Thursday, 9 July 2009

Fundamental Forces

Fundamental Forces :
Matter is effected by forces or interactions (the terms are interchangeable). There are
four fundamental forces in the Universe:
1. gravitation (between particles with mass)
2. electromagnetic (between particles with charge/magnetism)
3. strong nuclear force (between quarks)
4. weak nuclear force (operates between neutrinos and electrons)
The first two you are familiar with, gravity is the attractive force between all matter,
electromagnetic force describes the interaction of charged particles and magnetics.
Light (photons) is explained by the interaction of electric and magnetic fields.
The strong force binds quarks into protons, neutrons and mesons, and holds the
nucleus of the atom together despite the repulsive electromagnetic force between
protons. The weak force controls the radioactive decay of atomic nuclei and the
reactions between leptons (electrons and neutrinos).
Current physics (called quantum field theory) explains the exchange of energy in
interactions by the use of force carriers, called bosons. The long range forces have
zero mass force carriers, the graviaton and the photon. These operate on scales larger
than the solar system. Short range forces have very massive force carriers, the W+,
W- and Z for the weak force, the gluon for the strong force. These operate on scales
the size of atomic nuclei.

So, although the strong force has the greatest strength, it also has the shortest range.

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