On Mon, 30 Aug 2004 20:30:00 +0200, Theo Wollenleben
wrote:

Dirk Van de moortel wrote:
"Theo Wollenleben" wrote in message news
On Mon, 30 Aug 2004 15:27:19 +0200, Dirk Van de moortel
wrote:


The transformation equations are
x' = (x - v t) / sqrt(1-v^2/c^2)
t' = (t - vx/c^2) / sqrt(1-v^2/c^2)

That's right. Sorry for that mistake. But everything else I wrote was
right.


The best thing to do to never make a mistake, and to

Errare humanum est. It was a simple typo (forgotten "1/" in front of
right hand sides).

make sure that the ones who read it understand it
correctly, is to talk in terms of events.
Never say that A's clock is running slower than B's
clock. Never say that A measures time t and B
measures time t' and that t' t...
Always specify of *which events* A and B measure
times.

But it is common to say "Moving clocks run slower.". And the
corresponding formula to this sentence is (again):
t' = sqrt(1-(v/c)^2)*t.

To leave no doubt about what I mean:

Let A be the event when Bob starts from earth (set both clocks to t = t'
= 0 and x = x' = 0). And let B be the event (x = v*t, t) in Alice's
frame (it's an event on Bob's worldline). Then the coordinates of this
event B in Bob's frame are

x' = 1/sqrt(1-(v/c)^2) (x - v t)
= 1/sqrt(1-(v/c)^2) (v t - v t)
= 0 (unsurprisingly)
t' = 1/sqrt(1-(v/c)^2) (t - v/c^2 x)
= 1/sqrt(1-(v/c)^2) (t - v/c^2 v t)
= sqrt(1-(v/c)^2) t (time "dilatation" - "the shorter time t' t
has to be stretched (compared to t) between the two events" - this term
is in fact somewhat confusing)

I hope everybody agrees now (if we assume that special relativity is right).

(we don't..and it isn't)


Henri Wilson.
www.users.bigpond.com/hewn/index.htm

See proof that light speed is source dependent.
www.users.bigpond.com/hewn/variablestars.exe