Scusate, ma non so l'italiano abastanza bene per scriverlo, dunque
scrivero' in inglese (sono francese, ma sto en Spagnia).
> > Leggendo un libro di fisica ho letto che l'Eq.di Dirac
> > spiga matematicamente perchh l'elettrone possiede Spin 1/2.
Dirac's equation doesn't explain very much, but with very simple basis it
succeeds in discribing a particle with the classical limit. It gives a 1/2
spin (with a g factor equal to 2), and predicts negative energy states,
which can be interpreted as antiparticles if one is missing. Finally, you
get 4 states, and Dirac's equation is like a two 1/2 spins assembled in a
funny way. The more surprising is that it works, although the calculations
are usually horrible.
> L'equazione di Dirac "spiega" perche'
> l'elettrone abbia spin 1/2 in un ben preciso contesto: la meccanica
quantistica relativistica PRIMA della "seconda
> quentizzazione".
The second quantization is another business: it's a more practical way to
discribe how quantum phenomenons can create a photon, a phonon, or other
things. It is not relativistic, and you get the same results as you would
get without it, but it's easier in many cases with it.
> Esisteva
> gia' un'equazione quella di Kelin-Gordon,
> ma aveva dei problemi interpretativi (risolti con la "seconda
quantizzazione").
Klein-Gordon, which discribes particles without a spin. There too, you get
negative energy states. Indeed, why don't the particles fall to the
negative states? But it doesn't discribe the same thing as Dirac's
equation.
> Piu' avanti Pauli dimostro' un teorema generale detto "correlazione
spin-statistica"
E' dimostrato questo teorema? Me interesa se lo i, pensavo che era una
hipotesis.
Michel, Zaragoza (Spagnia)
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Received on Mon Feb 28 2000 - 00:00:00 CET