  Unphysical equations of state result from the unrestricted use of the Synge
G-trick of running the Einstein field equations backwards; in particular often
this results in $\rho + p < 0$ which implies negative inertial mass density,
which does not occur in reality. This is the basis of some unphysical spacetime
models including phantom energy in cosmology and traversable wormholes.
  The slogan ``ER = EPR'' appears to have no basis in physics and is merely the
result of vague and unbridled speculation. Wormholes (the ``ER'' of the slogan)
are a mathematical curiosity of general relativity that have little to no
application to a description of our universe. In contrast quantum correlations
(the ``EPR'' of the slogan) are a fundamental property of quantum mechanics
that follows from the principle of superposition and is true regardless of the
properties of gravity.
  The speculative line of thought that led to ``ER = EPR'' is part of a current
vogue for anti-geometrical thinking that runs counter to (and threatens to
erase) the great geometrical insights of the global structure program of
general relativity.
