A constant speed of light in all reference frames? Surely you can't be serious. [Physics]

Prev: Quantum Gravity 357.91: Croatia Shows That Probability of Vacuum Energy Density is More Important than its Vacuum Expectation Value (VEV) of the Hamiltonian Density, in line with Probable Causation/Influence (PI)
Next: Hubble Views Saturn's Northern/Southern Lights

From: PD on 3 Mar 2010 13:44

On Mar 3, 11:21 am, mpalenik <markpale...(a)gmail.com> wrote:
> 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)

Yes, ok, what you said and what I said are consistent. In the present
case, the ^ observer cannot verify that the events occurred
equidistant from the observer at the time of *emission*. This is what
marks the difference between Einstein's "train" gedanken (and my
variant) and yours.

There is another variant of the Einstein gedanken that I used when
trying to explain the same thing to Marcel a while ago. In it, there
are TWO pairs of events, one that emits green flashes and one that
emits yellow flashes. It is easy to set things up so that the green
flashes are simultaneous in one frame and not simultaneous in the
other frame, and the yellow flashes are vice versa. Then the symmetry
of the situation shows that it is impossible to decide which pair was
"really" simultaneous.

PD

From: mpalenik on 3 Mar 2010 14:52

On Mar 3, 1:23 pm, Ste <ste_ro...(a)hotmail.com> wrote:
> On 3 Mar, 12:40, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> wrote:
>
>
>
> > "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> >news:899e0123-23bd-47d9-b8d6-d32f3a59e32b(a)g10g2000yqh.googlegroups.com....
>
> > > On 3 Mar, 02:15, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> > > wrote:
> > >> Next, what is the fundamental cause (confining ourselves to SR) of
> > >> this non-simultaneity? As I say, as far as I can tell, it's a simple
> > >> function of the finite speed of propagation. But I'm told that it
> > >> isn't, so I need to know on what grounds a simple propagation
> > >> explanation does not suffice.
>
> > >> ________________________________
> > >> Hey! You asked a question about SR ! Far out!
>
> > >> The ultimate reason (or, more accurately "an" ultimate reason) is that
> > >> the
> > >> speed of light is the same in all inertial reference frames, and does not
> > >> depend on the speeds of two different observers. This makes the
> > >> propagation
> > >> delay a function of the frame of reference you pick, and not a function
> > >> of
> > >> the underlying dynamics.
>
> > > I won't pretend to understand how this is supposedly not a function of
> > > the speed of propagation.
>
> > Try and express your question more clearly.
>
> > What is it that you don't understand? You can't understand why what exactly
> > is not a function of the speed of propagation of what, exactly?
>
> Because, as far as I can tell, accounting for the relative distance
> between sender and receiver (and any changes in that distance) appears
> to fully account for the observed effects of SR.

See the thought experiment I just posted. It doesn't.

From: mpalenik on 3 Mar 2010 14:54

On Mar 3, 1:44 pm, PD <thedraperfam...(a)gmail.com> wrote:
> On Mar 3, 11:21 am, mpalenik <markpale...(a)gmail.com> wrote:
>
>
>
> > 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)
>
> Yes, ok, what you said and what I said are consistent.

Yeah, I thought I was responding to a similar looking message from
Ste. The paragraph I put that next to wasn't the one I meant to put
it next to, though. I should have read carefully after I clicked
reply.

From: mpalenik on 3 Mar 2010 15:01

On Mar 3, 12:52 pm, Ste <ste_ro...(a)hotmail.com> wrote:
> On 3 Mar, 12:30, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> wrote:
>
> > "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> > >> You say you are here to learn about SR.
>
> > > I am here to learn more about the *conceptual basis* of SR.
>
> > Minkowksi space time?
>
> No.
>
> > >> Do you believe SR is true?
>
> > > I accept it's mathematical form has some obvious truth, yes.
>
> > Do you believe that it correctly predicts the results of every experiment
> > that it claims to? That clocks run slower,
>
> No. In SR, clocks *appear* to run slower as you are increasing your
> distance from the clock. The effect is entirely apparent in SR.

You must just go through the entire thread and not pay any attention
to what anybody says. Ever.

1) What you've stated above is not an effect of SR. It is an effect
of propagation delay, which was used to calculate c from the motion of
the moons of jupiter hundreds of years ago.

2) If you were to move TOWARD the clock, it would appear to run
faster. But SR says nothing about whether you are moving toward or
away from an object.

3) The amount that the clock would appear to slow down is DIFFERENT
from the amount that SR predicts the clock *actually* slows down

3) This does not explain why atomic clocks on a jet register different
times AFTER being brought to rest than do their counterparts which
have been at rest the entire time--or why the difference in time that
they register is exactly consistant with the predictions of
relativity.

I know this isn't the first time this has been told to you, although
maybe not all at once. Do you just not pay any attention at all to
what anybody tells you?

From: Inertial on 3 Mar 2010 17:23

"Ste" <ste_rose0(a)hotmail.com> wrote in message
news:64d02f70-01e4-44a5-a5ab-41429bf37f71(a)q15g2000yqj.googlegroups.com...
> I'm sure I said something about the ludicrous assertions that some
> people here have made about the conceptual basis of SR. That is,
> assertions that verge on meaningless, like "rotation into time" as an
> explanation for length contraction. Or even observed time dilation (in
> SR) being "real" as opposed to merely a function of propagation
> delays. But none of this fundamentally challenges SR.

Time dilation isn't anything to do with propagation delays .. they do NOT
cause time dilation. It IS real in that it has been measured
experimentally.

Your denial of reality is another trademark of a crackpot.