Relativity problem
DSeppala
I don't understand the physical manifestions of this simple relativity
problem. Any insights would be greatly appreciated.
Let there be two rods, one 10 units in length and the other slightly
longer but with markings A and B 10 units apart when they are at rest wrt
to each other:
Figure 1. AB = DE = 10 (when at rest).
A+++++++++B++C
D+++++++++E
Now let ABC move to the right at v = 0.6c. In the DE frame, the length AB
is now 8 units (due to length contraction of reference frames with
relative velocity).
When A and D are coincident at the same point in space, in the DE frame, E
and C are also coincident at some point in space as shown in Figure 2:
A+++++++B+C
D+++++++++E
As seen in the DE frame, let A and D be clamped together, and let C and E
be clamped together when A and D meet. After an acceleration, the two
rods have zero relative velocity, but DE = 10 units, but AC is greater
than 10. What happens?
My attempts:
Some sort of physical deformation occurs making length DE = AC. From
what I understand, Lorentz thought the length contraction was due to a
rearrangement of atoms whereas Einstein thought it had to do with the
metric of space itself. There's numerous reasons why a deformation could
not occur (ex: must happen with all material and objects and shapes
including deformation of individual atoms and must occur with all relative
velocites, etc.).
Apparently, there's something physicists understand about relativity
that I'm missing completely. I would appreciate any insight anyone can
give. My solution of course is that Einstein's hypothesis is wrong, and I
know of two experiments which support the hypothesis that the velocity of
light depends on the velocity of the source and I know of no experiments
which support Einstein's hypothesis. Thanks
Dave Seppala email: DSep...@aol.com
Patrick Reany
1) It is all too easy to jump to the conclusion that Einstein was wrong.
People have been doing that since his first paper on SR was published in
1905. For a long time I had my own doubts, but not any more.
2) Let's not say Einstein's "hypothesis" when referring to his theory of
SR. An "hypothesis" is a testable cause-and-effect relationship that has
not yet been fully verified or disproven. When referring to SR one
should call it a "theory." Now, if you mean to refer to the length
contraction effect as an "hypothesis" that's OK, since it has never been
directly observed. However, the assumption of length contraction is used
to correctly account for the magnetic field of a conducting wire (see
French, Special Relativity).
3) The explanation of SR length contraction is this: The contraction is
not "real" per se, only because the term "real" has no meaning in
physics. Length contraction is "physical" simply because the physical
realm (at least in physics) is the realm of measurements, and SR
predicts that an actual measurement of one rod by two different inertial
observers would give different lengths, even if those two observers
started off with the same measuring instruments and then accelerated
into different relative inertial frames. The "cause" part of this
hypothesis is the dissagreement between the two different inertial
observers about which events are simultaneous in the two frames. Two
events judged as simultaneous in one frame will be regarded as not
simultaneous in the other frame. This is the heart of the explanation.
For more details on this explanation see any of a hundred books on SR.
And prefer the explanations that use Minkowski diagrams to those that
don't.
cheers,
Patrick
Edward Green
'dsep...@aol.com (DSeppala)' wrote:
>Some sort of physical deformation occurs making length DE = AC. From
>what I understand, Lorentz thought the length contraction was due to a
>rearrangement of atoms whereas Einstein thought it had to do with the
>metric of space itself.
>There's numerous reasons why a deformation could
>not occur (ex: must happen with all material and objects and shapes
>including deformation of individual atoms and must occur with all relative
>velocites, etc.).
That's true, but so? Why does that mean it is not a real deformation?
>Apparently, there's something physicists understand about relativity
>that I'm missing completely. I would appreciate any insight anyone can
>give. My solution of course is that Einstein's hypothesis is wrong, and I
>know of two experiments which support the hypothesis that the velocity of
>light depends on the velocity of the source...
References?
--
Ed Green / egr...@nyc.pipeline.com
"How long, I wonder, has he been constrained to come often to his glass
for inspection and instruction...?" J.R.R. Tolkien
Jonathan C. Dunn
This can be visualized humorously in terms of a desynchronized caboose.
The engine and the caboose(rear) of the train have exact timetables which
they always competently follow as far as what landmark the pass at a
particular time.
The caboose's clock gets ahead so that it passes each landmark a little
earlier than it 'should', and so the whole train is shortened in the
direction of travel.
The front and end of the rod no longer are synchronized as seen by the
relatively moving observer. These things should always be visualized with
digital clocks nailed to the front and end of the moving rod.
DSeppala
Response to Ed Green,
In my original post I wrote:
>There's numerous reasons why a deformation could
>not occur (ex: must happen with all material and objects and shapes
>including deformation of individual atoms and must occur with all
relative
>velocites, etc.).
Ed Green asked:
>> That's true, but so? Why does that mean it is not a real
deformation?
1. If a deformation occurs, then a deformation must occur to each and
every object that undergoes any sort of acceleration and then moves with
constant velocity. If this is not true, then some objects would not
follow the space-time variations of Einstein's theory. If a deformation
occurs, then objects such as atoms, or electrons, protons, etc., must
suffer a deformation if they are accelerated. There is no physical
evidence that there is any variation of properties in individual atoms
or particles related to length metric even though they continually
undergo accelerations. We for example do not find that particles in
accelerators that have decelerated to common velocities behave any
differently than they common velocity counterparts. In the problem
example we would expect accelerated and decelerated protons to occupy
a different amount of space than that common velocity counterparts.
I also said:
>Apparently, there's something physicists understand about relativity
>that I'm missing completely. I would appreciate any insight anyone can
>give. My solution of course is that Einstein's hypothesis is wrong,
and I
>know of two experiments which support the hypothesis that the velocity
of
>light depends on the velocity of the source...
Ed Green also asked:
>References?
The experiments I refer to are known to physicists who routinely
misinterpret them and ignore critical parts of the experiment, so I'm
reluctant to simply list them as they take some discussion that isn't
found
in physics literature. As an example we can take the well-known
Michelson-Morley experiment. In Stephen Hawking's book he states that:
They compared the speed of light in the direction of the earth's
motion with that at right angles to the earth's motion. To their
great surprise they found they were exactly the same!
As I'm sure you know, Michelson and Morley found no such thing.
Furthermore Hawking fails to mention that the experiment is trivia
to explain if the velocity of light depends on the velocity of the
light source, and requires a myriad of additional unproven hypotheses
if the oppossite hypothesis (Einstein's hypothesis) is used, and one
must ignore critical aspects of the experiment when explaining from
Einstein's point of view. You're probably well versed in the
experiment, but if you have any questions I'd be happy
to post responses to them under a separate thread.
Dave Seppala DSep...@aol.com
Matt McIrvin
In article <50hd1o$n...@newsbf02.news.aol.com>, dsep...@aol.com (DSeppala)
wrote:
> I don't understand the physical manifestions of this simple relativity
> problem. Any insights would be greatly appreciated.
> Let there be two rods, one 10 units in length and the other slightly
> longer but with markings A and B 10 units apart when they are at rest wrt
> to each other:
> Figure 1. AB = DE = 10 (when at rest).
> A+++++++++B++C
> D+++++++++E
> Now let ABC move to the right at v = 0.6c. In the DE frame, the length AB
> is now 8 units (due to length contraction of reference frames with
> relative velocity).
> When A and D are coincident at the same point in space, in the DE frame, E
> and C are also coincident at some point in space as shown in Figure 2:
> A+++++++B+C
> D+++++++++E
>
> As seen in the DE frame, let A and D be clamped together, and let C and E
> be clamped together when A and D meet. After an acceleration, the two
> rods have zero relative velocity, but DE = 10 units, but AC is greater
> than 10. What happens?
>
> My attempts:
> Some sort of physical deformation occurs making length DE = AC.
Yes, or else something breaks.
Suppose that everything is strong and compressible/extensible enough that
nothing actually breaks. Then the deformation persists after AC slows down
only *because* you clamped them together. Look at it from the frame of AC,
as the clamping occurs. The DE rod, which in this frame is shorter than
AC, moves to the left. In this frame, the clamping events are not
simultaneous. First, C and E are clamped together--and point E gets
dragged along by the AC bar, moving at tremendous speed. This compresses
the DE bar (due to its inertia, it deforms rather than just moving as a
unit), and stretches out the AC bar due to *its* inertia. Eventually they
are the same length, at which point A and D get clamped together.
The bars wouldn't end up the same length if you hadn't tried clamping them
together; the deformation that occurs at the end of the experiment is the
result of the huge forces exerted by the clamps.
Don't get too worried about the distinction between "deformations due to
forces" and "deformations due to Spacetime Itself." In the case of an
object being actively accelerated from one velocity to another, they
usually amount to the same thing; the Lorentz transformation makes forces
non-simultaneous in some frames, and in those frames the timing
differences end up stretching or squashing the material.
For this reason, it's easy to come up with paradoxes if you try to reason
about infinitely rigid, extended objects in relativity. In fact, according
to relativity, there is no such thing as an infinitely rigid, extended
object.
--
Matt McIrvin <http://world.std.com/~mmcirvin/>
George Dishman
In article: <322C42...@xroads.com> Patrick Reany <re...@xroads.com> writes:
>
> DSeppala wrote:
> >
> > I don't understand the physical manifestions of this simple relativity
> > problem. Any insights would be greatly appreciated.
> > Let there be two rods, one 10 units in length and the other slightly
> > longer but with markings A and B 10 units apart when they are at rest wrt
> > to each other:
> > Figure 1. AB = DE = 10 (when at rest).
> > A+++++++++B++C
> > D+++++++++E
> > Now let ABC move to the right at v = 0.6c. In the DE frame, the length AB
> > is now 8 units (due to length contraction of reference frames with
> > relative velocity).
> > When A and D are coincident at the same point in space, in the DE frame, E
> > and C are also coincident at some point in space as shown in Figure 2:
> > A+++++++B+C
> > D+++++++++E
> >
This assumes that the AD and CE events are simultaneous. You can't make that
assumption is SR. I think this is similar to the 'barn door' paradox described
in the physics FAQ.
--
George Dishman
Give me a small laser and I'll move the sun.
DSeppala
George Dishman wrote:
>This assumes that the AD and CE events are simultaneous. You can't make
>that assumption is SR. I think this is similar to the 'barn door'
paradox >described in the physics FAQ.
In one frame observers see events AD and CE as simultaneous, whereas in
the other frame the event AD occurs before CE. But the two rods in both
frames become attached at AD and at CE because this clamping takes place
when A and D are at the same point in space, and when C and E are at the
same point in space eventhough they occur at different times for different
observers. The problem is similar to the barn paradox, but it isn't simpy
explained (as yet).
Dave Seppala Email: DSep...@aol.com
DSeppala
Matt McIrvin <http://world.std.com/~mmcirvin/> wrote:
>Don't get too worried about the distinction between "deformations due to
>forces" and "deformations due to Spacetime Itself." In the case of an
>object being actively accelerated from one velocity to another, they
>usually amount to the same thing; the Lorentz transformation makes forces
>non-simultaneous in some frames, and in those frames the timing
>differences end up stretching or squashing the material.
There is a distinction between deformations due to forces and deformations
due to
space-time itself. All deformations ever observed (due to forces) have
been due to changes in chemical bonds. Hence all observed deformations
are non-linear. That is, only some bonds break, and there is no change in
the atoms themselves. Einstein's concept is different. The length
contraction is linear across the rod. Each increment of the rod must
deform by the same amount according to his equations. We cannot have some
bonds break and others remain as they were. Furthermore, atoms themselves
must undergo a deformation themselves otherwise we have objects which are
not subject
to the length contraction consequence of Einstein's theory. So I see a
rather large
distinction between deformation cause by forces and deformation caused by
space-time.
This problem is similar to the twins paradox in which supporters of
Einstein's theory
resolved the paradox by saying one twin underwent an acceleration so time
actually
ends up differently for him. (I have a gedanken experiment which shows
this solution
doesn't work). In this rod problem, the acceleration causes a change in
the
length metric (I guess), so objects that undergo this acceleration end up
with a length
metric that is different from what it was when they started (analogous to
the time
metric in the twins paradox). The problem is that we can't do the twins
paradox
experiment, but accelerations of objects occur all the time yet no one has
ever
observed that there are classes of atoms, protons, crystals, whatever,
that have any
noticeable difference in their length metric similar to what occurs in the
time metric
in the twins paradox.
Besides these thought experiments, there is actually physical evidence
that supports the contrary hypothesis on which relativity is based, namely
that the
velocity of light varies with the velocity of the source instead of
Einstein's
hypothesis that the speed of light is independent of the velocity of the
source but
the direction of emitted light depends on the velocity of the source
(implicitly used
by Einstein but not stated).
Dave Seppala Email: DSep...@aol.com
Steve Martin
On 3 Sep 1996 16:54:41 -0400, DSeppala <dsep...@aol.com> wrote:
>Response to Ed Green,
>In my original post I wrote:
>I also said:
>>Apparently, there's something physicists understand about relativity
>>that I'm missing completely. I would appreciate any insight anyone can
>>give. My solution of course is that Einstein's hypothesis is wrong, and I
>
>Ed Green also asked:
>>References?
> The experiments I refer to are known to physicists who routinely
>misinterpret them and ignore critical parts of the experiment, so I'm
>reluctant to simply list them as they take some discussion that isn't
>found in physics literature. As an example we can take the well-known
>Michelson-Morley experiment. In Stephen Hawking's book he states that:
> They compared the speed of light in the direction of the earth's
> motion with that at right angles to the earth's motion. To their
> great surprise they found they were exactly the same!
>As I'm sure you know, Michelson and Morley found no such thing.
Hmm, not the way I remember it at all. Michelson and Morley were sure
that their apparatus was so sensitive that it would reveal a difference
in the interference patterns even if the 'ether' were orders of magnitude
weaker than they expected it to be, or if the motion of the earth
relative to the 'ether' were much less than they expected. Their
experiment, and subsequent attempts to repeat the experiment, showed
that the velocity of light was the same as far as the accuracy of
the apparatus was concerned.
So I am sure I do not know that they found no such thing. What are
you referring to?
On the other hand, why don't you wish to quote your other references?
If the experiments you are referring to have been shown to be flawed
or incorrectly interpreted, then you shouldn't mention them in the
first place. If you are willing to bring them up to prove your point
then you should attribute them. Anything else is lazy science.
--
Steve Martin ----v/|
http://www.henge.com/~smartin \_ _ /
finger sma...@henge.com for pgp key V v
DSeppala
In reply to Steve Martin about Michelson Morley experiment.
I'll post response under new thread in sci.physics called
Michelson-Morley - Part 1
Dave Seppala Email: DSep...@aol.com
DSeppala
The second experiment I know of was also done by Michelson around 1913.
He tested
whether the speed of light changes after reflecting off a moving mirror.
He concluded
that the speed of light does not change after striking a moving mirror.
But be careful,
because the equations he used to come to this conclusion have errors in
them. If you
correct the errors, his data shows the opposite conclusion. I think his
paper was
called EFFECT OF REFLECTION FROM A MOVING MIRROR ON THE VELOCITY
OF LIGHT by A. A. Michelson, published circa 1913 in Physical Review.
I'm reluctant to name these sources not because I'm lazy, but because
often, as with
the Michelson-Morley experiment, readers have been told what was
discovered without
bothering to read the original paper in light of modern ideas and I am not
prepared to
reply to questions about these experiments. If someone simply reads
the 1913 paper referenced above, he can quote Michelson as saying that the
moving
mirror has no effect on the speed of light and not bother to verify that
Michelson's
equation for optical path lengths are wrong. The problem is similar to
the argument that
binary stars support the hypothesis that the speed of light is independent
of the velocity
of the light source. Everyone who reads the original paper could follow
the author's same
steps and come to the same conclusion without realizing the implicit
unproven hypothesis used in the binary star argument which renders the
argument useless.
Dave Seppala Email: DSep...@aol.com
Keith Stein
DSeppala writes
> Apparently, there's something physicists understand about relativity
>that I'm missing completely.
or vice versa !
Hi Dave,
Have you seen some of Alexander Abian's posting on relativity ?
Some of his postings are totally crazy, like you may have noticed that
he recommends that we "BLOW UP THE MOON" !?! and his "TIME IS MASS"
slogan makes about about sense as does "TIME IS LENGTH" to me !
However he does have some nice examples, you may have noticed
"ABIAN'S TROLLY" and "ABIAN'S WALL". Seriously i like both of Abian's
examples, although i'm still not sure what conclusion Abian draws from
them. (I do hope Abian doesn't feel obliged to leap in here to explain!)
However i digress......................................................
> My solution of course is that Einstein's hypothesis is wrong,
Correct.
> the velocity of
>light depends on the velocity of the source
Wrong.
From Maxwell's Equations we would expect the velocity of light
to depend on the electric permittivity and magnetic permeability of the
'medium' in which the light travels. This velocity will be relative to
this 'medium' and strictly therefore independent of the velocity of the
source.
Note however that in the case of the Michelson Moreley
Experiment, your explanation still works, providing we take the
medium to be the AIR in the laboratory. I should perhaps mention that
this is not currently the fashionable view, but is nevertheless very
reasonable since it is the permittivity and permeability of the AIR
which we must plug into Maxwell's Equations.
Note also that many sci.phys posters when confronted with the
above will object because one can not apply that to transmission of
light through a vacuum. This is a VALID OBJECTION, but since there AIN'T
NO VACUUMS NOWHERE, it ain't of the slightest importance either!
> and I know of no experiments
>which support Einstein's hypothesis.
Oh indeed there are some using planes, but for some strange reason the
SR crew have never bothered to measure the time dilations on an orbiting
space laboratory - (or if they have they choose not to publish!) This is
strange because if the SR time dilations really do exists, then they
would be BLATANT on the Mir space station, and they could silence at
least some of the more BLATANT SKEPTICS - if they could show that clocks
really do what Einstein says clocks do, on an orbiting space laboratory.
i hope that has been of some help Dave.
--
Keith Stein
George Dishman
In article: <8yHhCHAo...@sthbrum.demon.co.uk>
Keith Stein <sth...@sthbrum.demon.co.uk> writes:
[snip]
> From Maxwell's Equations we would expect the velocity of light
> to depend on the electric permittivity and magnetic permeability of the
> 'medium' in which the light travels. This velocity will be relative to
> this 'medium' and strictly therefore independent of the velocity of the
> source.
> Note however that in the case of the Michelson Moreley
> Experiment, your explanation still works, providing we take the
> medium to be the AIR in the laboratory. I should perhaps mention that
> this is not currently the fashionable view, but is nevertheless very
> reasonable since it is the permittivity and permeability of the AIR
> which we must plug into Maxwell's Equations.
> Note also that many sci.phys posters when confronted with the
> above will object because one can not apply that to transmission of
> light through a vacuum. This is a VALID OBJECTION, but since there AIN'T
> NO VACUUMS NOWHERE, it ain't of the slightest importance either!
>
> Oh indeed there are some using planes, but for some strange reason the
> SR crew have never bothered to measure the time dilations on an orbiting
> space laboratory - (or if they have they choose not to publish!) This is
> strange because if the SR time dilations really do exists, then they
> would be BLATANT on the Mir space station, and they could silence at
> least some of the more BLATANT SKEPTICS - if they could show that clocks
> really do what Einstein says clocks do, on an orbiting space laboratory.
As has been explained to you by several posters, the time shifts are
blatant in the satelite clocks in the GPS system, unless you really
believe that the radio signals we receive travel backwards in time, Keith.
Kris Croes
DSeppala (dsep...@aol.com) wrote:
: There is a distinction between deformations due to forces and deformations
: due to space-time itself.
I wonder whether we would ever be able to see "deformations due to
space-time itself". If we shine a light beam along the deformation, the
beam would follow it. We all "know" that light goes in straight lines,
so the deformations would be seen as not deformed at all.
Notice that I deliberately used the verb "to see", and not "to observe".
These deformations can be observed as gravity. I really meant: SEE.
Any ideas?
Kris
--
Kris Croes - mailto:cr...@imec.be - http://www.esat.kuleuven.ac.be/~croes/
"Due to budget cuts the light at the end of the tunnel has been turned off"
Keith Stein
George Dishman <geo...@briar.demon.co.uk> writes
>
> Keith Stein <sth...@sthbrum.demon.co.uk> writes:
>[snip]
>> From Maxwell's Equations we would expect the velocity of light
>> to depend on the electric permittivity and magnetic permeability of the
>> 'medium' in which the light travels. This velocity will be relative to
>> this 'medium' and strictly therefore independent of the velocity of the
>> source.
>> Note however that in the case of the Michelson Moreley
>> Experiment, your explanation still works, providing we take the
>> medium to be the AIR in the laboratory. I should perhaps mention that
>> this is not currently the fashionable view, but is nevertheless very
>> reasonable since it is the permittivity and permeability of the AIR
>> which we must plug into Maxwell's Equations.
>> Note also that many sci.phys posters when confronted with the
>> above will object because one can not apply that to transmission of
>> light through a vacuum. This is a VALID OBJECTION, but since there AIN'T
>> NO VACUUMS NOWHERE, it ain't of the slightest importance either!
>>
>[snip]
>
>> least some of the more BLATANT SKEPTICS - if they could show that clocks
>> really do what Einstein says clocks do, on an orbiting space laboratory.
>
>As has been explained to you by several posters, the time shifts are
>blatant in the satelite clocks in the GPS system, unless you really
>believe that the radio signals we receive travel backwards in time, Keith.
BUT in order to really claim to have verified the SR and GR predictions,
one needs results from both a high orbit satelite (eg GPS) where GR
effects dominate, and a low orbit satelite (eg Mir), where SR dominates.
This is because the results one gets from any one satelite necessarily
combine both the SR and the GR time dilations together into one result.
So you too would like to see the Mir time dilations confirm your SR/GR
predictions, now wouldn't you George, be honest :-)
--
Keith Stein
Tim Hollebeek
In article <1996Sep6.1...@imec.be>, cr...@imec.be writes:
> DSeppala (dsep...@aol.com) wrote:
>
> : There is a distinction between deformations due to forces and deformations
> : due to space-time itself.
>
> I wonder whether we would ever be able to see "deformations due to
> space-time itself". If we shine a light beam along the deformation, the
> beam would follow it. We all "know" that light goes in straight lines,
> so the deformations would be seen as not deformed at all.
>
> Notice that I deliberately used the verb "to see", and not "to observe".
> These deformations can be observed as gravity. I really meant: SEE.
Of course you can see the effects. If there is a heavy object in your line of sight, the light rays are curved towards you, much as there were a lens there. Astronomers can (and do) see such effects.
---------------------------------------------------------------------------
Tim Hollebeek | Disclaimer :=> Everything above is a true statement,
Electron Psychologist | for sufficiently false values of true.
Princeton University | email: t...@wfn-shop.princeton.edu
----------------------| http://wfn-shop.princeton.edu/~tim (NEW! IMPROVED!)
George Dishman
In article: <hvUy1rA7...@sthbrum.demon.co.uk>
Keith Stein <sth...@sthbrum.demon.co.uk> writes:
>
> George Dishman <geo...@briar.demon.co.uk> writes
> >
> > Keith Stein <sth...@sthbrum.demon.co.uk> writes:
[snip]
> >> least some of the more BLATANT SKEPTICS - if they could show that clocks
> >> really do what Einstein says clocks do, on an orbiting space laboratory.
> >
> >As has been explained to you by several posters, the time shifts are
> >blatant in the satelite clocks in the GPS system, unless you really
> >believe that the radio signals we receive travel backwards in time, Keith.
>
> BUT in order to really claim to have verified the SR and GR predictions,
> one needs results from both a high orbit satelite (eg GPS) where GR
> effects dominate, and a low orbit satelite (eg Mir), where SR dominates.
>
> This is because the results one gets from any one satelite necessarily
> combine both the SR and the GR time dilations together into one result.
I've always believed that SR isn't a separate theory, it is a simplification
of GR which can be made under certain well defined conditions. Evidence in
support of 'GR' therefore also confirms 'SR' while evidence supporting SR
alone doesn't necessarily say anything about GR. In fact the GPS time
dilation shows a greater effect as a result of the altitude (the extra part
in GR) than is due to the orbital velocity.
> So you too would like to see the Mir time dilations confirm your SR/GR
> predictions, now wouldn't you George, be honest :-)
To be honest, no, for a number of reasons.
There would be far more sources of error in this experiment than in the GPS
case. Flying clocks round the world (H&K) or taking them to Mir and back
introduces questions of acceleration, gravity changes, climatic changes,
handling, the influence of terrain over which they pass (mountains have
gravitational effects) etc. which generally do not apply or are very much
reduced in GPS. Continuously monitoring the clocks from the ground during the
trips to and from orbit would be very difficult, and on-board monitors would
be subject to the same dilations as the clocks hence unconvincing if not
useless. There are fewer uncontrolled effects in space. As the satelites
repeat the same orbits regularly, those effects that do occur are cyclic and
easily identified and calibrated.
Even supposing they moved Mir up to the altitude of GPS for the experiment to
maximise the time dilation effect and the 'GR' contribution, the clock shift
would only be around 1ms after a month. I am sure that the experimenters
could easily keep error effects to well below this but would they be able to
convince people like yourself? There are many possible arguments which could
be rolled out to discount the result so I don't think it would resolve the
debate or even make much of a dent in it!
The bottom line is that people who wish to discredit relativity at any cost
will be able to discard your experiment showing a shift of less than 1ms in a
month :(. The GPS result shows a clock shift of 150ms and the signal takes
only 70ms to reach us so is much harder to discount.
The real value of the GPS result is that it shows that the clocks must have
speeded up by over 50% of the value predicted by relativity (80ms/150ms).
This doesn't "prove SR" but it does eliminate any theory that says clocks
don't change rate at all (unless the theory introduces ludicrous properties
for the propagation time of the radio signals from the satelites).
The position accuracy of GPS is much better than 300m which is a propagation
time error of 1us. Compared to the predicted time shift of 150ms, this
confirms the relativistic prediction to better than one part in 10^5 assuming
constant c. Even allowing a hypothetical change of light speed for the
signals of 2% (=1.4ms) GPS still gives confirmation of the clock shift to
better than 1%.
Patrick van Esch
Tim Hollebeek (t...@franck.Princeton.EDU.composers) wrote:
: > These deformations can be observed as gravity. I really meant: SEE.
: Of course you can see the effects. If there is a heavy object in your line of sight, the light rays are curved towards you, much as there were a lens there. Astronomers can (and do) see such effects.
There are some very spectacular simulations at:
http://cossc.gsfc.nasa.gov/htmltest/rjn_bht.html
cheers,
Patrick.
--
Patrick Van Esch
mail: van...@dice2.desy.de
for PGP public key: finger van...@dice2.desy.de
Keith Stein
George Dishman <geo...@briar.demon.co.uk> writes
>
>I've always believed that SR isn't a separate theory, it is a simplification
>of GR which can be made under certain well defined conditions. Evidence in
>support of 'GR' therefore also confirms 'SR' while evidence supporting SR
>alone doesn't necessarily say anything about GR. In fact the GPS time
>dilation shows a greater effect as a result of the altitude (the extra part
>in GR) than is due to the orbital velocity.
>
>> So you too would like to see the Mir time dilations confirm your SR/GR
>> predictions, now wouldn't you George, be honest :-)
>
>To be honest, no, for a number of reasons.
>
>There would be far more sources of error in this experiment than in the GPS
>case.
"For extremely high-precision comparisons between clocks located
in different laboratories radio signals are inadequate,because
irregularities in their propagation through the atmosphere introduce
uncertainties in their travel time from one laboratiory to the other. To
deal with this difficulty, portable atomic clocks have been built. These
can be syncronised with a clock in one laboratory and then carried to
the other,transfering the synchronization" OHANIAN PHYSICS Chapter1.
So even for transfering "time" between terrestial laboratories,
"RADIO SIGNALS ARE INADAQUATE". Note that the terrestial case is much
simpler than for an orbiting laboratory, because at least the distance
between the laboratories remains fixed, and there are no Doppler
frequency shifts to worry about.
> Flying clocks round the world (H&K) or taking them to Mir and back
No No George. 'COMPARE THE CLOCKS IN SPACE'. This is a much BETTER
experimental technique, which was actually suggested to me by my 16 year
old son, so i'm suprised you didn't think of that yourself George! The
big virtue of this being that since all clocks have made just one and
the same journey, then any effects of acceleration will at least be the
same on both clocks.
>introduces questions of acceleration, gravity changes, climatic changes,
>handling, the influence of terrain over which they pass (mountains have
>gravitational effects) etc.
i could see why you might think that these would invalidate those old
measurements of SR/GR time dilations utilising planes George, but the
predicted effects on the Mir are about 1000 times as big. If you would
doubt results obtained from the Mir, then you must certainly discount
any of the existing claims to have made direct measurements of the SR/GR
time dilations.
> Continuously monitoring the clocks from the ground during the
>trips to and from orbit would be very difficult,
and unnecessary !
> and on-board monitors would
>be subject to the same dilations as the clocks hence unconvincing if not
>useless.
George. We syncronise two clocks.
We send up one clock to Mir.
x days later we send up the other.
If the first clock is 26x micro seconds slow then relativity OK.
So what is your problem here George? (Don't worry about the 26 micro
secs messing up the monitors. I'm sure they would cope with this, but i
any case, i don't really think these time-dilations happen George:-)
> There are fewer uncontrolled effects in space. As the satelites
>repeat the same orbits regularly,
Yet another good reason why time dilations would be much more easily
measured on the Mir than with those old experiments on planes.
> those effects that do occur are cyclic and
>easily identified and calibrated.
>
>Even supposing they moved Mir up to the altitude of GPS for the experiment
Well i doubt if they would do that for you George:-), but never mind
because it's in an excellent orbit for checking the SR time dilations
just were it is; and these are even more ify than the GR time dilations
if you ask me.
>maximise the time dilation effect and the 'GR' contribution, the clock shift
>would only be around 1ms after a month.
Well the time dilation must surely be course exactly the same amount
whether it is measured directly utilising stationary and adjacent
clocks, or with the less accurate transfer utilising radio signals.
--
Keith Stein
George Dishman
In article: <v0zHDOAi...@sthbrum.demon.co.uk>
Keith Stein <sth...@sthbrum.demon.co.uk> writes:
>
> George Dishman <geo...@briar.demon.co.uk> writes
> >
> >I've always believed that SR isn't a separate theory, it is a simplification
> >of GR which can be made under certain well defined conditions. Evidence in
> >support of 'GR' therefore also confirms 'SR' while evidence supporting SR
> >alone doesn't necessarily say anything about GR. In fact the GPS time
> >dilation shows a greater effect as a result of the altitude (the extra part
> >in GR) than is due to the orbital velocity.
> >
> >> So you too would like to see the Mir time dilations confirm your SR/GR
> >> predictions, now wouldn't you George, be honest :-)
> >
> >To be honest, no, for a number of reasons.
> >
> >There would be far more sources of error in this experiment than in the GPS
> >case.
>
> "For extremely high-precision comparisons between clocks located
> in different laboratories radio signals are inadequate,because
> irregularities in their propagation through the atmosphere introduce
> uncertainties in their travel time from one laboratiory to the other. To
> deal with this difficulty, portable atomic clocks have been built. These
> can be syncronised with a clock in one laboratory and then carried to
> the other,transfering the synchronization" OHANIAN PHYSICS Chapter1.
Absolutely correct. Transmissions between terrestrial labs, diffract
round the curvature of the earth, bounce of buildings, reflect of the
ionosphere and have all sorts of unpleasant things happen to them. :(
> So even for transfering "time" between terrestial laboratories,
> "RADIO SIGNALS ARE INADAQUATE". Note that the terrestial case is much
> simpler than for an orbiting laboratory, because at least the distance
> between the laboratories remains fixed, and there are no Doppler
> frequency shifts to worry about.
The signals to the GPS system on the other hand are line of sight.
There are two frequencies used so the differential delay allows assessment
of the refractive index, and the Doppler shift has no effect on the
propagation time.
The fact you keep ignoring is that we get a position accurate to much
better than 300m which means the receiver knows the delay accurate to
better than 1us.
>
> > Flying clocks round the world (H&K) or taking them to Mir and back
>
> No No George. 'COMPARE THE CLOCKS IN SPACE'. This is a much BETTER
> experimental technique, which was actually suggested to me by my 16 year
> old son, so i'm suprised you didn't think of that yourself George! The
The GPS system is in space, that's why _I_ suggested you try to understand
what it tells you. Perhaps you should listen to your son. :)
> big virtue of this being that since all clocks have made just one and
> the same journey, then any effects of acceleration will at least be the
> same on both clocks.
Even better, have no journeys and no acceleration. :))))
> >introduces questions of acceleration, gravity changes, climatic changes,
> >handling, the influence of terrain over which they pass (mountains have
> >gravitational effects) etc.
> i could see why you might think that these would invalidate those old
> measurements of SR/GR time dilations utilising planes George, but the
> predicted effects on the Mir are about 1000 times as big. If you would
> doubt results obtained from the Mir, then you must certainly discount
> any of the existing claims to have made direct measurements of the SR/GR
> time dilations.
You are the one who asked for "blatant" results Keith, not me. As I said
in one of the bits you seem to have snipped:
> > ... I am sure that the experimenters
> > could easily keep error effects to well below this but would they be able to
> > convince people like yourself? ...
> >
> > The bottom line is that people who wish to discredit relativity at any cost
> > will be able to discard your experiment showing a shift of less than 1ms in a
> > month :(. The GPS result shows a clock shift of 150ms and the signal takes
> > only 70ms to reach us so is much harder to discount.
> > Continuously monitoring the clocks from the ground during the
> >trips to and from orbit would be very difficult,
> and unnecessary !
>
> > and on-board monitors would
> >be subject to the same dilations as the clocks hence unconvincing if not
> >useless.
> George. We syncronise two clocks.
> We send up one clock to Mir.
> x days later we send up the other.
> If the first clock is 26x micro seconds slow then relativity OK.
> So what is your problem here George? (Don't worry about the 26 micro
> secs messing up the monitors. I'm sure they would cope with this, but i
a) I don't have a problem Keith, you're the one who wants more tests done.
b) The on board monitors can't monitor the dilation because they
experience the same change of time.
> any case, i don't really think these time-dilations happen George:-)
This is the real crux isn't it. If you don't believe the clocks change,
explain how we can receive the signals before they are sent. Until you
can do this, the GPS result eliminates your theory as I said:
> > The real value of the GPS result is that it shows that the clocks must have
> > speeded up by over 50% of the value predicted by relativity (80ms/150ms).
> > This doesn't "prove SR" but it does eliminate any theory that says clocks
> > don't change rate at all (unless the theory introduces ludicrous properties
> > for the propagation time of the radio signals from the satelites).
> > There are fewer uncontrolled effects in space. As the satelites
> >repeat the same orbits regularly,
> Yet another good reason why time dilations would be much more easily
> measured on the Mir than with those old experiments on planes.
>
> > those effects that do occur are cyclic and
> >easily identified and calibrated.
> >
> >Even supposing they moved Mir up to the altitude of GPS for the experiment
> Well i doubt if they would do that for you George:-), but never mind
We were discussing your test Keith.
> because it's in an excellent orbit for checking the SR time dilations
> just were it is; and these are even more ify than the GR time dilations
> if you ask me.
You still don't get it do you Keith, how can SR be more 'ify' than GR
when SR is a subset of GR?
> >maximise the time dilation effect and the 'GR' contribution, the clock shift
> >would only be around 1ms after a month.
> Well the time dilation must surely be course exactly the same amount
> whether it is measured directly utilising stationary and adjacent
> clocks, or with the less accurate transfer utilising radio signals.
Well perhaps a more accurate tranfer would confirm GR/SR to 1 in 10^6
rather than 1 in 10^5 as I said and you again snipped:
> > The position accuracy of GPS is much better than 300m which is a propagation
> > time error of 1us. Compared to the predicted time shift of 150ms, this
> > confirms the relativistic prediction to better than one part in 10^5 assuming
> > constant c. Even allowing a hypothetical change of light speed for the
> > signals of 2% (=1.4ms) GPS still gives confirmation of the clock shift to
> > better than 1%.
Or to put it another way:
Theory A predicts 150ms
Theory B predicts 0ms
Measured 150ms +/- 1us
Which one should a true skeptic discard first?
Keith Stein
In article <833399...@briar.demon.co.uk>, George Dishman
<geo...@briar.demon.co.uk> writes
>In article: <v0zHDOAi...@sthbrum.demon.co.uk>
>
>> > Flying clocks round the world (H&K) or taking them to Mir and back
>>
>> No No George. 'COMPARE THE CLOCKS IN SPACE'. This is a much BETTER
>> experimental technique, which was actually suggested to me by my 16 year
>> old son, so i'm suprised you didn't think of that yourself George! The
>
>The GPS system is in space, that's why _I_ suggested you try to understand
>what it tells you. Perhaps you should listen to your son. :)
>
Jesus Christ George ! You can't even understand when it is explained to
you. No wonder you didn't think of it yourself! GPS results do *NOT*
'COMPARE THE CLOCKS IN SPACE' George. They compare 'A CLOCK IN SPACE'
with 'A CLOCK ON THE GROUND'. It is exactly to find out if the apparent
frequency shift is real that we need to 'compare the clocks in space'.
>> big virtue of this being that since all clocks have made just one and
>> the same journey, then any effects of acceleration will at least be the
>> same on both clocks.
>
>Even better, have no journeys and no acceleration. :))))
>
Essentially George you refuse to entertain the idea that you could be
wrong. I don't think there is much point in us going over the same
arguments again and again. Someday someone will 'compare the clocks
IN SPACE', and then i think you will see that indeed you were wrong, but
i do at least entertain the idea that IT COULD BE ME :-))))
--
Keith Stein
George Dishman
In article: <gkAE3WAj...@sthbrum.demon.co.uk>
Keith Stein <sth...@sthbrum.demon.co.uk> writes:
>
> In article <833399...@briar.demon.co.uk>, George Dishman
> <geo...@briar.demon.co.uk> writes
> >
> >The GPS system is in space, that's why _I_ suggested you try to understand
> >what it tells you. Perhaps you should listen to your son. :)
>
> Jesus Christ George ! You can't even understand when it is explained to
> you. No wonder you didn't think of it yourself! GPS results do *NOT*
> 'COMPARE THE CLOCKS IN SPACE' George. They compare 'A CLOCK IN SPACE'
> with 'A CLOCK ON THE GROUND'. It is exactly to find out if the apparent
> frequency shift is real that we need to 'compare the clocks in space'.
Perhaps this is where we differ. I believe we need to compare clocks
which have been affected by different amounts of time dilation under
conditions which exclude any other interpretation. GPS allows this
and provides more than adequate accuracy. You asked me to say if I
would like to see your test performed - I answered honestly.
[snip]
> Essentially George you refuse to entertain the idea that you could be
> wrong. I don't think there is much point in us going over the same
> arguments again and again. Someday someone will 'compare the clocks
> IN SPACE', and then i think you will see that indeed you were wrong, but
> i do at least entertain the idea that IT COULD BE ME :-))))
If you want me to accept your theory -
first: state the theory in a way that allows me to apply it to GPS,
second: show it can explain the GPS observations I posted,
third: show that SR fails to predict the GPS observations.
I will then readily admit I was wrong but as long as you are unable to
explain the GPS result, I can't accept your ideas. Of course, others
may want you to show your theory also aplies to all the other confirmations
of SR.
Good luck Keith.