Super Conductivity

 One of the most amazing applications of the formalism of quantum mechanics was the explanation by Baarden, Cooper and Schrieffer (BCS) of the phenomenon of Superconductivity. At low temperatures roughly about 4K it was noticed by Onnes that some metals appeared to have a dramatic reduction in their resistance. Whilst classical models were developed describing this phenomenon it wasn't until the 1950's that a microscopic version of the theory was developed. At first sight given the Pauli exclusion principle the phenomenon would seem impossible as it implies many electrons are occupying the same state. Which electrons being Fermions was impossible. Cooper realised at low temperatures there was the possiblity of an interaction between the lattice of the solid and the electrons causing them to effectively pair off. At low temperatures this interaction would be stable as the lattice vibrations would be relatively low. If electrons pair off their total spin becomes zero and they now behave like bosons for which it is possible for many bosons to occupy the same state. Thus the resistance of the metal is lowered BCS quickly realised that the properties of superconductors could be explained and they were awarded the Nobel prize for this work in 1972. 

Compared to the endless debates about the meaning or not of quantum mechanics which are going nowhere. This gives us a real insight into how nature works and ia a triumph of Mankinds ability to understand nature, something that will never come from discussing the meaning of the wave-function. As an interesting foot-note it was discovered in 1986 that some cuprates exhibited Superconductivity at much Higher temperatures than the 'normal ones' As yet there is no convincing explanation for this phenomenon so if you want a Nobel prize get cracking 😅

Here is my poem 

Super Conductivity

 

When it becomes very cold,

Nature becomes extremely bold.

All resistance suddenly dies,

An electric current really flies.

 

Electrons interact with the grid,

Combined in pairs they are hid.

This really ingenious tactic,

Was explained by a quantum mechanic¹⁾

1)    Someone who uses their knowledge of quantum mechanics to explain a feature of nature. In this case it was Cooper (what a clever fellow 😅😅 ).