By that is meant, if you have
say a very long pipe and some chemical is inserted in one end, immediately
at the other end the mathematical solution says some of the chemical will
appear. In the case of Schrodinger's equation this is why it isn't
consistent with special relativity.
Might it not still be consistent with special relativity if the phase
velocity and not the derivative of displacement is greater than c? I thought
that special relativity was concerned with energy and information not
travelling faster than c, and energy in a way tavells at the speed of the
particles, not at phase velocity.