Failures

• The Hall coefficients are predicted to be independent of temperature, relaxation time, magnetic field, but in practice they do depend on these quantities.

• In practice the magnetoresistance does not vanish.

• The Wiedemann-Franz law is observed experimentally only at high (room) temperatures and very low (a few degrees K) temperatures, but fails at intermediate ones.

• DC electrical conductivity depends on temperature and, in some materials, even on the direction of transport.

• The linear term in the specific heat has the correct size for the alkali metals, but not for noble metals and transition metals.

• Experimentally one finds a cubic term in the specific heat which is definitely not due to high temperature corrections to the Sommerfeld calculation because of the different sign and the significantly different order of magnitude.

• There are some fundamental mysteries in the basic assumptions: Why, if all valence electrons should become conduction electrons, are there metals which apparently show different valencies or even fractional valencies? Why are there insulators which have valence electrons while in atomic state?