Atomic Nucleus" by Robley Evans will be able to look it up. 
> .....  Leigh.
                                                   Ludwik Kowalski