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

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From: Inertial on 10 Mar 2010 20:26

"Peter Webb" <webbfamily(a)DIESPAMDIEoptusnet.com.au> wrote in message
news:4b9843d1$0$6278$afc38c87(a)news.optusnet.com.au...
>
> 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.

Indeed. SR says nothing about there being an aether. It does not require
an aether .. only the light travels at c (or rather, that there is a maximum
speed c at which information can be transferred etc).

Though if one does combine SR with the notion of a fixed aether for EMR
propagation, then the associated aether inertial rest frame would be no
different in SR to any other frame (ie not preferred or absolute, and with
the same physics), and movement of objects through it would have no physical
/ material effects (as it does in LET), and it would remain undetectable.
The only thing about such at aether that is in any way 'detectable' is that
light propagates in it at c .. and in SR, anything travelling at c in one
inertial frame travels at c in all inertial frames.

From: Bruce Richmond on 10 Mar 2010 20:28

On Mar 10, 11:52 am, "Simple Simon" <pi.r.cubed-nos...(a)gmail.com>
wrote:
> PD wrote:
> > On Mar 9, 7:58 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
> >> On Mar 9, 9:31 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> >>> On Mar 8, 11:53 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> >>>> On Mar 8, 1:58 am, "Inertial" <relativ...(a)rest.com> wrote:
>
> >>>>> "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message
>
> news:29fd9f7d-c9b4-41e6-b33a-585c3e0e7acf(a)q23g2000yqd.googlegroups.com...
>
> >>>>>> On Mar 7, 9:48 pm, "Inertial" <relativ...(a)rest.com> wrote:
> >>>>>>> "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message
>
> news:1c6a2640-39f5-4ea4-9c85-127e71f4e6a2(a)33g2000yqj.googlegroups.com...
>
>
>
> >>>>>>>> On Mar 7, 6:58 pm, "Inertial" <relativ...(a)rest.com> wrote:
> >>>>>>>>> "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote in
> >>>>>>>>> message
>
> >>>>>>>>>news:4b943853$0$11336$afc38c87(a)news.optusnet.com.au...
>
> >>>>>>>>>> "Inertial" <relativ...(a)rest.com> wrote in message
> >>>>>>>>>>news:4b942bcf$0$27789$c3e8da3(a)news.astraweb.com...
> >>>>>>>>>>> "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote in
> >>>>>>>>>>> message
> >>>>>>>>>>>news:4b93bf73$0$28464$afc38c87(a)news.optusnet.com.au...
>
> >>>>>>>>>>>>>> 1) your statement: "For clarity, both effects are purely
> >>>>>>>>>>>>>> observational - SR presumes (ideal) clock mechanisms are
> >>>>>>>>>>>>>> completely
> >>>>>>>>>>>>>> unaffected by a clock's motion." -- I agree the physical
> >>>>>>>>>>>>>> mechanism
> >>>>>>>>>>>>>> of
> >>>>>>>>>>>>>> the clock is unaffected, but this is a really misleading
> >>>>>>>>>>>>>> statement,
> >>>>>>>>>>>>>> since the amount of proper time that the clock consumes
> >>>>>>>>>>>>>> is affected
> >>>>>>>>>>>>>> by
> >>>>>>>>>>>>>> its motion. Are you trying to say
>
> >>>>>>>>>>>>> I was "trying to say" exactly what I did say. If you
> >>>>>>>>>>>>> didn't find it
> >>>>>>>>>>>>> clear enough, try this: relative slow-downs/speed-ups
> >>>>>>>>>>>>> observed in the
> >>>>>>>>>>>>> readings of SR's ideal clocks aren't due to changes in
> >>>>>>>>>>>>> the tick mechanisms of those clocks.
>
> >>>>>>>>>>>> I still don't find it clear, as it begs the question - it
> >>>>>>>>>>>> says what
> >>>>>>>>>>>> doesn't cause the change, not what does cause the change.
>
> >>>>>>>>>>>> The standard SR answer is much more direct - the clocks
> >>>>>>>>>>>> slow down due
> >>>>>>>>>>>> to
> >>>>>>>>>>>> relativistic time dilatation from them being in different
> >>>>>>>>>>>> reference
> >>>>>>>>>>>> frames.
>
> >>>>>>>>>>>> Is that standard position of SR also your position? Or is
> >>>>>>>>>>>> your somehow
> >>>>>>>>>>>> different?
>
> >>>>>>>>>>> SR says that the difference in clock sync (clock settings)
> >>>>>>>>>>> cause the
> >>>>>>>>>>> measurement of length to be contracted and measurement of
> >>>>>>>>>>> clock ticking
> >>>>>>>>>>> rates to be dilated.
>
> >>>>>>>>>> More or less.
>
> >>>>>>>>> That's what it is :)
>
> >>>>>>>>>> But I asked you about *your* position, not SR's position.
>
> >>>>>>>>> My position is SR's position
>
> >>>>>>>>>> Do you agree that that the clocks slow down due to
> >>>>>>>>>> relativistic time dilation, as predicted by SR, or not?
>
> >>>>>>>>> They are measured as slower, just as a rod is measured as
> >>>>>>>>> shorter. This
> >>>>>>>>> is
> >>>>>>>>> due to the difference in simultaneity. They don't slow down
> >>>>>>>>> because a moving observer is looking at them any more than a
> >>>>>>>>> rod shrinks because a
> >>>>>>>>> relatively moving observer is looking at it.
>
> >>>>>>>>> Here's a little example you might follow .. with time
> >>>>>>>>> differences exagerated
> >>>>>>>>> for clarity
>
> >>>>>>>>> Here are six clocks, in tow rows (S and S'), all ticking at
> >>>>>>>>> the correct
> >>>>>>>>> rate, but set with different times...
>
> >>>>>>>>> S' 10:30 11:00=A 11:30 <--v
> >>>>>>>>> S 11:30=C 11:00=B 10:30 -->v
>
> >>>>>>>>> Clocks B sees the A is synchronized with it.
>
> >>>>>>>>> Now .. the clocks are moving in opposite directions so after
> >>>>>>>>> an hour we
> >>>>>>>>> have
>
> >>>>>>>>> S' 11:30 12:00=A 12:30
> >>>>>>>>> S 12:30=C 12:00=B 11:30
>
> >>>>>>>>> Clock A has moved away from clock B .. but another clock (C)
> >>>>>>>>> in S can see
> >>>>>>>>> the time on it. Clock C sees that clock A is half an hour
> >>>>>>>>> slow (A shows
> >>>>>>>>> 12:00 when C shows 12:30). So according to the clocks in S,
> >>>>>>>>> clock A is
> >>>>>>>>> ticking slower. We also note that clock B now sees a
> >>>>>>>>> *different* S' clock
> >>>>>>>>> next to it as being fast (it shows 12:30 when B shows 12:00)
>
> >>>>>>>>> If you look at the same scenario but from the point of view
> >>>>>>>>> of the other
> >>>>>>>>> row
> >>>>>>>>> of clocks, you get symmetric results.
>
> >>>>>>>>> This is how clock synch affects measured ticking rates for
> >>>>>>>>> moving clocks
> >>>>>>>>> in
> >>>>>>>>> SR. Even though the clocks themselves do NOT change their
> >>>>>>>>> intrinsic ticking
> >>>>>>>>> rates.- Hide quoted text -
>
> >>>>>>>> Looks good, but let's take it one step further. The observer
> >>>>>>>> with clock A jumps to frame S" which is traveling in the same
> >>>>>>>> direction as S relative to S' but at twice the velocity.
>
> >>>>>>>> S" 1:00 12:00=A 11:00 -->2v
> >>>>>>>> S' 11:30 12:00=A 12:30 <--v
> >>>>>>>> S 12:30=C 12:00=B 11:30 -->v
>
> >>>>>>>> Clocks A and B continue to tick at there same intrinsic
> >>>>>>>> ticking rate and an hour later A has overtaken B.
>
> >>>>>>>> S" 2:00 1:00=A 12:00 -->2v
> >>>>>>>> S' 12:30 1:00=A 1:30 <--v
> >>>>>>>> S 1:30=C 1:00=B 12:30 -->v
>
> >>>>>>>> The above provides the same situation as the twins paradox.
> >>>>>>>> Clock A left clock B and returned. So why doesn't clock A show
> >>>>>>>> less time elapsed than B? (Note the clocks in S" are further
> >>>>>>>> out of sync than those in S due to the higher velocity.)
>
> >>>>>>> The three clock situation cannot be so easily drawn .. bit like
> >>>>>>> trying to drawing a three dimensional figure in 2d :) This sort
> >>>>>>> of diagram only really works for a single pair of clocks
> >>>>>>> looking from a third frame in which
> >>>>>>> they move with the same speed. Things are trickier when there
> >>>>>>> is frame jumping going on :):)- Hide quoted text -
>
> >>>>>>> - Show quoted text -
>
> >>>>>> The question still remains, if there is no change in the tick
> >>>>>> rate of the clock, how can clock A have fewer ticks recorded
> >>>>>> when it is brought back to clock B?
>
> >>>>> Look at the Lorentz transforms to see. Its all due to clock
> >>>>> synch.- Hide quoted text -
>
> >>>>> - Show quoted text -
>
> >>>> You are going to give yourself a head cold with all that arm
> >>>> waving. You are saying the tick rate doesn't change, yet SR says
> >>>> that the returning twin's clock will show less elapsed time. You
> >>>> don't see any conflict there?
>
> >>> No, there is no conflict. When you say that the tick rate does not
> >>> change, this is a LOCAL statement. What it means is that a process
> >>> measured locally with this clock will still have the same duration.
>
> >> That is not what we were discussing. I agree that the clock continues
> >> to tick at a rate of one second per proper second in the rest frame
> >> of the clock. The question was whether the slowed tick rate measured
> >> in the frame of the stay at home twin is real, or an illusion due to
> >> the clock sync proceedure, as length contraction is.
>
> > I don't know that length contraction IS an illusion. Length is
> > *defined* operationally by relying on simultaneity, and so the REAL
> > length according to that definition is of course frame-dependent,
> > because simultaneity is frame-dependent.
>
> ** For Sale **
> One (1) slightly used Minkowsky (tm) Intervaler (with quantum sensors)

LOL, Thanks for the laughs. A little humor can be a good thing :)

> This space-time meter (aka clock-ruler) will measure and generate intervals
> in space-time.
> In measuring intervals it will also produce the components of the interval
> for any inertial frame.
> In generating intervals it can act as a ruler if the intended interval is
> space-like and a clock if time-like.
>
> Say you're in Phoenix and your buddy is driving in from Tucson.
> You want to know when she'll be there and ask her to generate intervals, so
> you'll know when she'll be there.
> She takes our her Intervaler and decides to generate simultaneous (in her
> frame) events at your respective positions.
> You measure the interval with your Intervaler.
> In addition to telling you the velocity (of the inertial frame in which the
> events are simultaneous) and components of the interval in each frame (yours
> and hers), simply by changing the sign of the interval and dividing by c you
> can synchronize the interval with your legacy measuring tools (e.g. A clock,
> to arrive at an ETA).
>
> Fine print: Guaranty void where prohibited, e.g. near significant
> gravitation.
>
> >> If it is an illusion
> >> the accumulated time on the two clocks should be the same when they
> >> are brought back together. The way Inertial described it, it came
> >> across as an illusion caused purely by clock sync.
>
> >> I hate discussing what is "real". In a sense length contraction is
> >> real because the pole will fit into the barn.
>
> > Absolutely. If I have a clear understanding of what "simultaneous"
> > means in a given reference frame, and I close the barn doors
> > simultaneously with the pole between them, and there are no marks on
> > the doors where the pole hit either one of them, then I can't think of
> > any sensible meaning of "fit" that would hold these circumstances to
> > be true and yet the pole does not fit in the barn in this frame. And
> > since the pole fits, I cannot think of any sensible meaning of
> > "shorter" where the pole would fit in the barn and yet be not shorter
> > than the barn.
>
> >> But with length
> >> contraction there is no accumulated length to inspect when the pole
> >> is brought to rest.
>
> > This is true. The twin puzzle is a different animal that the barn-pole
> > paradox. In the twin puzzle, there is no symmetry in terms of inertial
> > motion. One twin is DEFINITELY not residing wholly in one inertial
> > reference frame, and that is a frame-independent observation.
>
> >> I can see that the measured slowing of the clock is
> >> due to the rotation of the time coordinates when it changed frames,
> >> but that doesn't make it any less real.
>
> >>> For example, if the half-life of a muon that is slow in frame A and
> >>> is measured with a clock at rest in A is 2.2 us, then if you make
> >>> the same measurement of the half-life of a muon that is slow in
> >>> frame B and is measured with a clock at rest in B, clock B will
> >>> still show the half-life to be 2.2 us. In this sense, we say that
> >>> the clock tick rate has not changed, because measurements of local
> >>> phenomena are unchanged.
>
> >> Yes, but again you are measuring locally, more or less in the rest
> >> frame of the muon. We know that if we measure the half life of a fast
> >> moving muon it is longer, as if its personal clock was ticking
> >> slower.
>
> >>> However, this does NOT mean that the tick rate of clock B will agree
> >>> with the clock rate of all other clocks, nor that it will read the
> >>> durations of nonlocal processes to be the same.
>
> >>> Do you see the distinction?
>
> >> If we set up a light clock with a vertical bouncing beam, and have it
> >> send a flash back to the stay at home twin every time the beam hits
> >> the top, we can tell just how fast the clock is ticking. The signal
> >> will be doppler shifted, but the total count is what it is. None of
> >> the flashes drifted off and avoided detection. I am not claiming this
> >> slowing is due to motion wrt an ether. It is due to the finite speed
> >> of light and how we define/construct the coordinate systems.
>
> > The last sentence is right, but how we define/construct the coordinate
> > systems is constrained by the structure of spacetime (and this in fact
> > produces the finite speed of light). That is, there is no way to
> > define/construct a coordinate system in our spacetime such that these
> > effects go away. (You are free to try.)
>
> > PD
>
> >> Bruce

From: Inertial on 10 Mar 2010 20:31

"Ste" <ste_rose0(a)hotmail.com> wrote in message
news:7df1fc51-d0aa-461b-8c57-cbd52d6c9438(a)b7g2000yqd.googlegroups.com...
> On 9 Mar, 23:41, "Inertial" <relativ...(a)rest.com> wrote:
>> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>>
>> news:e37617e7-52f9-4fbd-a740-bac32eb220dd(a)o3g2000yqb.googlegroups.com...
>>
>> > On 9 Mar, 05:34, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
>> > wrote:
>> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>>
>> >> Did you look at the diagrams on the Wikipedia page on the twins
>> >> paradox
>> >> as I
>> >> suggested?
>>
>> >> This shows *exactly* what the moving and stationary clocks see as
>> >> happening
>> >> at all stages of the thought experiment.
>>
>> > This isn't the twins paradox,
>>
>> http://en.wikipedia.org/wiki/Twin_paradox
>>
>> Of course it is the twins paradox. Do you even know what the twins
>> paradox
>> is ? Lets see what the web page says
>>
>> "In physics, the twin paradox is a thought experiment in special
>> relativity,
>> in which a twin makes a journey into space in a high-speed rocket and
>> returns home to find he has aged less than his identical twin who stayed
>> on
>> Earth. This result appears puzzling because each twin sees the other twin
>> as
>> traveling, and so, according to the theory of special relativity,
>> paradoxically each should find the other to have aged more slowly. How
>> the
>> seeming contradiction is resolved, and how the absolute effect (one twin
>> really aging less) can result from a relative motion, can be explained
>> within the standard framework of special relativity. The effect has been
>> verified experimentally using precise measurements of clocks flown in
>> airplanes.[1][2]"
>
> I repeat myself again, the scenario we have here is *not* the twins
> paradox.

Then what are you talking about now?

>> > so it would be strange to find the
>> > answer to my question there. Also, I've read that page in the past,
>> > and I don't recall it having relevant detail.
>>
>> Clearly you are either lying about reading it, or you didn't understand
>> it.
>
> 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.

Then what are you talking about now?

From: Paul Stowe on 10 Mar 2010 20:32

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

Paul Stowe

From: Inertial on 10 Mar 2010 20:37

"Bruce Richmond" <bsr3997(a)my-deja.com> wrote in message
news:64e0eb18-73bc-47ca-8516-53fc758e9c06(a)o30g2000yqb.googlegroups.com...
> On Mar 10, 10:50 am, PD <thedraperfam...(a)gmail.com> wrote:
>> On Mar 9, 7:58 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>>
>> > On Mar 9, 9:31 am, PD <thedraperfam...(a)gmail.com> wrote:
>>
>> > > On Mar 8, 11:53 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>>
>> > > > On Mar 8, 1:58 am, "Inertial" <relativ...(a)rest.com> wrote:
>>
>> > > > > "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message
>>
>> > > > >news:29fd9f7d-c9b4-41e6-b33a-585c3e0e7acf(a)q23g2000yqd.googlegroups.com...
>>
>> > > > > > On Mar 7, 9:48 pm, "Inertial" <relativ...(a)rest.com> wrote:
>> > > > > >> "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message
>>
>> > > > > >>news:1c6a2640-39f5-4ea4-9c85-127e71f4e6a2(a)33g2000yqj.googlegroups.com...
>>
>> > > > > >> > On Mar 7, 6:58 pm, "Inertial" <relativ...(a)rest.com> wrote:
>> > > > > >> >> "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote
>> > > > > >> >> in message
>>
>> > > > > >> >>news:4b943853$0$11336$afc38c87(a)news.optusnet.com.au...
>>
>> > > > > >> >> > "Inertial" <relativ...(a)rest.com> wrote in message
>> > > > > >> >> >news:4b942bcf$0$27789$c3e8da3(a)news.astraweb.com...
>> > > > > >> >> >> "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
>> > > > > >> >> >> wrote in
>> > > > > >> >> >> message
>> > > > > >> >> >>news:4b93bf73$0$28464$afc38c87(a)news.optusnet.com.au...
>>
>> > > > > >> >> >>>>> 1) your statement: "For clarity, both effects are
>> > > > > >> >> >>>>> purely
>> > > > > >> >> >>>>> observational - SR presumes (ideal) clock mechanisms
>> > > > > >> >> >>>>> are
>> > > > > >> >> >>>>> completely
>> > > > > >> >> >>>>> unaffected by a clock's motion." -- I agree the
>> > > > > >> >> >>>>> physical
>> > > > > >> >> >>>>> mechanism
>> > > > > >> >> >>>>> of
>> > > > > >> >> >>>>> the clock is unaffected, but this is a really
>> > > > > >> >> >>>>> misleading
>> > > > > >> >> >>>>> statement,
>> > > > > >> >> >>>>> since the amount of proper time that the clock
>> > > > > >> >> >>>>> consumes is
>> > > > > >> >> >>>>> affected
>> > > > > >> >> >>>>> by
>> > > > > >> >> >>>>> its motion. Are you trying to say
>>
>> > > > > >> >> >>>> I was "trying to say" exactly what I did say. If you
>> > > > > >> >> >>>> didn't find
>> > > > > >> >> >>>> it
>> > > > > >> >> >>>> clear enough, try this: relative slow-downs/speed-ups
>> > > > > >> >> >>>> observed in
>> > > > > >> >> >>>> the
>> > > > > >> >> >>>> readings of SR's ideal clocks aren't due to changes in
>> > > > > >> >> >>>> the tick
>> > > > > >> >> >>>> mechanisms of those clocks.
>>
>> > > > > >> >> >>> I still don't find it clear, as it begs the question -
>> > > > > >> >> >>> it says
>> > > > > >> >> >>> what
>> > > > > >> >> >>> doesn't cause the change, not what does cause the
>> > > > > >> >> >>> change.
>>
>> > > > > >> >> >>> The standard SR answer is much more direct - the clocks
>> > > > > >> >> >>> slow down
>> > > > > >> >> >>> due
>> > > > > >> >> >>> to
>> > > > > >> >> >>> relativistic time dilatation from them being in
>> > > > > >> >> >>> different
>> > > > > >> >> >>> reference
>> > > > > >> >> >>> frames.
>>
>> > > > > >> >> >>> Is that standard position of SR also your position? Or
>> > > > > >> >> >>> is your
>> > > > > >> >> >>> somehow
>> > > > > >> >> >>> different?
>>
>> > > > > >> >> >> SR says that the difference in clock sync (clock
>> > > > > >> >> >> settings) cause
>> > > > > >> >> >> the
>> > > > > >> >> >> measurement of length to be contracted and measurement
>> > > > > >> >> >> of clock
>> > > > > >> >> >> ticking
>> > > > > >> >> >> rates to be dilated.
>>
>> > > > > >> >> > More or less.
>>
>> > > > > >> >> That's what it is :)
>>
>> > > > > >> >> > But I asked you about *your* position, not SR's position.
>>
>> > > > > >> >> My position is SR's position
>>
>> > > > > >> >> > Do you agree that that the clocks slow down due to
>> > > > > >> >> > relativistic time
>> > > > > >> >> > dilation, as predicted by SR, or not?
>>
>> > > > > >> >> They are measured as slower, just as a rod is measured as
>> > > > > >> >> shorter.
>> > > > > >> >> This
>> > > > > >> >> is
>> > > > > >> >> due to the difference in simultaneity. They don't slow
>> > > > > >> >> down because a
>> > > > > >> >> moving observer is looking at them any more than a rod
>> > > > > >> >> shrinks because
>> > > > > >> >> a
>> > > > > >> >> relatively moving observer is looking at it.
>>
>> > > > > >> >> Here's a little example you might follow .. with time
>> > > > > >> >> differences
>> > > > > >> >> exagerated
>> > > > > >> >> for clarity
>>
>> > > > > >> >> Here are six clocks, in tow rows (S and S'), all ticking at
>> > > > > >> >> the
>> > > > > >> >> correct
>> > > > > >> >> rate, but set with different times...
>>
>> > > > > >> >> S' 10:30 11:00=A 11:30 <--v
>> > > > > >> >> S 11:30=C 11:00=B 10:30 -->v
>>
>> > > > > >> >> Clocks B sees the A is synchronized with it.
>>
>> > > > > >> >> Now .. the clocks are moving in opposite directions so
>> > > > > >> >> after an hour
>> > > > > >> >> we
>> > > > > >> >> have
>>
>> > > > > >> >> S' 11:30 12:00=A 12:30
>> > > > > >> >> S 12:30=C 12:00=B 11:30
>>
>> > > > > >> >> Clock A has moved away from clock B .. but another clock
>> > > > > >> >> (C) in S can
>> > > > > >> >> see
>> > > > > >> >> the time on it. Clock C sees that clock A is half an hour
>> > > > > >> >> slow (A
>> > > > > >> >> shows
>> > > > > >> >> 12:00 when C shows 12:30). So according to the clocks in
>> > > > > >> >> S, clock A
>> > > > > >> >> is
>> > > > > >> >> ticking slower. We also note that clock B now sees a
>> > > > > >> >> *different* S'
>> > > > > >> >> clock
>> > > > > >> >> next to it as being fast (it shows 12:30 when B shows
>> > > > > >> >> 12:00)
>>
>> > > > > >> >> If you look at the same scenario but from the point of view
>> > > > > >> >> of the
>> > > > > >> >> other
>> > > > > >> >> row
>> > > > > >> >> of clocks, you get symmetric results.
>>
>> > > > > >> >> This is how clock synch affects measured ticking rates for
>> > > > > >> >> moving
>> > > > > >> >> clocks
>> > > > > >> >> in
>> > > > > >> >> SR. Even though the clocks themselves do NOT change their
>> > > > > >> >> intrinsic
>> > > > > >> >> ticking
>> > > > > >> >> rates.- Hide quoted text -
>>
>> > > > > >> > Looks good, but let's take it one step further. The
>> > > > > >> > observer with
>> > > > > >> > clock A jumps to frame S" which is traveling in the same
>> > > > > >> > direction as
>> > > > > >> > S relative to S' but at twice the velocity.
>>
>> > > > > >> > S" 1:00 12:00=A 11:00 -->2v
>> > > > > >> > S' 11:30 12:00=A 12:30 <--v
>> > > > > >> > S 12:30=C 12:00=B 11:30 -->v
>>
>> > > > > >> > Clocks A and B continue to tick at there same intrinsic
>> > > > > >> > ticking rate
>> > > > > >> > and an hour later A has overtaken B.
>>
>> > > > > >> > S" 2:00 1:00=A
>> > > > > >> > 12:00 -->2v
>> > > > > >> > S' 12:30 1:00=A 1:30
>> > > > > >> > <--v
>> > > > > >> > S 1:30=C 1:00=B
>> > > > > >> > 12:30 -->v
>>
>> > > > > >> > The above provides the same situation as the twins paradox.
>> > > > > >> > Clock A
>> > > > > >> > left clock B and returned. So why doesn't clock A show less
>> > > > > >> > time
>> > > > > >> > elapsed than B? (Note the clocks in S" are further out of
>> > > > > >> > sync than
>> > > > > >> > those in S due to the higher velocity.)
>>
>> > > > > >> The three clock situation cannot be so easily drawn .. bit
>> > > > > >> like trying to
>> > > > > >> drawing a three dimensional figure in 2d :) This sort of
>> > > > > >> diagram only
>> > > > > >> really works for a single pair of clocks looking from a third
>> > > > > >> frame in
>> > > > > >> which
>> > > > > >> they move with the same speed. Things are trickier when there
>> > > > > >> is frame
>> > > > > >> jumping going on :):)- Hide quoted text -
>>
>> > > > > >> - Show quoted text -
>>
>> > > > > > The question still remains, if there is no change in the tick
>> > > > > > rate of
>> > > > > > the clock, how can clock A have fewer ticks recorded when it is
>> > > > > > brought back to clock B?
>>
>> > > > > Look at the Lorentz transforms to see. Its all due to clock
>> > > > > synch.- Hide quoted text -
>>
>> > > > > - Show quoted text -
>>
>> > > > You are going to give yourself a head cold with all that arm
>> > > > waving.
>> > > > You are saying the tick rate doesn't change, yet SR says that the
>> > > > returning twin's clock will show less elapsed time. You don't see
>> > > > any
>> > > > conflict there?
>>
>> > > No, there is no conflict. When you say that the tick rate does not
>> > > change, this is a LOCAL statement. What it means is that a process
>> > > measured locally with this clock will still have the same duration.
>>
>> > That is not what we were discussing. I agree that the clock continues
>> > to tick at a rate of one second per proper second in the rest frame of
>> > the clock. The question was whether the slowed tick rate measured in
>> > the frame of the stay at home twin is real, or an illusion due to the
>> > clock sync proceedure, as length contraction is.
>>
>> I don't know that length contraction IS an illusion. Length is
>> *defined* operationally by relying on simultaneity, and so the REAL
>> length according to that definition is of course frame-dependent,
>> because simultaneity is frame-dependent.
>>
>> > If it is an illusion
>> > the accumulated time on the two clocks should be the same when they
>> > are brought back together. The way Inertial described it, it came
>> > across as an illusion caused purely by clock sync.
>>
>> > I hate discussing what is "real". In a sense length contraction is
>> > real because the pole will fit into the barn.
>>
>> Absolutely. If I have a clear understanding of what "simultaneous"
>> means in a given reference frame, and I close the barn doors
>> simultaneously with the pole between them, and there are no marks on
>> the doors where the pole hit either one of them, then I can't think of
>> any sensible meaning of "fit" that would hold these circumstances to
>> be true and yet the pole does not fit in the barn in this frame. And
>> since the pole fits, I cannot think of any sensible meaning of
>> "shorter" where the pole would fit in the barn and yet be not shorter
>> than the barn.
>
> Careful here. I don't see how you can claim that the rod really is
> shorter but that the clock didn't really slow down.

The measured length of a rod is shorter .. the measured rate of a clock is
slower.

However, there is no intrinsic change to the rod or the clock

> The fact that the
> rod has different measured lengths at the same time

Careful with 'at the same time' :):)

> tells me that the
> measured length is a matter of perception, which can be distorted.

No distortion invovled. Do you think velocity is a matter of perception
which can be distorted?

> But the fact that the returned clock has less elapsed time tells me
> that it isn't just how I looked at it. If we are to agree that length
> contraction and time dialation are real I'm good with that.

They are real in the sense that that is what is measured. A moving rod will
REALLY fit within the barn doors.

> But don't
> then tell me that the clock didn't slow down.

There was a change in simultaneity.

> It slowed in our frame
> but the traveling twin couldn't detect it because he used the
> coordinates of his new frame of reference to measure it.

We measure the twin's clock as running slower on the outbound journey, we
measure it as running slower on the return journey .. we've had not change
in frame of reference .. so when he returns we must measure his clock as
having less elapsed time.

From the travelling twin's point of view, when he gets to the turnaround
point, simultaneity changes abruptly, and his 'now' is equivalent to a
different time in the at-home-twins timeline.

>> > But with length
>> > contraction there is no accumulated length to inspect when the pole is
>> > brought to rest.
>>
>> This is true. The twin puzzle is a different animal that the barn-pole
>> paradox. In the twin puzzle, there is no symmetry in terms of inertial
>> motion. One twin is DEFINITELY not residing wholly in one inertial
>> reference frame, and that is a frame-independent observation.
>>
>> > I can see that the measured slowing of the clock is
>> > due to the rotation of the time coordinates when it changed frames,
>> > but that doesn't make it any less real.
>>
>> > > For example, if the half-life of a muon that is slow in frame A and
>> > > is
>> > > measured with a clock at rest in A is 2.2 us, then if you make the
>> > > same measurement of the half-life of a muon that is slow in frame B
>> > > and is measured with a clock at rest in B, clock B will still show
>> > > the
>> > > half-life to be 2.2 us. In this sense, we say that the clock tick
>> > > rate
>> > > has not changed, because measurements of local phenomena are
>> > > unchanged.
>>
>> > Yes, but again you are measuring locally, more or less in the rest
>> > frame of the muon. We know that if we measure the half life of a fast
>> > moving muon it is longer, as if its personal clock was ticking slower.
>>
>> > > However, this does NOT mean that the tick rate of clock B will agree
>> > > with the clock rate of all other clocks, nor that it will read the
>> > > durations of nonlocal processes to be the same.
>>
>> > > Do you see the distinction?
>>
>> > If we set up a light clock with a vertical bouncing beam, and have it
>> > send a flash back to the stay at home twin every time the beam hits
>> > the top, we can tell just how fast the clock is ticking. The signal
>> > will be doppler shifted, but the total count is what it is. None of
>> > the flashes drifted off and avoided detection. I am not claiming this
>> > slowing is due to motion wrt an ether. It is due to the finite speed
>> > of light and how we define/construct the coordinate systems.
>>
>> The last sentence is right, but how we define/construct the coordinate
>> systems is constrained by the structure of spacetime (and this in fact
>> produces the finite speed of light). That is, there is no way to
>> define/construct a coordinate system in our spacetime such that these
>> effects go away. (You are free to try.)
>>
>> PD
>>
>> > Bruce
>