gEDA-user: smd challenge board status

[John Doty]

On Nov 1, 2006, at 4:52 PM, Steve Meier wrote:

> John has it correct.

Well, kinda. I really shouldn't try to explain physics before morning  
tea ;-)

I should have said "a vacant negative energy state of a negatively  
charged particle has the same dynamics as an occupied positive energy  
state of a positively charged particle".

>
> It is facinating reading this text. A modern quantum physics book
> presents the theory as cold hard fact... but back in 1930 when it was
> brand new Heisenberg was presenting it in an almost appoligetic and  
> not
> quite sure manner.

Yes. In 1930 there were many mysteries and it wasn't clear that  
Dirac's relativistic Hamiltonian for the electron was a step in the  
right direction. The physical significance of the negative energy  
states was not yet understood. There were only two "elementary  
particles": the electron and the proton. Low energy states of the  
electron seemed adequately described by nonrelativistic theory, but  
sometimes a very energetic electron would emerge from an atomic  
nucleus in a process ("beta decay") that seemed not to conserve  
either energy or angular momentum. Dirac's theory didn't address  
this: Pauli's neutrinos and Fermi's theory of the weak interaction  
were in the future.


John Doty              Noqsi Aerospace, Ltd.
jpd at noqsi.com