Darren New <dne### [at] sanrrcom> writes:

>> "A seminal work by Dyson came in 1966 when, together with Andrew Lenard
>> and independently of Elliott H. Lieb and Walter Thirring, he proved
>> rigorously that the exclusion principle plays the main role in the
>> stability of bulk matter.[13] Hence, it is not the electromagnetic
>> repulsion between electrons and nuclei that is responsible for two wood
>> blocks that are left on top of each other not coalescing into a single
>> piece, but rather it is the exclusion principle applied to electrons and
>> protons that generates the classical macroscopic normal force. In
>> condensed matter physics"
>
> From what I understand, the exclusion principle is a result of the
> quantum electrodynamic theory, which is what used to be called
> "electromagnetic theory" before it was quantum.  I.e., it's the same
> math going on, with photons interacting with electrons and etc.  Clearly
> I'm not capable of talking about it at this level. :-)

Could be - I never studied QED. However, it's not plain old
electromagnetics. What Dyson showed was that the electromagnetic
interactions between/among nuclei and electrons is not sufficient to
explain the volume of matter - it would be smaller without the exclusion
principle. 

One aspect that keeps particles apart is the exchange interaction, which
is purely due to quantum mechanics (i.e. not, AFAIK, related to
electromagnetics). This was one of those oddities of the quantum world
in undergrad quantum mechanics - that two such particles would prefer to
stay apart even though there is no actual force interaction between them
(even for uncharged particles). 

IANAP

kkk

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