SR cannot determine Contraction
Peri of Pera
Lorentz proposed contraction of moving objects in a paper 'The
relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
1, 74 in 1892 and then published the Lorentz transformation formulas
in 1899 according to which objects moving through space contract
parallel to the direction of motion and in proportion to their speed
[L'=L/sqrt(1-v^2/c^2)]. Einstein accepted the formulas but writes in
1916 (Relativity: The Special and General Theory, Chapter 16): "The
contraction of moving bodies follows from the two fundamental
principles of the theory".
The real value of v in the formula is indeterminate i.e. the real
speed of a body is unknown. However, the speed relative to other
bodies may be known. If body A moves relative to body B with a speed
of 200000km/sec, body A is seen by observers on B to contract by L/
sqrt(1-200000km/sec^2/c^2) and if body A moves at the same time
relative to body C with a speed of 100000km/sec it is seen by
observers on C to contract by L/sqrt(1-100000km/sec^2/c^2).
Conclusion: SR is useless. It does not tell us anything about the
state and condition of A, B or C but gives in every instance an
incorrect amount of the contraction of body A.
Peter Riedt
Sue...
If the clocks in Chicago differ from the clocks in New York
by one hour, it can be quite *useful* to contract the
rail lines connecting them, for some particular speed.
<< if we want to work out the potentials at position r
and time t then we have to perform integrals of the
charge density and current density over all space
(just like in the steady-state situation). However,
when we calculate the contribution of charges and
currents at position r' to these integrals we do not
use the values at time t, instead we use the values
at some earlier time... >>
http://farside.ph.utexas.edu/teaching/em/lectures/node50.html
<<...a general Lorentz transformation preserves the
volume of space-time. Since time is dilated by a factor
gamma in a moving frame, the volume of space-time
can only be preserved if the volume of ordinary 3-space
is reduced by the same factor. As is well-known,
this is achieved by length contraction along the
direction of motion by a factor gamma. >>
http://farside.ph.utexas.edu/teaching/em/lectures/node114.html
Sue...
> Peter Riedt
Paul B. Andersen
According to SR, body A doesn't contract just because it is seen:
"by observers on B to contract by L/sqrt(1-200000km/sec^2/c^2)"
and:
"by observers on C to contract by L/sqrt(1-100000km/sec^2/c^2)"
So what "incorrect amount of the contraction of body A"
are you referring to?
In a previous posting, I wrote:
"A clock isn't affected in any way by an arbitrary
observer's motion relative to the clock.
But the clock's motion relative to the observer
will affect the observer's _observations_ of the clock."
A more general statement would be:
An object isn't affected in any way by an arbitrary
observer's motion relative to the object.
But the object's motion relative to the observer
will affect the observer's _observations_ of the object.
--
Paul
rot...@gmail.com
>
> Lorentz proposed contraction of moving objects in a paper 'The
> relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
> 1, 74 in 1892 and then published the Lorentz transformation formulas
> in 1899 according to which objects moving through space contract
> parallel to the direction of motion and in proportion to their speed
> [L'=L/sqrt(1-v^2/c^2)].
Is it not L *times* sqrt(...) ?
>Einstein accepted the formulas but writes in
> 1916 (Relativity: The Special and General Theory, Chapter 16): "The
> contraction of moving bodies follows from the two fundamental
> principles of the theory".
>
> The real value of v in the formula is indeterminate i.e. the real
> speed of a body is unknown.
Correct. The "v" in Lorentz work represents the "true" speed, the
speed relative to the ether (frame). As was well known since 1900,
this speed had (and has) no way to be determined and standard optical
and kinematical setups will not be able to detect it.
>However, the speed relative to other
> bodies may be known.
Do you mean "true" speed or *measured* speed? The true speed can not
be determined. The measured speed ( the now usual procedure-defined
speed) can be found (measured).
>If body A moves relative to body B with a speed
> of 200000km/sec,
You mean *measured* speed... ?
>body A is seen by observers
Not "seen" but *measured* ?
>on B to contract by L/sqrt(1-200000km/sec^2/c^2) and
Dont you mean L TIMES sqrt(...) ?
>if body A moves at the same time
> relative to body C with a speed of 100000km/sec it is seen
You mean *measured* ?
> by observers on C to contract by L/sqrt(1-100000km/sec^2/c^2).
Dont you mean L TIMES sqrt(...) ?
> Conclusion: SR is useless. It does not tell us anything about the
> state and condition of A, B or C but gives in every instance an
> incorrect amount of the contraction of body A.
> Peter Riedt
Its calculations (predictions) correctly predict experiments; is that
not useful?
kenseto
Your description of SR contraction is correct. SR contraction is a
perspective geometric effect....from the perspective of observer B,
A's rod is contracted by a factor of L/sqrt(1-200000km/sec^2/
c^2)"....from the persective of C, A's rod is contracted by a factor
of L/sqrt(1-100000km/sec^2/c^2)".
BTW, IRT agrees that there is no physical length contraction of a
moving rod. However, the light path length of a moving rod is changing
according the factor of 1/gamma or gamma. That means that the light
path length of a moving rod can be shorter or longer than the light
path length of the observer's rod.
OTOH, PD insisted that physicists have performed experiments that show
real physical length contraction. Can you comment on that?
Ken Seto
>
> In a previous posting, I wrote:
> "A clock isn't affected in any way by an arbitrary
> observer's motion relative to the clock.
> But the clock's motion relative to the observer
> will affect the observer's _observations_ of the clock."
>
> A more general statement would be:
> An object isn't affected in any way by an arbitrary
> observer's motion relative to the object.
> But the object's motion relative to the observer
> will affect the observer's _observations_ of the object.
>
> --
> Paul
>
> http://home.c2i.net/pb_andersen/- Hide quoted text -
>
> - Show quoted text -
kenseto
The problem with this statement is that a moving clock will
accumulates less clock seconds when it rejoins with the observer. So
that means that the rate of a moving clock is affected by relative
motion.
Ken Seto
>
> A more general statement would be:
> An object isn't affected in any way by an arbitrary
> observer's motion relative to the object.
> But the object's motion relative to the observer
> will affect the observer's _observations_ of the object.
>
> --
> Paul
>
Tom Roberts
> Lorentz proposed contraction of moving objects in a paper 'The
> relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
> 1, 74 in 1892 and then published the Lorentz transformation formulas
> in 1899 according to which objects moving through space contract
> parallel to the direction of motion and in proportion to their speed
> [L'=L/sqrt(1-v^2/c^2)].
Yes.
> Einstein accepted the formulas [...]
No! Einstein RE-DERIVED a similar formula using a completely different
conceptual basis. The symbols in the equations have DIFFERENT MEANINGS.
> The real value of v in the formula is indeterminate i.e. the real
> speed of a body is unknown.
Only for an unusual and essentially useless meaning of "real".
When I measure the velocity of a moving object, that measurement
measures the REAL velocity of the object relative to the coordinates I
am using. This is the meaning of "real" that physicists have used for
>300 years (when applied to this particular situation). That Peri does
not know this is his problem. <shrug>
Yes, different observers using different coordinates obtain different
values of velocity of the same object. Such variation with point of view
is common in the world we inhabit. That Peri does not realize this is
his problem. <shrug>
> Conclusion: SR is useless.
No! But it is clear that Peri of Pera does not understand it.
Tom Roberts
Androcles
"Tom Roberts" <tjrobe...@sbcglobal.net> wrote in message
news:MH_tj.57861$Pv2....@newssvr23.news.prodigy.net...
Yes! But it is clear that Humpty Roberts does not understand it. <shrug>
harry
"Paul B. Andersen" <paul.b....@guesswhatuia.no> wrote in message
news:47B84506...@guesswhatuia.no...
Well said! But will he listen?
Harald
wugi
>BTW, IRT agrees that there is no physical length contraction of a
SR does mean a physical Lorentz length contraction.
Because of relativistic simultaneity it is reciprocal so that
( http://home.scarlet.be/~pin12499/MySRT/LorentzObjects.PNG )
in the "rest" system length 3 is contracted wrt proper length 4, and
in the "moving" system length 2 is contracted wrt proper length 1,
with the same contraction factor 1/gama.
>moving rod. However, the light path length of a moving rod is changing
>according the factor of 1/gamma or gamma. That means that the light
>path length of a moving rod can be shorter or longer than the light
>path length of the observer's rod.
... and even of the ***observed*** rod itself.
This is really a secondary phenomenon that by itself does not invalidate the
Lorentz contraction (it appears as Doppler effect in non-relativistic media
as well).
These lengths (and likewise, velocities) are actually the observed ones, and
the Lorentz effect would have to be backcalculated from them as it is never
going to be observed directly.
The length seen at approach is greater than contracted, even than proper
length;
the velocity seen at approach is greater than v, and for v = c would reach
infinity (whole approach seen in one flash).
The length seen at recession is smaller than Lorentz length (extra
contraction) and velocity smaller than v (for v = c or beta = 1 it becomes
c/2).
See http://home.scarlet.be/~pin12499/MySRT/LinearMovin.PNG.
The "Doppler" contraction factor is not gama but beta = v/c :
Be Lorentz length L = L0/gama, then the observed lengths and velocities are:
At approach:
L- = L /(1-beta)
bet- = beta /(1-beta)
At recession:
L+ = L /(1+beta)
bet+ = beta /(1+beta)
>OTOH, PD insisted that physicists have performed experiments that show
>real physical length contraction. Can you comment on that?
See above.
Regards,
guido
http://home.scarlet.be/~pin12499/paratwin.htm
PD
> SR cannot determine Contraction
>
> Lorentz proposed contraction of moving objects in a paper 'The
> relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
> 1, 74 in 1892 and then published the Lorentz transformation formulas
> in 1899 according to which objects moving through space contract
> parallel to the direction of motion and in proportion to their speed
> [L'=L/sqrt(1-v^2/c^2)]. Einstein accepted the formulas but writes in
> 1916 (Relativity: The Special and General Theory, Chapter 16): "The
> contraction of moving bodies follows from the two fundamental
> principles of the theory".
>
> The real value of v in the formula is indeterminate i.e. the real
> speed of a body is unknown. However, the speed relative to other
> bodies may be known. If body A moves relative to body B with a speed
> of 200000km/sec, body A is seen by observers on B to contract by L/
> sqrt(1-200000km/sec^2/c^2) and if body A moves at the same time
> relative to body C with a speed of 100000km/sec it is seen by
> observers on C to contract by L/sqrt(1-100000km/sec^2/c^2).
That's right. The amount of contraction is not absolute and is not
inherent to the object. It is an observer-dependent measurable
quantity, much like momentum, kinetic energy, electric field, and a
host of other observer-dependent quantities.
>
> Conclusion: SR is useless.
Nonsense. Physics is not limited to statements about observer-
independent quantities, nor should it be.
Androcles
"PD" <TheDrap...@gmail.com> wrote in message
news:db28a30a-c9a1-4aa0...@e10g2000prf.googlegroups.com...
On Feb 17, 12:55 am, Peri of Pera <rie...@yahoo.co.uk> wrote:
> SR cannot determine Contraction
>
> Lorentz proposed contraction of moving objects in a paper 'The
> relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
> 1, 74 in 1892 and then published the Lorentz transformation formulas
> in 1899 according to which objects moving through space contract
> parallel to the direction of motion and in proportion to their speed
> [L'=L/sqrt(1-v^2/c^2)]. Einstein accepted the formulas but writes in
> 1916 (Relativity: The Special and General Theory, Chapter 16): "The
> contraction of moving bodies follows from the two fundamental
> principles of the theory".
>
> The real value of v in the formula is indeterminate i.e. the real
> speed of a body is unknown. However, the speed relative to other
> bodies may be known. If body A moves relative to body B with a speed
> of 200000km/sec, body A is seen by observers on B to contract by L/
> sqrt(1-200000km/sec^2/c^2) and if body A moves at the same time
> relative to body C with a speed of 100000km/sec it is seen by
> observers on C to contract by L/sqrt(1-100000km/sec^2/c^2).
That's right. The amount of contraction is not absolute and is not
inherent to the object. It is an observer-dependent measurable
quantity, much like momentum, kinetic energy, electric field, and a
host of other observer-dependent quantities.
Lying shit.
Randy Poe
> "PD" <TheDraperFam...@gmail.com> wrote in message
>
> That's right. The amount of contraction is not absolute and is not
> inherent to the object. It is an observer-dependent measurable
> quantity, much like momentum, kinetic energy, electric field, and a
> host of other observer-dependent quantities.
Those who didn't know your (lack of) quoting might
mistakenly think you'd just made a correct and intelligible
statement. But we your fans know this part is actually
PD's.
> Lying shit.
So which of those statements do you think is wrong?
Do you disagree that momentum, KE, and E are observer
dependent?
- Randy
Androcles
"Randy Poe" <poespa...@yahoo.com> wrote in message
news:2f4a80a1-21d2-44fe...@s37g2000prg.googlegroups.com...
| On Feb 18, 3:42 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
| > "PD" <TheDraperFam...@gmail.com> wrote in message
| >
| > That's right. The amount of contraction is not absolute and is not
| > inherent to the object. It is an observer-dependent measurable
| > quantity, much like momentum, kinetic energy, electric field, and a
| > host of other observer-dependent quantities.
|
| Those who didn't know your (lack of) quoting might
| mistakenly think you'd just made a correct and intelligible
| statement. But we your fans know this part is actually
| PD's.
It's clearly preceded by "PD wrote in message". What's your
difficulty with that, fuckhead?
Peri of Pera
Paul,
There is the real contraction of body A due to the absolute (real,
true) speed of the object. It is unknown. The amounts of contraction
as measured by observers on body B and C and any other observer are
incorrect because they are based on the individual motion of the
respective observer which has nothing to do with the real amount of
contraction. If the real contraction of a body is unknown or cannot be
identified, is it useful to substitute a fictitious one?
Peter Riedt
Peri of Pera
> On Feb 17, 1:55 am, Peri of Pera <rie...@yahoo.co.uk> wrote:
>
> > SR cannot determine Contraction
>
> > Lorentz proposed contraction of moving objects in a paper 'The
> > relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
> > 1, 74 in 1892 and then published the Lorentz transformation formulas
> > in 1899 according to which objects moving through space contract
> > parallel to the direction of motion and in proportion to their speed
> > [L'=L/sqrt(1-v^2/c^2)].
>
> Is it not L *times* sqrt(...) ?
yes, L'=L*sqrt(1-v^2/c^2)
> >Einstein accepted the formulas but writes in
> > 1916 (Relativity: The Special and General Theory, Chapter 16): "The
> > contraction of moving bodies follows from the two fundamental
> > principles of the theory".
>
> > The real value of v in the formula is indeterminate i.e. the real
> > speed of a body is unknown.
>
> Correct. The "v" in Lorentz work represents the "true" speed, the
> speed relative to the ether (frame). As was well known since 1900,
> this speed had (and has) no way to be determined and standard optical
> and kinematical setups will not be able to detect it.
>
> >However, the speed relative to other
> > bodies may be known.
>
> Do you mean "true" speed or *measured* speed? The true speed can not
> be determined. The measured speed ( the now usual procedure-defined
> speed) can be found (measured).
The only speed that can be established of any body is relative to a
reference point. You are correct that any absolute, real, true speed
cannot be measured as an absolute reference point does not exist.
> >If body A moves relative to body B with a speed
> > of 200000km/sec,
>
> You mean *measured* speed... ?
>
> >body A is seen by observers
>
> Not "seen" but *measured* ?
> >on B to contract by L/sqrt(1-200000km/sec^2/c^2) and
>
> Dont you mean L TIMES sqrt(...) ?
>
> >if body A moves at the same time
> > relative to body C with a speed of 100000km/sec it is seen
>
> You mean *measured* ?
>
> > by observers on C to contract by L/sqrt(1-100000km/sec^2/c^2).
>
> Dont you mean L TIMES sqrt(...) ?
>
> > Conclusion: SR is useless. It does not tell us anything about the
> > state and condition of A, B or C but gives in every instance an
> > incorrect amount of the contraction of body A.
> > Peter Riedt
>
> Its calculations (predictions) correctly predict experiments; is that
> not useful?
If the real contraction of a body cannot be identified, is it useful
Peri of Pera
Roger Penrose and James Terrell did some experiments in the 50's in
respect of contraction visibility.
Peter Riedt
>
>
>
> > In a previous posting, I wrote:
> > "A clock isn't affected in any way by an arbitrary
> > observer's motion relative to the clock.
> > But the clock's motion relative to the observer
> > will affect the observer's _observations_ of the clock."
>
> > A more general statement would be:
> > An object isn't affected in any way by an arbitrary
> > observer's motion relative to the object.
> > But the object's motion relative to the observer
> > will affect the observer's _observations_ of the object.
>
> > --
> > Paul
>
> >http://home.c2i.net/pb_andersen/-Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
Peri of Pera
Tom,
The symbols in the formula L'=L*sqrt(1-v^2/c^2) have the same meaning
for everybody, including Lorentz and AE: L' = length after
contraction, L = length before contraction, v = speed of object, c =
speed of light.
The velocity is not the issue. The issue is the contraction of body A.
Any amount of contraction derived from the relative speed between A
and an observer on any other body is fictitious and therefore useless.
Peter Riedt
rot...@gmail.com
previous reply and answer what I pose back to you.
> If the real contraction of a body cannot be identified, is it useful
> to substitute a fictitious one?
> Peter Riedt- Hide quoted text -
Yes, for the "fictitious" one is the one we can measure and "observe".
So, throw out the "real" length and define "real" length as the one we
measure. With that definition, we can accurately predict experiments.
i.e, we can predict what can be measured. That does not mean that the
previous notion of length (real length) can not be use to predict
accurately experiments. In fact, as is well known, you can use Lorentz
theory to predict experiments too...It is just that many prefer SR
over LET and that is their choice.
Paul B. Andersen
Paul B. Andersen
kenseto
"wugi" <br...@scarlet.be> wrote in message
news:47b9d5a7$0$831$5f6a...@news.scarlet.nl...
> "kenseto" :
>
> >BTW, IRT agrees that there is no physical length contraction of a
>
> SR does mean a physical Lorentz length contraction.
No it doesn't....if there is Lorentz contraction then there must be Lorentz
expansion!!!!! So where is the SR equation that shows Lorentz expansion???
Besides if Lorentz contraction is real then why is the observer's rod is the
longest rod in the universe?? Does that mean that the observer is at rest in
a preferred frame? OTOH, if the SR contraction is a geometric projection
effect there is no problem with the above problems. In addition every SR
observer can claim that his rod is longer than any projection of a moving
rod......much like I see you to be shorter from a distance and you see me to
be shorter from a distance.
Ken Seto
kenseto
"Peri of Pera" <rie...@yahoo.co.uk> wrote in message
news:bde0e4bc-e507-418e...@s8g2000prg.googlegroups.com...
What was the results of their experiments????
Ken Seto
PD
Peter, you apparently don't know what an experiment is.
Tom Roberts
> On Feb 18, 2:05 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
>> Peri of Pera wrote:
>>> Einstein accepted the formulas [...]
>> No! Einstein RE-DERIVED a similar formula using a completely different
>> conceptual basis. The symbols in the equations have DIFFERENT MEANINGS.
>
> for everybody, including Lorentz and AE: L' = length after
> contraction, L = length before contraction, v = speed of object, c =
> speed of light.
This is simply not true -- the ACTUAL meanings of several symbols are
different. For Lorentz, v was the speed of the object relative to the
(absolute) rest frame of the ether; for SR, v is the speed of the object
relative to the inertial frame OF THE OBSERVER.
*** This is part of a complete change of viewpoint, corresponding
*** to a new understanding and a major revolution in science,
*** instigated by Einstein.
Saying "length before/after contraction" is also wrong (there is no
temporal or logical sequence here). Lorentz would say: L = absolute
length of the object, L' = local coordinate length of the object. In SR
one would say: L = proper length, L' = length measured in the observer's
frame.
> The velocity is not the issue. The issue is the contraction of body A.
> Any amount of contraction derived from the relative speed between A
> and an observer on any other body is fictitious and therefore useless.
It is neither fictitious nor useless. It is MEASURABLE. And it has
physical consequences (e.g. the difference in angular distributions
between fixed-target and colliding-beam experiments with elementary
particles).
I suggest that you STUDY and LEARN the actual theories of Lorentz and SR
before attempting to make claims about what they say. Your
misunderstandings completely hide the actual theories from you.
Tom Roberts
Randy Poe
> "Randy Poe" <poespam-t...@yahoo.com> wrote in message
Both paragraphs were.
And in your reply, the heading
> | On Feb 18, 3:42 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
clearly precedes.... nothing that you wrote on Feb 18 at
3:42 pm.
> What's your
> difficulty with that, fuckhead?
That you don't distinguish between what you write
and what anybody else writes with any clues of
punctuation or indentation. This is neither standard
for Usenet nor for writing in English in general.
So which of PD's statements did you disagree with
when you called him a liar? Are KE and momentum
observer dependent?
- Randy
Androcles
| On Feb 18, 5:27 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
| > "Randy Poe" <poespam-t...@yahoo.com> wrote in message
| >
| >
news:2f4a80a1-21d2-44fe...@s37g2000prg.googlegroups.com...
| > | On Feb 18, 3:42 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
| > | > "PD" <TheDraperFam...@gmail.com> wrote in message
| > | >
| > | > That's right. The amount of contraction is not absolute and is not
| > | > inherent to the object. It is an observer-dependent measurable
| > | > quantity, much like momentum, kinetic energy, electric field, and a
| > | > host of other observer-dependent quantities.
| > |
| > | Those who didn't know your (lack of) quoting might
| > | mistakenly think you'd just made a correct and intelligible
| > | statement. But we your fans know this part is actually
| > | PD's.
| >
| > It's clearly preceded by "PD wrote in message".
|
| Both paragraphs were.
Randy Poe
> "Randy Poe" <poespam-t...@yahoo.com> wrote in message
>
> news:2512815f-61c3-4ab7...@s13g2000prd.googlegroups.com...
> | On Feb 18, 5:27 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
> | > "Randy Poe" <poespam-t...@yahoo.com> wrote in message
> | >
> | >news:2f4a80a1-21d2-44fe...@s37g2000prg.googlegroups.com...
> | > | On Feb 18, 3:42 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
> | > | > "PD" <TheDraperFam...@gmail.com> wrote in message
> | > | >
> | > | > That's right. The amount of contraction is not absolute and is not
> | > | > inherent to the object. It is an observer-dependent measurable
> | > | > quantity, much like momentum, kinetic energy, electric field, and a
> | > | > host of other observer-dependent quantities.
> | > |
> | > | Those who didn't know your (lack of) quoting might
> | > | mistakenly think you'd just made a correct and intelligible
> | > | statement. But we your fans know this part is actually
> | > | PD's.
> | >
> | > It's clearly preceded by "PD wrote in message".
> |
> | Both paragraphs were.
> | What "both paragraphs", snipper?
Funnier and funnier. OK, here you go, snipper.
Your original post had two paragraphs:
Paragraph 1.
That's right. The amount of contraction is not absolute and is not
inherent to the object. It is an observer-dependent measurable
quantity, much like momentum, kinetic energy, electric field, and a
host of other observer-dependent quantities.
Paragraph 2.
Lying shit.
You snipped the second one in this interchange.
Then started your usual rant about snipping, despite
the fact that I didn't snip a word, but *you* did. You
really are getting more incoherent, aren't you?
- Randy
kenseto
"Paul B. Andersen" <paul.b....@hiadeletethis.no> wrote in message
news:47BAE5C...@hiadeletethis.no...
But observations for a moving clock shows that it is in fact really running
slow.....it accumulates less elapsed time. So your claim that relative
motion isn't affecting the rate of a clock is bogus.
Ken Seto
kenseto
> Peri of Pera wrote:
> > On Feb 18, 2:05 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
> >> Peri of Pera wrote:
> >>> Einstein accepted the formulas [...]
> >> No! Einstein RE-DERIVED a similar formula using a completely different
> >> conceptual basis. The symbols in the equations have DIFFERENT MEANINGS.
> >
> > The symbols in the formula L'=L*sqrt(1-v^2/c^2) have the same meaning
> > for everybody, including Lorentz and AE: L' = length after
> > contraction, L = length before contraction, v = speed of object, c =
> > speed of light.
>
> This is simply not true -- the ACTUAL meanings of several symbols are
> different. For Lorentz, v was the speed of the object relative to the
> (absolute) rest frame of the ether; for SR, v is the speed of the object
> relative to the inertial frame OF THE OBSERVER.
>
> *** This is part of a complete change of viewpoint, corresponding
> *** to a new understanding and a major revolution in science,
> *** instigated by Einstein.
>
> Saying "length before/after contraction" is also wrong (there is no
> temporal or logical sequence here). Lorentz would say: L = absolute
> length of the object, L' = local coordinate length of the object. In SR
> one would say: L = proper length, L' = length measured in the observer's
> frame.
But L' is never measured.
PD
> "Tom Roberts" <tjroberts...@sbcglobal.net> wrote in message
>
> news:HsCuj.1195$pl4...@newssvr22.news.prodigy.net...
>
>
>
>
>
> > Peri of Pera wrote:
> > > On Feb 18, 2:05 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
> > >> Peri of Pera wrote:
> > >>> Einstein accepted the formulas [...]
> > >> No! Einstein RE-DERIVED a similar formula using a completely different
> > >> conceptual basis. The symbols in the equations have DIFFERENT MEANINGS.
>
> > > The symbols in the formula L'=L*sqrt(1-v^2/c^2) have the same meaning
> > > for everybody, including Lorentz and AE: L' = length after
> > > contraction, L = length before contraction, v = speed of object, c =
> > > speed of light.
>
> > This is simply not true -- the ACTUAL meanings of several symbols are
> > different. For Lorentz, v was the speed of the object relative to the
> > (absolute) rest frame of the ether; for SR, v is the speed of the object
> > relative to the inertial frame OF THE OBSERVER.
>
> > *** This is part of a complete change of viewpoint, corresponding
> > *** to a new understanding and a major revolution in science,
> > *** instigated by Einstein.
>
> > Saying "length before/after contraction" is also wrong (there is no
> > temporal or logical sequence here). Lorentz would say: L = absolute
> > length of the object, L' = local coordinate length of the object. In SR
> > one would say: L = proper length, L' = length measured in the observer's
> > frame.
>
> But L' is never measured.
Yes, it is. You apparently don't know how experimental confirmation of
theoretical predictions is part and parcel of doing science.
Androcles
| On Feb 19, 11:24 am, "Androcles" <Headmas...@Hogwarts.physics> wrote:
| > "Randy Poe" <poespam-t...@yahoo.com> wrote in message
| >
| >
news:2512815f-61c3-4ab7...@s13g2000prd.googlegroups.com...
| > | On Feb 18, 5:27 pm, "Androcles" <Headmas...@Hogwarts.physics> wrote:
| > | > "Randy Poe" <poespam-t...@yahoo.com> wrote in message
| > | >
| > |
>news:2f4a80a1-21d2-44fe...@s37g2000prg.googlegroups.com...
| > | > | On Feb 18, 3:42 pm, "Androcles" <Headmas...@Hogwarts.physics>
wrote:
| > | > | > "PD" <TheDraperFam...@gmail.com> wrote in message
| > | > | >
| > | > | > That's right. The amount of contraction is not absolute and is
not
| > | > | > inherent to the object. It is an observer-dependent measurable
| > | > | > quantity, much like momentum, kinetic energy, electric field,
and a
| > | > | > host of other observer-dependent quantities.
| > | > |
| > | > | Those who didn't know your (lack of) quoting might
| > | > | mistakenly think you'd just made a correct and intelligible
| > | > | statement. But we your fans know this part is actually
| > | > | PD's.
| > | >
| > | > It's clearly preceded by "PD wrote in message".
| > |
| > | Both paragraphs were.
| > | What "both paragraphs", snipper?
|
snip because you are beaten and cannot answer.
[snip here]
Produce the evidence that established the false statement:
'the "time" required by light to travel from A to B equals the "time" it
requires to travel from B to A' -- Rabbi Albert Einstein
It's the scientific method, you see.
Of course, being a fool and a liar (and a fuckheaded troll), you cannot.
Funnier and funnier.
Peri of Pera
Tom,
Thanks for the explanation of the symbols in the Lorentz formula. Body
A is a rod in space with a proper length of 100m. An observer on body
B measures the length of the rod in his frame of reference. The
objective of the measurement is to determine the amount of contraction
of body A. Corresponding to the speed of B, an infinite number of
different contracted lengths in the range 0m to 100m can be measured.
Which of the infinite number of measurable lengths is the correct one?
Which are not fictitious and useless in terms of identifying the
contraction of A? In my mind, the only correct one can be obtained
when B has the same speed as A and then the length is measured to be
100m.
Peter Riedt
Peri of Pera
the result was negative.
Peter Riedt
>
>
>
> > > > In a previous posting, I wrote:
> > > > "A clock isn't affected in any way by an arbitrary
> > > > observer's motion relative to the clock.
> > > > But the clock's motion relative to the observer
> > > > will affect the observer's _observations_ of the clock."
>
> > > > A more general statement would be:
> > > > An object isn't affected in any way by an arbitrary
> > > > observer's motion relative to the object.
> > > > But the object's motion relative to the observer
> > > > will affect the observer's _observations_ of the object.
>
> > > > --
> > > > Paul
>
Peri of Pera
Rotchm,
I did send you an answer. In response to this post I would like to say
that I am talking about the correct measurement of the contraction of
a body not about 'real length'. I cannot see how a fictitious
contraction amount can be of any use in any experiment. Believable
experiments must be based on factual data.
Peter Riedt
Eric Gisse
If you don't know what the symbols mean, WHAT THE FUCK ARE YOU ARGUING
ABOUT?
[snip remaining]
kenseto
No it is not. Tom admitted that the physical length of a moving rod never
been measured. The experiments you pointed out as proof of measuring the
contracted length is bogus......the physical length between the particles
was not known or measurable.
PD
Good plan. When you follow up to something you've made up out of thin
air, might as well make up the follow-up comment, too.
PD
PD
> "PD" <TheDraperFam...@gmail.com> wrote in message
Sure it was. It might help to read the papers.
PD
PD
Length is an observer-dependent quantity. There is no "correct one".
Different observers will measure you to have different momenta, all at
the same time. Which one is the correct one?
I don't know where you got the impression that physics only deals in
quantities where there is a single, absolute, "correct" value.
> Which are not fictitious and useless in terms of identifying the
> contraction of A? In my mind, the only correct one can be obtained
> when B has the same speed as A and then the length is measured to be
> 100m.
> Peter Riedt- Hide quoted text -
>
kenseto
It was not. It might help if you understood what they wrote.
PD
wugi
> "wugi" :
> >
> > >BTW, IRT agrees that there is no physical length contraction of a
> >
> > SR does mean a physical Lorentz length contraction.
>
> No it doesn't....if there is Lorentz contraction then there must be
Lorentz
> expansion!!!!! So where is the SR equation that shows Lorentz expansion???
Of course it is there.
Suppose an object OA' is moving past your "rest" object OA when both left
sides coincide in O :
OxxxxxxxxxxxxxA'xxxAxxxxxA"xxxxxxxxA"'
Length contraction tells you
OA' = OA / gamma
The moving system tells you that a later position A" (and not A') is
simultaneous with O, so that
OA = OA" / gamma, or
OA" = OA * gamma.
But he will also tell you that actually your event A to him coincides
spatially with an event A"' so that
OA" = OA"' / gamma, or
OA"' = OA * gamma
So, either contraction (in both systems) is paired with an expansion when
taking in account the other party's simultaneity.
Minkowsky makes it clear for you:
( http://home.scarlet.be/~pin12499/MySRT/LorentzObjects.Detail.png )
As you see, a matter of homothecy in triangles ;-)
> Besides if Lorentz contraction is real then why is the observer's rod is
the
> longest rod in the universe?? Does that mean that the observer is at rest
in
Each observer's rod is the longest to himself...
> a preferred frame? OTOH, if the SR contraction is a geometric projection
... because each observer experiences a different, relativistic,
simultaneity. No preferred frames involved.
> effect there is no problem with the above problems. In addition every SR
> observer can claim that his rod is longer than any projection of a moving
> rod......much like I see you to be shorter from a distance and you see me
to
> be shorter from a distance.
Right, homothecy in vanishing triangles ;-)
> > Regards,
> > guido
> > http://home.scarlet.be/~pin12499/paratwin.htm
Same.
wugi
Sorry, link:
> Minkowsky makes it clear for you:
> ( http://home.scarlet.be/~pin12499/MySRT/LorentzObjectsDetail.png )
> As you see, a matter of homothecy in triangles ;-)
> > > Regards,
> > > guido
> > > http://home.scarlet.be/~pin12499/paratwin.htm
> Same.
And again.
Peri of Pera
Tom,
Once again thanks for your explanation of the symbols in the Lorentz
contraction formula.
Lorentz: L' = local coordinate length of the object
SR: L' = length measured in the observer's frame
Lorentz: L = absolute length of the object
SR: L = proper length
Lorentz: v = the speed of the object relative to the (absolute) rest
frame of the ether
SR: v = the speed of the object relative to the inertial frame of the
observer
Lorentz, AE: c = speed of light = 300000km/sec
Inserting the values in one of my examples into the formula
L'=L*sqrt(1-v^2/c^2) the result becomes 74.53m=100m*sqrt(1-200000km/
sec^2/300000km/sec^2). The answer does not change because the symbols
are called different names by Lorentz, AE or me.
The measurements of the coordinate points of a moving object by an
observer and applying the Lorentz contraction formula does not
constitute a valid measurement. It is only a perception of the
observer, depending on his speed, just as the perspective of a
building depends on the visual angle to the building. The actual
dimensions of the moving object or the building remain the same.
Whatever an observer can measure as the contraction of an observed
body is a fictitious result. It cannot be used in credible
experiments.
Peter Riedt
Tom Roberts
> [... rephrasing of various aspects of my earlier statements]
Yes.
> The measurements of the coordinate points of a moving object by an
> observer and applying the Lorentz contraction formula does not
> constitute a valid measurement.
Hmmm. Making a measurement of the length of a moving object in the usual
way DOES constitute a valid measurement, and one obtains the "contracted
value". The "usual way" means having pre-positioned assistants mark the
endpoints of the moving object simultaneously in the observer's frame,
and then measuring the distance between the marks using rulers at rest
in the observer's frame.
> It is only a perception of the
> observer, depending on his speed,
No! It depends on the RELATIVE speed of the object RELATIVE to the
observer's frame. You must get out of your head all notions of "absolute
velocity", for there is no such thing. There is no "his speed", there is
only the speed of the object RELATIVE to the observer's frame.
It is not really "speed relative to the observer", because
specifying speed requires a system of coordinates (frame),
not just an observer.
> just as the perspective of a
> building depends on the visual angle to the building. The actual
> dimensions of the moving object or the building remain the same.
You MUST be more precise. In particular, dimensions MEASURED BY WHOM?
"actual dimensions" depend on WHO is doing the measurements. Of course
this does not affect the object itself in any way. But dimensions are
not attributes of the object, they are a RELATIONSHIP between the
coordinate system used for measurement and the object.
> Whatever an observer can measure as the contraction of an observed
> body is a fictitious result.
Not really. It is a MEASURABLE result, and that is not "fictitious".
Note that fictitious forces, such as "centrifugal and
Coriolis forces" cannot be measured. One can measure an
acceleration ascribed to them, but not the force itself
(there is nowhere to put the other end of a spring scale,
for instance). Lorentz contraction can be measured, and
is not "fictitious" in that sense.
> It cannot be used in credible
> experiments.
Sure it can! If you look at a building from the front it is wide, and
shooting laser beams to graze its two sides will subtend a certain
angle; moving to a corner and doing the same, the laser beams will
subtend a smaller angle. This is a "credible" experiment, and the
results depend on the point of view. Similarly, measurements of the
length of a moving object depend on the speed of the object relative to
the frame in which the measurement is made.
Tom Roberts
Pentcho Valev
sci.physics.relativity:
> Peri of Pera wrote:
> > [... rephrasing of various aspects of my earlier statements]
>
> Yes.
>
> > The measurements of the coordinate points of a moving object by an
> > observer and applying the Lorentz contraction formula does not
> > constitute a valid measurement.
>
> Hmmm. Making a measurement of the length of a moving object in the usual
> way DOES constitute a valid measurement, and one obtains the "contracted
> value". The "usual way" means having pre-positioned assistants mark the
> endpoints of the moving object simultaneously in the observer's frame,
> and then measuring the distance between the marks using rulers at rest
> in the observer's frame.
Roberts Roberts you are still a freshman among hypnotists in Einstein
criminal cult and do not have the courage to give breathtaking
examples when explaining length contraction. Superior brothers replace
"marking the endpoints of the moving object simultaneously in the
observer's frame" with "closing both doors simultaneously" and so they
can trap a long train inside a short tunnel:
http://www.youtube.com/watch?v=VSRIyDfo_mY&mode=related&search=
and also a 80m long pole inside a 40m long barn:
http://www.math.ucr.edu/home/baez/physics/Relativity/SR/barn_pole.html
"These are the props. You own a barn, 40m long, with automatic doors
at either end, that can be opened and closed simultaneously by a
switch. You also have a pole, 80m long, which of course won't fit in
the barn....So, as the pole passes through the barn, there is an
instant when it is completely within the barn. At that instant, you
close both doors simultaneously, with your switch. Of course, you open
them again pretty quickly, but at least momentarily you had the
contracted pole shut up in your barn."
So Roberts Roberts, by trapping long things inside short things,
superior brothers are able to demonstrate the real grandeur of
Einstein's discoveries.
Pentcho Valev
pva...@yahoo.com
Yanick Toutain
Pentcho, avez vous lu ma page sur l'équation qui prend la place de la
transformation de Lorentz avec un temps absolu, des vitesses absolues
et un délai de signal ?
http://site.voila.fr/monsyte/de/SCIENCES/scphys/COURS/objectif/Cours_de_science_objective_Les_equations.htm
Could you translate for English readers ?
Please
YT
R. Josh iii
Les crétins entre eux, cuvent leur haine de la science et de la
civilisation...
RJ
dedanoe
north to south pole contraction can only be result of higly forceful
pro-pro or anti-anti spinning of the equator. north to south pole
elongation can only be result of higly forceful pro-anti or anti-pro
spinning parallel with and on (+/-)height from the equator. plane and
simple, no sr needed!
Igor
Maybe you need to stop worrying about those things that change under
the LT and start thinking about the invariants. That's where the real
physics actually lies. Too bad you don't understand it.
Artful
news:4d7a4156-1486-45a7...@e10g2000prf.googlegroups.com...
> SR cannot determine Contraction
>
> Lorentz proposed contraction of moving objects in a paper 'The
> relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
> 1, 74 in 1892 and then published the Lorentz transformation formulas
> in 1899 according to which objects moving through space contract
> parallel to the direction of motion and in proportion to their speed
> [L'=L/sqrt(1-v^2/c^2)]. Einstein accepted the formulas but writes in
> 1916 (Relativity: The Special and General Theory, Chapter 16): "The
> contraction of moving bodies follows from the two fundamental
> principles of the theory".
>
> The real value of v in the formula is indeterminate
No .. it is not.
> i.e. the real speed of a body is unknown.
The real speed is what you measure it to be, relative to you. That is what
the 'v' is in the above
> However, the speed relative to other bodies may be known.
That is what the 'v' is .. its a relative speed. You seem confused about
the very basics here
Artful
news:47bae6a7$0$24118$4c36...@roadrunner.com...
> "wugi" <br...@scarlet.be> wrote in message
> news:47b9d5a7$0$831$5f6a...@news.scarlet.nl...
>> "kenseto" :
>> >BTW, IRT agrees that there is no physical length contraction of a
>> SR does mean a physical Lorentz length contraction.
> No it doesn't
It depends on what you mean by 'physical'. Is there a physical change to
the rod itself because a moving observer observes it .. then no. If you
mean does a moving rod take up less space than when not moving .. then yes.
> ....if there is Lorentz contraction then there must be Lorentz
> expansion!!!!!
Eh?
> So where is the SR equation that shows Lorentz expansion???
Why should there be?
> Besides if Lorentz contraction is real then why is the observer's rod is
> the
> longest rod in the universe??
If you are talking aobut LET instead of SR, then the contraction *is* real
.. but the results we measure are due to changes in our measuring tools that
give us the appearance that our rod is the longest (even if some other rod
is physically longer)
> Does that mean that the observer is at rest in
> a preferred frame?
In LET, yes .. there is a preferred frame, and everything htat moves
relative to the frame contracts.
> OTOH, if the SR contraction is a geometric projection
> effect there is no problem with the above problems.
Yeup.
> In addition every SR
> observer can claim that his rod is longer than any projection of a moving
> rod......much like I see you to be shorter from a distance and you see me
> to
> be shorter from a distance.
Yeup. And, of course, due to that projection, a moving rod really does tkae
up less physical space at any given time than a stationary rod.
Artful
news:d2bed7a3-ff4d-4b75...@q70g2000hsb.googlegroups.com...
>> In a previous posting, I wrote:
>> "A clock isn't affected in any way by an arbitrary
>> observer's motion relative to the clock.
>> But the clock's motion relative to the observer
>> will affect the observer's _observations_ of the clock."
>
> accumulates less clock seconds when it rejoins with the observer.
Why is that a problem ?
> So
> that means that the rate of a moving clock is affected by relative
> motion.
It means the amount of proper time that elapses for the clock is different
due to a different space-time path. And that one clock will see changes in
the ticking of the other clock.
Artful
> "Paul B. Andersen" <paul.b....@hiadeletethis.no> wrote in message
> news:47BAE5C...@hiadeletethis.no...
>> observer's motion relative to the object.
>> But the object's motion relative to the observer
>> will affect the observer's _observations_ of the object.
>
> But observations for a moving clock shows that it is in fact really
> running
> slow.....it accumulates less elapsed time. So your claim that relative
> motion isn't affecting the rate of a clock is bogus.
No .. it doesn't mean that at all .. it meas that there is less elapsed
time. Unless you are talking about the rate of ticking of the moving clock
as observed by the stationary observer .. in which case it is not
contradictory to what was claimed.
Dono
> Yeup. And, of course, due to that projection, a moving rod really does tkae
> up less physical space at any given time than a stationary rod.
No, it doesn't "take up less physical space". It is just a projective
effect THROUGHOUT.
Read references [9][10] here:
http://en.wikipedia.org/wiki/Length_contraction#A_trigonometric_effect.3F
Artful
news:c768bdb1-ea99-4360...@o77g2000hsf.googlegroups.com...
> On Feb 24, 5:33 am, "Artful" <art...@dodger.com> wrote:
>
>> Yeup. And, of course, due to that projection, a moving rod really does
>> tkae
>> up less physical space at any given time than a stationary rod.
>
>
> No, it doesn't "take up less physical space".
Yes .. it does
> It is just a projective
> effect THROUGHOUT.
> Read references [9][10] here:
>
> http://en.wikipedia.org/wiki/Length_contraction#A_trigonometric_effect.3F
Sorry .. but you are wrong there. See the rod and barn paradox for a nice
example. A contracted 'moving' rod takes up less physical space in a
'stationary' frame at a given time in that frame.
kenseto
"Artful" <art...@dodger.com> wrote in message
news:13s2sr1...@corp.supernews.com...
Hey idiot accumulating less elapsed time means that it is running at a
slower rate.
Ken Seto
Artful
I'm not an idiot. You seem to be confused about that as well.
> accumulating less elapsed time means that it is running at a
> slower rate.
No .. it means there is less time elapsed. That doesn't mean the clock is
running slower. If you have two roads (X and Y) between towns A and town B,
and road X is longer than road Y, then you would see a difference in
odometer readings for cars going on road X vs road Y. That does not mean
that the odometer in one car was measuring distance differently to the other
.. just that the distance being measured is different. Similarly, that two
clocks show different elapsed time does not mean that one had its rate of
ticking changed.. but simply that they measured different amounts of elapsed
time (proper time).
Of course, if you are observing a clock remotely, you will observe it as
ticking at a slower rate .. but then you are talking about coordinate time,
not proper time. And you are talking about the projection of that clock
into your frame of reference.
Dono
> "Dono" <sa...@comcast.net> wrote in message
>
> news:c768bdb1-ea99-4360...@o77g2000hsf.googlegroups.com...
>
> > On Feb 24, 5:33 am, "Artful" <art...@dodger.com> wrote:
>
> >> Yeup. And, of course, due to that projection, a moving rod really does
> >> tkae
> >> up less physical space at any given time than a stationary rod.
>
> > No, it doesn't "take up less physical space".
>
> Yes .. it does
>
> > It is just a projective
> > effect THROUGHOUT.
> > Read references [9][10] here:
>
>
> Sorry .. but you are wrong there. See the rod and barn paradox for a nice
> example. A contracted 'moving' rod takes up less physical space in a
> 'stationary' frame at a given time in that frame.
Jekyll,
I know the paradox, this simple exercise doesn't support your view.
BTW: there is no such thing as a 'stationary' frame in SR. Please try
reading the recommended reference.
The above should not be misconstrued in any form or fashion as my
agreeing with the Ken Shito crackpot.
Artful
> I know the paradox, this simple exercise doesn't support your view.
Yes .. it does. If the pole was not taking up less space in the barn's
frame of reference, it would not fit inside the barn.
> BTW: there is no such thing as a 'stationary' frame in SR.
Yes .. hence the '' around 'stationary' and 'moving' .. did you not see
that?
Your attempt at trying to score pedantic point is just an attempty to divert
from your fundamental error here.
> Please try reading the recommended reference.
I have .. have you? It appears not. if you had, you would not be arguing
with me.
> The above should not be misconstrued in any form or fashion as my
> agreeing with the Ken Shito crackpot.
Indeed. But you are wrong here. It happen as much as you hate to admit it
A 'moving' object DOES take up less 'space' in a 'stationary' frame of
reference at a given time in that frame (and, as you seem to have problems
with understanding what is meant by that .. the 'moving' and 'stationary'
are wrt the observer).
Dono
>
> A 'moving' object DOES take up less 'space' in a 'stationary' frame of
> reference at a given time in that frame (and, as you seem to have problems
> with understanding what is meant by that .. the 'moving' and 'stationary'
> are wrt the observer).
Try reading from the top. Pay attention to the txt:
http://en.wikipedia.org/wiki/Length_contraction#A_trigonometric_effect.3F
You also need to learn that hypotetical situations, like the "pole in
the barn" , do not constitute "proofs" .
Dono
>
> news:1a9d4300-fd43-45a6...@q33g2000hsh.googlegroups.com...
>
> > I know the paradox, this simple exercise doesn't support your view.
>
> Yes .. it does. If the pole was not taking up less space in the barn's
> frame of reference, it would not fit inside the barn.
No one has seen it "fitting" :-)
And no one will. Try to understand the difference between hypotetical
experiments and real ones. :-)
Artful
> On Feb 24, 4:03 pm, "Artful" <art...@dodger.com> wrote:
>
>>
>> A 'moving' object DOES take up less 'space' in a 'stationary' frame of
>> reference at a given time in that frame (and, as you seem to have
>> problems
>> with understanding what is meant by that .. the 'moving' and 'stationary'
>> are wrt the observer).
>
> Try reading from the top.
I have
You are still wrong.
SR says that an object takes up less physical space at any given moment in a
frame of reference in which the object is moving.
Artful
> On Feb 24, 4:03 pm, "Artful" <art...@dodger.com> wrote:
>> "Dono" <sa...@comcast.net> wrote in message
>>
>> news:1a9d4300-fd43-45a6...@q33g2000hsh.googlegroups.com...
>>
>> > I know the paradox, this simple exercise doesn't support your view.
>>
>> Yes .. it does. If the pole was not taking up less space in the barn's
>> frame of reference, it would not fit inside the barn.
>
>
> No one has seen it "fitting" :-)
> And no one will.
Why not .. it is a prediction of SR. It would be incredibly difficult to do
as described, of course :), but I have read that real experiments have been
conducted where length contraction has been observed. Length contraction
cannot be measured as occuring unless the length is actually contracted ..
ie an object (or a distance between objects) is taking up less physical
space in a given frame of reference and a given time in that frame.
> Try to understand the difference between hypotetical
> experiments and real ones. :-)
Try to understand the difference between your misunderstanding of SR and
what it actually says. Most of the time you get it right, but in the case
you've gotten it wrong.
SR most definitely predicts that a moving object (a rod, lets say) will take
up less physical distance (ie the distance from one end of the rod to the
other in the direction of motion) at a given instance in an inertial frame
of reference (in which it is moving).
Dono
Try engaging the brain. Well, I tried teaching you something
interesting, it obviously didn't work, why don't you try asking Tom
Roberts' opinion?
Dono
> "Dono" <sa...@comcast.net> wrote in message
>
> news:9b1a4567-8235-47bd...@u72g2000hsf.googlegroups.com...
>
> > On Feb 24, 4:03 pm, "Artful" <art...@dodger.com> wrote:
> >> "Dono" <sa...@comcast.net> wrote in message
>
> >>news:1a9d4300-fd43-45a6...@q33g2000hsh.googlegroups.com...
>
> >> > I know the paradox, this simple exercise doesn't support your view.
>
> >> Yes .. it does. If the pole was not taking up less space in the barn's
> >> frame of reference, it would not fit inside the barn.
>
> > No one has seen it "fitting" :-)
> > And no one will.
>
> Why not .. it is a prediction of SR. It would be incredibly difficult to do
> as described, of course :), but I have read that real experiments have been
> conducted where length contraction has been observed.
No, none to date.
> > Try to understand the difference between hypotetical
> > experiments and real ones. :-)
>
> Try to understand the difference between your misunderstanding of SR and
> what it actually says. Most of the time you get it right, but in the case
> you've gotten it wrong.
>
Umm, no.
Artful
> On Feb 24, 4:28 pm, "Artful" <art...@dodger.com> wrote:
>> "Dono" <sa...@comcast.net> wrote in message
>>
>> news:6d3472f6-4ac8-4049...@u10g2000prn.googlegroups.com...
>>
>> > On Feb 24, 4:03 pm, "Artful" <art...@dodger.com> wrote:
>>
>> >> A 'moving' object DOES take up less 'space' in a 'stationary' frame of
>> >> reference at a given time in that frame (and, as you seem to have
>> >> problems
>> >> with understanding what is meant by that .. the 'moving' and
>> >> 'stationary'
>> >> are wrt the observer).
>>
>> > Try reading from the top.
>>
>> I have
>>
>> You are still wrong.
>>
>> SR says that an object takes up less physical space at any given moment
>> in a
>> frame of reference in which the object is moving.
>
> Try engaging the brain.
I have .. try using yours.
> Well, I tried teaching you something interesting,
You can't teach someone something they already know .. I've read and
understood the geometric projection concept before, and it is in perfect
agreement with what I am saying.
> it obviously didn't work,
First, you need to have some knowledge greater than the one you think you
are teaching .. perhaps that is why you failed.
> why don't you try asking Tom Roberts' opinion?
I'm sure he'll give one if and when he feels fit. . I'm sure he will agree
with me completely. Its not really a matter of opinion .. its a matter of
fact.
Dono
>
> > why don't you try asking Tom Roberts' opinion?
>
> I'm sure he'll give one if and when he feels fit. . I'm sure he will agree
> with me completely. Its not really a matter of opinion .. its a matter of
> fact.
Ask Tom Roberts, ok?
Artful
> On Feb 24, 4:34 pm, "Artful" <art...@dodger.com> wrote:
>> "Dono" <sa...@comcast.net> wrote in message
>> news:9b1a4567-8235-47bd...@u72g2000hsf.googlegroups.com...
>>
>> > On Feb 24, 4:03 pm, "Artful" <art...@dodger.com> wrote:
>> >> "Dono" <sa...@comcast.net> wrote in message
>>
>> >>news:1a9d4300-fd43-45a6...@q33g2000hsh.googlegroups.com...
>>
>> >> > I know the paradox, this simple exercise doesn't support your view.
>> >> Yes .. it does. If the pole was not taking up less space in the
>> >> barn's
>> >> frame of reference, it would not fit inside the barn.
>> > No one has seen it "fitting" :-)
>> > And no one will.
>> Why not .. it is a prediction of SR. It would be incredibly difficult to
>> do
>> as described, of course :), but I have read that real experiments have
>> been
>> conducted where length contraction has been observed.
> No, none to date.
Not according to Tom (I think it was him). Note that these are not direct
go-out-with-a-tape-measure-and-measure-it experiments .. but ones in which
the effects of length contraction can be measured.
>> > Try to understand the difference between hypotetical
>> > experiments and real ones. :-)
>> Try to understand the difference between your misunderstanding of SR and
>> what it actually says. Most of the time you get it right, but in the
>> case
>> you've gotten it wrong.
> Umm, no.
Umm .. yes. You have indeed got it wrong, if you claim the contrary to what
I do. They contrary view to mine is that the moving object occupies the
*same* space (eg the same distance from start to end of a rod) in the
observer's frame of reference at a given time as it does when it is at rest,
and so there is no 'length contraction' (as it is commonly called). You
will be at odds with SR if you claim that .. do you support some theory
other than SR that does not involve length contraction? Note that SR does
not say there is a physical contraction of the rod itself (indeed, SR says
there really cannot be any change to the rod itself in its own frame of
reference) but just because the physical rod is unchanged in its own frame
does not mean that it can occupy less space when projected into the
observers frame of reference.
Perhaps you are simply not expressing your position clearly. I'm more than
happy if you want to clarify what it is *you* think is happening. It may
just be that you are talking about something different.
Peri of Pera
> Peri of Pera wrote:
> > [... rephrasing of various aspects of my earlier statements]
>
> Yes.
>
> > The measurements of the coordinate points of a moving object by an
> > observer and applying the Lorentz contraction formula does not
> > constitute a valid measurement.
>
> Hmmm. Making a measurement of the length of a moving object in the usual
> way DOES constitute a valid measurement, and one obtains the "contracted
> value". The "usual way" means having pre-positioned assistants mark the
> endpoints of the moving object simultaneously in the observer's frame,
> and then measuring the distance between the marks using rulers at rest
> in the observer's frame.
>
> > It is only a perception of the
> > observer, depending on his speed,
>
> No! It depends on the RELATIVE speed of the object RELATIVE to the
> observer's frame. You must get out of your head all notions of "absolute
> velocity", for there is no such thing. There is no "his speed", there is
> only the speed of the object RELATIVE to the observer's frame.
Tom, I am talking about the relative speed. Absolute speed cannot be
identified.
I agree there is the speed of the object relative to the observer's
frame. However, it is the same speed as the observer's speed to the
object. No difference between the two. Whichever speed is used as a
reference, it is the same as the other. No need to state the obvious.
Also, the use of co-ordinates is implied as part of the measuring
method. So once again, the absolute contraction of the observed object
cannot be measured, only the contraction measured by the observer and
as that depends on the relative speed between object and observer, it
is fictitious in the sense that it has no meaning.
Peter Riedt
Artful
You should ask him .. seeing you're the one who is wrong :)
But if you like, I'll post a thread asking Tom to reply .. although I doubt
that he necessarily would do so. You probably have more sway with Tom
(assuming he hasn't plonked you).
Dono
> other than SR that does not involve length contraction? Note that SR does
> not say there is a physical contraction of the rod itself (indeed, SR says
> there really cannot be any change to the rod itself in its own frame of
> reference) but just because the physical rod is unchanged in its own frame
> does not mean that it can occupy less space when projected into the
> observers frame of reference.
All correct and fine.
So, how will the rod occupy less space and fit inside the barn? With
Both doors of the barn closed simultaneously in the barn frame. Think
hard before you rush to answer.
Peri of Pera
> "Peri of Pera" <rie...@yahoo.co.uk> wrote in messagenews:4d7a4156-1486-45a7...@e10g2000prf.googlegroups.com...
Artful,
originally v was thought to be identifiable as the real speed of a
body but as it dawned on the SR fraternity it couldn't, they changed
the definition to what you now believe it is. This also destroyed any
claim that the measurement by an observer is useful data.
Peter Riedt
Artful
> Tom, I am talking about the relative speed.
> Absolute speed cannot be identified.
If there is such a thing. SR doesn't need one. Are you thinking of LET
instead?
> I agree there is the speed of the object relative to the observer's
> frame.
Yes
> However, it is the same speed as the observer's speed to the
> object. No difference between the two
Yes .. that's jus what you'd expect (of couse, the direction is opposite)
> Whichever speed is used as a reference,
> it is the same as the other.
Why is that a problem .. it is a 'good thing'
> No need to state the obvious.
Then what is your problem?
> Also, the use of co-ordinates is implied as part of the measuring
> method. So once again, the absolute contraction of the observed object
> cannot be measured,
What absolute contraction? SR does not have an absolute contraction. Are
you thinking of LET instead?
> only the contraction measured by the observer and
> as that depends on the relative speed between object and observer, it
> is fictitious in the sense that it has no meaning.
No .. it has very clear and very useful meaning. In fact, he realtiy that
physics deals with is all about what is measured by observers.
Artful
> On Feb 24, 5:12 pm, "Artful" <art...@dodger.com> wrote:
>
>> other than SR that does not involve length contraction? Note that SR
>> does
>> not say there is a physical contraction of the rod itself (indeed, SR
>> says
>> there really cannot be any change to the rod itself in its own frame of
>> reference) but just because the physical rod is unchanged in its own
>> frame
>> does not mean that it can occupy less space when projected into the
>> observers frame of reference.
>
> All correct and fine.
> So, how will the rod occupy less space and fit inside the barn?
What do you mean 'how'?
> With
> Both doors of the barn closed simultaneously in the barn frame.
Yes.. no rason why it can't .. that is what SR says will happen. If you say
it doesn't, then you are saying SR is wrong. Is that what you are saying?
> Think hard before you rush to answer.
There's not really anything to think about. How about you go and read up on
the pole and barn 'paradox', if you don't understand what SR says about it.
Peri of Pera
> "Peri of Pera" <rie...@yahoo.co.uk> wrote in messagenews:db84a1b1-038d-43e0...@i12g2000prf.googlegroups.com...
Artful,
to be able to measure the real contraction of an object by one and
only one speed would have been useful. To measure contraction using an
infinite number of possible relative speeds is not. In your attempt to
stubbornly defend SR, this fundamental point is lost on you.
Peter Riedt
Dono
>
> > Think hard before you rush to answer.
>
> There's not really anything to think about. How about you go and read up on
> the pole and barn 'paradox', if you don't understand what SR says about it.
I was afraid that this is what you'll blurt without much thinking. :-)
Dono
>
> But if you like, I'll post a thread asking Tom to reply .. although I doubt
> that he necessarily would do so. You probably have more sway with Tom
> (assuming he hasn't plonked you).
Post the thread, you'll be surprised about the new things you'll be
able to learn :-)
Artful
On Feb 24, 9:26 pm, "Artful" <art...@dodger.com> wrote:
> "Peri of Pera" <rie...@yahoo.co.uk> wrote in
> messagenews:4d7a4156-1486-45a7...@e10g2000prf.googlegroups.com...
>
> > SR cannot determine Contraction
>
> > Lorentz proposed contraction of moving objects in a paper 'The
> > relative motion of the earth and the ether', Versl.Kon.Akad.Wetensch.
> > 1, 74 in 1892 and then published the Lorentz transformation formulas
> > in 1899 according to which objects moving through space contract
> > parallel to the direction of motion and in proportion to their speed
> > [L'=L/sqrt(1-v^2/c^2)]. Einstein accepted the formulas but writes in
> > 1916 (Relativity: The Special and General Theory, Chapter 16): "The
> > contraction of moving bodies follows from the two fundamental
> > principles of the theory".
>
> > The real value of v in the formula is indeterminate
>
> No .. it is not.
>
> > i.e. the real speed of a body is unknown.
>
> The real speed is what you measure it to be, relative to you. That is what
> the 'v' is in the above
>
> > However, the speed relative to other bodies may be known.
>
> That is what the 'v' is .. its a relative speed. You seem confused about
> the very basics here
> Artful,
> originally v was thought to be identifiable as the real speed of a
> body
By whom?
> but as it dawned on the SR fraternity it couldn't,
The SR fraternity never thought that. I thini you are confusing your own
mmisconceptions about what you think SR says (or said) with reality. What
you mean to say is "v was thought be Peter to be identifiable as the real
speed of a body..."
> they changed the definition to what you now believe it is.
No .. they didn't change anything
> This also destroyed any
> claim that the measurement by an observer is useful data.
No .. it is the ONLY useful data.
N:dlzc D:aol T:com (dlzc)
"Artful" <art...@dodger.com> wrote in message
news:13s41e3...@corp.supernews.com...
> "Dono" <sa...@comcast.net> wrote in message
> news:1a9d4300-fd43-45a6...@q33g2000hsh.googlegroups.com...
>> I know the paradox, this simple exercise doesn't
>> support your view.
>
> Yes .. it does. If the pole was not taking up less
> space in the barn's frame of reference, it would
> not fit inside the barn.
There is no "barn's" frame of reference. In the rest frame of
the barn, an observer in the front of the barn and an observer in
the back of the barn will not agree that both doors were closed
"simultaneously". It is very important that you not imagine you
can have instantaneous signalling from the front to the back of
the barn.
The pole is "really" contracted, AND it is entirely a matter of
perspective.
David A. Smith
Artful
I always learn new things .. because (unlike you) I am happy to admit when I
am wrong. Perhaps you should take you own advice here, as you are clearly
wrong if you say a moving object takes up the same physical space (same
distance from one end to the other) in a given frame of reference at a given
time as a stationary one. You are effectively saying the Lorentz transforms
do not apply.
Artful
You are the one here who needs to put away your ego and have a look at what
SR says happens. Currently you are in denial of Lorentz transforms (either
that or you are very poor at expressing your point of view).
Artful
> Artful,
> to be able to measure the real contraction of an object
What "real contraction". And object does not change simply because an
observer moves past it. The contraction is a projection into a frame of
reference .. the amount of 'contraction' depends on who is measuring it.
There is no single 'real' contraction.
> by one and only one speed would have been useful.
There is no such thing as 'one and only one speed' .. speed is relative.
> To measure contraction using an
> infinite number of possible relative speeds is not.
You don't need ot measure from an infinite number of possible speeds .. you
measure it from whatever your frame of reference is . What other frames of
reference may see doesn't matter
> In your attempt to stubbornly defend SR, this fundamental point is lost on
> you.
I think it is lost well before it gets to me .. somewhere on your side of
the keyboard.
Artful
news:mrpwj.3400$kp6....@newsfe07.phx...
> Dear Artful:
>
> "Artful" <art...@dodger.com> wrote in message
> news:13s41e3...@corp.supernews.com...
>> "Dono" <sa...@comcast.net> wrote in message
>> news:1a9d4300-fd43-45a6...@q33g2000hsh.googlegroups.com...
>>> I know the paradox, this simple exercise doesn't
>>> support your view.
>>
>> Yes .. it does. If the pole was not taking up less
>> space in the barn's frame of reference, it would
>> not fit inside the barn.
>
> There is no "barn's" frame of reference. In the rest frame of the barn,
You just said there wasn't one.
> an observer in the front of the barn and an observer in the back of the
> barn will not agree that both doors were closed "simultaneously".
They certainly can. Simulaneity is well defined in SR
>It is very important that you not imagine you can have instantaneous
>signalling from the front to the back of the barn.
You don't need it. You can have a signal sent from the centre of the barn
to the two equidistant observers. Anyawy .. this is not about the physical
ability to construct a real and literal pole-in-the-barn experiment. It is
about the fact that, in SR, a moving object occupies less 'space' in a given
frame of reference at a given time than it does if it were at rest.
> The pole is "really" contracted,
Yes .. it is. In the pole-and-barn for a ceratin time, the pole is entirely
within the barn (whether or not you close the doors), even though the barn
has a shorter rest length than the pole.
> AND it is entirely a matter of perspective.
Yes, it is. Reality is what we measure.
PD
Uh, no. Several mistakes in that short paragraph.
> Peter Riedt- Hide quoted text -
>
> - Show quoted text -
PD
But it's not a fundamental point. You seem to think that a required
fundamental point is that a physical parameter has a single, absolute
value that you call "real". That is simply not the case. There are
many very real physical parameters that are also completely observer
dependent. The cast of real physical parameters is in fact divided
into two categories: those that are frame-dependent and those that are
frame independent. Neither is more real than the other.
PD
> "N:dlzc D:aol T:com (dlzc)" <dl...@cox.net> wrote in messagenews:mrpwj.3400$kp6....@newsfe07.phx...
I have to agree with Artful on a simple but important point.
Length is a purely spatial quantity by definition. The invariant
interval between two events that occur at the ends of the rod may
indeed be frame-independent, but it is in no way a length, because in
any other frame, it involves both space and time components. What is
true is that in a particular frame, the invariant interval and the
length happen to numerically coincide. This is the frame where the
time difference between the two rod-end events happens to vanish. This
coincidence in this frame in no way turns the interval into a length.
The length is an inherently 3D quantity. The interval is inherently a
4D quantity.
Another example can be taken from simple Euclidean 2-D geometry. Draw
two orthogonal axes and a vector from the origin, so that there is a
component of that vector along one of the axes. By choice of axes, you
can make it so the component numerically coincides with the vector,
but even in this case the component is NOT the vector. The vector is a
2D object, and the component is a 1D object by definition.
PD
Androcles
"PD" <TheDrap...@gmail.com> wrote in message
news:a8968a37-1203-4cad...@q78g2000hsh.googlegroups.com...
Yes it is a fundamental point.
Androcles
| Uh, no.
Uh, yes.
Androcles
| I have to agree
No you don't.
Dono
Hey, bozo
1. You admit that the Lorentz contraction is a projective effect, i.e.
it is not physical (see also here, for a more detailed description :
http://en.wikipedia.org/wiki/Length_contraction#A_trigonometric_effect.3F)
2. Therefore, in the IMAGINARY experiment of the pole in the barn
paradox, when a clown like you attempts to close both doors
simultaneously in the barn frames, it effectively brackets the pole.
This means that , in order to fit, the contraction needs to be
PHYSICAL (see here: http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/polebarn.html)
But, according to point 1, the Lorentz contraction is NOT PHYSICAL (it
is just a projective effect affecting the measurements of the object,
not the object itself). So, you have a contradiction. The
contradiction stems from point 2, the clownish interpretation of
length contraction.
Dono
> Yes .. it is. In the pole-and-barn for a ceratin time, the pole is entirely
> within the barn (whether or not you close the doors), even though the barn
> has a shorter rest length than the pole.
>
Umm, no. This is unphysical, as explained earlier.
Artful
> On Feb 24, 6:09 pm, "Artful" <art...@dodger.com> wrote:
>> "Dono" <sa...@comcast.net> wrote in message
>>
>> news:5e81ddd1-b0b8-4d5f...@s37g2000prg.googlegroups.com...
>>
>> > On Feb 24, 5:22 pm, "Artful" <art...@dodger.com> wrote:
>>
>> >> But if you like, I'll post a thread asking Tom to reply .. although I
>> >> doubt
>> >> that he necessarily would do so. You probably have more sway with Tom
>> >> (assuming he hasn't plonked you).
>>
>> > Post the thread, you'll be surprised about the new things you'll be
>> > able to learn :-)
>>
>> I always learn new things .. because (unlike you) I am happy to admit
>> when I
>> am wrong. Perhaps you should take you own advice here, as you are
>> clearly
>> wrong if you say a moving object takes up the same physical space (same
>> distance from one end to the other) in a given frame of reference at a
>> given
>> time as a stationary one. You are effectively saying the Lorentz
>> transforms
>> do not apply.
>
> Hey, bozo
Ah .. here we go with the name calling
> 1. You admit that the Lorentz contraction is a projective effect, i.e.
> it is not physical
What do you mean by 'physical'? Why do you think a projective effect is not
'physical' in the frame into which it is a projection.
> (see also here, for a more detailed description :
> http://en.wikipedia.org/wiki/Length_contraction#A_trigonometric_effect.3F)
Yes .. been there, done that .. it agrees with what I say.
> 2. Therefore, in the IMAGINARY experiment of the pole in the barn
> paradox, when a clown like you attempts to close both doors
> simultaneously in the barn frames, it effectively brackets the pole.
You sound a little upset .. guess you don't like it when you're wrong.
> This means that , in order to fit, the contraction needs to be
> PHYSICAL (see here:
> http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/polebarn.html)
It is physical.
> But, according to point 1, the Lorentz contraction is NOT PHYSICAL
No .. according to your interpreation it is not 'physical' .. it is your
interpreation that is wrong, possibly due to a misunderstanding.
> (it
> is just a projective effect affecting the measurements of the object,
> not the object itself). So, you have a contradiction.
No .. you have a contradiction, becuse you are confused about what is meant
by 'physical' and 'real' and 'projection'. When you have these sorted out
in your mind, your confusion and your apparent contradiction will disappear.
> The
> contradiction stems from point 2, the clownish interpretation of
> length contraction.
It is what SR predicts. So you must think SR is clownish. Do you have a
better theory that is not so clownish?
Artful
Umm, yes .. it is a physical effect that is being described in that thought
experiment .. its not some sort of optical illusion.
At a fast enough speed wrt the barn, a moving pole would physically fit
within the 'shorter' barn at a given instant.
Objects that undergo length contraction do really occupy less physical space
in the frame of reference where the are moving. The measured length .. ie
the spatial distance between one end point and the other of the moving rod,
at any given instant in that frame .. is shorter than the rest length of the
rod. It occupies less space in that frame. This is real and physical (in
the frame of the observer).
Many people have trouble coming to terms with what length contraction (and
time dilation and relativity of simultaneity) mean, you appear to be one of
those people. Most seem to think it is a physical effect on the rod itself,
making the rod squash up and shrink (ie within the rest frame of the rod,
and like in LET), whereas you are at the other extreme who don't think
anything really happens at all and that it is all some sort of illusion.
This is very sad, because you seem to have a reasonable grasp of other SR
related issue.
I'm sure you'll get it once you come down off your ego horse.
Artful
news:bb460ef8-1117-41cb...@71g2000hse.googlegroups.com...
>Length is a purely spatial quantity by definition. The invariant
>interval between two events that occur at the ends of the rod may
>indeed be frame-independent, but it is in no way a length, because in
>any other frame, it involves both space and time components. What is
>true is that in a particular frame, the invariant interval and the
>length happen to numerically coincide. This is the frame where the
>time difference between the two rod-end events happens to vanish. This
>coincidence in this frame in no way turns the interval into a length.
>The length is an inherently 3D quantity. The interval is inherently a
>4D quantity.
>
>Another example can be taken from simple Euclidean 2-D geometry. Draw
>two orthogonal axes and a vector from the origin, so that there is a
>component of that vector along one of the axes. By choice of axes, you
>can make it so the component numerically coincides with the vector,
>but even in this case the component is NOT the vector. The vector is a
>2D object, and the component is a 1D object by definition.
Nicely put. Now we've just got to convince dono that an object *does*
'physically' have a shorter spatial length (ie take up less physical space;
have a shorter spatial distance between its endpoint) at a given instant
within a frame of reference in which the object is moving, than in a frame
of reference in which it is at rest.
PD
> "PD" <TheDraperFam...@gmail.com> wrote in message
And it's not yours. I know you don't have a point any more, but still
it's rude to hijack others'.
PD
Dono
>
> Nicely put. Now we've just got to convince dono that an object *does*
> 'physically' have a shorter spatial length (ie take up less physical space;
I had a hunch that you will not get this. This is what happens when
you are more interested in being always right instead of getting it
right <shrug>
PD
Let's put it this way. Length is a result obtained through a
prescription, one that typically involves recording two spatial
locations simulataneously. Length is a physical property. However,
because simultaneity is frame-dependent, the physical property length
is also frame-dependent. There is, however, no physical process or
interaction occurring to or in the rod to change its length.
PD
Dono
Correct.
-This is why one can't close the doors simultaneously in the barn
frame without hitting the pole.
-This is why the pole in the barn, being a thought experiment, is a
very poor illustration for length contraction.
-This is why, to date, we have no experimental test for length
contraction (http://www.edu-observatory.org/physics-faq/Relativity/SR/
experiments.html#Length_Contraction)
Androcles
Yes it is.