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From: PD on 3 Mar 2010 11:56
On Mar 3, 6:28 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
> On Mar 3, 1:33 am, "Inertial" <relativ...(a)rest.com> wrote:

>
> > So you understand it and think it is correct?
>
> > What exactly *IS* your position?- Hide quoted text -
>
> > - Show quoted text -
>
> I understand it and think it is correct.
>
> My position is that far more people would understand it if it was
> explained differently.

Like all pedagogical strategies, something is best understood if it is
explained in several different ways. Some readers will "see" it with
presentation B, rather than A, C, or D. Other readers will need to see
both A and C but find B incomprehensible. Others still will get it
after reading A, B, and C, and will only appreciate D after having
grasped the others.

Again, there is a marked difference between the value of a theory, and
the value of the different ways to explain the theory.

From: mpalenik on 3 Mar 2010 12:04
On Mar 3, 11:21 am, PD <thedraperfam...(a)gmail.com> wrote:
> On Mar 2, 8:12 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
>
>
> > > It is not a function of finite propagation speeds, this we know,
> > > because we took into account the finite propagation speeds in our
> > > procedure for determining simultaneity/nonsimultaneity. Do you not
> > > remember that?
>
> > I beg to differ.  It is not a "mere" or "simple" function of finite
> > propagation speed, but it *is* a function of it IMO.  RoS only took it
> > into account by allowing us to use different time coordinates in each
> > frame.  If the speed of light was infinite there would be no RoS.
>
> I disagree. All that is needed in relativity of simultaneity is a
> signal speed that can be VERIFIED to be the same from both events by
> either observer. Since the distance from the events to the observer is
> equal, as verifiable at any time by each observer, we learn from this
> that each observer KNOWS the propagation delays from each event to the
> observer are equal. This acknowledges the propagation delays
> completely, but simply allows for verification that they are the same.
> Then the determination of simultaneity or nonsimultaneity of the
> original events is completely unambiguous: If the observer receives
> both signals at the same time, then (because the propagation delays
> are the same) the original events were simultaneous; if the observer
> receives both signals at different times, then (because the
> propagation delays are the same) the original events were
> nonsimultaneous.


Ste, there is a very easy thought experiment that I posted a few pages
back that proves this wrong. Get someone to run through it with you.
I don't have the patience or time. Even if a moving observer receives
two pulses at the same time while half way between the two sources, he
will conclude that they were not emitted at the same time BECAUSE the
speed of light is the same in every frame. If the speed of light were
different in the moving observer's frame (like it is with sound), you
would be correct. But since the speed of light is the same in the
moving observer's frame as in the rest frame, he has no choice but to
conclude that the two pulses were emitted at different times, despite
the fact that he receives them at the same time and he is half way
between the two emitters.
From: Ste on 3 Mar 2010 12:05
On 3 Mar, 11:53, "Inertial" <relativ...(a)rest.com> wrote:
> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> > (a bit like how
> > Christians claim the Bible characterises the practice of their
> > religion).
>
> They don't .. not if they know what they are saying.  They may claim that
> concepts and principles that they chose to find in the bible are the basis
> for how they practice their religion .. but Christian religious practice
> (which varies considerably from denomination to denomination) is certainly
> never solely based on the bible.  Indeed, much of what is practiced has no
> valid biblical basis, but is rather cultural and historical traditions.
>
> However, as with most religions, there are a set of beliefs that one who is
> to be a member of a religion must hold to be true, whether or not there is
> any evidence or proof of those beliefs.

Indeed. And the same is true of science! The "scientific method" is
about as correspondent with reality as the Bible.



> > I'm not gloating because some here were proved wrong.
>
> Not so much wrong, but the way they expressed what SR says was poor

Yes, and more than one person managed to "express themselves poorly"
on more than one occasion, even despite my repeated corrections.
From: PD on 3 Mar 2010 12:15
On Mar 3, 11:04 am, mpalenik <markpale...(a)gmail.com> wrote:
> On Mar 3, 11:21 am, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Mar 2, 8:12 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > > It is not a function of finite propagation speeds, this we know,
> > > > because we took into account the finite propagation speeds in our
> > > > procedure for determining simultaneity/nonsimultaneity. Do you not
> > > > remember that?
>
> > > I beg to differ.  It is not a "mere" or "simple" function of finite
> > > propagation speed, but it *is* a function of it IMO.  RoS only took it
> > > into account by allowing us to use different time coordinates in each
> > > frame.  If the speed of light was infinite there would be no RoS.
>
> > I disagree. All that is needed in relativity of simultaneity is a
> > signal speed that can be VERIFIED to be the same from both events by
> > either observer. Since the distance from the events to the observer is
> > equal, as verifiable at any time by each observer, we learn from this
> > that each observer KNOWS the propagation delays from each event to the
> > observer are equal. This acknowledges the propagation delays
> > completely, but simply allows for verification that they are the same.
> > Then the determination of simultaneity or nonsimultaneity of the
> > original events is completely unambiguous: If the observer receives
> > both signals at the same time, then (because the propagation delays
> > are the same) the original events were simultaneous; if the observer
> > receives both signals at different times, then (because the
> > propagation delays are the same) the original events were
> > nonsimultaneous.
>
> Ste, there is a very easy thought experiment that I posted a few pages
> back that proves this wrong.  Get someone to run through it with you.
> I don't have the patience or time.  Even if a moving observer receives
> two pulses at the same time while half way between the two sources, he
> will conclude that they were not emitted at the same time BECAUSE the
> speed of light is the same in every frame.  If the speed of light were
> different in the moving observer's frame (like it is with sound), you
> would be correct.  But since the speed of light is the same in the
> moving observer's frame as in the rest frame, he has no choice but to
> conclude that the two pulses were emitted at different times, despite
> the fact that he receives them at the same time and he is half way
> between the two emitters.

???
From: mpalenik on 3 Mar 2010 12:21
On Mar 3, 12:15 pm, PD <thedraperfam...(a)gmail.com> wrote:
> On Mar 3, 11:04 am, mpalenik <markpale...(a)gmail.com> wrote:
>
>
>
> > On Mar 3, 11:21 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Mar 2, 8:12 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > > > It is not a function of finite propagation speeds, this we know,
> > > > > because we took into account the finite propagation speeds in our
> > > > > procedure for determining simultaneity/nonsimultaneity. Do you not
> > > > > remember that?
>
> > > > I beg to differ.  It is not a "mere" or "simple" function of finite
> > > > propagation speed, but it *is* a function of it IMO.  RoS only took it
> > > > into account by allowing us to use different time coordinates in each
> > > > frame.  If the speed of light was infinite there would be no RoS.
>
> > > I disagree. All that is needed in relativity of simultaneity is a
> > > signal speed that can be VERIFIED to be the same from both events by
> > > either observer. Since the distance from the events to the observer is
> > > equal, as verifiable at any time by each observer, we learn from this
> > > that each observer KNOWS the propagation delays from each event to the
> > > observer are equal. This acknowledges the propagation delays
> > > completely, but simply allows for verification that they are the same..
> > > Then the determination of simultaneity or nonsimultaneity of the
> > > original events is completely unambiguous: If the observer receives
> > > both signals at the same time, then (because the propagation delays
> > > are the same) the original events were simultaneous; if the observer
> > > receives both signals at different times, then (because the
> > > propagation delays are the same) the original events were
> > > nonsimultaneous.
>
> > Ste, there is a very easy thought experiment that I posted a few pages
> > back that proves this wrong.  Get someone to run through it with you.
> > I don't have the patience or time.  Even if a moving observer receives
> > two pulses at the same time while half way between the two sources, he
> > will conclude that they were not emitted at the same time BECAUSE the
> > speed of light is the same in every frame.  If the speed of light were
> > different in the moving observer's frame (like it is with sound), you
> > would be correct.  But since the speed of light is the same in the
> > moving observer's frame as in the rest frame, he has no choice but to
> > conclude that the two pulses were emitted at different times, despite
> > the fact that he receives them at the same time and he is half way
> > between the two emitters.
>
> ???

I'll post it again:

------x-----

^

------x-----

An object, indicated by the "^" is moving vertically along the
screen. The two x's send out light pulses simultaneously in the rest
frame that both reach the moving ^ when it is exactly half way between
the two x's.

Because of this, the ^ will recieve both pulses simultaneously in
every frame--however, in the ^ frame, the observer will say that the
two x's did not emmit the light pulse simultaneously, even though he
recieved both pulses simultaneously.

This proves that SR has nothing to do with correcting for propagation
delays. I don't have the time or patience to explain this to Ste, but
I'm sure it's easily comprehensible to everyone else.

(PD: note that since it's the x's moving in the ^ frame, and since the
light is emitted when the lower x is closer to the ^ and the upper x
is farther, the moving ^ must conclude that the light from the upper x
was emitted first, even though both pulses hit him at the same time.
This is because the light is moving at speed c in his frame and not c
+v and c-v. This probably isn't clear to Ste, but I think you see
what I'm going for)
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