Bill, Thanks for the reference.
Steve M. On Wed, 2006-11-01 at 16:40 +0100, Bill Sloman wrote: > At 05:25 1-11-2006, you wrote: > >I think I will drop into this group a brief passage fom Heisenberg's > >"Quantum Theory" translated into English in 1930. > > > >"Dirac has set up a wave equation which is valid for one electron and is > >invarient under the Lorentian transformation. It fulfills all > >requirements of the quantum theory, and is able to give a good account > >of the phenomena of the "spinning" electron, which could previously only > >be treated by, ad hoc assumptions. The essential difficulty which arises > >with all relativistic quantum theories is not eliminated however. This > >arises from the relation > > > >1/c^2 = u^2C^2 + p^2 in x + p^2 in y + p^2 in z > > > >between the energy and the momentum of a free electron. According to > >this equation there are two values of E which differ in sign associated > >with each set of P in z, P in y and P in Z. The classical theory could > >eliminate this by arbitrarily excluding the one sign, but this is not > >possible according to the principles og quantum theory. Here > >spontaneuos transitions may occure to the states of negative energy; as > >these have never been observed, the theory is certainly wrong. Under > >these conditions it is very remarkable that the positive energy-levels > >(at least in the case of one electron) coincide with those actually > >observed." > > > >So what was wrong? What occured that proved both theories were correct? > > Dirac solved the problem by hypothesising the positron, > > http://www.siam.org/siamnews/03-03/dirac.pdf > > which was then sought and found by the experimental physicist Carl > David Anderson in 1932 > > http://en.wikipedia.org/wiki/Carl_D._Anderson > > It is one of the nicer stories from the early days of quantum physics. > > Dirac's normal interaction with experimental physicists is described > by the Dirac Effect - which, in the classic version of the story - > had Dirac's presence in Cologne (sitting in a stationary train for a > couple of hours) as a necessary and sufficient explanation for a > couple of hours of temperamental behaviour by a sensitive quadrant > electrometer. > > Bill Sloman, Nijmegen > > > > > _______________________________________________ > geda-user mailing list > [email protected] > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
