On May 5, 5:24�pm, YBM wrote:
rbwinn wrote:
The speed c is squared everywhere it appears in the Lorentz
equations. �Have you ever wondered why? �Well, there is a reason. �(-
c)^2 = c^2

Just read any derivation of LT. Another argument is that any kind
of transformation cannot depend on the direction of a specific
velocity because they are arbitrate given the system of coordinate
you choose.

So with regard to whether the Lorentz equations are using speed of
light or velocity of light can only be determined by x and x', since
Einstein says x=ct, x'=ct', and I say that the equations should show
velocity of light. �

You confuse speed and velocity, this is hopeless...
Anyway let's try to clarify the issue :

Velocity is a 3-D vector, in the case of a uniform
movement this is quite simple : if a body is moving at
velocity (vx,vy,vz) then its equation of movement is :

(vector OM)=V.t + OA

where M is the position of the body at time t, A is
the coordinate of the body at time t=0. When you
are considering bodies moving along the x axis you
can omit y and z coordinate, hence identifying
OM with x.

In the case of light moving in "+x" direction :
V=(c,0,0)
x=ct

In the case of light moving in "-x" direction :
V=(-c,0,0)
x=-ct

Speed in the norm of the velocity vector : here in
both case : c.

So if x is a negative number in the Lorentz
equation for t', is c positive or negative in Einstein's little
equation? �Well, it has to be negative if t is positive, so the
Lorentz equations are using velocity of light, just as I said.

It doesn't make sense... How could someone be confused on such
elementary issues ? Your problem is not about LT, but about
what a equation of movement is, about what speed and velocity
are... No doubt you'll have some trouble with Galilean transformations
as well : it's all about the same things !

[...]

Well, what is quite obvious to me is that the velocity of a photon
traveling in the -x direction has a velocity of -c, something no
scientist will admit. �So here we are. �You think I am in doubt about
who is right

If you limit yourself to movments on the x axis (both direction),
you are perfectly right in calling (c,0,0) as c and (-c,0,0) as
-c, both are velocities, not speed. Everyone would admin that
-c or c can represent a velocity on such case.

[...]

Well, this is not trivial. �Your claim is that a photon traveling on
the x' axis in the -x' direction has a velocity of c. �I say it has a
velocity of -c. �We cannot both be correct. �Sorry, but you are the
one who is wrong.

I've never made such a claim... Please write less and read more.

P.S. your newsreader has problems with tabulations in messages, you'd
better switch to some decent software.

Good to see you back down. I will just have to live with whatever
Google does with tabulations. I am not subsidized by the government
the way scientists are.
Here is what I do with the Galilean transformation equations.

x'=x-vt
y'=y
z'=z
t'=t

x=wt
x'=wn'
w=velocity of light

wn'=wt-vt

n'=t(1-v/w)

n' is time on a cesium clock in S'. There is no distance
contraction.
Robert B. Winn