This statement made in an explanation of addition of velocities shows
the confusion existing in the minds of scientists about velocity of
light.
"The constancy of light (Einstein's dictum) tells us that the velocity
of light in the forward direction is equal to the velocity of light in
the backward direction, i.e. CF = CB = C."

Relative to a set of coordinates S, if a photon is traveling on the x
axis in the +x direction, it has a velocity of c. If a photon is
traveling on the x axis in the -x direction, it has a velocity of
(-c). Scientists do not seem to be aware that the Lorentz equations
automatically resolve the velocities of photons because c is always
squared in those equations, and the velocity of a photon is only shown
implicitly in the variables x and x'. Einstein's own equations for
velocity of light do not work in the Lorentz equations if x or x' are
negative. The equations x=ct and x'=ct' should have been x=wt and
x'=wt', where w is the velocity of light. This can be shown by
considering the equation for t'.

t'=(t-vx/c^2)/sqrt(1-v^2/c^2)

If x is negative, then w = (-c).
What Einstein was actually doing was using photons as clocks, but
without the Lorentz equations to keep velocities straight, his logic
did not hold together because CF does not = CB as this statement
claims is shown by Einstein's dictum. This results in the devotion
that scientists of today have for the distance contraction generated
by the Lorentz equations.
Robert B. Winn