Simple question about SR paradox
Marc Fleury
I am happy to see the sci.physics of old are still alive and kicking!!
I didn't post since the mid 90's when I was doing my PhD :)
Anyway, quick question, I have some time these days and decided to
finally go back and try to "get" relativity. I am struggling still
but making more progress than I used to. The math, was never the
problem (not even GR) but the "mental model" always was hard for me.
To the point I want clarity on. I assume I have two inertial frames,
with an atomic clock in each of them. They have a relative velocity
of v. SR tells us that the coordinates are lorentz transformed so
that time in both frames with respect to the other has to be
multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
a moving framework". I have no problem with slowing down 'time'
understood as coordinates (meaning with no physical, or ontological,
reality and just props in my calculations) but have a profound problem
admitting that both CLOCKS (as counting ticks) will slow down with
respect to the other. Just by symmetry of the problem, the
proposition seems non-sensical to me.
Somewhere between the 'physical clock' and the 'coordinates', I am
missing a step? Does SR say anything about the number of clock
ticks? This also seems completely basic to the understanding of SR
and so must have been covered countless time. Any help or pointers
are greatly appreciated.
Androcles
"Marc Fleury" <marc...@gmail.com> wrote in message
news:e9614ffe-cf1e-4640...@x3g2000yqj.googlegroups.com...
http://www.androcles01.pwp.blueyonder.co.uk/SR4kids/SR4kids.htm
Any questions, just ask.
dlzc
Easy really. If Reality is just what you measure, then you are
halfway home.
> Just by symmetry of the problem, the
> proposition seems non-sensical to me.
The answer lies in your belief in some Reality separate from what can
be measured.
> Somewhere between the 'physical clock'
> and the 'coordinates', I am missing a
> step?
No difference.
> Does SR say anything about the number of
> clock ticks?
Sure, as soon as you assign one frame or the other as "rest". The
moving clock has fewer ticks accumulated over some trip, and then you
have distance accumulated and relativistic Doppler shift.
How do you feel about the "clock tick difference" in a gravity well?
> This also seems completely basic to the
> understanding of SR and so must have been
> covered countless time. Any help or pointers
> are greatly appreciated.
It is not completely basic, and it is covered a number of times both
here and elsewhere. Your common sense is trained where c -> infinity,
and you have not let the equations guide you through any interesting
solution spaces... You were busy navigating, and not paying attention
to the terrain.
I'd recommend you get something basic like "Spacetime Physics" by
Taylor and Wheeler, and take your time with it.
David A. Smith
rotchm
> a moving framework". I have no problem with slowing down 'time'
> understood as coordinates (meaning with no physical, or ontological,
> reality and just props in my calculations)
You already understand more than most posters here!
Position and time (x,t) in SR represent the values obtained (or
predicted) by the experiment and not just "props in calculations". To
verify SR's prediction, one makes measurements. In this sense, (x,t)
or lengths and "clock slowdown" are "real/physical". But again, those
are just loose descriptive words and dont change th fact about what
SR's calculations predict.
> but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
By symmetry, both clocks will view the other as "slowing down". This
is also predicted by SR's algebra, not just by its "symmetry"
principle. Note that "slow down" is just a very loose expression
again and is irrelevant to what SR *predicts*. SR says that if
observer A performs the measurement procedure and obtains value V,
then B will obtain the same value if he does the same procedure.
An analogy is the 'angle-height'. You and your twin are at some
distance apart. Looking at each other, both will measure each others
"angle-height" as the same, say 10 deg, even though YOU measure your
own angle-height as 90deg.
> Somewhere between the 'physical clock' and the 'coordinates', I am
> missing a step?
Dont forget, in SR you have a multitude of clocks. "Time" is the value
on a (synched) clock that is at the *location* of the analyzed event.
Every location of an observers frame has such a (hypothetical) clock.
> Does SR say anything about the number of clock
> ticks?
Sort of, yes. An observer can not count the ticks of a clock "over
there" (moving clock or not). The observer must preform a well defined
measurement procedure. The value(s) he obtains is what he calls the
"number of ticks" (or any other measured quantity). SR algebra will
predict what these values will be. One can say that SR is about the
relationships of measurements from one frame to another.
> This also seems completely basic to the understanding of SR
> and so must have been covered countless time. Any help or pointers
> are greatly appreciated.
Hope this clears up a little.
Tom Roberts
> I have no problem with slowing down 'time'
> understood as coordinates (meaning with no physical, or ontological,
> reality and just props in my calculations) but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
Yes. This is really a GEOMETRICAL PROJECTION, not any actual "slowing down" of
any clock.
Draw x-y coordinates on a plane, and draw x'-y' coordinates rotated
30 degrees relative to them. The projection of a unit length along
x onto the x' axis is shorter than 1; the projection of a unit length
along x' onto x is also shorter than 1. This is just geometrical
projection, and no length actually "got shorter", but if one insists
on speaking VERY LOOSELY, one might claim "each sees the other as
shorter" (where by "sees" one means this projection). The error
implicit in such loose speech ought to be obvious.
In SR, relatively-moving clocks behave similarly. That's why I always
put "time dilation" and "length contraction" in quotes -- these are
misnomers because it is not any time interval that is dilating or any
object's length that is contracting, but rather MEASUREMENTS that are
affected.
In relativity, clocks do not slow down due to any sort of motion. It is only
MEASUREMENTS of clock rates in other frames that vary. When at rest in any
inertial frame, any good clock will tick at its standard rate.
The relationship between relatively-moving inertial frames is a hyperbolic
rotation in spacetime. The usual "time dilation" and "length contraction" are
merely the way geometric projections work between such coordinates -- they are
directly analogous to rotating a ladder to carry it through a doorway (the
ladder itself is unchanged, only its RELATIONSHIP to the doorway is changed; the
moving clock itself is unchanged, the only change is in its relationship to the
inertial frame measuring its tick rate.).
BTW this is generalized in GR, and one finds that both clocks and
EM signals are unaffected by either gravitation or relative motion.
But both gravitation and relative motion affect the orientations of
4-vectors in spacetime, and "time dilation", "length contraction",
"gravitational redshift", and "cosmological redshift" are simply
the way projections relate to such orientations.
Bottom line: both SR and GR are theories about geometry; geometry does not
affect any physical object, but geometrical relationships can affect
measurements, because a measurement is inherently the projection of some
quantity onto a measuring instrument.
Tom Roberts
OG
To observe a clock in one frame from another frame you have to use light.
Because light travels at a finite speed, the relative movement of the
frames makes a difference to the observed rate of the clocks when seen
from one frame or the other.
The only non-intuitive thing is that the speed of all light is measured
to be the same in both frames.
artful
> Hello folks,
>
> I am happy to see the sci.physics of old are still alive and kicking!!
Many kicking and screaming :)
> I didn't post since the mid 90's when I was doing my PhD :)
>
> Anyway, quick question, I have some time these days and decided to
> finally go back and try to "get" relativity. I am struggling still
> but making more progress than I used to. The math, was never the
> problem (not even GR) but the "mental model" always was hard for me.
Yeup .. SR math is pretty straight forward (though many crackpots here
can't even manage that .. Androcles being a case in point) .. getting
your mind around what it 'means' is far more difficult for many. Some
just refuse to admit that they do't get it and instead decalre the
relativity must be wrong .. then they don't have to deal with their
inability to understand it. Sad .. but that's how some people cope.
> To the point I want clarity on. I assume I have two inertial frames,
> with an atomic clock in each of them.
Fine. Of course by 'in each of them' you mean 'AT REST in each of
them'. The atomic clocks are *in* all the frames .. as every frame
contains everything in the universe :)
> They have a relative velocity
> of v. SR tells us that the coordinates are lorentz transformed so
> that time in both frames with respect to the other has to be
> multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> a moving framework".
Not really. The gamma factor on its own only applies is certain
degenerate cases .. eg if you look at the different in x values when
the time value is the same same, you get the gamma factor applied to
length.
Time doesn't really slow down in a moving frame. Time is time in any
inertial frame. A second my any other name would tick as fast :) ...
Its when you try to MEASURE the rate of a moving clock or the length
of a moving ruler that you get differences from rest measurements.
It is important to note that to measure the rate of a moving clock,
you need to take two difference readings of it at different times.
And because it is moving, that means at two different locations.
The things is .. clock sync is position dependent .. as things move,
their 'sync' slips.
Imagine you take filing a train as it moves past from three different
camera positions (assume no SR effects here). The cameras are
arranges so that when the rear of the train is adjacent the first
camera, then the middle of the train is adjacent to the second camera,
then the front adjacent to the third. So the first and third camera
as the same distance apart as the length of the train.
When playing back, you position TV screens at the same distances apart
as the cameras were and play the films in sync. Someone watching will
see three glimpses of the train moving past and would work out its
length to be as expected (because it will see the rear and front of
the train in the first and third screen at the same time.
However .. if you start the playback at different times .. os you
start playing the first tv a bit before the second which is a bit
before the third .. then you'll see what appears to be a shorter train
going past. If you measure the difference between where the first and
third camera show the read and front of the train being, the distance
will be shorter.
You've just gotten a 'length contraction' because your movies were out
of sync.
> I have no problem with slowing down 'time'
> understood as coordinates (meaning with no physical, or ontological,
> reality and just props in my calculations) but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
Many have that problem. The apparent slowing is really an effect of
differences in clock sync
Lets look at clock rates (instead of train lengths) to see how
differences in clock sync give you mutual time dilation.
Consider this a series of clocks moving to the left at a speed v, and
another moving to the right at speed v (in our frame) (so relative
speed is 2v here). From our point of view we see them as being out of
sync.
A1 A2
<-- v 6.........7.........8.........9.........10........11
11........10........9.........8.........7.........6 --> v
B
An observer at A1 looks at the time on clock B as it passes. They
both show the same time (8 o'clock).
Some time later, clock B passes A2, and the observer there records the
times
A1 A2
7.........8.........9.........10........11........12
12........11........10........9.........8.........7
B
Now, clock A2 shows 11 o-clock, while clock B shows only 9 o-clock.
So now B is two hours behind. So A would determine that B is ticking
slow.
Now look at the identical situation from B's point of view
A
<-- v 6.........7.........8.........9.........10........11
11........10........9.........8.........7.........6 --> v
B1
A1
7.........8.........9.........10........11........12
12........11........10........9.........8.........7
B2 B1
The B clocks record the same thing, only in reverse . three hours
differnce B clock readings but only one in A.
So you can see that clocks being out of sync (ie time depends on
posiion) results in mutual time dilation
Does that help?
Vilas Tamhane
PhD in physics?
Before you raise a question about actual ticking of a clock I have a
counter question for you.
Even more basic than your basic question.
If O finds that the clock in O’ runs slow and reciprocally if O’ finds
that the clock of O is running slow then what inference should we make
out of it?
Isn’t it a sloppy statement? Can a theory be based on such a
statement?
Tom Roberts
> To observe a clock in one frame from another frame you have to use light.
This is not true.
In the usual scenario, one has multiple assistants all at rest in the
measurement frame, each with a clock synchronized in the measurement frame with
all the others; assistants are pre-positioned along the path of the moving
clock. When the moving clock passes each assistant, he records the value of his
clock and the value of the moving clock. The multiple recordings are then
combined into a single measurement of the rate of the moving clock.
This has no need for light signals, and is completely independent of any
properties of light.
> The only non-intuitive thing is that the speed of all light is measured to be
> the same in both frames.
This is best understood as the clocks and rulers in different frames having
different orientations in spacetime, with "time dilation" and "length
contraction" being simple results of the geometric projections involved in the
corresponding measurements. These effects combine to make measurements of the
speed of light in vacuum always yield c.
Stated differently, relative to any inertial frame the orientation of a light
ray is always such that its speed is c (it can propagate in any spatial
direction, of course).
Tom Roberts
artful
How would he determine that .. its important that you know how he does
that .. and to know what 'runs slow' means in this context.
> and reciprocally if O’ finds
> that the clock of O is running slow then what inference should we make
> out of it?
That O measure O' as slow and O' measures O as slow. A bit like how
you look small in the distance compared to me (eg I can fit you
between two of my fingers), and I look small compared to you .. yet we
are both really the same heights.
> Isn’t it a sloppy statement?
Not really .. but even if so, the math and physics that you are
summarizing with 'sloppy' statements is not itself sloppy.
> Can a theory be based on such a
> statement?
Do you think physics theories are based on a particular English
wording of a statement?
Vilas Tamhane
If relativistic effects are not real then proper place for SR is a
dust bin. Actually physicists play jugglery with poor students. In
theory the effects have to be apparent, as that is what relativity
means. But to apply it to experimental results, one way predictions
are mentioned. Therefore only the clock that is accelerated runs slow.
Your ladder and door example is a good one. But remember that when
ladder is tilted, it has now two components, x and y (door has only
one-y). So SR is not about geometry and no need to bring in space-time
diagram.
If there is no real length contraction or time dilation then the
MEASUREMENTS which are affected have no value. These are wrong or
unreliable measurements.
Dono.
>
> If O finds that the clock in O’ runs slow and reciprocally if O’ finds
> that the clock of O is running slow then what inference should we make
> out of it?
> Isn’t it a sloppy statement?
No.
> Can a theory be based on such a
> statement?
Yes.
Don Stockbauer
Cybernetics is much more important than SR-GR, since it tells you how
to build arbitrarily large artificial minds.
Vilas Tamhane
If according to your measurements my height is 12mm. Will you treat it
as real and use it in real world? For example will you give shirt for
me for stitching based on this measurement or using optical angle you
will fix my height as I measure it.
> > Isn’t it a sloppy statement?
>
> Not really .. but even if so, the math and physics that you are
> summarizing with 'sloppy' statements is not itself sloppy.
>
May be. But it makes theory wrong and concepts behind your math (not
physics) are different. But like a fundamentalist you make physics a
religion.
> > Can a theory be based on such a
> > statement?
>
> Do you think physics theories are based on a particular English
> wording of a statement?- Hide quoted text -
>
This is not only a statement. This is the law of SR.
> - Show quoted text -
kenseto
But no such direct measurement ever been made....in fact it is
impossible to do so. What you SRians claim is that predictions are
measurements.
> David A. Smith- Hide quoted text -
shuba
> I am happy to see the sci.physics of old are still alive and kicking!!
> I didn't post since the mid 90's when I was doing my PhD :)
Great, then presumably you are well-equipped to figure out which
replies are worth taking seriously. I'll add another to the mix.
> I have no problem with slowing down 'time' understood as
> coordinates (meaning with no physical, or ontological, reality and
> just props in my calculations) but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
It's actually an abuse of language to say that clocks slow down at
all. A clock ticks at, say, one tick per second, as measured by
someone holding it or another clock colocated with it. That
definition is perfectly symmetric. Relativity says that the ticks of
a moving clock, when compared by you to a clock you are holding,
occur at less than one tick per second. Again perfectly symmetric.
The "time dilation" factor that you wrote is just the ratio of the
time between 'colocated clock ticks' (T) to the time between 'moving
clock ticks' (t).
T/t = sqrt(1-(v/c)^2)
The big T is called the "proper time" and is the elapsed time read on
a clock's dial. For arbitrary motion, the differentials dT and dt can
be used, giving the proper time for a clock moving along any
trajectory by calculus.
T = integral-of [sqrt(1-(v/c)^2)] dt
This integral is the same as calculated from any inertial frame, and
the proper time T is the elapsed time on an arbitrarily moving
clock.
---Tim Shuba---
PD
> Hello folks,
>
> I am happy to see the sci.physics of old are still alive and kicking!!
> I didn't post since the mid 90's when I was doing my PhD :)
>
> Anyway, quick question, I have some time these days and decided to
> finally go back and try to "get" relativity. I am struggling still
> but making more progress than I used to. The math, was never the
> problem (not even GR) but the "mental model" always was hard for me.
>
> To the point I want clarity on. I assume I have two inertial frames,
> with an atomic clock in each of them. They have a relative velocity
> of v. SR tells us that the coordinates are lorentz transformed so
> that time in both frames with respect to the other has to be
> multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> a moving framework". I have no problem with slowing down 'time'
> understood as coordinates (meaning with no physical, or ontological,
> reality and just props in my calculations) but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
>
> Somewhere between the 'physical clock' and the 'coordinates', I am
> missing a step?
Yes, a LOT of steps, and this is the part you have to start paying
attention to.
Stop skipping steps and start paying attention to all those
intermediate things, and this is how you will get to this point and
realize that it is not a contradiction at all.
What are you using to study this phenomenon. What is the source
material where all that "bla bla bla" is?
Paul B. Andersen
> Hello folks,
>
> I am happy to see the sci.physics of old are still alive and kicking!!
> I didn't post since the mid 90's when I was doing my PhD :)
>
> Anyway, quick question, I have some time these days and decided to
> finally go back and try to "get" relativity. I am struggling still
> but making more progress than I used to. The math, was never the
> problem (not even GR) but the "mental model" always was hard for me.
>
> To the point I want clarity on. I assume I have two inertial frames,
> with an atomic clock in each of them. They have a relative velocity
> of v. SR tells us that the coordinates are lorentz transformed so
> that time in both frames with respect to the other has to be
> multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> a moving framework". I have no problem with slowing down 'time'
> understood as coordinates (meaning with no physical, or ontological,
> reality and just props in my calculations) but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
Have a look at this:
http://home.c2i.net/pb_andersen/pdf/Mutual_time_dilation.pdf
> Somewhere between the 'physical clock' and the 'coordinates', I am
> missing a step? Does SR say anything about the number of clock
> ticks? This also seems completely basic to the understanding of SR
> and so must have been covered countless time. Any help or pointers
> are greatly appreciated.
--
Paul
Koobee Wublee
> To the point I want clarity on. I assume I have two inertial frames,
> with an atomic clock in each of them. They have a relative velocity
> of v. SR tells us that the coordinates are lorentz transformed so
> that time in both frames with respect to the other has to be
> multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> a moving framework". I have no problem with slowing down 'time'
> understood as coordinates (meaning with no physical, or ontological,
> reality and just props in my calculations) but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
This is the twins’ paradox, and it is never resolved. Yet, when you
ask each self-styled physicist, each one will tell you a bullshit
resolution or wild interpretation with no sound mathematical basis in
which each one is contradictory of the others. That is because the
self-styled physicists have hypnotized themselves into believing that
this paradox is OK to swallow based on the following Orwellian
ideology:
** FAITH IS THEORY
** LYING IS TEACHING
** NITWIT IS GENIUS
** OCCULT IS SCIENCE
** PARADOX IS KOSHER
** FUDGING IS DERIVATION
** BULLSHIT IS TRUTH
** BELIEVING IS LEARNING
** MYSTICISM IS WISDOM
** IGNORANCE IS KNOWLEDGE
** CONJECTURE IS REALITY
** PLAGIARISM IS CREATIVITY
** MATHEMAGICS IS MATHEMATICS
<shrug>
The only logical action is to flush the Lorentz transform down the
toilet since it manifests the twins’ paradox. <shrug>
Prai Jei
continuum:
> This is the twins’ paradox, and it is never resolved.
How much acceleration does the travelling twin experience as he turns round?
How much acceleration does the stay-at-home twin experience as the
travelling twin turns round?
There ain't no symmetry between the twins.
Twin paradox resolved.
--
ξ:) Proud to be curly
Interchange the alphabetic letter groups to reply
Darwin123
> Koobee Wublee set the following eddies spiralling through the space-time
> continuum:
>
> > This is the twins’ paradox, and it is never resolved.
>
> How much acceleration does the travelling twin experience as he turns round?
>
> How much acceleration does the stay-at-home twin experience as the
> travelling twin turns round?
>
> There ain't no symmetry between the twins.
>
> Twin paradox resolved.
associated with an external force on the observer's instruments.
What confuses people is the mistaken belief that there is no
absolute acceleration in SR. There is no absolute velocity in SR but
there is absolute acceleration.
By absolute acceleration, I mean the external force on the
observer's instrument divided by the mass of the instrument. Perhaps I
should call that the dynamic force.
The dynamic force places the observer in a series of inertial
frames. The observer can not stay in one inertial frame if a dynamic
force is acting upon it. Therefore, the law of reciprocity does not
apply to an observer that switches from one inertial frame to the
other. In this one sense, the force is important in SR.
If there were no such thing as absolute acceleration, then the
cranks would be right. There would be a symmetry between the twins.
Sam Wormley
>
> There ain't no symmetry between the twins.
>
> Twin paradox resolved.
The Twin Paradox for Seto, Schubert, Sefton and Ralph (Henry)
http://www.phys.vt.edu/~takeuchi/relativity/notes/section15.html
http://www.phys.vt.edu/~takeuchi/relativity/notes/twin.gif
OG
I suspect this is almost entirely unhelpful to the OP.
Androcles
"Paul B. Andersen" <som...@somewhere.no> wrote in message
news:4DDAC0BD...@somewhere.no...Bwhahahahahahahaha!
Never fails to amuse, Tusseladd!
It is essential to have time defined by means of stationary clocks in the
stationary system, and the time now defined being appropriate to the
stationary system we call it "the time of the stationary system." --
Einstein.
Your diagram is quite good, but you should have four synchronized clocks,
two in each frame at 0 and d, 0' and d' then bounce ONE ray of light from
the initial point of k to d' and back to the origin of coordinates.
3/10... the pass mark was 5/10. Must try harder.
Koobee Wublee
I this thread, we are shown with the following resolutions to the
twins’ paradox so far:
**** “Observation is not reality” championed by Tom Roberts
http://groups.google.com/group/sci.physics.relativity/msg/39de128ca7e50362?hl=en
The morale of the story on this one is that physics is a bullshit
science according to these self-styled physicists. <shrug>
**** “Mathemagics rules in SR” championed by Paul Andersen
http://home.c2i.net/pb_andersen/pdf/Mutual_time_dilation.pdf
The author conjured up the most common mathemagical trick in a
desperate attempt to resolve the paradox.
The Lorentz transform (and the good old Galilean transform) is a tale
of three points with two observers (primed and unprimed) and one
observed. The time transformation equation is:
** dt’ = (dt + [v] * d[s] / c^2) / sqrt(1 – v^2 / c^2)
Where
** [v] = Velocity of (t) as observed by (t’)
** [s] = Position vector of the observed as observed by (t)
** t’ = Time measurement of the observed as observed by (t’)
** t = Time measurement of the observed as observed by (t)
** [] * [] = Dot product of two vectors
The little professor tried to play the mathemagic trick of:
** [v] = d[s] / dt
He has been told so, but sadly to this day, the little remains an
idiot. <shrug>
Also, to My surprise, a lot of the self-styled physicists are
illiterate in the dot product. WTF! <shrug>
**** “Spacetime diagram cartoon” championed by Takeuchi
http://www.phys.vt.edu/~takeuchi/relativity/notes/twin.gif
If you look closely, you will see Buzz Lightyear yelling “to infinity
and beyond”. <shrug>
**** “Breaking of the symmetry” championed by Prai Jei
http://groups.google.com/group/sci.physics.relativity/msg/fc9f1c3c836d16e6?hl=en
This was first championed by Olivia Newton-John’s grandfather (a Nobel
Laureate) and Einstein the nitwit, the plagiarist, and the liar. Over
the years, many self-styled physicists have walked away from this
stupid conjecture. Only the ones who love to live in sewage still
cling on to this piece of shit. <shrug>
Michael Moroney
Peter Webb
So what would happen if the Twins paradox was actually tried?
Would the travelling twin be younger, older or the same age as the
stay-at-home twin when they are re-united?
Sam Wormley
> This was first championed by Olivia Newton-John’s grandfather (a Nobel
> Laureate) and Einstein the nitwit, the plagiarist, and the liar. Over
> the years, many self-styled physicists have walked away from this
> stupid conjecture. Only the ones who love to live in sewage still
> cling on to this piece of shit.<shrug>
You've got to admit that Einstein's equation sing sweetly--Particle
accelerators, cosmic ray muons making to the ground, and global
navigation satellite systems work!
1treePetrifiedForestLane
maybe Hell *is* freezing over.d
1treePetrifiedForestLane
identically-dressed twins, was the result of symmetrical acceleration
between them, there'd be equal time-doilation, and
both of them would be the same age ... but
older than anyone who "stayed at the home for wayward twins."
Don Stockbauer
I think these Einstein-haters are just jealous of a man whose results
have held up and who had a million times the depth of personality of
any of them.
Tom Roberts
> So what would happen if the Twins paradox was actually tried?
It has been, several times, in several different ways. Measurements are in
agreement with the predictions of relativity (SR or GR, depending on details).
IMHO the best is by Bailey et al.
Tom Roberts
Excerpt from http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html
The so-called “twin paradox” occurs when two clocks are synchronized, separated,
and rejoined. If one clock remains in an inertial frame, then the other must be
accelerated sometime during its journey, and it displays less elapsed proper
time than the inertial clock. This is a “paradox” only in that it appears to be
inconsistent but is not.
* Hafele and Keating, Nature 227 (1970), pg 270 (proposal). Science Vol.
177 pg 166–170 (1972) (experiment).
They flew atomic clocks on commercial airliners around the world in both
directions, and compared the time elapsed on the airborne clocks with the time
elapsed on an earthbound clock (USNO). Their eastbound clock lost 59 ns on the
USNO clock; their westbound clock gained 273 ns; these agree with GR predictions
to well within their experimental resolution and uncertainties (which total
about 25 ns). By using four cesium-beam atomic clocks they greatly reduced their
systematic errors due to clock drift.
Criticised in: A. G. Kelly, “Reliability of Relativistic Effect Tests on
Airborne Clocks”, Inst. Engineers Ireland Monograph No. 3 (February 1996),
http://www.cartesio-episteme.net/H&KPaper.htm. His criticism does not stand up,
as he does not understand the properties of the atomic clocks and the way the
four clocks were reduced to a single “paper” clock. The simple averages he
advocates are not nearly as accurate as the paper clock used in the final
paper—that was the whole point of flying four clocks (they call this “correlated
rate change”; this technique is used by all standards organizations today to
minimize the deficiencies of atomic clocks).
Also commented on in Schlegel, AJP 42, pg 183 (1974). He identifies the
East–West time difference as the Sagnac effect, notes that this is independent
of the clock's velocity relative to the (rotating) Earth, and proposes a
coordinate system in which it is treated just like the international date line
(for use in highly accurate time transfer around the world); while correct, this
has been superceded by the ECI coordinate system of the GPS.
Here is a brief description of a repetition in the UK (2005):
http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf (Page 2)
* Vessot et al., “A Test of the Equivalence Principle Using a Space-borne
Clock”, Gel. Rel. Grav., 10, (1979) 181–204. “Test of Relativistic Gravitation
with a Space borne Hydrogen Maser”, Phys. Rev. Lett. 45 2081–2084.
They flew a hydrogen maser in a Scout rocket up into space and back (not
recovered). Gravitational effects are important, as are the velocity effects of
SR. This experiment is also known as “Gravity Probe A”.
* C. Alley, “Proper Time Experiments in Gravitational Fields with Atomic
Clocks, Aircraft, and Laser Light Pulses,” in Quantum Optics, Experimental
Gravity, and Measurement Theory, eds. Pierre Meystre and Marlan O. Scully,
Proceedings Conf. Bad Windsheim 1981, 1983 Plenum Press New York, ISBN
0-306-41354-X, pg 363–427.
They flew atomic clocks in airplanes that remained localized over
Chesapeake Bay, and also which flew to Greenland and back.
* Bailey et al., “Measurements of relativistic time dilation for positive
and negative muons in a circular orbit,” Nature 268 (July 28, 1977) pg 301.
Bailey et al., Nuclear Physics B 150 pg 1–79 (1979).
They stored muons in a storage ring and measured their lifetime. When
combined with measurements of the muon lifetime at rest this becomes a highly
relativistic twin scenario (v ~0.9994 c), for which the stored muons are the
traveling twin and return to a given point in the lab every few microseconds.
Muon lifetime at rest: Meyer et al., Physical Review 132, pg 2693; Balandin et
al., JETP 40, pg 811 (1974); Bardin et al., Physics Letters 137B, pg 135 (1984).
Also a test of the clock hypotheses (below).
The Clock Hypothesis
The clock hypothesis states that the tick rate of a clock when measured in an
inertial frame depends only upon its velocity relative to that frame, and is
independent of its acceleration or higher derivatives. The experiment of Bailey
et al. referenced above stored muons in a magnetic storage ring and measured
their lifetime. While being stored in the ring they were subject to a proper
acceleration of approximately 1018 g (1 g = 9.8 m/s2). The observed agreement
between the lifetime of the stored muons with that of muons with the same energy
moving inertially confirms the clock hypothesis for accelerations of that magnitude.
* Sherwin, “Some Recent Experimental Tests of the 'Clock Paradox'”, Phys.
Rev. 129 no. 1 (1960), pg 17.
He discusses some Mössbauer experiments that show that the rate of a
clock is independent of acceleration (~1016 g) and depends only upon velocity.
Sam Wormley
Thanks Tom.
-Sam
hanson
>
Einstein Dingleberry "Sam Wormley" <swor...@gmail.com> wrote:
>
>
>
Koobee Wublee wrote:
>> This was first championed by Olivia Newton-John’s grandfather (a Nobel
>> stupid conjecture. Only the ones who love to live in sewage still cling
>
Einstein Dingleberry "Sam Wormley" wrote:
> KW, You've got to admit that Einstein's equation sing sweetly--Particle
> satellite
> systems work!
THREE (3) things!??... that's all you could come up with?
ahahahaha... AHAHAHAHA... AHAHAHA... 3 things...
>
----- [[[[ KW 1 : Sam 0, zero, zilch, nada ]]]] ----
>
To boot, yeah, yeah, they all work WITHOUT any of
Einstein's Shit! Only Einstein Dingleberries, like you
Sam, believe that a theory, (= a story that DESCRIBES),
is needed to make such machines work.... ahahaha...
>
Stick to teaching such theories as being a TOOL to
convey the heuristic BELIEF that illustrates more or
less, the likely working modes of such systems,...
Stop right there and be done with it.
>
Sam, don't be a Dingleberry sized brain & read more
into things & situations than are there. That's, in KW's
words, voodoo-physics & magicmathics you are doing.
>
Even your idol Albert said so. Want me to repost
his own words for you,... for the 98th time? Do not
desecrate, Albert's sphincter, the place you worship
at, Sam.
>
Physics does MEASURE things, not build and run
them. You poor Sod, Sam, you confuse Engineering
with physics... .... "You've got to admit, Sam, that
Engineering sings sweetly -- Particle accelerators,
cosmic ray muons detectors, and global navigation
satellite systems work!... thanks to engineering!
>
Don't be a fanatic, Sam, and send your remedial
night school pupils out into the world armed with
a crock that Einstein himself said, was useless!
Thanks for the laughs, though,... ahahahanson
>
hanson
"Don Stockbauer" <http://en.wiktionary.org/wiki/kalter_Bauer> wrote:
- Sam Wormley <sworml...@gmail.com> wrote:
-- Koobee Wublee wrote:
>
>
KW wrote
> > This was first championed by Olivia Newton-John’s grandfather (a Nobel
> > Laureate) and Einstein the nitwit, the plagiarist, and the liar. Over
> > the years, many self-styled physicists have walked away from this
> > stupid conjecture. Only the ones who love to live in sewage still
> > cling on to this piece of shit.<shrug>
>
> You've got to admit that Einstein's equation sing sweetly--Particle
> accelerators, cosmic ray muons making to the ground, and global
> navigation satellite systems work!
One (1) hour ago Don Kalterbauer wrote:
||| Don said: Sadly, I Can't Be Adolph Hitler Anymore.
||| Don said: OK, well, then, just for tonight, you be
||| Don said: Eva and I'll be Adolph.
and now mental patient Kalterbauer makes a 180 & says:
I think these Einstein-haters are just jealous of a man
whose results have held up and who had a million times
the depth of personality of any of them.
>
hanson wrote:
But patient Kalter Bauer, your 2-faced, phony attempt
of trying to exculpate yourself is too late and too little.
Here is your standard anti-Semitic belief about Albert
with you have posted over a long period of time:
>
||| Don said: I actually think that you're discussing an
||| Don said: important topic. We are better than Einstein.
||| Don said: That Einstein. I can't stand the guy, OOOHHHH,
||| Don said: he makes me want to chew the bark off a tree.
||| Don said: I hate him. Einstein has trouble standing up
||| Don said: against the intellect of the current Global Brain.
||| Don said: Einstein is no match for the Global Brain,
||| Don said: thus he is ridiculed today. Einstein was a
||| Don said: motherfucking rapist. Einstein should be shot.
Peter Webb
Hopefully Koobee will find time to post the TRUTH.
Androcles
"Peter Webb" <webbf...@optusnetDIESPAMDIE.com.au> wrote in message
news:4ddb3b34$0$22470$afc3...@news.optusnet.com.au...
| Well, Koobee Woobee thinks SR's prediction is wrong.
|
| Hopefully Koobee will find time to post the TRUTH.
|
Webb says Bailey is gibberish.
So do you gibber one is older than the other, Duckfoot?
Peter Webb
"Androcles" <Headm...@Hogwarts.physics.May.2011> wrote in message
news:i2HCp.24953$7H.2...@newsfe08.ams2...
>
> "Peter Webb" <webbf...@optusnetDIESPAMDIE.com.au> wrote in message
> news:4ddb3b34$0$22470$afc3...@news.optusnet.com.au...
> | Well, Koobee Woobee thinks SR's prediction is wrong.
> |
> | Hopefully Koobee will find time to post the TRUTH.
> |
> Roberts cited Bailey.
> Webb says Bailey is gibberish.
>
Correction: I said your web page is gibberish.
> So do you gibber one is older than the other, Duckfoot?
>
And, FWIW, so are many of your posts.
Androcles
artful
> On May 23, 10:51 am, artful <artful...@hotmail.com> wrote:
> > On May 24, 3:40 am, Vilas Tamhane <vilastamh...@gmail.com> wrote:
[snip for brevity]
> > > Even more basic than your basic question.
> > > If O finds that the clock in O’ runs slow
>
> > How would he determine that .. its important that you know how he does
> > that .. and to know what 'runs slow' means in this context.
Do you know how it is done?
> > > and reciprocally if O’ finds
> > > that the clock of O is running slow then what inference should we make
> > > out of it?
>
> > That O measure O' as slow and O' measures O as slow. A bit like how
> > you look small in the distance compared to me (eg I can fit you
> > between two of my fingers), and I look small compared to you .. yet we
> > are both really the same heights.
>
> If according to your measurements my height is 12mm. Will you treat it
> as real and use it in real world? For example will you give shirt for
> me for stitching based on this measurement or using optical angle you
> will fix my height as I measure it.
As I have told you before .. you have to know what a measurement
MEANS.
And that was just an analogy of how A can measure B as smaller than A,
and B can measure A as smaller than B .. and there is no contradiction
in that. Yet when it comes to SR, you find that notion a problem.
Why is that?
> > > Isn’t it a sloppy statement?
>
> > Not really .. but even if so, the math and physics that you are
> > summarizing with 'sloppy' statements is not itself sloppy.
>
> May be. But it makes theory wrong
No .. it doesn't .. because the theory is not bsaed on a supposedly
'sloppy' sentence.
> and concepts behind your math (not
> physics) are different. But like a fundamentalist you make physics a
> religion.
No .. I don't. I make it something I undersatnad .. if you did the
same you'd be far better off.
> > > Can a theory be based on such a
> > > statement?
>
> > Do you think physics theories are based on a particular English
> > wording of a statement?- Hide quoted text -
>
> This is not only a statement. This is the law of SR.
No .. its not .. it was just a statement you made (sloppily)
Marc Fleury
> be measured.
actually I am thinking about http://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
Hafele-keating, talk about "real" clocks. It is that step to "reality"
that throws me off. I have no problem with a mathematical lorentz
transformation, however my brain locks up at real clocks and physical
processes. I know HK works once you refer to the "inertial earth
frame" but really wondering about this "thought experiment" with
purely inertial frames.
> Sure, as soon as you assign one frame or the other as "rest". The
> moving clock has fewer ticks accumulated over some trip, and then you
> have distance accumulated and relativistic Doppler shift.
ok, so since both are inertial, I can consider one or the other at
rest, in which case both clocks are slowing down with respect to each
other. I get a brain dump at that stage, can you help me parse this
step.
> How do you feel about the "clock tick difference" in a gravity well?
GR says clocks slow down in a gravity well. I have no issue with
that. I am talking about inertial frames here.
> I'd recommend you get something basic like "Spacetime Physics" by
> Taylor and Wheeler, and take your time with it.
I might, I have time and this is really fascinating me.
>
> David A. Smith
Thanks David,
Marc Fleury
> is also predicted by SR's algebra, not just by its "symmetry"
> principle. Note that "slow down" is just a very loose expression
> again and is irrelevant to what SR *predicts*. SR says that if
> observer A performs the measurement procedure and obtains value V,
> then B will obtain the same value if he does the same procedure.
I understand the part where the symmetry says "both will measure the
same thing" but in the Hafele-Keating sense how BOTH clocks be ticking
less with respect to each other?
Take a HK thought experiment where clocks move inertially and meat at
some point 0 so we can compare the clocks. How can both clocks have
LESS ticks than the others? You seem to grasp something I don't here.
> Dont forget, in SR you have a multitude of clocks. "Time" is the value
> on a (synched) clock that is at the *location* of the analyzed event.
> Every location of an observers frame has such a (hypothetical) clock.
In a HK experiment where both inertial frames overlap in point 0 what
do the clock counts say? How can they be different? How does SR treat
this?
> > Does SR say anything about the number of clock
> > ticks?
>
> Sort of, yes. An observer can not count the ticks of a clock "over
> there" (moving clock or not). The observer must preform a well defined
> measurement procedure. The value(s) he obtains is what he calls the
> "number of ticks" (or any other measured quantity). SR algebra will
> predict what these values will be. One can say that SR is about the
> relationships of measurements from one frame to another.
I understand this part. Which is why I want to think about the Hafele-
Keating type experiment with inertial frames meeting in point 0.
> Hope this clears up a little.
It slowly does, still foggy to me, I am still missing an insight.
Thanks
Marc Fleury
> Bottom line: both SR and GR are theories about geometry; geometry does not
> affect any physical object, but geometrical relationships can affect
> measurements, because a measurement is inherently the projection of some
> quantity onto a measuring instrument.
Help me think through Hafele-Keating with this framework then. In HK,
we certainly are 'counting clicks'. I don't talk about time, but
'clicks'. Also take a generalization of HK: inertial frames moving
towards each other and meeting at point 0. Obviously they will read
the same thing and we can compare them they obviously will read the
same thing by symmetry of the setup. Yet SR says "each will run slow
to the other". Can you reconcile the two statements for me? I think
that somewhere in there I am missing an insight.
>
> Tom Roberts
Thanks Tom.
Marc Fleury
> PhD in physics?
In theoretical physics actually.
> Even more basic than your basic question.
> If O finds that the clock in O’ runs slow and reciprocally if O’ finds
> that the clock of O is running slow then what inference should we make
> out of it?
> Isn’t it a sloppy statement? Can a theory be based on such a
> statement?
hmmm, it is the same thing I have asked but with the sloppiness that I
try to talk about inertial frames to quality SR only and not GR.
Re; basing a theory on that, well that is what SR is, so yes the
theory is based on that :) just to be clear, I am keenly aware of my
'missing' something in SR. Not the other way around :)
Marc Fleury
I think we got a winner here, let me get back to this, I am trying to
read the whole thread, and I want to spend time on your explanation.
thanks, brb
MF
On May 23, 7:31 pm, artful <artful...@hotmail.com> wrote:
> On May 23, 11:26 pm, Marc Fleury <marcf...@gmail.com> wrote:
>
> > Hello folks,
>
> > I am happy to see the sci.physics of old are still alive and kicking!!
>
> Many kicking and screaming :)
>
> > I didn't post since the mid 90's when I was doing my PhD :)
>
> > Anyway, quick question, I have some time these days and decided to
> > finally go back and try to "get" relativity. I am struggling still
> > but making more progress than I used to. The math, was never the
> > problem (not even GR) but the "mental model" always was hard for me.
>
> Yeup .. SR math is pretty straight forward (though many crackpots here
> can't even manage that .. Androcles being a case in point) .. getting
> your mind around what it 'means' is far more difficult for many. Some
> just refuse to admit that they do't get it and instead decalre the
> relativity must be wrong .. then they don't have to deal with their
> inability to understand it. Sad .. but that's how some people cope.
>
> > To the point I want clarity on. I assume I have two inertial frames,
> > with an atomic clock in each of them.
>
> Fine. Of course by 'in each of them' you mean 'AT REST in each of
> them'. The atomic clocks are *in* all the frames .. as every frame
> contains everything in the universe :)
>
> > They have a relative velocity
> > of v. SR tells us that the coordinates are lorentz transformed so
> > that time in both frames with respect to the other has to be
> > multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> > a moving framework".
>
> Not really. The gamma factor on its own only applies is certain
> degenerate cases .. eg if you look at the different in x values when
> the time value is the same same, you get the gamma factor applied to
> length.
>
> Time doesn't really slow down in a moving frame. Time is time in any
> inertial frame. A second my any other name would tick as fast :) ...
> Its when you try to MEASURE the rate of a moving clock or the length
> of a moving ruler that you get differences from rest measurements.
>
> It is important to note that to measure the rate of a moving clock,
> you need to take two difference readings of it at different times.
> And because it is moving, that means at two different locations.
>
> The things is .. clock sync is position dependent .. as things move,
> their 'sync' slips.
>
> Imagine you take filing a train as it moves past from three different
> camera positions (assume no SR effects here). The cameras are
> arranges so that when the rear of the train is adjacent the first
> camera, then the middle of the train is adjacent to the second camera,
> then the front adjacent to the third. So the first and third camera
> as the same distance apart as the length of the train.
>
> When playing back, you position TV screens at the same distances apart
> as the cameras were and play the films in sync. Someone watching will
> see three glimpses of the train moving past and would work out its
> length to be as expected (because it will see the rear and front of
> the train in the first and third screen at the same time.
>
> However .. if you start the playback at different times .. os you
> start playing the first tv a bit before the second which is a bit
> before the third .. then you'll see what appears to be a shorter train
> going past. If you measure the difference between where the first and
> third camera show the read and front of the train being, the distance
> will be shorter.
>
> You've just gotten a 'length contraction' because your movies were out
> of sync.
>
> > I have no problem with slowing down 'time'
> > understood as coordinates (meaning with no physical, or ontological,
> > reality and just props in my calculations) but have a profound problem
> > admitting that both CLOCKS (as counting ticks) will slow down with
> > respect to the other. Just by symmetry of the problem, the
> > proposition seems non-sensical to me.
>
> Many have that problem. The apparent slowing is really an effect of
> differences in clock sync
>
> Lets look at clock rates (instead of train lengths) to see how
> differences in clock sync give you mutual time dilation.
>
> Consider this a series of clocks moving to the left at a speed v, and
> another moving to the right at speed v (in our frame) (so relative
> speed is 2v here). From our point of view we see them as being out of
> sync.
>
> A1 A2
> <-- v 6.........7.........8.........9.........10........11
> 11........10........9.........8.........7.........6 --> v
> B
>
> An observer at A1 looks at the time on clock B as it passes. They
> both show the same time (8 o'clock).
>
> Some time later, clock B passes A2, and the observer there records the
> times
>
> A1 A2
> 7.........8.........9.........10........11........12
> 12........11........10........9.........8.........7
> B
>
> Now, clock A2 shows 11 o-clock, while clock B shows only 9 o-clock.
> So now B is two hours behind. So A would determine that B is ticking
> slow.
>
> Now look at the identical situation from B's point of view
>
> A
> <-- v 6.........7.........8.........9.........10........11
> 11........10........9.........8.........7.........6 --> v
> B1
>
> A1
> 7.........8.........9.........10........11........12
> 12........11........10........9.........8.........7
> B2 B1
>
> The B clocks record the same thing, only in reverse . three hours
> differnce B clock readings but only one in A.
>
> So you can see that clocks being out of sync (ie time depends on
> posiion) results in mutual time dilation
>
> Does that help?
>
>
>
>
>
>
>
> > Somewhere between the 'physical clock' and the 'coordinates', I am
> > missing a step? Does SR say anything about the number of clock
> > ticks? This also seems completely basic to the understanding of SR
> > and so must have been covered countless time. Any help or pointers
> > are greatly appreciated.
Marc Fleury
> > PhD in physics?
> > Before you raise a question about actual ticking of a clock I have a
> > counter question for you.
> > Even more basic than your basic question.
> > If O finds that the clock in O’ runs slow
>
> that .. and to know what 'runs slow' means in this context.
thanks for qualifying. Take Hafele-Keating (clocks counting) and put
them in inertial frames and have them meet, sort of what artful draws
in his thread.
Marc Fleury
> On May 23, 9:59 am, dlzc <dl...@cox.net> wrote:
>
>
>
>
>
>
>
>
>
> > Dear Marc Fleury:
>
> > On May 23, 6:26 am, Marc Fleury <marcf...@gmail.com> wrote:
>
> > > Hello folks,
>
> > > I am happy to see the sci.physics of old are
> > > the mid 90's when I was doing my PhD :)
>
> > > Anyway, quick question, I have some time these
> > > days and decided to finally go back and try to
> > > "get" relativity. I am struggling still but
> > > making more progress than I used to. The math,
> > > was never the problem (not even GR) but the
> > > "mental model" always was hard for me.
>
> > > have two inertial frames, with an atomic
> > > velocity of v. SR tells us that the
> > > coordinates are lorentz transformed so
> > > that time in both frames with respect to the
> > > other has to be multiplied by sqrt(1-v/c^2)
> > > bla bla bla the usual "time slows down in
> > > slowing down 'time' understood as coordinates
> > > (meaning with no physical, or ontological,
> > > reality and just props in my calculations)
> > > but have a profound problem admitting that
> > > both CLOCKS (as counting ticks) will slow
> > > down with respect to the other.
>
> > halfway home.
>
> But no such direct measurement ever been made....in fact it is
> impossible to do so. What you SRians claim is that predictions are
> measurements.
>
http://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
among a hundred others not invalidating the measurement predicted by
both SR and GR.
Marc Fleury
> Marc Fleury wrote:
> > I am happy to see the sci.physics of old are still alive and kicking!!
> > I didn't post since the mid 90's when I was doing my PhD :)
>
> replies are worth taking seriously. I'll add another to the mix.
>
> > I have no problem with slowing down 'time' understood as
> > coordinates (meaning with no physical, or ontological, reality and
> > just props in my calculations) but have a profound problem
> > admitting that both CLOCKS (as counting ticks) will slow down with
> > proposition seems non-sensical to me.
>
> all. A clock ticks at, say, one tick per second, as measured by
> someone holding it or another clock colocated with it. That
> definition is perfectly symmetric. Relativity says that the ticks of
> a moving clock, when compared by you to a clock you are holding,
> occur at less than one tick per second. Again perfectly symmetric.
>
> The "time dilation" factor that you wrote is just the ratio of the
> time between 'colocated clock ticks' (T) to the time between 'moving
> clock ticks' (t).
>
> T/t = sqrt(1-(v/c)^2)
>
> The big T is called the "proper time" and is the elapsed time read on
> a clock's dial. For arbitrary motion, the differentials dT and dt can
> be used, giving the proper time for a clock moving along any
> trajectory by calculus.
>
> T = integral-of [sqrt(1-(v/c)^2)] dt
>
> This integral is the same as calculated from any inertial frame, and
> the proper time T is the elapsed time on an arbitrarily moving
> clock.
>
> ---Tim Shuba---
I am lost, will spend more time. Need to get my ideas straighter.
Marc Fleury
> > I didn't post since the mid 90's when I was doing my PhD :)
>
> > finally go back and try to "get" relativity. I am struggling still
> > but making more progress than I used to. The math, was never the
> > problem (not even GR) but the "mental model" always was hard for me.
>
> > To the point I want clarity on. I assume I have two inertial frames,
> > with an atomic clock in each of them. They have a relative velocity
> > of v. SR tells us that the coordinates are lorentz transformed so
> > that time in both frames with respect to the other has to be
> > multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> > understood as coordinates (meaning with no physical, or ontological,
> > reality and just props in my calculations) but have a profound problem
> > admitting that both CLOCKS (as counting ticks) will slow down with
> > respect to the other. Just by symmetry of the problem, the
> > proposition seems non-sensical to me.
>
> > missing a step?
>
> attention to.
> Stop skipping steps and start paying attention to all those
> intermediate things, and this is how you will get to this point and
> realize that it is not a contradiction at all.
>
> What are you using to study this phenomenon. What is the source
> material where all that "bla bla bla" is?
>
This is the typical not-helpful and flame bait answer I remember from
my days. XD
bla bla bla== ANY textbook on einstein talking about Lorentz
transforms as a consequence of the postulate of c as a constant. In my
case getting re-acquainted with the Feynman not-so-easy pieces.
but thank you XD
Marc Fleury
> On 23.05.2011 15:26, Marc Fleury wrote:
>
>
>
>
>
>
>
>
>
> > Hello folks,
>
> > I am happy to see the sci.physics of old are still alive and kicking!!
> > I didn't post since the mid 90's when I was doing my PhD :)
>
> > Anyway, quick question, I have some time these days and decided to
> > finally go back and try to "get" relativity. I am struggling still
> > but making more progress than I used to. The math, was never the
> > problem (not even GR) but the "mental model" always was hard for me.
>
> > To the point I want clarity on. I assume I have two inertial frames,
> > with an atomic clock in each of them. They have a relative velocity
> > of v. SR tells us that the coordinates are lorentz transformed so
> > that time in both frames with respect to the other has to be
> > multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> > a moving framework". I have no problem with slowing down 'time'
> > understood as coordinates (meaning with no physical, or ontological,
> > reality and just props in my calculations) but have a profound problem
> > admitting that both CLOCKS (as counting ticks) will slow down with
> > respect to the other. Just by symmetry of the problem, the
> > proposition seems non-sensical to me.
>
>
> > Somewhere between the 'physical clock' and the 'coordinates', I am
> > ticks? This also seems completely basic to the understanding of SR
> > and so must have been covered countless time. Any help or pointers
> > are greatly appreciated.
>
> Paul
>
> http://home.c2i.net/pb_andersen/
Paul,
will study this in detail and get back to you, essentially seems to be
the "right" answer ala artful above. Thanks for taking the time to
link this. Be right back.
Marc Fleury
> Peter Webb wrote:
> > So what would happen if the Twins paradox was actually tried?
>
> It has been, several times, in several different ways. Measurements are in
> agreement with the predictions of relativity (SR or GR, depending on details).
>
> IMHO the best is by Bailey et al.
>
> Tom Roberts
>
>
> The so-called “twin paradox” occurs when two clocks are synchronized, separated,
> and rejoined. If one clock remains in an inertial frame, then the other must be
> accelerated sometime during its journey, and it displays less elapsed proper
> time than the inertial clock. This is a “paradox” only in that it appears to be
> inconsistent but is not.
>
> * Hafele and Keating, Nature 227 (1970), pg 270 (proposal). Science Vol.
> 177 pg 166–170 (1972) (experiment).
>
> They flew atomic clocks on commercial airliners around the world in both
> directions, and compared the time elapsed on the airborne clocks with the time
> elapsed on an earthbound clock (USNO). Their eastbound clock lost 59 ns on the
> USNO clock; their westbound clock gained 273 ns; these agree with GR predictions
> to well within their experimental resolution and uncertainties (which total
> about 25 ns). By using four cesium-beam atomic clocks they greatly reduced their
> systematic errors due to clock drift.
>
> Criticised in: A. G. Kelly, “Reliability of Relativistic Effect Tests on
> as he does not understand the properties of the atomic clocks and the way the
> four clocks were reduced to a single “paper” clock. The simple averages he
> advocates are not nearly as accurate as the paper clock used in the final
> paper—that was the whole point of flying four clocks (they call this “correlated
> rate change”; this technique is used by all standards organizations today to
> minimize the deficiencies of atomic clocks).
>
> Also commented on in Schlegel, AJP 42, pg 183 (1974). He identifies the
> East–West time difference as the Sagnac effect, notes that this is independent
> of the clock's velocity relative to the (rotating) Earth, and proposes a
> coordinate system in which it is treated just like the international date line
> (for use in highly accurate time transfer around the world); while correct, this
> has been superceded by the ECI coordinate system of the GPS.
>
interesting. thanks tom.
kenseto
What I said is that the rate of a moving clock cannot be measured
directly.....for example mutual time dilation and mutual length
contraction. SRians uses the word measure in place of predict to give
their theory more credence.
My theory of relativity (IRT) eliminates all the paradoxes encountered
by SR. A paper on IRT is available in the following link:
http://www.modelmechanics.org/2011irt.dtg.xps
Ken Seto
- Hide quoted text -
>
> - Show quoted text -
Marc Fleury
Artful,
will take the discussion to the andersen answer, just because, by
symmetry I pick one :)
MF
kenseto
> > understood as coordinates (meaning with no physical, or ontological,
> > reality and just props in my calculations)
>
> Position and time (x,t) in SR represent the values obtained (or
> predicted) by the experiment and not just "props in calculations". To
> verify SR's prediction, one makes measurements. In this sense, (x,t)
> or lengths and "clock slowdown" are "real/physical". But again, those
> are just loose descriptive words and dont change th fact about what
> SR's calculations predict.
>
> > but have a profound problem
> > admitting that both CLOCKS (as counting ticks) will slow down with
> > respect to the other. Just by symmetry of the problem, the
> > proposition seems non-sensical to me.
>
> is also predicted by SR's algebra, not just by its "symmetry"
> principle.
There is no experiment confirming mutual time dilation....there is one-
way confirmation that a moving clock runs slower than the observer's
clock. The GPS refute the claim of mutual time dilation. From the
ground clock point of view the GPS is 7 us/day runs slow. From the GPS
point of view the SR effect is ~7 us/day runs fast.
Ken Seto
>Note that "slow down" is just a very loose expression
> again and is irrelevant to what SR *predicts*. SR says that if
> observer A performs the measurement procedure and obtains value V,
> then B will obtain the same value if he does the same procedure.
>
> An analogy is the 'angle-height'. You and your twin are at some
> distance apart. Looking at each other, both will measure each others
> "angle-height" as the same, say 10 deg, even though YOU measure your
> own angle-height as 90deg.
>
> > Somewhere between the 'physical clock' and the 'coordinates', I am
> > missing a step?
>
> Dont forget, in SR you have a multitude of clocks. "Time" is the value
> on a (synched) clock that is at the *location* of the analyzed event.
> Every location of an observers frame has such a (hypothetical) clock.
>
> > Does SR say anything about the number of clock
> > ticks?
>
> Sort of, yes. An observer can not count the ticks of a clock "over
> there" (moving clock or not). The observer must preform a well defined
> measurement procedure. The value(s) he obtains is what he calls the
> "number of ticks" (or any other measured quantity). SR algebra will
> predict what these values will be. One can say that SR is about the
> relationships of measurements from one frame to another.
>
> > This also seems completely basic to the understanding of SR
> > and so must have been covered countless time. Any help or pointers
> > are greatly appreciated.
>
kenseto
> On 5/23/11 5/23/11 - 8:26 AM, Marc Fleury wrote:
>
> > I have no problem with slowing down 'time'
> > understood as coordinates (meaning with no physical, or ontological,
> > admitting that both CLOCKS (as counting ticks) will slow down with
> > respect to the other. Just by symmetry of the problem, the
> > proposition seems non-sensical to me.
>
> any clock.
But experiments show that one of the clocks accumulates less clock
seconds (geometric projection doesn't include real clock
slowing)....so that means that one of the SR predictions about clock
slowing is correct. The problem is that both clocks claim each other
as running slow...an impossible claim.
Ken Seto
>
> Draw x-y coordinates on a plane, and draw x'-y' coordinates rotated
> 30 degrees relative to them. The projection of a unit length along
> x onto the x' axis is shorter than 1; the projection of a unit length
> along x' onto x is also shorter than 1. This is just geometrical
> projection, and no length actually "got shorter", but if one insists
> on speaking VERY LOOSELY, one might claim "each sees the other as
> shorter" (where by "sees" one means this projection). The error
> implicit in such loose speech ought to be obvious.
>
> In SR, relatively-moving clocks behave similarly. That's why I always
> put "time dilation" and "length contraction" in quotes -- these are
> misnomers because it is not any time interval that is dilating or any
> object's length that is contracting, but rather MEASUREMENTS that are
> affected.
>
> In relativity, clocks do not slow down due to any sort of motion. It is only
> MEASUREMENTS of clock rates in other frames that vary. When at rest in any
> inertial frame, any good clock will tick at its standard rate.
>
> The relationship between relatively-moving inertial frames is a hyperbolic
> rotation in spacetime. The usual "time dilation" and "length contraction" are
> merely the way geometric projections work between such coordinates -- they are
> directly analogous to rotating a ladder to carry it through a doorway (the
> ladder itself is unchanged, only its RELATIONSHIP to the doorway is changed; the
> moving clock itself is unchanged, the only change is in its relationship to the
> inertial frame measuring its tick rate.).
>
> BTW this is generalized in GR, and one finds that both clocks and
> EM signals are unaffected by either gravitation or relative motion.
> But both gravitation and relative motion affect the orientations of
> 4-vectors in spacetime, and "time dilation", "length contraction",
> "gravitational redshift", and "cosmological redshift" are simply
> the way projections relate to such orientations.
>
> Bottom line: both SR and GR are theories about geometry; geometry does not
> affect any physical object, but geometrical relationships can affect
> measurements, because a measurement is inherently the projection of some
> quantity onto a measuring instrument.
>
> Tom Roberts
kenseto
Every inertial SR observer assumes that he is at rest in a preferred
frame and thus claims the exclusive properties of the preferred frame
which are: all the clocks moving wrt an SR observer are running slow
and all the rulers moving wrt an SR observer are contracted. Such
claims lead to the bogus concepts of mutual time dilation and mutual
length contraction.
>
>
>
> > Tom Roberts
>
> Thanks Tom.
kenseto
> On May 23, 11:26 pm, Marc Fleury <marcf...@gmail.com> wrote:
>
> > Hello folks,
>
> > I am happy to see the sci.physics of old are still alive and kicking!!
>
> Many kicking and screaming :)
>
> > I didn't post since the mid 90's when I was doing my PhD :)
>
> > Anyway, quick question, I have some time these days and decided to
> > finally go back and try to "get" relativity. I am struggling still
> > but making more progress than I used to. The math, was never the
> > problem (not even GR) but the "mental model" always was hard for me.
>
> Yeup .. SR math is pretty straight forward (though many crackpots here
> can't even manage that .. Androcles being a case in point) .. getting
> your mind around what it 'means' is far more difficult for many. Some
> just refuse to admit that they do't get it and instead decalre the
> relativity must be wrong .. then they don't have to deal with their
> inability to understand it. Sad .. but that's how some people cope.
>
> > To the point I want clarity on. I assume I have two inertial frames,
> > with an atomic clock in each of them.
>
> Fine. Of course by 'in each of them' you mean 'AT REST in each of
> them'. The atomic clocks are *in* all the frames .. as every frame
> contains everything in the universe :)
>
> > They have a relative velocity
> > of v. SR tells us that the coordinates are lorentz transformed so
> > that time in both frames with respect to the other has to be
> > a moving framework".
>
> Not really. The gamma factor on its own only applies is certain
> degenerate cases .. eg if you look at the different in x values when
> the time value is the same same, you get the gamma factor applied to
> length.
>
> Time doesn't really slow down in a moving frame.
Wrong clock time does slow down....the GPS confirms this clearly. The
SR effect on the GPS is 7us/day running slow. Perhaps you are talking
about absolute time....absolute time does not slow down that is the
rate of passage of absolute time is constant and not affect by motion.
The relationship between clock time and absolute time is a clock
second will represent a different amount of absolute time in different
frames.
> Time is time in any
> inertial frame.
Absolute time is time in any frame.
>A second my any other name would tick as fast :)
No a second in different frame would represent a different amount of
absolute time. This is the reason why the passage of a clock second in
A's frame does not correspond to the passage of a clock second in B's
frame.
...
> Its when you try to MEASURE the rate of a moving clock or the length
> of a moving ruler that you get differences from rest measurements.
No such measurement is possible whike the clock is in motion. An SR
observer claims the exclusive properties of a preferred frame and thus
PREDICTS every clock moving wrt him is running slower than his clock.
Your use of the word measure in place of predict is not justified.
>
> It is important to note that to measure the rate of a moving clock,
> you need to take two difference readings of it at different times.
> And because it is moving, that means at two different locations.
No such measurement is possible. You have to have two absolute synch
clocks in the observer's frame to do such measurement and there is no
way to get two absolute synched clocks in the observer's frame. You
can use two e-synched clocks to make such measurement. But the e-
synched clocks are asynchronous...the distant clock is advanced by a
time interval of L/c. That's why every SR observer will measure the
one moving clock runs slow.
Ken Seto
>
> The things is .. clock sync is position dependent .. as things move,
> their 'sync' slips.
>
> Imagine you take filing a train as it moves past from three different
> camera positions (assume no SR effects here). The cameras are
> arranges so that when the rear of the train is adjacent the first
> camera, then the middle of the train is adjacent to the second camera,
> then the front adjacent to the third. So the first and third camera
> as the same distance apart as the length of the train.
>
> When playing back, you position TV screens at the same distances apart
> as the cameras were and play the films in sync. Someone watching will
> see three glimpses of the train moving past and would work out its
> length to be as expected (because it will see the rear and front of
> the train in the first and third screen at the same time.
>
> However .. if you start the playback at different times .. os you
> start playing the first tv a bit before the second which is a bit
> before the third .. then you'll see what appears to be a shorter train
> going past. If you measure the difference between where the first and
> third camera show the read and front of the train being, the distance
> will be shorter.
>
> You've just gotten a 'length contraction' because your movies were out
> of sync.
>
> > I have no problem with slowing down 'time'
> > understood as coordinates (meaning with no physical, or ontological,
> > reality and just props in my calculations) but have a profound problem
> > admitting that both CLOCKS (as counting ticks) will slow down with
> > respect to the other. Just by symmetry of the problem, the
> > proposition seems non-sensical to me.
>
> > Somewhere between the 'physical clock' and the 'coordinates', I am
> > missing a step? Does SR say anything about the number of clock
> > ticks? This also seems completely basic to the understanding of SR
> > and so must have been covered countless time. Any help or pointers
> > are greatly appreciated.- Hide quoted text -
Marc Fleury
First thanks to the both of you for taking the time to put the
question is some framework. I will use the definition in paul's link
http://home.c2i.net/pb_andersen/pdf/Mutual_time_dilation.pdf
I have read through the paper. Let me see if I can pinpoint where I
fail.
Event E2: the two clocks A and B' are adjacent. One gives proper
time. The other the time multiplied by the Lorentz factor, or slow.
They are at the same point, we can compare them. They give different
amounts of ticks. How can this be by symmetry? the problem is equiv
to K' stationary and K inertial at V and would give symmetrical
results. Where I am tripping? it really hurts my brain. Hopefully we
can pinpoint it in this formalism, without having to resort to name-
calling (wow, that groups gotten worse :))
Thanks for your patience.
Marc Fleury
Ken, I am having trouble following you. I you have a link to IRT that
is not an executable excell I would gladly check it out.
Also what exactly are you saying about the 'paradox'.
MF
kenseto
Check out this pdf link:
http://www.modelmechanics.org/2011irt.dtg.pdf
>
> Also what exactly are you saying about the 'paradox'.
Read the paper and then we can discuss your questions.
Marc Fleury
I did, in my lost moments I like to entertain a toy model I call
'spring theory', for the past 20 years. (http://
www.thedelphicfuture.org/2011/04/musings-about-physics-spring-theory.html),
similar to your e-strings but I use it for intellectual fun only since
ether based theory are mostly garbage :) In other words I don't take
it that seriously.
In any case, elastic ethers do trivially account for expansion, dark
matter, dark energy etc, but it is not meant for anything serious but
the "fun".
So now that we cleared that. Exactly what are you saying about the
'non-paradox' of mutual time dilation. I am confused.
funkenstein
> Hello folks,
>
> I am happy to see the sci.physics of old are still alive and kicking!!
>
> Anyway, quick question, I have some time these days and decided to
> finally go back and try to "get" relativity. I am struggling still
> but making more progress than I used to. The math, was never the
> problem (not even GR) but the "mental model" always was hard for me.
>
> of v. SR tells us that the coordinates are lorentz transformed so
> that time in both frames with respect to the other has to be
> multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> understood as coordinates (meaning with no physical, or ontological,
> reality and just props in my calculations) but have a profound problem
> admitting that both CLOCKS (as counting ticks) will slow down with
> respect to the other. Just by symmetry of the problem, the
> proposition seems non-sensical to me.
>
> missing a step? Does SR say anything about the number of clock
> ticks? This also seems completely basic to the understanding of SR
> and so must have been covered countless time. Any help or pointers
> are greatly appreciated.
Hello Marc, it looks like you have a lot of good responses already :)
One further thing that might help is that there is no problem with
both clocks looking slower to one another.. One similar example of
such a thing is that people look smaller when they are far apart due
to perspective. Each one looks smaller to the other, this can agree
with intuition.
Keep in mind also that each reference frame has an implicit network of
synchronized clocks (synchronized in that frame). As one clock moves
through the others frame, the "tick" will occur at a different
location. Because the two observers don't agree on the
synchronization, they will also disagree about the rate of ticks..
hence the symmetrical time dilation.
Cheers -
papa...@gmail.com
> Artful and Mr Andersen,
>
> First thanks to the both of you for taking the time to put the
>
> I have read through the paper. Let me see if I can pinpoint where I
> fail.
>
> Event E2: the two clocks A and B' are adjacent. One gives proper
> time. The other the time multiplied by the Lorentz factor, or slow.
> They are at the same point, we can compare them. They give different
> amounts of ticks. How can this be by symmetry? the problem is equiv
> to K' stationary and K inertial at V and would give symmetrical
> results. Where I am tripping? it really hurts my brain. Hopefully we
> can pinpoint it in this formalism, without having to resort to name-
> calling (wow, that groups gotten worse :))
>
> Thanks for your patience.
Let see if this explanation, from Lev Landau (The Classical Theory of
Fields, pp.6-9) can help you.
Suppose that in a certain inertial reference system we observe clocks
which are moving relative to us in an arbitrary manner. At each
different moment of time this motion can be considered as uniform.
Thus at each moment of time we can introduce a coordinate system
rigidly linked to the moving clocks, which with the clocks constitutes
an inertial reference system.
In the course of an infinitesimal time interval dt (as read by a clock
in our rest frame) the moving clocks go a distance sqrt(dx^2 + dy^2 +
dz^2). Let us ask what time interval dt' is indicated for this period
by the moving clocks. In a system of coordinates linked to the moving
clocks, the latter are at rest, i.e., dx' = dy' = dz' = 0. Because of
the invariance of spacetime intervals
ds^2 = c^2dt^2 - dx^2 - dy^2 - dz^2= c^2(dt')^2
from which it follows that
dt’=dt sqrt((1-(dx^2+dy^2+dz^2)/( c^2dt^2)) (3.1)
But
(dx^2+dy^2+dz^2)/dt^2 = v^2
where v is the velocity of the moving clocks; therefore
dt' = ds/c = dt sqrt(1 - v^2/c^2)
Integrating this expression, we can obtain the time interval indicated
by the moving clocks when the elapsed time, according to a clock at
rest is t2 - tl:
t2’-t1’ = integral(t1,t2) (sqrt(1 - v^2/c^2) dt) (3.2)
As we see from (3.1) or (3.2), the time interval of a moving object is
always less than the corresponding interval in the rest system. In
other words, moving clocks go more slowly than those at rest.
Suppose some clocks are moving in uniform rectilinear motion relative
to an inertial system K. A reference frame K' linked to the latter is
also inertial. Then from the point of view of an observer in the K
system the clocks in the K' system fall behind. And conversely, from
the point of view of the K' system, the clocks in K lag. To convince
ourselves that there is no contradiction, let us note the following.
In order to establish that the clocks in the K' system lag behind
those in the K system, we must proceed in the following fashion.
Suppose that at a certain moment the clock in K' passes by the clock
in K and, at that moment, the readings of the two clocks coincide. To
compare the rates of the two clocks in K and K' we must once more
compare the readings of the same moving clock in K' with the clocks in
K. But now we compare this clock with different clocks in K with those
past which the clock in K' goes at this new time. Then we find that
the clock in K' lags behind the clocks in K with which it is being
compared. We see that "to compare the rates of clocks in two reference
frames we require several clocks in one frame and one in the other",
and that therefore this process is not symmetric with respect to the
two systems. The clock that appears to lag is always the one which is
being compared with different clocks in the other system. If we have
two clocks, one of which describes a closed path returning to the
starting point (the position of the clock which remained at rest),
then clearly the moving clock appears to lag relative to the one at
rest. The converse reasoning, in which the moving clock would be
considered to be at rest (and vice versa) is now impossible, since the
clock describing a closed trajectory does not carry out a uniform
rectilinear motion, so that a coordinate system linked to it will not
be inertial.
Miguel Rios
Marc Fleury
clear thanks.
>
> Keep in mind also that each reference frame has an implicit network of
> synchronized clocks (synchronized in that frame). As one clock moves
> through the others frame, the "tick" will occur at a different
> location. Because the two observers don't agree on the
> synchronization, they will also disagree about the rate of ticks..
> hence the symmetrical time dilation.
>
"two observers don't agree on the synchronization", can you expand?
sorry to be thick, really struggling with this one for the past 20
years :)
MF
> Cheers -
Tom Roberts
> One further thing that might help is that there is no problem with
> both clocks looking slower to one another.. One similar example of
> such a thing is that people look smaller when they are far apart due
> to perspective. Each one looks smaller to the other, this can agree
> with intuition.
Thank you for reminding me of this. This is a similar geometric projection, but
in angle not distance (your eyes gauge size via angular spread). Yes, there need
be no inconsistency in "both see the other as smaller".
Tom Roberts
Marc Fleury
gracias miguel. This is obviously the source reference for andresen
and artful as well (including the K K' frames). Funny thing is the
Landau/Lifshits was one of my textbooks. I guess I skipped page 6-9.
I am starting to understand something about "multiple clocks", need to
think some more see if the question I had for Andresen goes away.
Dono.
> > Bottom line: both SR and GR are theories about geometry; geometry does not
> > affect any physical object, but geometrical relationships can affect
> > measurements, because a measurement is inherently the projection of some
> > quantity onto a measuring instrument.
>
> Help me think through Hafele-Keating with this framework then. In HK,
> we certainly are 'counting clicks'.
It is very simple:
-IF two clocks are in inertial motion with speed v wrt each other,
EACH clock measurement appears time - dilated with respect to the
other clock by the SAME factor that depends ONLY on the relative speed
v between the two frames co-moving with the two clocks.
-The HK experiment DOES NOT involve clocks in inertial motion, so the
above DOES NOT apply. The two clocks are in CIRCULAR motion with
DIFFERENT speeds wrt a pseudo-inertial frame attached to the Earth
center. In ADDITION to the above, the two clocks moved UP and DOWN
against the gravitational field. So, this is not the mutual time
dilation of SR but a GR problem very similar to the twins paradox.
Because the two clocks have different paths through spacetime, when
they are reunited they show DIFFERENT TOTAL ELAPSED time, in perfect
accordance to the predictions of GR.
rotchm
> There is no experiment confirming mutual time dilation....
Yes there is.
Scientist with their clocks/detectors/sources (K1) have sent identical
clocks/detectors/sources (K2) with speed v.
The scientist (K1) have measured the incoming info from K2 to be time
dilated.
The K2 instruments have measured the info from K1 to be time dilated.
Marc Fleury
I do like the analogy as well because it does put the finger squarely
on "percieved" vs "real" or "measured"/"proper". Trying to figure out
if it totally applies here. The thing with "clocks" and the reason i
keep thinking of "Hafele/Keating" is that those are "ticking clocks"
so there is no 'percieved' there is a absolute number of clicks. I am
still being pedestrian and trying to think through this. Haven't had
this much time to think about it since well...ever. Fun.
Dono.
Can you provide a reference from a mainstream journal?
Or did you just make it up? Based on the incorrect English, it appears
that it is the latter, not the former.
Marc Fleury
I am familiar (or got familiar) with HK. GR applies. No need to
expand on it here.
I use HK for the "counting clocks" example and assume inertial
movement. When you say 'each clock MEASUREMENT appears time dilated'
it is the measurement part that I fail to grasp. The number of clicks
is the number of clicks as displayed by the reader. What is a "clock
measurement", what clock. I am referring to the kk' (landau)
discussion taken in the other threads for a more robust formalism to
discuss this. The clocks will intersect, I can compare the readers on
the clocks when they do. I don't introduce "time flow" in the
thinking, just clicks. What do I see then.
In other words, trying to grasp the "dual time dilution non-paradox"
by imagining clocks ticks. Just to get away from geometrical
projections.
Dono.
You can't assume inertial movement in HK. I have already explained
that in my post.
> When you say 'each clock MEASUREMENT appears time dilated'
IN INERTIAL MOTION.
> it is the measurement part that I fail to grasp. The number of clicks
> is the number of clicks as displayed by the reader.
Stop thinking in terms of digital "clicks" and start thinking in terms
of frequency. The way the two observers communicate is in terms of
sending (light) signals between them.
> What is a "clock
> measurement", what clock. I am referring to the kk' (landau)
> discussion taken in the other threads for a more robust formalism to
> discuss this. The clocks will intersect, I can compare the readers on
> the clocks when they do. I don't introduce "time flow" in the
> thinking, just clicks. What do I see then.
>
I have no idea what you are talking about, you are talking cross-
purposes. You talked about HK, I explained HK to you.
> In other words, trying to grasp the "dual time dilution non-paradox"
> by imagining clocks ticks. Just to get away from geometrical
> projections.
You are back to the inertial case, the Dingle "paradox". The
explanation in terms of SR is very simple.
The Lorentz transform for time is :
t'=\gamma(t+vx/c^2)
For time intervals, the above becomes:
dt'=\gamma(dt+vdx/c^2)
Since the "clicks" come from a clock located at a fixed location in
the unprimed frame, it follows that dx=0:
dt'=\gamma*dt
The reverse Lorentz transform says that:
t=\gamma(t'-vx'/c^2)
For time intervals, this becomes:
dt=\gamma (dt'-vdx'/c^2)
Since the "clicks" come from a clock located at a fixed location in
the primed frame, it follows that dx'=0:
dt=\gamma*dt'
Compare against the previous expression:
dt'=\gamma*dt
Marc Fleury
OK, actually had to turn on the "focus" and read through that with
calm. I can finally see it but my brain locks up and barfs at the
"the problem is not symmetric because we compare one clock to many
clocks".
The clock moves. For argument sakes the distance is "10 clicks". When
the ONE clock reaches the second clock, it reads something different
in terms of clicks? 8?
It is the same thing with the andresen explanation (they are from the
same stock so no wonder) and at least the Andresen explanation has a
nice diagram with it (unlike landau, that speaks of one clock and many
on the other). I can see everyone calculates this thing called "time"
and "time'" but please speak to me in terms of clicks. This
"perceived time" notion is VERY fuzzy to me.
Hafele-Keating has click readouts, that were compared upon coming back
from a trip. Is Landau saying "you can't compare the clocks that are
distant.
For god sakes. I am still so confused I could shoot myself right
here.
Dono.
>
> Hafele-Keating has click readouts, that were compared upon coming back
> from a trip.
In this case the clocks were brought back at the same location in
order to be compared. What is being compared in THIS case is the TOTAL
ELAPSED TIME.
> Is Landau saying "you can't compare the clocks that are
> distant".
Correct, this is what he's saying. This is why I told you that the
frequency of (light) signals is used in order to compare the ticking
rate of remote clocks.
What is being compared in this case are the RATES of ticking of two
REMOTE clocks.
As I explained to you earlier in a very extensive post, the two cases
are totally unrelated. You need to understand that in order to be able
to move forward.
Tom Roberts
> On May 23, 10:01 am, Tom Roberts<tjrob...@sbcglobal.net> wrote:
>> [...]
>
> If relativistic effects are not real then proper place for SR is a
> dust bin.
I have no idea where you got that from -- CERTAINLY not from anything I wrote.
I have stated repeatedly that words like "real" are FAR TOO AMBIGUOUS for any
good use in such discussions. "Length contraction" and "time dilation" are
"real" in the sense that they affect measurements and engineering designs [#];
they are not "real" in the sense of affecting the rod or clock itself.
[#] The effects of relativity are essential aspects of the designs
of accelerator facilities around the world. It simply is not possible
to construct a working high-energy accelerator without applying SR in
its design.
> Actually physicists play jugglery with poor students. In
> theory the effects have to be apparent, as that is what relativity
> means. But to apply it to experimental results, one way predictions
> are mentioned. Therefore only the clock that is accelerated runs slow.
You need to read what I write, and not put into my words what you think you
already "know" about the world. Yes, relativity is subtle; yes, relativity is
complicated; yes, you are a poor student; yes, you have been "juggled", but by
your own misconceptions, not by any physicist.
As I have said many times, one CANNOT claim "the clock that is accelerated runs
slow". What one CAN say is that in a twin scenario the traveling twin/clock
shows less elapsed proper time than the stay-at-home (inertial) twin/clock.
These are QUITE DIFFERENT statements, and the latter carries no implication
about any clock "running slow" -- such claims are made only by fools like
yourself who insist on using sound bites.
The sound bites CANNOT capture the truth, because the language has
evolved independent of relativity, and one needs caveats and
conditions to make a correct statement.
> Your ladder and door example is a good one. But remember that when
> ladder is tilted, it has now two components, x and y (door has only
> one-y).
Yes, of course.
> So SR is not about geometry and no need to bring in space-time
> diagram.
Your "So" is unwarranted, as your previous (correct) statement does not imply
this at all. Indeed, recognizing that the relationship between ladder and
doorway is geometrical is the necessary first step toward understanding these
relationships in SR.
> If there is no real length contraction or time dilation then the
> MEASUREMENTS which are affected have no value. These are wrong or
> unreliable measurements.
This is also not true:
A) The ladder has no "real length contraction" (in that the ladder itself is
unaffected by rotations), and yet it either fits through the doorway or
not depending on how it is oriented. The analogy of SR's "length
contraction" is the PROJECTION of ladder onto the plane of the doorway --
that does indeed "contract", and is the relevant quantity in determining
whether the ladder fits through.
B) Pions are unstable particles that have a proper lifetime of 26 nanoseconds;
yet there are pion beams at Fermilab and CERN that are hundreds of meters
long -- the pions are measured to travel with speed very close to to c,
so during 26 nanoseconds they could travel only 7.8 meters. The "time
dilation" of SR permits them to travel hundreds of meters in the lab; in
the pion's rest frame, the beam line is "length contracted" -- the entire
beamline passes by the pion in less than 26 ns (while moving with speed c).
These effects have value, and are NOT "wrong or unreliable measurements" -- it
is your personal understanding that is wrong and unreliable.
Tom Roberts
Mike Fontenot
> Just by symmetry of the problem, the
> proposition seems non-sensical to me.
>
Get yourself a copy of Einstein's little book "Relativity - The Special
and General Theory" by Crown publishers. CAREFULLY read just the
special relativity part (including the derivation of the Lorentz
equations, in the appendix). Then read it again. Maybe even a third
time. Don't quit until you thoroughly understand EVERYTHING he said.
--
Mike Fontenot
Tom Roberts
> On May 24, 4:56 pm, Tom Roberts<tjrob...@sbcglobal.net> wrote:
>> On 5/24/11 5/24/11 - 9:06 AM, funkenstein wrote:
>>> One further thing that might help is that there is no problem with
>>> both clocks looking slower to one another.. One similar example of
>>> such a thing is that people look smaller when they are far apart due
>>> to perspective. Each one looks smaller to the other, this can agree
>>> with intuition.
>> Thank you for reminding me of this. This is a similar geometric projection, but
>> in angle not distance (your eyes gauge size via angular spread). Yes, there need
>> be no inconsistency in "both see the other as smaller".
>
> on "percieved" vs "real" or "measured"/"proper".
Be careful -- those words are ambiguous and are loaded with contradictions when
applied cavalierly.
For instance, the reduction in angular size of a more distant object might seem
to be "perceived", yet it has physical implications -- for instance, one can see
the distant object through a smaller aperture than when it was closer.
Similarly, the "time dilation" of SR permits us to construct pion beam lines
that are hundreds of meters long, even though the pion has a lifetime of only 26
nanoseconds, and 26 ns times the speed of light is only 7.8 meters (they are
measured to travel down the beam line with speed quite close to c).
So don't think these effects are "just perceptions" or "just measurements". But
don't think they affect the objects themselves, either. The world is more subtle
than such sound bites can capture.
> Trying to figure out
> if it totally applies here. The thing with "clocks" and the reason i
> keep thinking of "Hafele/Keating" is that those are "ticking clocks"
> so there is no 'percieved' there is a absolute number of clicks.
Yes. But remember that this is a different phenomenon -- the total elapsed
proper time over a path is not the same as "time dilation".
Two sides of a triangle always have a longer total path length
than the third side. That is the analogy to total proper time
over a path [#]. But the sides of the triangle have different slopes
relative to each other, and the projections of one side onto another
are different -- that is the analogy to "time dilation" and "length
contraction".
[#] The usual twin scenario is a triangle in the x-t plane, with the
stay-at-home (inertial) twin traversing one side (aligned along her
time axis), and the traveling twin traversing two sides (which have
both temporal and spatial extent). But the x-t plane has hyperbolic
geometry, which makes the two sides sum to a smaller value than the
third.
In a twin scenario, one cannot claim that "the traveling twin's clock ticks more
slowly than the inertial twin's clock". But the traveling twin's clock does
display fewer ticks than the inertial twin's clock.
The two sides of a triangle have a longer path length than the
third, yet the odometers traversing the two paths are identical
and have identical calibrations. The two twins' clocks are identical
and have identical calibrations. (This is a poor analogy because the
use of odometers implies time -- a third dimension which is not
present; consider only the lengths of the sides, using identical
standards of length.)
Tom Roberts
Androcles
"Mike Fontenot" <mlf...@comcast.net> wrote in message
news:4DDBDFA...@comcast.net...
contain EVERYTHING he said. Read this until you understand
EVERYTHING the idiot said.
http://www.fourmilab.ch/etexts/einstein/specrel/www/
Then read it again. Maybe even a fiftieth time. Don't quit until you
thoroughly understand he was a moron hopeless at mathematics.
--
"Let there be given a stationary rigid rod; and let its length be L as
measured by a measuring-rod which is also stationary. We now imagine
the axis of the rod lying along the axis of x of the stationary system of
co-ordinates, and that a uniform motion of parallel translation with
velocity v along the axis of x in the direction of increasing x is then
imparted to the rod. We now inquire as to the length of the moving rod" --
Einstein
"The length to be discovered by the operation (b) we will call ``the length
of the (moving) rod in the stationary system.''"-- Einstein
"This we shall determine on the basis of our two principles, and we shall
find that it differs from L." -- Einstein.
AND THE ANSWER IS...
"xi = (x-vt)/sqrt(1 - v^2/c^2)" -- Einstein.
Yep, xi differs from L, Greek letters differ from Roman letters.
In agreement with experience we further assume the deranged babbling
incompetent cretin couldn't answer his own inquiry, he was too stupid
to realise xi is greater than L when he wrote 'for v=c all moving
objects--viewed from the "stationary'' system--shrivel up into plane
figures', whereas his own equation shows they stretch to infinity...
sqrt(1-c^2/c^2) = 0.
"But the ray moves relatively to the initial point of k, when measured in
the stationary system, with the velocity c-v" - Einstein
"the velocity of light in our theory plays the part, physically, of an
infinitely great velocity" - Einstein.
"In agreement with experience we further assume the quantity
2AB/(t'A -tA) = c to be a universal constant--the velocity of light in
empty space." -- Einstein
He was right. The distance from A to A divided by the time it takes
to get there is undefined. Anyone that divides by zero is a lunatic.
Darwin123
> On May 23, 1:21 pm, Koobee Wublee wrote:
>
>
>
>
>
>
>
>
>
> > On May 23, 6:26 am, Marc Fleury wrote:
>
> > > To the point I want clarity on. I assume I have two inertial frames,
> > > with an atomic clock in each of them. They have a relative velocity
> > > of v. SR tells us that the coordinates are lorentz transformed so
> > > that time in both frames with respect to the other has to be
> > > multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> > > a moving framework". I have no problem with slowing down 'time'
> > > understood as coordinates (meaning with no physical, or ontological,
> > > reality and just props in my calculations) but have a profound problem
> > > admitting that both CLOCKS (as counting ticks) will slow down with
> > > proposition seems non-sensical to me.
>
Bullshit!
>Yet, when you
> > ask each self-styled physicist, each one will tell you a bullshit
> > resolution or wild interpretation with no sound mathematical basis in
> > which each one is contradictory of the others.
You have not addressed any physical arguments. For example, you
have addressed neither Prai Jei's resolution or my own.
As predicted by "1treePetrifiedForset," you will not address any
our arguments till "Hell freezes over." However, I have to disagree
with him on one point. You will not address any our arguments even
after "Hell freezes over".
Koobee Wublee
Oh, isn’t that the cookbook on mathemaGics where Einstein the nitwit,
the plagiarist, and the liar was able to start with two identical
equations equating zero with zero and pulled out half of the Lorentz
transform out of these two equations? <shrug>
As Yours Truly has said many times over, the feat was merely
mathemaGics only for the kindergarten kids. However, the self-styled
physicists seem to be ever so bedazzled by the mathemaGic trick
performed by Einstein the nitwit, the plagiarist, and the liar.
<shrug>
Marc Fleury
So, coming back from a workout where I could focus some more on what
Landau is trying to say. Using his formalism let me try to capture
the problem as I see it. (sorry for the multiple posts, just trying to
get the attention of people).
Let K be an inertial frame with 2 clocks at rest in K and they
synchronized. Call clocks K0 and K1. They are separated by distance
d. Let L be an inertial frame with 1 clock, L0 at rest in it, that is
moving with a speed v relative to K.
EVENT 0:
K: ----K0----K1---- AT REST
L: ----L0-------- MOVING AT V
EVENT 1:
K: ----K0----K1----
L: ----------L0---
EVENT 0, both clocks have readout zero
K0 reads 0 clicks
L0 reads 0 clicks
Both clocks are together
EVENT1: K1 and L0 are together (not distant)
ANALYSED IN THE K FRAME:
time elapsed for K0 and K1: d/v
CLOCK K1 and K0 read 1000 clicks
time elapsed for L0 in K frame: d/v*gamma (lorentz transform)
Clock L0 reads 800 clicks.
ANALYSED IN THE L FRAME:
time elapse for L0 : d/v
Clock L0 reads 1000 clicks
time elapsed for K0 and K1 d/v*gamma
Clocks K0 and K1 read 800 clicks
And right there I freeze up again. I cannot move forward, can you help
me with that.
(and again stop talking about HK "the real experiment" as it pertains
to GR, not SR and I am very aware of that)
Thanks for your help
Koobee Wublee
> Peter Webb wrote:
> > So what would happen if the Twins paradox was actually tried?
>
> It has been, several times, in several different ways. Measurements are in
> agreement with the predictions of relativity (SR or GR, depending on details).
This is just not true. SR predicts the fallacy in the Twins’
paradox. In real life, one would expect no such paradox. <shrug>
> IMHO the best is by Bailey et al.
> * Hafele and Keating, Nature 227 (1970), pg 270 (proposal). Science Vol.
> . . .
All these experiments show no such twins’ paradox and thus
definitively prove SR wrong. Only the ignorant, the stupid, and the
zealous are claiming otherwise. <shrug>
jacob navia
>
> Oh, isn’t that the cookbook on mathemaGics where Einstein the nitwit,
> the plagiarist, and the liar was able to start with two identical
> equations equating zero with zero and pulled out half of the Lorentz
> transform out of these two equations?<shrug>
Who are you?
What are YOUR credentials to insult Einstein (nothing less)?
What are YOUR contributions to physics?
You do not even dare to write under your own name. Anonymous
cowards like you are half a dime the dozen here in Usenet.
Go back to your hole now, and take your meds.
jacob navia
P.S. And yes, sorry, I forgot:
<SHRUG>
kenseto
> similar to your e-strings but I use it for intellectual fun only since
> ether based theory are mostly garbage :) In other words I don't take
> it that seriously.
No your spring-theory is NOT similar to my E-Strings. Since you think
ehter based theory are mostly garbage then there is no need to waste
each other's time.
>
> In any case, elastic ethers do trivially account for expansion, dark
> matter, dark energy etc, but it is not meant for anything serious but
> the "fun".
>
> So now that we cleared that. Exactly what are you saying about the
> 'non-paradox' of mutual time dilation. I am confused.
An IRT observer does not consider that he is in a preferred frame. So
he has two equations to predict the rate of a moving clock: one to
predict a clock moving wrt him is running slow by a factor of 1/gamma
and the other to predict that the same clock is running fast by a
factor of gamma. Only one of these predictions is correct for any
specific irt observer.
This eliminates the bogus concept of mutual time dilation.
kenseto
The problem with such analogy is that clocks in relative motion do
accumulate clock seconds in different rate between meetings.
>
> Tom Roberts
Koobee Wublee
> Le 24/05/11 19:55, Koobee Wublee a crit :
> > Oh, isn’t that the cookbook on mathemaGics where Einstein the nitwit,
> > the plagiarist, and the liar was able to start with two identical
> > equations equating zero with zero and pulled out half of the Lorentz
> > transform out of these two equations? <shrug>
>
> Who are you?
Koobee Wublee, Yours Truly. Is it really that difficult to figure it
out? <shrug>
> What are YOUR credentials to insult Einstein (nothing less)?
None of your business. <shrug>
> What are YOUR contributions to physics?
Demystification. <shrug>
> You do not even dare to write under your own name. Anonymous
> cowards like you are half a dime the dozen here in Usenet.
>
> Go back to your hole now, and take your meds.
>
> P.S. And yes, sorry, I forgot:
>
> <SHRUG>
Are you done with personal insults? If so, Yours Truly would like to
remind you that Einstein the nitwit, the plagiarist, and the liar was
indeed a nitwit, a plagiarist, and a liar, and you have been
worshipping a nitwit, a plagiarist, and a liar. Get over with it.
<shrug>
Marc Fleury
> > I did, in my lost moments I like to entertain a toy model I call
> > similar to your e-strings but I use it for intellectual fun only since
> > ether based theory are mostly garbage :) In other words I don't take
> > it that seriously.
>
> No your spring-theory is NOT similar to my E-Strings. Since you think
> ehter based theory are mostly garbage then there is no need to waste
> each other's time.
Thank you. I would appreciate that.
Dono.
Sure. You recovered the results I showed you earlier. To help you
understand the difference in the "number of clicks" let's do the
following.
You have two digital clocks. They are synchronized and placed next to
each other at point O.
The two clocks are transported (very slowly) with the SAME speed to
points A and B at EQUAL distances on either side of O. The clocks are
still synchronized.
An observer placed in O sends a light pulse to both A and B, when they
receive the signal, the are supposed to send their digital readout to
the other clock.
B receives a readout of 800 "clicks" from A. When he looks at his
clock, B reads 1000 "clicks". Why is it so? Because the readout from A
took some time to propagate all the way to B. In the meanwhile, the
clock at B advanced (by 200 "clicks").
Marc Fleury
> On May 23, 10:17 pm, "Paul B. Andersen" <some...@somewhere.no> wrote:
>
>
>
>
>
>
>
>
>
> > On 23.05.2011 15:26, Marc Fleury wrote:
>
> > > Hello folks,
>
> > > I am happy to see the sci.physics of old are still alive and kicking!!
>
> > > Anyway, quick question, I have some time these days and decided to
> > > finally go back and try to "get" relativity. I am struggling still
> > > but making more progress than I used to. The math, was never the
> > > problem (not even GR) but the "mental model" always was hard for me.
>
> > > of v. SR tells us that the coordinates are lorentz transformed so
> > > that time in both frames with respect to the other has to be
> > > multiplied by sqrt(1-v/c^2) bla bla bla the usual "time slows down in
> > > understood as coordinates (meaning with no physical, or ontological,
> > > reality and just props in my calculations) but have a profound problem
> > > admitting that both CLOCKS (as counting ticks) will slow down with
> > > respect to the other. Just by symmetry of the problem, the
> > > proposition seems non-sensical to me.
>
>
> > > Somewhere between the 'physical clock' and the 'coordinates', I am
> > > missing a step? Does SR say anything about the number of clock
> > > ticks? This also seems completely basic to the understanding of SR
> > > and so must have been covered countless time. Any help or pointers
> > > are greatly appreciated.
>
> > Paul
>
> >http://home.c2i.net/pb_andersen/
>
> Paul,
>
> will study this in detail and get back to you, essentially seems to be
> the "right" answer ala artful above. Thanks for taking the time to
> link this. Be right back.
Using the Landau/your formalism to be precise
This is obviously non-sensical. If you could help pinpoint the error
i would be immensely grateful
Marc Fleury
dono, I do not understand what you are saying. Event 0 and Event 1 are
collocated. I don't need the clocks to communicate.
I got to tell you, I would appreciate if you just STFU. Your
explanations are really not helping me. I do not want help from you.
thank you.
Marc Fleury
> On May 23, 4:39 pm, Prai Jei <pvstownsend.zyx....@ntlworld.com> wrote:> Koobee Wublee set the following eddies spiralling through the space-time
> > continuum:
>
> > > This is the twins’ paradox, and it is never resolved.
>
>
> > How much acceleration does the stay-at-home twin experience as the
> > travelling twin turns round?
>
> > There ain't no symmetry between the twins.
>
> > Twin paradox resolved.
>
> May I add the the acceleration that breaks the symmetry has to be
> associated with an external force on the observer's instruments.
> What confuses people is the mistaken belief that there is no
> absolute acceleration in SR. There is no absolute velocity in SR but
> there is absolute acceleration.
> By absolute acceleration, I mean the external force on the
> observer's instrument divided by the mass of the instrument. Perhaps I
> should call that the dynamic force.
> The dynamic force places the observer in a series of inertial
> frames. The observer can not stay in one inertial frame if a dynamic
> force is acting upon it. Therefore, the law of reciprocity does not
> apply to an observer that switches from one inertial frame to the
> other. In this one sense, the force is important in SR.
> If there were no such thing as absolute acceleration, then the
> cranks would be right. There would be a symmetry between the twins.
very simply put this is not the twins paradox. At all.
Landau (in a post in another thread) is bang on, but dismisses the
symmetry based on the fact that you have to compare one clock to many
other clocks and that is not symmetric. refer to the other threads.
Dono.
Stupid motherfucker,
You should STFU, you are unable to understand the simplest concepts.
And you claim to have a PhD in physics? It must be from the same
"university" as Ralph Babbige, you fucking liar.
Dono.
>
>
> This is obviously non-sensical.
It is nonsensical for a pathetic imbecile and liar like you.
Marc Fleury
Tom, thanks
let me try and solidify the "problem" in the Landau example.
papa...@gmail.com
You are quite wrong in that Landau dismisses symmetry. What he does is
explain why, using relatively moving inertial frames, observers
located at any one of those inertial frames and performing measures of
moving clocks, will determine that those relatively moving clocks run
slow compared with the observers local clocks.
Landau is also quite clear in explaining that the measure of those
moving clocks has to be done by locating several observer helpers,
with synchronized clocks, which take note of the moving clocks
readings.
But Artful, in post number 7, already has shown to you a nice diagram
illustrating all these concepts, so why you keep on insisting you do
not understand is really curious.
Miguel Rios
Miguel Rios
Marc Fleury
From Landau:
papa...@gmail.com
What do you mean with freezing up?
The situation is symmetric. You are comparing the measurements of TWO
observers in TWO different frames and, of course, you get TWO
different values. The symmetry of the situation implies exactly that.
It is completely absurd to expect ONE value for the number of clicks.
Miguel Rios
Marc Fleury
Because I honestly do not understand. I have read the andersen and
artful post. Similar to the landau thought experiment (with k k'
frameworks). I have simplified it in the other threads. I still
reach a "syntax error".
Marc Fleury
not following, sorry. Event 0 and Event 1 happen independently of the
frame I use. Depending on the frame I use I get different results for
the readout of the atomic clock ? I freeze up at that. If you don't
please expand. Honestly.