The theory of high- T<SUB>c</SUB> superconductors — comparisons with experiment

We show that the "normal" metal from which high- Tc oxide superconductors condense is a two-dimensional quantum spin fluid whose low-energy excitations are fermions with spin and no charge (spinons) and bosons with charge and no spin (holons). Conventional electron excitations cost 0.5 to 1 eV of energy. At Tc the holons pair condense due primarily to cooperative interlayer Josephson tunneling. We will discuss a number of experimental consequences of the above, and possibly also new developments in the theory of the insulating RVB