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From: jbriggs444 on 5 Mar 2010 16:19
On Mar 5, 3:55 pm, mpalenik <markpale...(a)gmail.com> wrote:
> On Mar 5, 3:47 pm, jbriggs444 <jbriggs...(a)gmail.com> wrote:
>
>
>
>
>
> > On Mar 5, 3:07 pm, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > On Mar 5, 2:17 pm, jbriggs444 <jbriggs...(a)gmail.com> wrote:
>
> > > > On Mar 5, 1:54 pm, jbriggs444 <jbriggs...(a)gmail.com> wrote:
> > > > [discussing the scenario in which two clocks symmetrically accelerate
> > > > toward each other and this is observed from the point of view of one
> > > > of the clocks]
>
> > > > > Your initial assertions are correct.  Both will report a slow down....
> > > > > During part of the trip.  And a different slowdown  during a different
> > > > > part of the trip.
>
> > > > I should correct myself here.
>
> > > > The part I wrote about "a different slowdown during a different part
> > > > of the trip" was an erroneous reference to a scenario in which a clock
> > > > is reporting the Doppler shift that is _seen_ (i.e. without accounting
> > > > for transit delays).
>
> > > In fact, what I was trying to describe to Ste was the effects that are
> > > specifically not due to Doppler shifting, as I was specifically making
> > > the point that the predictions of SR for time dilation are
> > > mathematically different than those which are due to the observed rate
> > > of change on a ticking clock to transit delays.
>
> > Ok good.  So we're both not talking about that.
>
> > > > In such a scenario, the clock sees an interval after it has
> > > > accelerated and before its peer has accelerated and then a second
> > > > interval after the peer has accelerated.  The Doppler shifts for the
> > > > intervals are, of course, different.
>
> > > > In the scenario at hand we are trying to discuss what is _observed_
> > > > (i.e. accounting for transit delays and adopting particular standards
> > > > of simultaneity)
>
> > > No, that's not actually what we were talking about at all.
> > > > What is _observed_ is only a single interval during which the two
> > > > clocks are in constant relative motion, not two such intervals.  [From
> > > > an "observed" point of view, the period when the peer clock remains
> > > > motionless does not fall within the interval of the journey.  Instead,
> > > > it is in the relative past]
>
> > > The relevant quantity was the time that each clock displays after the
> > > two are brought into comoving frames, which once again, depends on the
> > > frame that they are brought into.
>
> > In the scenario in question they are not brought into co-moving frames
> > (whatever that means -- the notion of things being "brought into"
> > frames is very questionable)  They are brought _TOGETHER_.
>
> All I can say is read what I originally wrote again.
>
> BTW, "together" is ambiguous.  Together can mean comoving or it can
> mean "they pass each other."  Each of those warrants a different
> answer.- Hide quoted text -
>
> - Show quoted text -

No it doesn't, dufus.
From: BURT on 5 Mar 2010 17:31
On Mar 5, 9:46 am, PD <thedraperfam...(a)gmail.com> wrote:
> On Mar 5, 10:41 am, "Y.Porat" <y.y.po...(a)gmail.com> wrote:
>
>
>
>
>
> > On Mar 5, 1:51 pm, "Inertial" <relativ...(a)rest.com> wrote:
>
> > > "Y.Porat" <y.y.po...(a)gmail.com> wrote in message
>
> > >news:868926cb-233d-417e-86c8-cd8987c43419(a)q16g2000yqq.googlegroups.com....
>
> > > > On Mar 4, 7:44 pm, PD <thedraperfam...(a)gmail.com> wrote:
> > > >> On Mar 4, 11:09 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > >> > On 4 Mar, 16:48, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > >> > > On Mar 4, 10:19 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > >> > > > 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.
>
> > > >> > > The problem is your use of the term "total acceleration".  If by
> > > >> > > total
> > > >> > > acceleration, you mean integral(a dt), then yes, you are correct.
> > > >> > > However, there is already a word for integral(a dt) -- it's called
> > > >> > > "the change in velocity".  The term "total acceleration" isn't
> > > >> > > actually defined.  Acceleration is defined, velocity is defined,
> > > >> > > deltav is defined.  But "total acceleration is not".
>
> > > >> > Essentially, I'm defining "total acceleration" as something akin to
> > > >> > total force, so that even though the force may be small, if it
> > > >> > continues for a long time then the total force will be the same as if
> > > >> > a large force was applied for a short period of time. In this way, if
> > > >> > the application of force is what is causing either part or the whole
> > > >> > of the time dilation effect, then it is the final speed that counts,
> > > >> > not how quickly the object reached that speed.
>
> > > >> Indeed. This should tell you that it is not the details of the
> > > >> acceleration that matter.
> > > >> The overly simplistic statement would be, "Yes, you see that is why
> > > >> SR's effects are based on speed, not on acceleration."
>
> > > >> In fact, there is a speed time dilation effect on GPS satellites,
> > > >> which are going around in a circular path at constant speed, relative
> > > >> to earth clocks, and accounting for this is crucial to their proper
> > > >> operation. This is the same speed dilation effect, though different
> > > >> size, as seen in muons in a circulating ring. (Since, by the way, the
> > > >> GPS satellites are certainly not inside a magnetic ring but still
> > > >> experience time dilation properly calculated by SR, this is another
> > > >> good way to be sure that the magnetic ring is not what's responsible
> > > >> for the time dilation of the muons.)
>
> > > >> Regarding something I alluded to earlier, though, what really matters
> > > >> is how straight the path through spacetime is. We're used to thinking
> > > >> that the shortest path through space is the straight one (and that's
> > > >> right), but the straightest path through spacetime yields the LONGEST
> > > >> duration. Any change in motion (such as an acceleration) introduces a
> > > >> kink in this path (something that can be illustrated visually very
> > > >> easily) and so lowers the duration. Why this is, has to do with the
> > > >> structure of spacetime and we could discuss that. But this is perhaps
> > > >> the most intuitive way (once these concepts are explained) to
> > > >> understand why the traveling twin returns younger.
>
> > > >> > > Also, you could just be dealing with a system where the velocity
> > > >> > > started out high and you never measured any acceleration.
>
> > > >> > Indeed.
>
> > > > ----------------------
> > > > (:-)
> > > > to mix **biologic process**  with
> > > > inorganic physics
> > > > is ridiculous!!!
>
> > > He didn't .. there was no biologic process mentioned in the above.
>
> > > > (i said it in a big understatement ...(:-)
> > > > Y.Porat
> > > > -----------------------
>
> > here is a quote from PD
> > quote
>
> > 'and so lowers the duration. Why this is, has to do with the
> > structure of spacetime and we could discuss that. But this is perhaps
> > the most intuitive way (once these concepts are explained) to
> > understand why the traveling twin returns younger.
> > end of quote
> > -------------
> > so the tarveling twin returns  younger ???!!!
>
> Yes. ALL clocks behave this way, including the chemical clocks that
> drive biological processes.
>
>
>
> > 2
> > if you dont rmind
> > EM radiation  HAS MASS!
>
> >  therefore it i influenced by gravity
> >  SIMILAR BUT NOT EXACTLY AS ANY OTHER MASS!!
> > no curvature and no shmervature of space
>
> > but that is again not for born parrots
> > BYE
> > Y.P
> > ------------------------------- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -

Two time rates by gravity and motion can slow down. One rate can be
faster than the other.

Mitch Raemsch
From: BURT on 5 Mar 2010 21:50
On Mar 5, 6:36 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
wrote:
> > Well, let's see who backs you up.
>
> In SR, time dilation is a real property, and it is observed every day in
> particle accelerators and elsewhere. In SR, two twins, blah blah, one will
> be older. Do not confuse this with gravitational time dilation under GR;
> this is a completely different and independent thing, is orders of magnitude
> smaller that SR time dilation for most real world experiments, and was not
> predicted until well after the twins paradox was discussed and resolved in
> SR.

There are two rates or times in the universe; Gravity's strength and
changing flow of energy through space.

Mitch Raemsch
From: Bruce Richmond on 5 Mar 2010 23:43
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:
>
>
>
>
>
> > On Mar 4, 10:48 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > Yes, there is. That's what isotropy experiments have determined. I'm
> > > surprised you weren't aware of this.
>
> > Do you mean like this one?
>
> >http://mysite.verizon.net/cephalobus_alienus/papers/Gagnon_et_al_1988...
>
> > 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.

> > Recently I have been going back and re-reading some of the books I
> > have bought over the years to see if I can come to grips with some of
> > the modern interpertations of SR.  After thinking about it for awhile
> > I have realized that my objections about the changing definition of c
> > were petty/anal.  An analogy would be that there used to be 24 hours
> > in a day, 60 minutes in an hour, and 60 seconds in a minute.  Now we
> > have defined a second as so many transitions of an atom, and can
> > measure the variation in the length of a day.  The new way is better.
> > That it is not in perfect agreement with the old doesn't change much.
> > There was nothing sacred about the old.  So yes, an old dog can be
> > taught new tricks :)
>
> Thank goodness!
>
> Jerry- Hide quoted text -
>
> - Show quoted text -

From: Bruce Richmond on 6 Mar 2010 01:15
On Mar 5, 12:12 am, "Inertial" <relativ...(a)rest.com> wrote:
> "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message
>
> news:7806715d-93d2-49ff-ad67-6dac8ea64d8c(a)e7g2000yqf.googlegroups.com...
>
>
>
>
>
> > On Mar 4, 10:48 am, PD <thedraperfam...(a)gmail.com> wrote:
> >> On Mar 3, 10:59 pm, Bruce Richmond <bsr3...(a)my-deja.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.
>
> >> > Well you are going to have problems with that.  There is no way to
> >> > *know* that the speed is the same both ways.
>
> >> Yes, there is. That's what isotropy experiments have determined. I'm
> >> surprised you weren't aware of this.
>
> > Do you mean like this one?
>
> >http://mysite.verizon.net/cephalobus_alienus/papers/Gagnon_et_al_1988...
>
> > 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.
>
> >> > That is why Einstein
> >> > wrote, "But it is not possible without further assumption to compare,
> >> > in respect of time, an event at A with an event at B. We have so far
> >> > defined only an ``A time'' and a ``B time.'' We have not defined a
> >> > common ``time'' for A and B, for the latter cannot be defined at all
> >> > unless we establish by definition that the ``time'' required by light
> >> > to travel from A to B equals the ``time'' it requires to travel from B
> >> > to A."
>
> >> > > 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.
>
> >> > Assuming the speed of light is the same in both directions.
>
> >> Which is an experimentally confirmed fact. Done well after Einstein's
> >> comments on the matter, by the way.
>
> > Provide a link to an experiment and I'll take a look.
>
> >> > > 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.
>
> >> > > Then the frame-dependence of simultaneity follows directly from the
> >> > > experimental *observation* that for the same pair of events, one
> >> > > observer correctly and unambiguously concludes the events were
> >> > > simultaneous, and the other observer correctly and unambiguously
> >> > > concludes the events were nonsimultaneous.
>
> >> > > You've mentioned in the past that you found your disbelief in
> >> > > relativity stems from being unable to find a good, understandable
> >> > > explanation of it. I invite you to read back on this thread where I
> >> > > was trying to explain to Ste (who has a similar complaint) how this
> >> > > comes about.
>
> >> > No need.  Lorentz showed how all frames could measure the speed of
> >> > light to be c.  That in effect confirms the second postulate, which is
> >> > the stumbling block for many.
>
> >> Well then, you are just *choosing* what you would like to believe. In
> >> this case, lodging a complaint against relativity that it is not well
> >> explained, when you are not interested in pursuing a better
> >> explanation, having settled on LET instead, is a bit on the
> >> disingenuous side.
>
> > You are reading more into that than what I wrote.  I am not choosing
> > LET over SR.  They use the same math
>
> Yes
>
> > and I consider them two
> > interpertations of the same thing.
>
> Not at all.  Very different as far as how they explain reality
>
> LET has and required a fixed (theoretically undetectable) aether in a fixed
> absolute frame.
> SR does not specify nor require anything about an aether
>
> LET has objects physically compressed due to absolute motion thru the aether
> SR has no absolute motion, so objects are not affected by such motion
>
> LET has processes physically slowed due to absolute motion thru the aether
> SR has no absolute motion, so processes are not affected by such motion
>
> LET has a side-effect of the speed of light being measured as the same in
> all frames of reference, due to measuring with compressed rulers and slowed
> clocks, even though its only really has that speed relative to the aether,
> SR has no absolute compression and slowing, and the speed of light really is
> c
>
> LET has a side-effect of an appearance of the lorentz transforms holding on
> measured values, due to measuring with compressed rulers and slowed clocks.
> SR has no absolute compression and slowing, so the lorentz transform hold

Read what I actually wrote, not what you think I wrote. I wrote, "I
consider them two interpertations of the same thing." The events are
the same. The predictions are the same. The interpertation of why
things appear the way they do is different.

> >  The LET interpertation had the
> > advantage, for me, of showing how c + or - v could end up being
> > measured c in all frames.
>
> In SR there is no c+v or c-v, because there is no fixed absolute aether
> frame in which light really travels at c.

There most certainly is a c+v and c-v in SR. They are called closing
speed. And one of the most difficult things for a new student to
understand is why unlike anything else EM waves have the same speed in
all frames. I will probably screw up how I put this but IMO it is
because we made it that way. Nature does what it wants to, but we
still have some choice in how we write the equations that describe
what nature is doing.

Say you have a cannon that launches a projectile using a spring.
Given the strength of the spring, how far it is compressed, the weight
of the projectile and the inclination of the barrel, you could
calculate the trajectory of the projectile. Put the cannon on a
flatbed of a moving train and it would be easiest to calculate the
trajectory relative to the train, and then add the velocity of the
train to get the position of the projectile relative to the ground at
any given instant. But it is possible to work things out directly
from the FoR of the ground, so long as you are consistant. For
example, the spring may only expand a foot in the barrel of the
cannon, but in doing so it pushes the projectilie six feet relative to
the ground.

When we make a calculation from the track FoR that involves the train
we use the closing speed of c+v and get a correct answer. There is
nothing stopping a rider on the train from using the same track
coordinates and the same c+v to get the same answer. It just makes
things a whole lot easier if he uses coordinates from his rest frame.
Maxwell had found that the speed of light always seemed to be c, as
measured using clocks synchronized in the rest frame the measurement
was made in. I don't know if he was aware of RoS or not, but it
certainly made the writing of his equations easier to keep the speed
of light a constant.

> >  Given that was possible I no longer had any
> > problem accepting the second postulate.  Eventually I became aware
> > that the second postulate wasn't so much an assumption as a
> > stipulation.  We will consider the speed of light to be our standard.
>
> No .. it is an observed fact.  Not a stipulation

It was an observed fact in part because of the proceedures used to
observe it. As I have said before, light behaved differently than
anything else and it wasn't clear how it could do so.

> > Recently I have been going back and re-reading some of the books I
> > have bought over the years to see if I can come to grips with some of
> > the modern interpertations of SR.  After thinking about it for awhile
> > I have realized that my objections about the changing definition of c
> > were petty/anal.
>
> :)  Always a good conclusion to reach .. it shows you really are thinking
> and learning and advancing.

Reading Bondi he gave a good explaination for why time is considered a
fourth dimension and how rotations fit in. I wont say any more at
this point because I would probably screw it up. Sometimes it is
easier to understand things than it is to express the ideas to
others. Then again, it could be because I don't really understand it
that well yet.

> >  An analogy would be that there used to be 24 hours
> > in a day, 60 minutes in an hour, and 60 seconds in a minute.  Now we
> > have defined a second as so many transitions of an atom, and can
> > measure the variation in the length of a day.  The new way is better.
> > That it is not in perfect agreement with the old doesn't change much.
> > There was nothing sacred about the old.  So yes, an old dog can be
> > taught new tricks :)
>
> > Bruce
>
> And several points up my estimation ladder for doing so and admitting it
> :):)- Hide quoted text -
>
> - Show quoted text -

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