  The quasiparticles in the normal state of cuprate superconductors have been
shown to behave universally as a 3-dimensional Fermi liquid. Because of
interactions and the presence of the Fermi surfaces (or Fermi energies), the
quasiparticle energy contains, as a function of the momentum $\boldmath{p}$, a
term of the form $(p-p_0)^3 \ln ( | p-p_0 | / p_0 )$, where $p = | \boldmath{p}
|$ and $p_0$ is the Fermi momentum. The electronic specific heat coefficient
$\gamma(T)$, electrical resistivity, Hall coefficient and thermoelectric power
divided by temperature $T$, follow the logarithmic formula $a - b T^2 \ln (
T/T^*) $, $a$, $b$, and $T^*$ being constant. Singularities in the Landau
$f$-function produce the $T^2 \ln T$ dependence of the magnetic susceptibility
$\chi (T)$, and Knight shift, which gives rise to the phenomenon of the
susceptibility maximum. The logarithmic $T$-dependence of the transport
properties arises exclusively from the impurity scattering in 3-dimensional
(3D) systems, but does not from the electron-electron scattering in 2D systems.
The above logarithmic formula has been shown to explain universally the
experimental data for the normal state of all cuprate superconductors. The
decrease of $\gamma(T)$ or $\chi(T)$ with decreasing $T$ is not due to the
appearance of pseudogap or spin gap but due to its $T^2 \ln T$ variation.
