On 6 mayo, 01:19, rbwinn wrote:
On May 5, 9:08�pm, The Ghost In The Machine



wrote:
In sci.physics.relativity, rbwinn

�wrote
on Mon, 5 May 2008 13:30:45 -0700 (PDT)
:

On May 5, 12:07�pm, YBM wrote:
rbwinn a �crit :

On May 5, 11:18?am, YBM wrote:
rbwinn wrote:
Einstein's own equations for
velocity of light do not work in the Lorentz equations if x or x' are
negative.
Wrong. They work.

No, they do not work. �Einstein said that x=ct, x'=ct'. �If x is
negative, then

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

cannot be used with the equation x=ct. �The velocity of light has to
be -c in the equation for t' in order for the equation to work if x is
negative. � x=(-c)t, not x=ct.

Wrong.

Let's assume that x=ct

By LT we get :

x'= gamma*(x-vt)
t'= gamma*(t-vx/c^2) � �where gamma=1/sqrt(1-v^2/c^2)

let's have a look at x'/t' (*) under the condition that x=ct :

� x'/t' = (x-vt)/(t-vx^2/c^2) = (ct-vt)/(t-vct/c^2)
� � � � = t(c-v)/( t (1 - v/c) ) = c(c-v)/(c-v)
� � � � = c

= x'=ct'

(*) the case t'=0 is trivially ok (0=c0).

You neglect the fact that if x or x' is negative in the equations
x=ct, x'=ct', then either the velocity of light has to be negative or
time has to be negative.

The substitution x^2 = c^2t^2 works equally well, yielding
x'^2 = c^2t'^2. �This is a more accurate specification of the
problem anyway, as light expands spherically from a point source.

[rest snipped]

Well, what about a photon traveling in the +x direction reflected by a
mirror back in the direction it came from? I would just say it had a
velocity of -c.
I know that c^2 seems like a good idea to scientists. (-c)^2=c^2
Robert B. Winn

Assume you are in a rocket in deep space, and you are not feeling any
acceleration force whatsoever. From your window you see nothing (no
stars or other objects are visible) but another rocket who appears to
be approaching you.

Now, which is the correct answer that best describe the reality (or
truth) of the situation.

a) You are moving at a constant speed approaching a static rocket.
b) The rocket you see is moving at a constant speed towards your
location.
c) Both you and the approaching rocket are moving at constant speeds
towards each other.

This is the first step in understanding relativity.

Miguel Rios