physics-subatomic-particles

some of the well-established symmetries in the universe may have to be abandoned .In about 1930 it was noticed that when a proton passed closer than about 1 .4 fmto the nucleus of an atom, it was attracted to it, rather the repelled, an Coulomb' slaw would suggest . However, when two protons actually carne into contact, they werenaturally repelled, because of the 'exclusion Principle . It was already accepted tha telectromagnetic forces were caused by the exchange of massless quanta, photons ,between particles . As we can see from looking at the binding energies of differen tnuclei on a Periodic Table, these are all roughly the same, and equal to 8 HeV ,whereas the ionization potentials of different elements are very irregular . Thi ssuggests that the nuclear force, which is responsible for holding nuclei together i s'saturated', unlike the Coulomb force, and this fact led Heisenberg to propose, i n1932, that the nuclear force was a so-called 'exchange force' . An exchange force i sone in which the properties of the particles interacting through it are exchanged .For this reason, it cannot be represented simply by a simple potential V(r), but onlyby the product PayV(r), where P is the so-called 'permutation operator' and a and bare the particles taking part in the reaction . Thus, if the wave function of the pai rof interacting particles is O)f(a,b), we see tha tP o 67~ (a, b ) _ '1'c( b , a ) .Before we discuss the nature of the strong nuclear force in any greater detail, le tus first consider how H .Yukawa managed to make his startling predictions about it squanta in 1935 . Yukawa reasoned that, because of the very short range of the nuclea rforce, its quanta must be comparatively massive . But, if this were the case, how wa sit that mass fluctuations were not observed in protons and neutrons? The only answe rto this question was that the emission and reabsorbtion of quanta took place in tooshort a time for the Uncertainty Principle to allow one to observe . Invoking the time -energy uncertainty relation we then havemt