Subject: Is thermal noise 'truly' random?

Like, for example, the electrical noise residual in any source warmer 
than absolute zero. We are told that heat causes (or is stored as) 
"random" agitation of atoms, hence Brownian motion and so on. Is this 
chaotic but deterministic or truly non-deterministic like quantum 
uncertainty? (I don't know the mechanism of it, maybe it *is* a 
quantum phenomenon, seen at some level.) A pointer to a solid discussion of 
what this "random heat motion" amounts to would be very helpful. (I can't 
even lay hands on my Fenyman Lectures right now!)

Re: Is thermal noise 'truly' random?