scott_alexsk said:
So is there still a real argument between wave and particle theories, or do most, like zapperz, apply each when it is necessary instead of trying to create a unified theory?
-Scott
OK, for the LAST TIME, I will make this explictly clear - there is NO DUALITY in QM between "wave" and "particle". Let shock rings through the forum!
There's no separate description for "wave" and another separate description for "particle". QM simply doesn't differentiate between the two. It is only classical physics that distinguish one from the other and designate those to be incompatible behavior! But if you look at QM's description of the phenomena, there's just ONE for electrons, photons, neutrons, etc... No "duality"!
However, when you try to accurately describe a situation, you cannot simply rush into something head first! Even when we know that the "free electron" concept in metals isn't valid, the Drude model is still a good approximation for many cases - it is what gave you Ohm's Law! If that is all the one needs, it is absolutely stupid to force someone to treat electrons as complicted QM wave. This does nothing be create unnecessary complicatons that do not contribute to anything useful for such a simple scenario.
Note that even in more complicated scenario, especially in condensed matter physics, we STILL deal with a single-particle phenomenon. One can clearly see this via the Landau Fermi Liquid model in which the electronic many-body interaction has been renormalized into a many one-body quasiparticle problem. Here, you STILL talk about the quasiparticle as if it is a classical particle, with scattering rate, lifetimes, self-interaction, etc. Yet, this is purely a QM description using Second Quantization.
You want more? What about transport problem in solids? The description of optical, electronic, and thermal transport in matter are done, in many cases, using purely classical-like formulation - The Boltzmann transport equation! How light moves through a solid, how charge moves through a solid, and how heat moves through a solid, are accurately described in the majority of cases via a classical-like description. The distribution function and "forces" acting on the system are all using a classical particle pictures. Is there a QM description for this? You betcha! But there's a QM description to build your house too. It doesn't mean your contractor should use it!
Zz.