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

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From: Bruce Richmond on 10 Mar 2010 20:45

On Mar 10, 8:10 pm, mpc755 <mpc...(a)gmail.com> wrote:
> On Mar 10, 7:45 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
>
>
>
>
> > On Mar 10, 9:36 am, mpc755 <mpc...(a)gmail.com> wrote:
>
> > > On Mar 10, 8:05 am, "Inertial" <relativ...(a)rest.com> wrote:
>
> > > > "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote in message
>
> > > >news:4b970c19$0$8039$afc38c87(a)news.optusnet.com.au...
>
> > > > > I know I still have a long way to go but my goal here is to truely
> > > > > understand SR, not to just parrot explainations. LET helped me see
> > > > > that the math of SR is correct, but I also realize it has become a
> > > > > hiderence in understanding SR.
>
> > > > > ________________________________
> > > > > Good. There is one key insight which makes the jump from LET to SR a
> > > > > little easier (in my opinion).
>
> > > > > For all the talk of relative motion against the ether in LET, the
> > > > > equations work out exactly the same whatever you choose as the rest frame
> > > > > of the ether. So the actual rest frame of the ether cannot be detected
> > > > > within LET.
>
> > > > That's right. That's what Dono doesn't get.
>
> > > > > Its only a small hop, skip and jump from saying that "it cannot be
> > > > > detected" to "it doesn't exist".
>
> > > > Or at least 'it doesn't matter'.
>
> > > > Once you go beyond just the aether frame, and relating frames directly to
> > > > it, LET becomes more of a hinderance than a help
>
> > > > LET tells you (for instance) that even though objects at rest in frame A may
> > > > be more length compressed and time slowed than those in frame B (where A
> > > > moves faster in the aether frame than B) .. yet A will see objects at rest
> > > > in B as being more contracted and time dilated than its own. Which really
> > > > confuses those who use the simple 'motion in the aether shrinks and slows
> > > > things' idea of LET as a way to 'understand' into a spin. You end up with a
> > > > strange combination of real compression and apparent contraction, real
> > > > slowing and apparent time dilaton. Its not really helpful :):)
>
> > > It is helpful in that it gets 'us' closer to understanding what occurs
> > > to objects as they move with respect to the aether.
>
> > > The issue with LET is everything is relative.
>
> > > For example, "the state of the [ether] is at every place determined by
> > > connections with the matter and the state of the ether in neighbouring
> > > places" - Albert Einstein.
>
> > You like Einstein quotes about the ether so try this one:
>
> >http://www-groups.dcs.st-and.ac.uk/~history/Extras/Einstein_ether.html
>
> > "We may assume the existence of an ether; only we must give up
> > ascribing a definite state of motion to it" - Albert Einstein.
>
> "If the existence of such floats for tracking the motion of the
> particles of a fluid were a fundamental impossibility in physics - if,
> in fact nothing else whatever were observable than the shape of the
> space occupied by the water as it varies in time, we should have no
> ground for the assumption that water consists of movable particles.
> But all the same we could characterise it as a medium."
>
> "[extended physical objects to which the idea of motion cannot be
> applied] may not be thought of as consisting of particles which allow
> themselves to be separately tracked through time."
>
> "The special theory of relativity forbids us to assume the ether to
> consist of particles observable through time, but the hypothesis of
> ether in itself is not in conflict with the special theory of
> relativity. Only we must be on our guard against ascribing a state of
> motion to the ether."
>
> "But this ether may not be thought of as endowed with the quality
> characteristic of ponderable media, as consisting of parts which may
> be tracked through time. The idea of motion may not be applied to it."
>
> Once you are willing to understand how Einstein defined motion, as
> particles which can be separately tracked through time, maybe you can
> advance from your statement.
>
> p.s. You still haven't answered how it is the train is length
> contacted because it is moving relative to the aether and the
> embankment is more at rest with respect to the embankment but at the
> same time LET has everything being relative. The answer is both the
> Observer at M and the Observer at M' will determine the train to be
> length contracted and for the clocks on the train to be ticking slower
> than the clocks on the embankment.
>
>
>
>
>
>
>
> > > This means the aether is more at rest with
> > > respect to the embankment than it is with respect to the train. The
> > > train is moving relative to the aether so it will be length contracted
> > > while the embankment will not. The ruler the Observer on the
> > > embankment uses to measure the length of the train is not length
> > > contracted. The ruler the Observer on the train uses to measure the
> > > length of the embankment is length contracted. The Observer on the
> > > embankment and the Observer on the train conclude the embankment is
> > > longer than the train.
>
> > > The same holds true for the clocks on the train and on the embankment..
> > > Since the train is moving relative to the aether while the embankment
> > > is more at rest with respect to the aether there will be a greater
> > > pressure associated with the aether on the clock on the train causing
> > > it to tick slower. If the Observers on the embankment and on the train
> > > where able to 'see' each others clocks as the M and M' pass each other
> > > both the Observer on the train and the Observer on the embankment
> > > would conclude the clock on the train ticks slower than the clock on
> > > the embankment.

You know for a while you were making progress. (I'm sure some here
are thinking the same about me ;) You managed to get away from each
frame having its own ether to having them share a single ether (for EM
waves anyway). Now if you could just get away from trying to attach
one of the frames to the ether...

Did you ever get anywhere with that diagram I made to explain RoS to
you. Einstein presented the train experiment from the point of view
of the tracks, but he never said that the tracks were at rest WRT the
ether.

- Hide quoted text -
>
> > > - Show quoted text -
>
> > According to both SR and LET there is no experiment that can reveal
> > which frame is at rest WRT the ether, so there is no way to know which
> > frame is more at rest WRT the ether.
>
> The clock which ticks the fastest is most at rest with respect to the
> aether.

But you have no way of knowing which clock is ticking faster. To
measure the tick rate of a moving clock requires more than one clock
at rest. And then you end up making assumptions to sychronize them.
Those assumptions affect your measurements.

From: Inertial on 10 Mar 2010 20:46

"Paul Stowe" <theaetherist(a)gmail.com> wrote in message
news:d6198d45-a883-41d6-956d-657bd388173e(a)u5g2000prd.googlegroups.com...
> On Mar 9, 9:12 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> wrote:
>> "PaulStowe" <theaether...(a)gmail.com> wrote in message
>>
>> news:5dfdcd4c-53e4-4131-9cb8-2ead41af6f77(a)c37g2000prb.googlegroups.com...
>> On Mar 8, 9:27 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
>> wrote:
>>
>>
>>
>>
>>
>> > "PaulStowe" <theaether...(a)gmail.com> wrote in message
>>
>> >news:3355b6f6-1826-4819-b7cb-b85913a5cae0(a)t9g2000prh.googlegroups.com...
>> > On Mar 7, 8:32 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
>> > wrote:
>>
>> > > "PaulStowe" <theaether...(a)gmail.com> wrote in message
>>
>> > >news:9c1e1ae6-c9c1-497d-a293-35fb68100abb(a)c34g2000pri.googlegroups.com...
>> > > On Mar 7, 8:10 pm, "Peter Webb"
>> > > <webbfam...(a)DIESPAMDIEoptusnet.com.au>
>> > > wrote:
>>
>> > > > "PaulStowe" <theaether...(a)gmail.com> wrote in message
>>
>> > > >news:720fa6a7-6744-4bf7-85fe-6050215ee277(a)k5g2000pra.googlegroups.com...
>> > > > On Mar 7, 6:52 pm, "Peter Webb"
>> > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au>
>> > > > wrote:
>>
>> > > > > > LET is as possibly valid as SR .. Neither is refuted
>> > > > > > experimentally.
>> > > > > > I
>> > > > > > just don't think it is the correct physical explanation. LET is
>> > > > > > not
>> > > > > > compatible AFAIK with GR .. so is a bit of a dead end .. and
>> > > > > > has
>> > > > > > the
>> > > > > > assumption of an undetectableaetherwith properties that don't
>> > > > > > make
>> > > > > > sense.
>>
>> > > > > The experimental support for a fixed ether in SR is comparable to
>> > > > > the
>> > > > > experimental support for unicorns in zoology. Lots of luck
>> > > > > proving
>> > > > > either
>> > > > > exists.
>>
>> > > > What is a 'fixed ether'?
>>
>> > > > _______________________
>> > > > Non-existent.
>>
>> > > That is your 'belief'. The question was in physical model arena.
>> > > Give or reference a basic hypothetical definition...
>>
>> > > _____________________________
>> > > A priveleged inertial reference frame. Of course, as I don't believe
>> > > it
>> > > exists, I am hardly in a position to extol its qualities. This seems
>> > > to
>> > > be
>> > > what believers in a "fixed ether" mean by the term, but you would be
>> > > better
>> > > off asking them. I know as much about ether as I do about Unicorns.
>> > > In
>> > > fact,
>> > > I don't even know if Unicorns are horses with a single spiral horn,
>> > > or
>> > > are
>> > > a
>> > > completely different species that just looks like a horse with a
>> > > horn.
>> > > If
>> > > you really want to know, ask somebody who believes in Unicorns and/or
>> > > the
>> > > fixed ether what they are exactly.
>>
>> > > PaulStowe
>>
>> > I'm sorry about these questions but, what does privileged mean?
>>
>> > _______________________________
>> > Somehow better than the others. Special in some sense. For example, the
>> > reference frame of the ether is privleged because it is the only
>> > reference
>> > frame where lengths and times are "correct".
>>
>> > There
>> > is certainly physical consequences of the medium (such as field
>> > profile alterations due to motion) but there is certainly nothing
>> > priveleged as in having different properties about it.
>>
>> > _____________________________
>> > It is privileged; it is the unique reference frame for which the real
>> > length
>> > is the same as the measured length. Or so I understand it; as I said, I
>> > don't actually believe it exists at all.
>>
>> Real length? What makes length real?
>>
>> __________________________
>> According to LET, an objects real length is the measured length when
>> stationary wrt to the ether.
>>
>> Yes, I know that is a circular definition. All such definitions end up
>> being
>> circular. That is one of the big reasons that LET was dropped and
>> replaced
>> by SR very quickly once SR was developed; SR doesn't suffer from this
>> problem of an ether which cannot even in principle be detected, or real
>> lengths which are unknowable.
>>
>> PaulStowe
>
> Spacial distances and time are absolutes,

Combined proper spacetime intervals are. Spatial distance (at a given time)
are not.

> but, how one chooses to
> define them and do measurements are certainly not. But, that does not
> make their definitions and measurements 'unreal', or invalid.

Indeed .. frame dependence doesn't mean 'unreal' or invalid. Velcoity is
frame dependent and it is 'real' and valid

> It's
> certainly not inconsistent with LET's physical premise either.

LET posits that what we measure is not what is real, because our measurement
devices (indeed, our whole perception of reality) are affected (distorted)
by motion through the Aether. And they are distorted in such a way that
what we measure has the same mathematical relationships as SR has (even
though, according to LET, the underlying reality is not like that at all).

From: Peter Webb on 10 Mar 2010 20:51

No, perhaps you didn't understand. As I say, this is *not* the twins
paradox, because in the twins paradox only *one* twin leaves Earth.

________________________
Its functionally the same. It is exactly the twins paradox, but with two
twins apparently doing exactly the same thing.

Even if you cannot see that, the explanation on the Wikipedia page of the
Twins Paradox is trivially adapted for two twins.

I assume that you do not understand the Wikipedia twins paradox page, or
else you would know the answers to your questions already. Which parts don't
you understand?

From: Bruce Richmond on 10 Mar 2010 20:52

On Mar 10, 8:13 pm, "Peter Webb"
<webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> According to both SR and LET there is no experiment that can reveal
> which frame is at rest WRT the ether, so there is no way to know which
> frame is more at rest WRT the ether.
>
> ______________________
> Wrong. Only LET has this problem. There is no ether in SR, so the question
> of its velocity doesn't even arise.

Einstein did not rule out the possibility of an ether, he said that it
made no difference if there was one, that it was superfluous. If you
claim my statement is wrong you are claiming there is an experiment
that can reveal the ether frame.

From: Peter Webb on 10 Mar 2010 20:58

"Ste" <ste_rose0(a)hotmail.com> wrote in message
news:f9dcfd34-a685-4d84-8f9e-3bf68e303d3c(a)b7g2000yqd.googlegroups.com...
> On 10 Mar, 01:09, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> wrote:
>> When we talk of the "turnaround", can we be a bit more specific about
>> what is happening? Also, bear in mind that *both* turnaround at the
>> same time.
>>
>> I also find it implausible that C could leap ahead of B. The more
>> plausible explanation, surely, is that B slows down dramatically
>> relative to C. So for example, if both clocks stopped moving (relative
>> to A) while at their farthest distance from each other, then for a
>> short time the other clock would appear to leap ahead (actually a
>> slowing of the reference clock), until the effects of each clock
>> stopping had actually propagated to the other clock, at which point
>> they would snap back into synchronisation again (propagation delays
>> disregarded). Yes?
>>
>> ____________________________________
>>
>> No.
>>
>> As I keep saying to you - but you fail to understand (which is itself a
>> worry) - is that statements like "the clocks are synchronisation" are not
>> really meaningful, as whether they show the same time is a function of
>> the
>> inertial reference frame in which the clocks are observed; it is not a
>> function of the underlying dynamics, it is an artifact of the co-ordinate
>> system you choose.
>
> I'm not yet convinced of this.
>

Well, its what SR says; you can choose to believe or not belive in SR as you
wish.

>
>
>> That is why you can only ask questions about what is observed to happen
>> for
>> a specific observer.
>
> Of course, but that doesn't stop us reconciling the experience of
> specific observers in a logically and physically consistent way.
>
>
>
>> In answer to your question about "snapping back into synchronisation",
>> apart
>> from the fact that it is meaningless, even if we reformulated this as a
>> question about observable quantities it is still wrong. When B and C
>> become
>> relatively stationary, there is no sudden dramatic change to the clock to
>> the time they read on each others clocks; no jumps or discontinuities or
>> "snaps".
>
> No, the snap should happen when news of the turnaround has propagated
> to the other observer. There is simply no plausible explanation for
> why the distant clock would "leap ahead" of the reference clock (in
> terms of the absolute number of ticks elapsed),

It doesn't. As I said. And so for that matter does the wiki page on the
twins paradox. And nor does SR predict this would happen.

> except for the fairly
> obvious explanation that it is the reference clock which is undergoing
> a "real" slowdown.

Or, that you have no idea of what SR predicts, and have completely and
falsely assumed that observers see clocks jump ahead when turnaround occurs.

Have you even bothered to look at the Wikipedia page on the twins paradox?