Date: Around 1993
I have read that bosons are particles that convey force (gravtons,
photons, etc.) and fermions (protons, neutrons, the heavy stuff) are the
particles themselves that are acted upon by these messenger particles. How do
messenger particles convey force, ("pursuadine)? Example: How is a graviton
going to convince a hydrogen molecule to change direction and head towards the
The question really is, how to get an attractive interaction.
Getting a repulsive interaction looks easy - particle 1 fires off an exchange
particle in the direction of particle 2, which receives it, and the momentum
of the exchange particle causes the 2 interacting particles to head away from
each other. Imagine 2 kids on skateboards, exchanging a basketball. This
repulsive interaction is just what happens when they throw the basketball
straight at each other back and forth. So, how can we get an attractive
interaction? If the kids are close enough, they can just hand the ball to one
another, and this can be done in such a way that the net momentum transferred
is in the other direction - so they really are pulled towards one another.
But this does not seem to be directly related to the physical system -
particles do not have long arms! Or do they? Remember Heisenberg's
uncertainty principle? If you have specified momentum completely, position is
completely uncertain. I think this is most of the explanation.
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Update: June 2012