Re: What is Proper Time?

Dr. Henri Wilson wrote:
On Thu, 28 Feb 2008 13:34:26 +0100, "Paul B. Andersen"
<paul.b.andersen@xxxxxxxxxxxxxxxx> wrote:

The Ghost In The Machine wrote:
In sci.physics.relativity, Paul B. Andersen
<paul.b.andersen@xxxxxxxxxxxxxxx>

Is the expression "the reading of a clock" confusing you?
If you look up the word "reading" in Webster, you will see
than one of its meanings is "data indicated by an instrument".
So "the reading of a clock" means "the data indicated by the clock".
Whether or not anybody is visually observing the clock is utterly
irrelevant to what the clock is reading.
Not at all. How am I supposed to read a clock without
light getting involved? If you wish to postulate
infinite-speed particles, be my guest, but such a postulate
runs afoul of a fairly fundamental SR assumption.

Without such particles there is an inherent delay in the
clock, say, striking 12, and the record of that striking
reaching an observer some distance away...and in most
problems of this type the observer is moving, complicating
the issue even more.

Of course the "delay" is not directly observable.
Come on, Ghost.
You know better that this, don't you?

Look at what you are saying.
You are disagreeing to the statement:
"The reading of a clock is frame independent"
because all practical clocks will have a finite
precision.

You might as well say:
"The speed of light is observer dependent because
different observers will because of the finite
precision of their instruments measure slightly
different speed of light."

So:
The reading of a clock is an invariant.
Observer independent.
Not depending on frames of reference.
The same in all frames.

A pedant should know this.

Depends on when the clock is in fact read. The clock
striking 12 defines a locus -- the traditional depiction
is a cone in 3-space but it's really a cone in 4-space,
the solution to the equation (x-x0)^2 + (y-y0)^2 + (z-z0)^2
- c^2(t-t0)^2 = 0 -- and all observers intersecting that
locus will observe the strike at the point of intersection.
The trouble is that their movement distorts the space
in a characteristic fashion (as they see the world),
making life interesting from a computational standpoint.
Best I can do here is solve the 4-dimensional equivalent
of the Lorentz, giving it the desired clock reading.

It turns out this results in an equation

(x'-x'0)^2 + (y'-y'0)^2 + (z'-z'0)^2 - c^2(t'-t'0)^2 = 0

so the cone is not distorted, strangely enough, though
it is shifted. Furthermore, (x'0,y'0,z'0,t'0) is
(x0,y0,z0,t0) run through the Lorentz.
Oh, my dear. :-)

"The clock striking 12" defines an event,
a 'point' on its world line.

You cannot seriously claim that the proper time
of the clock at this event depend on arbitrary
observers seeing or hearing the clock, can you?

And a comment to your (quite irrelevant) "light cone".
It is never called a cone it 3-space,
it is an expanding sphere (2-surface)in 3-space,
and a cone (3-surface) in 4-space.

It is hard to imagine how anyone can misinterpret to such an extent what Ghost
is saying and try to complicate a simple issue with meaningless jargon.

Here's a simpler version of the problem.

Let there be a very LOUD sonic clock positioned at the N pole.

Every ten seconds, it yells out the time for everyone in the world to hear.

Do you really believe everybody receives the same time reading simultaneously?
Do you really believe that 4D 'spacetime' has any significance in explaining
what is happeneing.

You are just as full of crap as the rest of your indoctrinated
colleagues....and a constant source of amusement....


I think the fact that you are defending
Ghost should make him think! :-)

--
Paul

http://home.c2i.net/pb_andersen/
.

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