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

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From: Bruce Richmond on 6 Mar 2010 01:20

On Mar 5, 1:04 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
wrote:
> > You are reading more into that than what I wrote. I am not choosing
> > LET over SR. They use the same math
> > ==================================================
>
> Well, e = mc^2 is maths. It appears in SR, but not LET.
>
> So I guess you were wrong, and they don't use the same maths.

It can be derived using LET. SR wasn't the first place it showed up,
so it doesn't own it any more than LET does.

Others here say they use the same math, so I guess you are wrong :)~

From: Jerry on 6 Mar 2010 05:21

On Mar 5, 10:43 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
> On Mar 5, 12:08 am, Jerry <Cephalobus_alie...(a)comcast.net> wrote:
> > On Mar 4, 10:33 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:

> > > The author is kind enough to point out problems in some similar
> > > experiments, while failing to notice any in his own.
>
> > > For example, has he made any assumption about contraction of his
> > > equipment in the direction of motion? Tom Roberts has written posts
> > > in this group showing where some of these experiments are in effect
> > > two way measurements.
>
> > Do you understand the principle of Gagnon's experiment? Do you
> > understand the inverse relationship between group velocity and
> > phase velocity that exists in a wave guide? Do you understand
> > that length contraction would be a second order phenomenon, while
> > Gagnon's experiment should be sensitive to first order, assuming
> > an anisotropy exists? Do you understand that Gagnon's experiment
> > is a true one-clock measurement of OWLS anisotropy? Do you
> > understand the difference between an attempt to detect OWLS
> > anisotropy versus an attempt to perform a one way light speed
> > measurement?
>
> I know what OWLS is, and I know what assume means.
>
> > On the negative side, I probably know a lot more about defects
> > in Gagnon's experiment than you have ever dreamed of. Gagnon
> > drove the wave guides near cutoff. What does that imply about
> > heating? Take a good look at the test theory that they used to
> > analyze their results. Do you notice something about its internal
> > consistency in terms of an important criterion that I shall not
> > name, but which you ought to be aware of? Is the fact that the
> > test theory does not meet this standard of internal consistency
> > important in their analysis? Can you guess what this problem is?
> > Can you guess why I consider Gagnon et al. to be an important
> > experiment, despite some problems in analysis?
>
> > Start with the basics. I've given you important clues. How does
> > Gagnon et al's xperiment work?
>
> I haven't looked it over that closely but off hand I would say it is a
> gussied up MMX.

No, their experiment was very different from MMX.
http://mysite.verizon.net/cephalobus_alienus/papers/Gagnon_et_al_1988.pdf

There is a reciprocal relationship between group velocity and
phase velocity in a waveguide. Depending on the frequency, a
typical waveguide transmits microwave signals at 70% of the speed
of light. However, the phase velocity would be 140% of the speed
of light (the product of group velocity and phase velocity is c^2).

Gagnon et al. used two parallel waveguides with different cutoff
frequencies, one close to the oscillator frequency, the other
widely different from the oscillator frequency. At the cutoff
frequency, the wavelength in an ideal waveguide would become
infinite,and there would no longitudinal position dependence for
the electrical phase of the wave along the waveguide. At the far
end of the waveguides, Gagnon et al. situated a phase comparator.

The signal was injected at one end of the two waveguides. The
phase difference was measured at the other end of the two
waveguides. Here is an ascii art representation of their setup:

---------------------------------------------------
---------------------------------------------------
@ >
===================================================

The top parallel set of hyphens represents the first waveguide.
The equal signs represents the second waveguide.
The @ represents the oscillator at one end.
The > represent the phase comparator at the other end.

In the first waveguide (operating at close to cutoff frequency),
the phase of the RF exiting the waveguide would be essentially
identical to the phase of the RF entering the waveguide. In the
second waveguide, variation in OWLS would alter the phase of the
RF exiting the waveguide as a first-order effect. So DEPENDING ON
THE THEORY BEING TESTED, the setup should be highly sensitive to
anisotropies in the one way speed of light (OWLS).

if you wish to measure OWLS, you need synced clocks at different
points. The hidden assumption in most measurements of OWLS is
that the synchronization procedure for the clocks either involves
two-way signaling (as for instance in Einstein synchronization),
or can be shown to be equivalent to the Einstein sync procedure.

Gagnon et al. didn't measure OWLS. Rather, they measured
DELTA OWLS. That's a -very- different measurement, and hence
they were able to use a single clock.

If Tim Lincecum simultaneously throws a baseball and a paper
airplane to you against the wind, you do not need a clock
synchronized to Lincecum's watch to determine that they arrive
at your location at different times.

Gagnon et al. "threw" two continuous RF beams simultaneously in
the same direction, one, like the baseball, relatively
insensitive to any hypothetical aether wind, the other, like the
paper airplane, sensitive to a classical aether wind.

There are no hidden assumptions concerning clock synchronization
in their experiment. They did make assumptions, however, about
their "test theory" that turn out to have been unwarranted.
Gagnon et al. believed that their setup was capable of
distinguishing between between LET and SR. In other words, they
believed their experiment capable of detecting a LORENTZIAN
aether wind. This turns out to have been wrong.

Despite defects in their test theory that led them to erroneous
conclusions concerning their ability to distinguish between LET
and SR, the experiment of Gagnon et al. is important because it
represents a true one-clock measurement of OWLS anisotropy.

Jerry

From: Ste on 6 Mar 2010 06:12

On 5 Mar, 14:46, mpalenik <markpale...(a)gmail.com> wrote:
> On Mar 5, 3:55 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > So what you're saying (and I had recognised this problem before you
> > said it) is that it is the "original" position of emission that
> > matters?
>
> > And the "original" position changes depending on the frame (i.e. in
> > the source frame, the source does not move, whereas in the receiver
> > frame, the sources are constantly moving from their "original"
> > positions)?
>
> Right. The sources send out one pulse at one particular point in
> time. The only thing that matters is where they were located when
> they sent out that pulse. That location is the "source" of the pulse.

Ok. But one observation I would make first is that, I presume, from
the source inertial frame, both the rising and falling edges of the
wave have the same origin. However, in the receiver inertial frame,
the rising edge does not have the same origin as the falling edge - so
there is a lack of symmetry between what is being described in these
inertial frames.

Secondly, we talk of the sources being in a "particular place" when
the pulse is emitted, and yet by your own argument they are not in a
"particular place" at all - in one frame, the sources are in the same
place at all times, and in the other frame, the sources are never in
the same place for more than an instant. So is it really meaningful to
talk of the "place of origin" of the source as a well-defined, single
point in space and time?

From: Ste on 6 Mar 2010 06:41

On 5 Mar, 16:02, PD <thedraperfam...(a)gmail.com> wrote:
> On Mar 5, 2:55 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
>
>
>
>
> > On 4 Mar, 18:12, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Mar 4, 12:04 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > On 4 Mar, 17:46, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > On Mar 4, 11:17 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > > > On 4 Mar, 16:49, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > > > > > On Mar 4, 11:45 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > > > > > On 4 Mar, 16:32, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > > > > > > > On Mar 4, 11:28 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > > > > > > > On 4 Mar, 16:20, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > > > > > > > > > On Mar 4, 10:31 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > > > > > > > > > On 4 Mar, 13:40, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > > > > > > > > > > > On Mar 4, 3:12 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > > > > > > > > > > > On 3 Mar, 20:01, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > > > > > > > > > > > > > On Mar 3, 12:52 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > > > > > > > > > > > > > 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.
>
> > > > > > > > > > > > > > Ok.
>
> > > > > > > > > > > > > > > 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.
>
> > > > > > > > > > > > > > <suspicious eyebrow raised> Ok.
>
> > > > > > > > > > > > > > > 3) The amount that the clock would appear to slow down is DIFFERENT
> > > > > > > > > > > > > > > from the amount that SR predicts the clock *actually* slows down
>
> > > > > > > > > > > > > > Really? I'm growing increasingly suspicious. In what way does SR
> > > > > > > > > > > > > > predict the "actual" slowdown, as opposed to the "apparent" slowdown?
> > > > > > > > > > > > > > And for example, if we racked up the value of 'c' to near infinity,
> > > > > > > > > > > > > > would SR still predict an "actual" slowdown, even though the
> > > > > > > > > > > > > > propagation delays would approach zero?
>
> > > > > > > > > > > > > With what you have described, I checked just to be sure, even though I
> > > > > > > > > > > > > was already pretty sure what the answer would be, the time you read
> > > > > > > > > > > > > moving away the clock would be:
>
> > > > > > > > > > > > > t2 = t - (x+vt)/c = t(1-v/c) - x
>
> > > > > > > > > > > > > and when you move toward the clock
>
> > > > > > > > > > > > > t2 = t + (x+vt)/c = t(1+v/c) + x
>
> > > > > > > > > > > > > so moving away from the clock:
> > > > > > > > > > > > > dt2/dt = 1-v/c
> > > > > > > > > > > > > and toward
> > > > > > > > > > > > > dt2/dt = 1-v/c
>
> > > > > > > > > > > > > Special relativity predicts that the moving clock will always slow
> > > > > > > > > > > > > down as
> > > > > > > > > > > > > dt2/dt = sqrt(1-v^2/c^2)
>
> > > > > > > > > > > > > What you *measure* is a combination of the actual slow down predicted
> > > > > > > > > > > > > by SR (sqrt(1-v^2/c^2) and whatever changes occur due to propagation
> > > > > > > > > > > > > delays (which depend on the direction of motion).
>
> > > > > > > > > > > > Ok. So let us suppose that we take two clocks. Separate them by a
> > > > > > > > > > > > certain distance, synchronise them when they are both stationary, and
> > > > > > > > > > > > then accelerate them both towards each other (and just before they
> > > > > > > > > > > > collide, we bring them stationary again). Are you seriously saying
> > > > > > > > > > > > that both clocks report that the other clock has slowed down, even
> > > > > > > > > > > > though they have both undergone symmetrical processes? Because there
> > > > > > > > > > > > is obviously a contradiction there.
>
> > > > > > > > > > > Yes, that is correct. Both will report a slow down.. And in fact,
> > > > > > > > > > > which ever one breaks the inertial frame to match speed with the other
> > > > > > > > > > > is the one that will be "wrong". This is still within the realm of
> > > > > > > > > > > SR, not GR.
>
> > > > > > > > > > What if they both "break the inertial frame"?
>
> > > > > > > > > Then whichever frame they both accelerate into will be the one that
> > > > > > > > > has measured the "correct" time dilation.
>
> > > > > > > > So in other words, the clocks will register the same time, but will
> > > > > > > > have slowed in some "absolute sense"?
>
> > > > > > > Yes--assuming they both accelerated by the same amount (that is to
> > > > > > > say, assuming they both broke the inertial frame in a symmetric way).
> > > > > > > Otherwise, they will register different times.
>
> > > > > > Agreed.
>
> > > > > > So let's explore an extension of this scenario. Let's say you have two
> > > > > > clocks, and you accelerate both of them up to a common speed, and
> > > > > > after they have travelled a certain distance, you turn them around and
> > > > > > return them to the starting point. The only difference is that one
> > > > > > clock goes a certain distance, and the other clock goes twice that
> > > > > > distance, but they *both* have the same acceleration profile - the
> > > > > > only difference is that one clock spends more time travelling on
> > > > > > inertia.
>
> > > > > > Obviously, one clock will return to the starting point earlier than
> > > > > > the other. But when both have returned, are their times still in
> > > > > > agreement with each other, or have they changed?
>
> > > > > Agreement. Both of them will agree, but will be showing a time earlier
> > > > > than a third clock that was left behind at the starting point.
>
> > > > Oh dear. Mark contends otherwise.
>
> > > Right. I misunderstood. He's right. I was wrong.
>
> > Ok. So what you're (both) saying is that time dilation (in SR) is a
> > simple function of speed and distance, so that the quicker you travel
> > the more time dilates, and the further you travel the more time
> > dilates? And, to boot, you're saying that it's only *relative*
> > distance and speed that counts (i.e. there is no absolute measure of
> > movement in space)?
>
> The time dilation *factor* (by what factor is the clock moving more
> slowly) is a simple function of relative speed. The difference in the
> time *elapsed* between the two clocks is also a function of the
> relative distance.
>
> This should make perfect sense to you. If a clock is running 2%
> slower, then it is running 2% slower regardless of distance. But if,
> as a result of running 2% slower, it falls behind 6 minutes after
> running a certain amount of time, then it will fall behind 12 minutes
> after running for twice as long.

Agreed.

The question now is, if we agree that both clocks suffer time dilation
in this way, then when they return to the start point, how do they
each reconcile the fact that (after accounting for the effects of
acceleration) it ought to be the other clock which is slow, when in
fact one clock (the one that went furthest from the start point) will
be slower than the other? And a third clock, left at the start point,
will be running ahead of both?

From: Ste on 6 Mar 2010 06:58

On 5 Mar, 15:59, PD <thedraperfam...(a)gmail.com> wrote:
> On Mar 5, 4:55 am, "Inertial" <relativ...(a)rest.com> wrote:
>
>
>
>
>
> > "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> >news:057b5351-82a4-4487-8501-6308451c921a(a)x22g2000yqx.googlegroups.com....
>
> > > On 5 Mar, 01:31, "Inertial" <relativ...(a)rest.com> wrote:
> > >> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> > >>news:8c0ae071-8d13-491b-92d0-cd2e2727af1a(a)u9g2000yqb.googlegroups.com....
>
> > >> > On 4 Mar, 12:19, "Inertial" <relativ...(a)rest.com> wrote:
> > >> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> > >> >> > Not really, because if the total acceleration is small, then so is
> > >> >> > the
> > >> >> > speed.
>
> > >> >> That is a nonsense argument. Acceleration can be small and speeds
> > >> >> very
> > >> >> large.
>
> > >> > When I went to school, you could not have a large change of speed with
> > >> > only a small amount of total acceleration.
>
> > >> Then you were badly taught.
>
> > >> a) if you start at speed 0.8c and acceleration at 0.00001 m/s/s .. then
> > >> your
> > >> speed is still large. you claimed small acceleration means small speed
>
> > >> b) if you start at speed 0.0 and acceleration at 0.00001 m/s/s .. then
> > >> your
> > >> speed after a million years will be quite fast. Yet the acceleration was
> > >> small and constant.
>
> > >> You do realize that you cannot 'total' acceleration. and acceleration of
> > >> 1m/s/s followed by an acceleration of 1m/s/s is still an acceleration of
> > >> 1m/s/s
>
> > > In any event, we've resolved the meaning of "total acceleration" -
> > > Mark suggests using the concept of "impulse" instead.
>
> > You certainly are taking the long and painful route (for yourself and us) to
> > learn the basics of physics.
>
> Ste: This is exactly what I was telling you earlier, that people will
> be less inclined to teach things on your terms, using your language
> and indulging your lack of skills, and will advise you that it is more
> efficient in the long run to teach after you've acquired some relevant
> skills and vocabulary. You didn't seem to think this was the case, and
> here you have others telling you the same thing. Reconsider?

As I say Paul, the words "total acceleration" I think should have
given people some clue as to the meaning - and indeed the more
intelligent amongst us here did recognise the meaning, and suggested
an alternative word. That said, in this case I'm happy to use an
alternative formulation like "impulse", because I can see that it will
add further precision to my meanings in future.

It's quite different from the disputes that arose over words like
"physical" and "material", where each side seems to battle childishly
over whose idiosyncratic understanding of the word will prevail, when
the time could be better used getting on with the substantive argument.