A better conceptual model for cooper pairs in a superconductor The conceptual model I have been introduced to for cooper pairs in a bulk superconductor is what I would call the "wake" model, where one electron deforms the positively charged lattice, changing the potential energy landscape and causing the second electron to be drawn closer. 
This seems like a terrible conceptual picture both because the electrons in a superconductor should have a well defined localized wave function and because the ground state of the BCS theory has zero net momentum, which would suggest they orbit around each other or something... 
If anyone can explain how I should be thinking about this I would be very grateful.  
 A: It is an incorrect picture to envision the Cooper pairs as existing as an isolated occurrence in a lattice, since the very existence of Cooper pairs depends on a supporting cast of other electrons.  In his work, Cooper showed that the ground state of a metal is unstable against an arbitrarily small net attraction between two electrons of opposite momentum, with this momentum near the Fermi momentum of the system.  Therefore, the energetically favorable state is the paired state, and the superconducting state exists when all of the conduction electrons are bound into such pairs. 
Further, something which is under-emphasized in the "wake model" is the size of the Cooper pairs in "classical" superconductors (ie, superconductors that have the pairing mechanism described by BCS theory). The spatial extent of Cooper pairs is quite large, on the order of thousands of angstroms (many, many lattice spacings), meaning that the pair condensation results in millions (or more) over lapping pairs.
In effect, in the superconducting state, these millions of paired electrons travel like a superfluid through the material.  
