Androcles <Me@May.2012> wrote in message
  J0usr.436195$o93.317273@fx05.am4
> "Dirk Van de moortel" <dirkvandemoortel@hotspam.comnot> wrote in
> message news:4fb20fe8$0$3118$ba620e4c@news.skynet.be...
> > Androcles <Me@May.2012> wrote in message
> >   ikJrr.403715$o93.207265@fx05.am4
> > > "Henry Wilson DSc." <..@..> wrote in message
> > > news:4s0uq7dl1f9utrh0gnhdg6h2qa37e8qnmr@4ax.com...
> > > > On Sun, 13 May 2012 00:15:12 +0100, "Androcles" <Me@May.2012>
> > > > wrote:
> > > > > "Henry Wilson DSc." <..@..> wrote in message
> > > > news:ktotq7pa4kbeffchbb3s0iqtqb09qed7qh@4ax.com...

[snip]

> > > > > > It doesn't. Why don't you give up that silly line of argument.
> > > > > > You have the equations arse up.
> > > > > 
> > > > > L = L0 * sqrt(1-v^2/c^2) (LET)
> > > > > xi = x' / sqrt(1-v^2/c^2) (SR)
> > > > > 
> > > > > http://androcles01.pwp.blueyonder.co.uk/SR4kids/x'=x-vt.gif
> > > > > 
> > > > > I do NOT have the equations arsed up, YOU do.
> > > > >
> > > > So here the notation x' stands for
> > > >    x' = x - v t,
> > > > and the equation is
> > > >    xi = (x - v t) /sqrt(1-v^2/c^2)           [1]
> > > 
> > > That's right, shithead.
> > > 
> > > 
> > > 
> > > > The other relevant equation is
> > > >    tau = (t - v/c^2 x) /sqrt(1-v^2/c^2)        [2]
> > > 
> > > If you knew any algebra you'd see it was
> > > tau = t * sqrt(1-v^2/c^2) as Einstein states in
> > > 
> > > http://www.fourmilab.ch/etexts/einstein/specrel/www/figures/img61.gif
> > > 
> > > But you don't, you stupid thick fumbling bastard, so fuck off.
> > 
> > You mean as in
> >  http://www.fourmilab.ch/etexts/einstein/specrel/www/figures/img60.gif
> > 
> > 
> No, I mean if you knew any algebra you'd see it simplifies to
>  tau = t * sqrt(1-v^2/c^2) as Einstein states in
>  http://www.fourmilab.ch/etexts/einstein/specrel/www/figures/img61.gif
> 
> but you don't know any algebra, you stupid thick fumbling fuckwit,
> so fuck off.

[unsnip]

> > > > Equations [1] and [2] are fully equivalent with
> > > >     x = (xi + v tau) /sqrt(1-v^2/c^2)           [3]
> > > >     t = (tau + v/c^2 xi) /sqrt(1-v^2/c^2)        [4]
> > > > 
> > > > We can use these equation to express the length of a ruler
> > > > which is at rest in the (x,t) system having length L0 there,
> > > > and moving in the (xi,tau)-system: having length L there.
> > > > 
> > > > Since it is moving in the (xi,tau)-system, the coordinates
> > > > MUST have the SAME tau-value, so we can take equation [3]:
> > > >     x1 = (xi1 + v tau1) /sqrt(1-v^2/c^2)           [3-1]
> > > >     x2 = (xi2 + v tau2) /sqrt(1-v^2/c^2)           [3-2]
> > > > 
> > > > Now, with the assumptions
> > > >     L0 = x2 - x1    = the length in the (x,t)-system
> > > >     L = xi2 - xi1   = the length in the (xi,tau)-system
> > > >     tau1 = tau2
> > > > we subtract equation [3-1] from [3-2] side by side, giving
> > > >     L0 = L /sqrt(1-v^2/c^2)
> > > > and thus
> > > >     L = L0 * sqrt(1-v^2/c^2)
> > > > saying that the moving ruler will be SHORTER than when
> > > > it is measured at rest.
> > > > 
> > > > So the equations
> > > >     L = L0 * sqrt(1-v^2/c^2) (LET)
> > > >     xi = x' / sqrt(1-v^2/c^2) (SR)
> > > > are fully compatible, and the first equation directly follows from the
> > > > second, provided one understands the meanings of the variables in
> > > > the equations.
> > > > 
> > > > Dirk Vdm