Re: Einstein's Train Gedanken Re-visited

On Jun 14, 8:30 am, Uncle Ben <b...@xxxxxxxxxxx> wrote:
On Jun 14, 6:46 am, "Androcles" <Headmas...@xxxxxxxxxxxxxxxx> wrote:> "G" <gehan.ameresek...@xxxxxxxxx> wrote in message

news:7ab963ee-23dc-4e57-8b6e-fbadf806b457@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jun 13, 6:16 pm, "Androcles" <Headmas...@xxxxxxxxxxxxxxxx> wrote:

http://tinyurl.com/c53cqo

Thanks for the hyperlink, but I have read the scruffy rat theory and
it is not clear to me where A and B are

Let me put it this way;

...

No, let's not. Instead, let's help Androcles sort out his scruffy
story.

The references to A and B are found in Einstein's famous 1905 paper
that shook the world. In particular they refer to a thought xperiment
described the first section, called the "Kinematical Part", after the
introduction, in subsection 2.

There Einstein first raises the question, if clocks are synchronized
in one inertial frame of reference, are they thereby also synchronized
with respect to another frame of reference in motion with respect to
the first.  His result, no, they are not.

To synchronize clocks well apart from each other, Newton assumed that
there is no problem: time is universal and absolute.  But to be
consistent with Maxwell's theory, AE has to question that assumption.
If the speed of light is to be a universal constant, as he proposes,
he uses that postulate to define synchronization with light rays as
Androcles describes.

So AE uses a rod to define distance, uses c as his standard, and
imagines clocks synchronized along the x axis of a frame of reference
that he calls the "statioary system," although one must not get too
attached to the term "stationary," which has no privileged status in
relativity.

A abd B are the coordinates of the ends of the rod, as Androcles could
have said at the outset, since he finally admits that he knew very
well.

To answer the present question, "Are the clocks just set up
synchronized also with respect to another frame of reference moving at
speed v w.r.t. the first system?", he sets out in imagination with the
rod now moving at v along with two moving observers at points A and B.

His moving observers test the clocks of the stationary system for
synchronization.  They send light from A to B and then back to A.  We
know from our omniscient position as readers that it is not going

to work:  Because of the motion of the rod while the light is
travelling, the time to go from A to B according to the stationary
system is now longer than it was when the rod was at rest in that
system, and the return time is now shorter.  (The round trip is also
shorter, as any first-year physics student should be able to show.)
Thus the clocks are not synchronized w.r.t. the moving observers.

This line of reasoning is based on the bogus assumption that the
"stationary" observer asserts that speed of light in the moving frame
of A and B is anisotropic. It violates the SR postulate that the speed
of ight is isotropic in all inertial frames.

Ken Seto




(Note: I avoided the term "closing speed" so as not to cause Androcles
heart failure.)

How can they fix this problem?  They have to build their own clock
system. Their clocks must be re-synchronized.  In particular a moving
clock at B must be set to the time that Androcles ridicules: (t1+t2)/
2, in an obvious notation. Time is relative!

How can this be justified?  The biggest point that Androcles misses is
that the "moving" observers are entitled by his new Principle of
Relativity to consider themselves stationary and the other system as
moving backwards.  Therefore their synchronization should be just as
valid in their system as the original process in the "stationary
system."

In other words, Androcles missed the whole point of the exercise.

If he didn't have such a foul mouth and horrible personality, I would
say that Androcles is still a good person in spite of his error.  But
that would obviously be incorrect.

Uncle Ben

.

Relevant Pages

  • Re: Einsteins Train Gedanken Re-visited
    ... let's help Androcles sort out his scruffy ... There Einstein first raises the question, if clocks are synchronized ... he uses that postulate to define synchronization with light rays as ... rod now moving at v along with two moving observers at points A and B. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... he uses that postulate to define synchronization with light rays as ... rod now moving at v along with two moving observers at points A and B. ... Thus the clocks are not synchronized w.r.t. the moving observers. ... physics student will find that the round-trip time computed from the ...
    (sci.physics.relativity)
  • Re: Hansen discovers how to reason.
    ... His procedure is, after all, for a stationary observer ... Which point, A or B, is moving in k? ... >> clocks in a moving frame synchronizes his own clocks, ... > contributors would then say " Good ol' Androcles, ...
    (sci.physics)
  • Re: Hansen discovers how to reason.
    ... His procedure is, after all, for a stationary observer ... Which point, A or B, is moving in k? ... >> clocks in a moving frame synchronizes his own clocks, ... > contributors would then say " Good ol' Androcles, ...
    (sci.physics.relativity)
  • Re: What are the SR predictions for these experiments??
    ... No. Moving is moving. ... >>Synchronization is a procedure ONLY on clocks that are ... IF the clocks are brought to ... >> Is the ruler stationary with respect to A or with respect to B? ...
    (sci.physics)
Quantcast