Re: Simultaneity

On Aug 16, 2:27 pm, Tom Roberts <tjroberts...@xxxxxxxxxxxxx> wrote:
alen wrote:
On Aug 15, 10:06 am, Tom Roberts <tjroberts...@xxxxxxxxxxxxx> wrote:
As I said before, all that is needed to demonstrate that the string will
break is showing that in the ICIRF of a portion of the string the
rockets (string endpoints) are moving apart. And they are.

I guess, as usual on s.p.r., we are not going to be
able to agree. You are satisfied that they are moving
apart, but I see no evidence for it.

There is no "evidence", there is only a computation using SR -- this is
a GEDANKEN EXPERIMENT.

I see the ships as
always remaining the same distance apart.

That's your problem -- in SR "distance" depends on which frame is used
to measure it. Yes indeed, IN THE LAUNCH FRAME the rockets remain the
same distance apart. But that is IRRELEVANT because the string is not at
rest in that frame. In the string frame [#] the rockets are moving
apart, and THAT is what the string experiences -- being pulled apart by
the rockets.

        [#] There is actually a different frame for each small
        portion of the string. No matter, because for each small
        portion the rockets are moving apart in its ICIRF.

I don't regard
the spacetime theory as evidence that can refute this,
and regard the on-board instruments (clocks and
accelerometers) as much more relevant in proving
that the ships always remain the same distance apart,
and always share a common ICIRF.

This ENTIRE DISCUSSION is about a GEDANKEN EXPERIMENT. So there is no
"evidence", all there is is an analysis using SR. There are no rocket
ships, there is no string, and the non-existent rockets have no clocks
or accelerometers. IN THE ANALYSIS USING SR any clocks or accelerometers
aboard the rockets are IRRELEVANT to what happens to the string -- what
matters is what the string experiences IN ITS REST FRAME.

So this is the chasm that cannot be crossed.

Right. You need to learn what "gedanken experiment" means. And you need
to learn how a gedanken experiment is analyzed. And you need to learn
how to distinguish between aspects of a physical situation that are
relevant, and those which are not. And you need to learn how to apply SR.

Nonsimultaneity, here, really is
as magical as Alice in Wonderland, isn't it?

No. You are confused and keep switching frames and expecting
frame-dependent quantities to be independent of frame (such as when the
rockets started blasting, or the distance between the rockets). You
REALLY need to learn what SR actually says about such things. It is not
"magic", it is a valid and self-consistent MODEL of the world we
inhabit, within its domain (and it's domain includes everything in your
everyday life except gravity). Yes, it does not conform to your personal
expectations -- that is YOUR problem, not SR's.

        [This is going nowhere and is merely repeating; don't
         expect me to continue.]

Tom Roberts

Yes, I don't expect you waste your time continuing
with repetitions to which I am not able to give
my assent.

Alen
.

Relevant Pages

  • Re: BELLS PARADOX FOR DUMMIES
    ... Relativity that confounds many professional physicists. ... terms of one inertial frame of reference to another inertial frame of ... with a light string. ... their rockets at the same time w.r.t. their common rest frame. ...
    (sci.physics.relativity)
  • Re: Simultaneity
    ... all that is needed to demonstrate that the string>> will ... IN THE LAUNCH FRAME the rockets remain the ... This ENTIRE DISCUSSION is about a GEDANKEN EXPERIMENT. ...
    (sci.physics.relativity)
  • Re: Simultaneity
    ... all that is needed to demonstrate that the string>> will ... IN THE LAUNCH FRAME the rockets remain the ... This ENTIRE DISCUSSION is about a GEDANKEN EXPERIMENT. ...
    (sci.physics.relativity)
  • Re: BELLS PARADOX FOR DUMMIES
    ... Relativity that confounds many professional physicists. ... terms of one inertial frame of reference to another inertial frame of ... with a light string. ... their rockets at the same time w.r.t. their common rest frame. ...
    (sci.physics.relativity)
  • Re: Simultaneity
    ... rockets (string endpoints) are moving apart. ... IN THE LAUNCH FRAME the rockets remain the ... concerns within the framework of special relativity, ...
    (sci.physics.relativity)