  Our goals are to assist a non-practitioner understand likely resolution of
the controversy about the boson that couples Cooper pairs in Cu oxides and to
consider if high temperature superconductivity (HTS) in solid oxides might be
related to predicted HTS in liquid metallic hydrogen (LMH) near 0 K. High
temperatures (T~Tc~!D~100 K, where Tc is superconducting critical temperature
and !D is the Debye temperature) induce phonon-phonon scattering in ordered
materials, which is sensitive to impurities and disorder. Experimental results
suggest the boson that couples Cooper pairs in Bi2SrCa2Cu2O8 is incoherent ion
vibration caused by disorder, which is observed from ~100 K down to 4 K.
Phonons are not well-defined in BSSCO and its coherence length is comparable to
the dimension of its unit cell (~1 nm), as for other oxides. Sr2CuO3+d (Tc=95
K) has a crystal structure that enables experimental demonstration that
disorder of apical oxygen atoms has a strong affect on Tc. Disorder in sold
oxides on an atomic scale and the temperature dependence of phonons at high
temperatures (T~!D) probably must be taken into account to understand HTS.
There are several reasons to believe that LMH will be a high temperature
superconductor and no known reason why LMH cannot be one.
