[srean]

This is so wrong at so many levels (sadly quite characteristic of the GA crowd) that I can only suggest reading up on the background and the math of it. Good keywords would be stochastic gradient descent, spin glasses and renormalization groups.

[reader5000]

Whether nns have an interpretation as spin systems is completely nonresponsive to the hardness of training them. Ie minimizing "free energy" in spin systems is as NP-hard as minimizing training error in nns.