"Spaceman" wrote in message
...

"OG" wrote in message
...
| You need to ask HOW observer (B) would measure the separation between
the
| lines. Think of this as a real practical problem. How would YOU do it?
|
| When you have thought of a method, you then need to remember that
sucessive
| lines will be moving relative to the observer (B) with a speed of .5c -
this
| inevitably affects the measurement of the separation between the lines.

You stated " however the observer in (B)
wouldn't agree that the lines are 1 mile apart."

I did not make that statement, you did.
so...
It is you that should give a reason for such.

What makes you think that observer (B) would measure the same as observer
(A). He's not in the same coordinate frame at all is he?

If I were trying to "physically measure" something like such
I would turn around and stop the ship and physically measure
it in reality, so I would not have any problems
with the measurement being a "non physical" abstraction instead
that could be wrong compared to the physical reality of the
physical measurement.

Ah, but your measurement would not be made by observer (B), would it? After
all, while you have stopped, gone back and measured the separation between
two successive lines, maybe double checked them etc etc, observer (B) has
whistled off into the distance at a speed of .5c. Not the same thing at all
is it? Again, by stopping to measure the distances, you are removing (B)'s
involvement in the measurement.

I want to hear "your version" of why observer (B)
would not agree to the lines being 1 mile apart
since you stated such.

Of course,
The reason that (B) does not agree is because when you have one coordinate
frame moving relative to another, distance measurements made in one frame
are contracted relative to the measurements made in the other.

Since distance measurements in ANY coordinate frame depends on information
travelling between successive lines, the speed of light is an important
factor.

When you have two coordinate frames moving relative to each other, the ratio
of relative speed:light speed is important.