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Dono
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 Posted: Sun Jul 13, 2008 5:41 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 12, 10:35 pm, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 13, 1:25 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
On Jul 13, 12:40 am, Uncle Ben <b...@greenba.com> wrote:
[...]
No, I have no problem with the answer. But I think the answer can be
explained much more simply than in the Wikipedia article or in the
sci.physics.relativity FAQ paper on the Bell paradox. I will post the
simple argument next weekend.
I was at MIT a year or so after the problem appeared in the Am. J. of
Physics. I was delighted with the short paper explaining the result,
because I had bet several of my colleagues a small amount that the
paper was correct and that I could persuade them of it with a simple
argument. Somehow none of them had the time to spend to settle the
question.
It happened that the editor of the AJP was on the faculty of the
physics department and later told us that the little paper had been
greatly delayed in publication because various reviewers were arguing
among themselves whether the result was correct. It took the
authority of respected specialists in relativity theory, special and
general, to beat down the sceptics!
I had had a pet peeve about physics textbook authors using language in
describing relativity thought experiments in terms like "appears to be
shortened" and "according to observer B" and the like. I preferred
language that says straight out that the length with respect to frame
A is shorter than the length with respect to frame B. Nothing about
"appearing" or involving observers and their human frailties. The key
word in my version is "IS", in place of "appears to be."
(All of this is about what the theory of special relativity says; not
about whether it is true or not. The theory says that moving clocks
run slow and moving meter sticks are shorter. It does not say anthing
about thoughts or illusions or mere appearances.)
The 1905 paper may be that way but from the 1920 publication:
"The *Apparent* Incompatibility of the Law of
Propagation of Light with the Principle of Relativity"
With time dependent Maxwell's equations the conflict
indeed seem to be only apparent.
or
As *judged* from K, the clock is moving with
the velocity v; as judged from this reference-body,
the time which elapses between two strokes of the
clock is not one second, but
http://www.bartleby.com/173/M5.GIF
seconds, i.e. a somewhat larger time. >>http://www.bartleby.com/173/12.html
I don't infer black robes and white wigs from
the term *judged* but a path subject to
the finite speed of light and a pair of
eyes seems the mimimum. Clocks don't
change with inertial motion unless we
include a changing path as part of their
mechanism.
That was a long time ago, but the question is far from settled in the
minds of many practicing physicsts of my acquaintance with endowed
chairs in famous universities, not to mention in the minds of physics
afficianados writing confidently in newsgroups. So I think it proper
to bring up the problem from time to time for the enlightenment of
subsequent generations.
Uncle Ben
Age 78
You might post back if you think the 1920 paper
better qualifies what is real, what is seen,
what is perceived and what is imaginary (sqrt -1)
compared to the paper of you criticism. (1905?)
Sue...- Hide quoted text -
- Show quoted text -
Sue, I'm not interested in what Einstein said at one time or another.
I care what the theory of relativity says. I claim that given the
postulates of the theory, the usual textbook proofs of time dilation
and length contraction show what the theory implies. The theory could
be wrong and not describe reality at all (although I believe it to be
true); I just want to be clear about what the theory says.
|
Sue is a crank, you can safely ignore IT. |
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PD
Guest
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| Posted: Sun Jul 13, 2008 5:47 am Post subject: Re: Are SR effects real or not? Simplified case. |
|
|
On Jul 12, 11:40 pm, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 12, 5:28 pm, Dono <sa...@comcast.net> wrote:
On Jul 12, 12:30 pm, Uncle Ben <b...@greenba.com> wrote:
On Jul 12, 1:42 pm, "Sue..." <suzysewns...@yahoo.com.au> wrote:
On Jul 12, 11:59 am, Uncle Ben <b...@greenba.com> wrote:
There is another thread in sci.physics.relativity entitled "Are
'observed' SR effects real?" I have trouble following the discussion,
as maybe you do too. I prefer to phrase the question in a way that to
me is much clearer.
The following thought experiment is an old problem, not original with
me, but I will not give any reference to it just yet. Just think
about it and draw your own conclusion. I'll post my explanation in
about a week.
*****************
Imagine two rocket ships at rest, one behind the other at a distance
x0, in intergalactic space. Let's tie a light string between the two
ships -- so light that it cannot affect the motion of the ships.
Let both ships be aimed at a distant galaxy that is on the line
connecting the ships. The ships synchronize watches and fire their
identical rocket engines at the same time.
Theorem: According to either classical mechanics or relativistic
mechanics, as the two ships accelerate, they keep a constant distance
between them with respect to (w.r.t.) their intial rest frames.
-------------------------------
Proof:
1) According to Newton, the position of a ship under constant
acceleration is given by x=t*t in some units. In an obvious notation,
the equations of motion are
x1 = t*t + x0,
x2 = t*t,
so
x1-x2 = x0.
2) According to Einstein, the position of a ship under constant proper
acceleration is given by x=cosh(t). The equations of motion will be
x1 = cosh(t) + x0,
x2 = cosh(t).
so
x1-x2 = x0.
QED
-------------------------------
But what about the string? When the ships are moving at almost the
speed of light, the string must have tried to contract a lot. But it
is constrained to stay at a fixed length x0. Sooner or later it will
reach its breaking point and will snap!
Do you believe this? Does the string break or not? Is the Lorentz-
Fitzgerad contraction real or not real?
The contraction is just as real as the light particles
which Einstein did not win a Nobel prize for.
~The famous Lorentz transformation ensures that the velocity
of [inertially moving] light [particles] is invariant
between different inertial frames~http://farside.ph.utexas.edu/teaching/em/lectures/node109.html
The Nobel Committee avoids committing itself to the
particle concept. Light-quanta or with modern terminology,
photons, were explicitly mentioned in the reports on
which the prize decision rested only in connection with
emission and absorption processes. The Committee says
that the most important application of Einstein's photoelectric
law and also its most convincing confirmation has come from
the use Bohr made of it in his theory of atoms, which explains
a vast amount of spectroscopic data. >>http://nobelprize.org/physics/articles/ekspong/index.html
where $\epsilon_0$ and $\mu_0$ are physical constants
which can be evaluated by performing two simple experiments
which involve measuring the force of attraction between
two fixed changes and two fixed parallel current carrying
wires. According to the relativity principle,
these experiments must yield the same values for
$\epsilon_0$ and $\mu_0$ in all inertial frames.
Thus, the speed of light must be the same in
all inertial frames. >>http://farside.ph.utexas.edu/teaching/em/lectures/node108.html
IOW the string neither breaks nor slacks.
See also:
4-velocity and 4-accelerationhttp://farside.ph.utexas.edu/teaching/em/lectures/node115.html
Sue...
Uncle Ben- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -
Dono: breaks
Sue: doesn't
Androcles: <snarl
1:1 so far. (And you thought the question was too old!)
This is not a sports contest. Science shows the answer quite clearly.
Do you have a problem with the answer?- Hide quoted text -
- Show quoted text -
No, I have no problem with the answer. But I think the answer can be
explained much more simply than in the Wikipedia article or in the
sci.physics.relativity FAQ paper on the Bell paradox. I will post the
simple argument next weekend.
I was at MIT a year or so after the problem appeared in the Am. J. of
Physics. I was delighted with the short paper explaining the result,
because I had bet several of my colleagues a small amount that the
paper was correct and that I could persuade them of it with a simple
argument. Somehow none of them had the time to spend to settle the
question.
It happened that the editor of the AJP was on the faculty of the
physics department and later told us that the little paper had been
greatly delayed in publication because various reviewers were arguing
among themselves whether the result was correct. It took the
authority of respected specialists in relativity theory, special and
general, to beat down the sceptics!
I had had a pet peeve about physics textbook authors using language in
describing relativity thought experiments in terms like "appears to be
shortened" and "according to observer B" and the like. I preferred
language that says straight out that the length with respect to frame
A is shorter than the length with respect to frame B. Nothing about
"appearing" or involving observers and their human frailties. The key
word in my version is "IS", in place of "appears to be."
|
I agree with this. Physics textbook authors spend elaborate efforts to
explain Newton's 3rd law properly, but they chronically do a crappy
job with the last few "teaser" chapters on what is clumped together as
"modern" physics. I think the rationalization is that they don't have
the space to give relativity and quantum mechanics and particle
physics the attention they would need, and that most teachers don't
get around to those chapters in the course anyway, and so they give
those topics the lightest lip service possible.
My other pet peeve is that hardly any author takes pains to point out
that what was taught in chapters 2-8 works fine as an approximate
model for a lot of cases that we see in our conventional (and highly
limited) domain, but which are KNOWN to be WRONG. I think it would
have more impact for the author to announce that what was taught in an
earlier chapter is a *lie*, though certainly a plausible one. The
first place I'd start would be that chapter 2 "definition" of relative
motion v = v1 - v2, which is a *lie* and *known* to be wrong.
| Quote: |
(All of this is about what the theory of special relativity says; not
about whether it is true or not. The theory says that moving clocks
run slow and moving meter sticks are shorter. It does not say anthing
about thoughts or illusions or mere appearances.)
That was a long time ago, but the question is far from settled in the
minds of many practicing physicsts of my acquaintance with endowed
chairs in famous universities, not to mention in the minds of physics
afficianados writing confidently in newsgroups. So I think it proper
to bring up the problem from time to time for the enlightenment of
subsequent generations.
Uncle Ben
Age 78 |
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Sue...
Guest
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| Posted: Sun Jul 13, 2008 6:04 am Post subject: Re: Are SR effects real or not? Simplified case. |
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|
On Jul 13, 1:35 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 13, 1:25 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
[...]
Sue, I'm not interested in what Einstein said at one time or another.
I care what the theory of relativity says. I claim that given the
postulates of the theory, the usual textbook proofs of time dilation
and length contraction show what the theory implies. The theory could
be wrong and not describe reality at all (although I believe it to be
true); I just want to be clear about what the theory says.
|
I use a modern version that the time travelers don't like.
Without inertial light bullets (photons) to be in conflict
with inertial frames, the SOL conflict vanishes in the near field
and eliminates the Lorentz transform over the path as a
resolver of non existant conflicts.
Uncle Ben:
<<I just want to be clear about what the theory says.>>
IMHO Richard Fitzpatrick has it right:
<<The key to understanding special relativity is
Einstein's relativity principle, which states that:
All inertial frames are totally equivalent for
the performance of all physical experiments.
In other words, it is impossible to perform a physical
experiment which differentiates in any fundamental sense
between different inertial frames. By definition,
Newton's laws of motion take the same form in all
inertial frames. Einstein generalized this result in
his special theory of relativity by asserting that all
laws of physics take the same form in all inertial frames.>>
http://farside.ph.utexas.edu/teaching/em/lectures/node108.html
No funny clocks or funny rulers required. :-)
Sue... |
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Uncle Ben
Guest
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| Posted: Sun Jul 13, 2008 3:45 pm Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 13, 2:04 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
| Quote: |
On Jul 13, 1:35 am, Uncle Ben <b...@greenba.com> wrote:
On Jul 13, 1:25 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
[...]
Sue, I'm not interested in what Einstein said at one time or another.
I care what the theory of relativity says. I claim that given the
postulates of the theory, the usual textbook proofs of time dilation
and length contraction show what the theory implies. The theory could
be wrong and not describe reality at all (although I believe it to be
true); I just want to be clear about what the theory says.
I use a modern version that the time travelers don't like.
Without inertial light bullets (photons) to be in conflict
with inertial frames, the SOL conflict vanishes in the near field
and eliminates the Lorentz transform over the path as a
resolver of non existant conflicts.
Uncle Ben:
I just want to be clear about what the theory says.
IMHO Richard Fitzpatrick has it right:
The key to understanding special relativity is
Einstein's relativity principle, which states that:
All inertial frames are totally equivalent for
the performance of all physical experiments.
In other words, it is impossible to perform a physical
experiment which differentiates in any fundamental sense
between different inertial frames. By definition,
Newton's laws of motion take the same form in all
inertial frames. Einstein generalized this result in
his special theory of relativity by asserting that all
laws of physics take the same form in all inertial frames.>>http://farside.ph.utexas.edu/teaching/em/lectures/node108.html
No funny clocks or funny rulers required. :-)
Sue...
|
Sue, I was with you up to your last sentence. For when you impose the
requirement of equivalence on electromagnetism, what frame do you use
to measure the vector v in F=v x B? It must be the Lorentz
transformation. And there you find the requirement of funny clocks and
funny rulers.
Uncle Ben |
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Sue...
Guest
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| Posted: Sun Jul 13, 2008 5:18 pm Post subject: Re: Are SR effects real or not? Simplified case. |
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|
On Jul 13, 11:45 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 13, 2:04 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
On Jul 13, 1:35 am, Uncle Ben <b...@greenba.com> wrote:
On Jul 13, 1:25 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
[...]
Sue, I'm not interested in what Einstein said at one time or another.
I care what the theory of relativity says. I claim that given the
postulates of the theory, the usual textbook proofs of time dilation
and length contraction show what the theory implies. The theory could
be wrong and not describe reality at all (although I believe it to be
true); I just want to be clear about what the theory says.
I use a modern version that the time travelers don't like.
Without inertial light bullets (photons) to be in conflict
with inertial frames, the SOL conflict vanishes in the near field
and eliminates the Lorentz transform over the path as a
resolver of non existant conflicts.
Uncle Ben:
I just want to be clear about what the theory says.
IMHO Richard Fitzpatrick has it right:
The key to understanding special relativity is
Einstein's relativity principle, which states that:
All inertial frames are totally equivalent for
the performance of all physical experiments.
In other words, it is impossible to perform a physical
experiment which differentiates in any fundamental sense
between different inertial frames. By definition,
Newton's laws of motion take the same form in all
inertial frames. Einstein generalized this result in
his special theory of relativity by asserting that all
laws of physics take the same form in all inertial frames.>>http://farside.ph.utexas.edu/teaching/em/lectures/node108.html
No funny clocks or funny rulers required. :-)
Sue...
Sue, I was with you up to your last sentence. For when you impose the
requirement of equivalence on electromagnetism, what frame do you use
to measure the vector v in F=v x B? It must be the Lorentz
transformation. And there you find the requirement of funny clocks and
funny rulers.
|
The Maxwell structures are in triple integral form
with a light delay added so that force is imaginary (reactive)
in the near field.
"Retarded potentials"
http://farside.ph.utexas.edu/teaching/em/lectures/node50.html
For relativistic dynamics, four-vectors are used.
"The force on a moving charge"
http://farside.ph.utexas.edu/teaching/em/lectures/node127.html
Those clocks are not *funny*. They carry the appropriate
rigour of a general Lorentz transformation.
Space-time
<< Note that space-time cannot be regarded as a
straightforward generalization of Euclidian
3-space to four dimensions, with time as the fourth
dimension. The distribution of signs in the metric
ensures that the time coordinate $x^4$ is not on
the same footing as the three space coordinates.
Thus, space-time has a non-isotropic nature which
is quite unlike Euclidian space, with its positive
definite metric. According to the relativity principle,
all physical laws are expressible as interrelationships
between 4-tensors in space-time. >>
http://farside.ph.utexas.edu/teaching/em/lectures/node113.html
Sue...
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Martin Hogbin
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| Posted: Sun Jul 13, 2008 5:50 pm Post subject: Re: Are SR effects real or not? Simplified case. |
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Uncle Ben wrote:
| Quote: |
On Jul 12, 5:28 pm, Dono <sa...@comcast.net> wrote:
On Jul 12, 12:30 pm, Uncle Ben <b...@greenba.com> wrote:
No, I have no problem with the answer. But I think the answer can be
explained much more simply than in the Wikipedia article or in the
sci.physics.relativity FAQ paper on the Bell paradox. I will post the
simple argument next weekend.
|
<snip>
| Quote: |
So I think it proper
to bring up the problem from time to time for the enlightenment of
subsequent generations.
|
I look forward to seing your answer.
Martin Hogbin |
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Uncle Ben
Guest
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| Posted: Mon Jul 14, 2008 4:16 am Post subject: Re: Are SR effects real or not? Simplified case. |
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Sue, we need to crawl before we can walk. Before we get into four-
vectors and retarded potentials, let's get clear about the force on a
moving charge. Are you familiar with the vector relation represented
by
F = qE + q(v x B)
v is a velocity. Velocity with respect to what? the laboratory? the
earth? the sun?
Uncle Ben |
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Sue...
Guest
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| Posted: Mon Jul 14, 2008 5:35 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 14, 12:16 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
Sue, we need to crawl before we can walk.
|
OK, that would be the first moving charge
| Quote: |
Before we get into four-
vectors and retarded potentials, let's get clear about the force on a
moving charge. Are you familiar with the vector relation represented
by
F = qE + q(v x B)
v is a velocity. Velocity with respect to what? the laboratory? the
earth? the sun?
|
Elegant equation but let's not move that fast.
There are some volumes of 3 space we should
examine first.
I beleive the first charge ~illuminates~ space this way
http://en.wikipedia.org/wiki/Multiple_integral
Isn't that a fair way to represent the
superposition of moving charge?
Sue...
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Sue...
Guest
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| Posted: Mon Jul 14, 2008 5:44 am Post subject: Re: Are SR effects real or not? Simplified case. |
|
|
On Jul 14, 12:16 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
Sue, we need to crawl before we can walk.
|
OK, that would be the first moving charge
| Quote: |
Before we get into four-
vectors and retarded potentials, let's get clear about the force on a
moving charge. Are you familiar with the vector relation represented
by
F = qE + q(v x B)
v is a velocity. Velocity with respect to what? the laboratory? the
earth? the sun?
|
Elegant equation but let's not move that fast.
There are some volumes of 3 space we should
examine first.
I beleive the first charge ~illuminates~ space this way
http://en.wikipedia.org/wiki/Multiple_integral#Some_practical_applications
Isn't that a fair way to represent the
superposition of moving charge?
Sue... |
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Uncle Ben
Guest
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| Posted: Mon Jul 14, 2008 6:51 am Post subject: Re: Are SR effects real or not? Simplified case. |
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|
On Jul 14, 1:44 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
| Quote: |
On Jul 14, 12:16 am, Uncle Ben <b...@greenba.com> wrote:
Sue, we need to crawl before we can walk.
OK, that would be the first moving charge
Before we get into four-
vectors and retarded potentials, let's get clear about the force on a
moving charge. Are you familiar with the vector relation represented
by
F = qE + q(v x B)
v is a velocity. Velocity with respect to what? the laboratory? the
earth? the sun?
Elegant equation but let's not move that fast.
There are some volumes of 3 space we should
examine first.
I beleive the first charge ~illuminates~ space this way
http://en.wikipedia.org/wiki/Multiple_integral#Some_practical_applica...
Isn't that a fair way to represent the
superposition of moving charge?
Sue...
|
Sue, you may be right. |
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Sue...
Guest
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| Posted: Mon Jul 14, 2008 7:09 am Post subject: Re: Are SR effects real or not? Simplified case. |
|
|
On Jul 14, 2:51 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 14, 1:44 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
On Jul 14, 12:16 am, Uncle Ben <b...@greenba.com> wrote:
Sue, we need to crawl before we can walk.
OK, that would be the first moving charge
Before we get into four-
vectors and retarded potentials, let's get clear about the force on a
moving charge. Are you familiar with the vector relation represented
by
F = qE + q(v x B)
v is a velocity. Velocity with respect to what? the laboratory? the
earth? the sun?
Elegant equation but let's not move that fast.
There are some volumes of 3 space we should
examine first.
I beleive the first charge ~illuminates~ space this way
http://en.wikipedia.org/wiki/Multiple_integral#Some_practical_applica...
Isn't that a fair way to represent the
superposition of moving charge?
Sue...
Sue, you may be right.
|
As an aside:
<<Trajectory of a particle with charge q,
under the influence of a magnetic field B
(directed perpendicularly out of the screen),
for different values of q. >>
http://en.wikipedia.org/wiki/Lorentz_force
That trajectory looks like no bullet I
have ever seen so reasonable folk can
question whether it is proper (pun intended)
to relate the interaction of charged
particles to ANY inertial frame of reference
at all. (IMHO Fitzpatrick's 4-vector method
is correct)
If I am slow in my responses it is because I
really have my hands full trying to locate
a bottle of electrons so I can compare its
weight to a bottle of helium. ;-)
Sue... |
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Sue...
Guest
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| Posted: Mon Jul 14, 2008 7:29 am Post subject: Re: Are SR effects real or not? Simplified case. |
|
|
On Jul 14, 2:51 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 14, 1:44 am, "Sue..." <suzysewns...@yahoo.com.au> wrote:
On Jul 14, 12:16 am, Uncle Ben <b...@greenba.com> wrote:
Sue, we need to crawl before we can walk.
OK, that would be the first moving charge
Before we get into four-
vectors and retarded potentials, let's get clear about the force on a
moving charge. Are you familiar with the vector relation represented
by
F = qE + q(v x B)
v is a velocity. Velocity with respect to what? the laboratory? the
earth? the sun?
Elegant equation but let's not move that fast.
There are some volumes of 3 space we should
examine first.
I beleive the first charge ~illuminates~ space this way
http://en.wikipedia.org/wiki/Multiple_integral#Some_practical_applica...
Isn't that a fair way to represent the
superposition of moving charge?
Sue...
Sue, you may be right.
|
A seond aside:
The velocity in the equation you asked about
F = qE + q(v x B)
has a temporal component.
You are, no doubt, familiar with Noether's theorem
which relates time and energy.
Without some stipulation whether the system
is radiating light energy or conserving
its energy as a permanent magnet the expresson
can have ambiguous interpretation.
Probably for the same reason anti-differential
is not quite an integral, the triple integral
form has no time component.
That is consistant with what we don't
know about the particles far-field
radiation or near evanescent field.
Sue... |
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Alen
Guest
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| Posted: Mon Jul 14, 2008 1:58 pm Post subject: Re: Are SR effects real or not? Simplified case. |
|
|
On Jul 13, 1:59 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
There is another thread in sci.physics.relativity entitled "Are
'observed' SR effects real?" I have trouble following the discussion,
as maybe you do too. I prefer to phrase the question in a way that to
me is much clearer.
The following thought experiment is an old problem, not original with
me, but I will not give any reference to it just yet. Just think
about it and draw your own conclusion. I'll post my explanation in
about a week.
*****************
Imagine two rocket ships at rest, one behind the other at a distance
x0, in intergalactic space. Let's tie a light string between the two
ships -- so light that it cannot affect the motion of the ships.
Let both ships be aimed at a distant galaxy that is on the line
connecting the ships. The ships synchronize watches and fire their
identical rocket engines at the same time.
Theorem: According to either classical mechanics or relativistic
mechanics, as the two ships accelerate, they keep a constant distance
between them with respect to (w.r.t.) their intial rest frames.
-------------------------------
Proof:
1) According to Newton, the position of a ship under constant
acceleration is given by x=t*t in some units. In an obvious notation,
the equations of motion are
x1 = t*t + x0,
x2 = t*t,
so
x1-x2 = x0.
2) According to Einstein, the position of a ship under constant proper
acceleration is given by x=cosh(t). The equations of motion will be
x1 = cosh(t) + x0,
x2 = cosh(t).
so
x1-x2 = x0.
QED
-------------------------------
But what about the string? When the ships are moving at almost the
speed of light, the string must have tried to contract a lot. But it
is constrained to stay at a fixed length x0. Sooner or later it will
reach its breaking point and will snap!
Do you believe this? Does the string break or not? Is the Lorentz-
Fitzgerad contraction real or not real?
Uncle Ben
|
The following Wikipedia article supposedly gives the correct
spacetime explanation, but the spacetime explanation cannot
possibly be correct, as I have argued before:
http://en.wikipedia.org/wiki/Bell_spaceship_paradox#Analysis
In the Wikipedia article illustration we have the spacetime
trajectory AA' for one acceleration, and BB'' for the other.
We thus have physically identical accelerations producing
results dependent on location, if the acceleration is viewed in
the context of the moving frame. This means that an experiment
that is physically unchanged will produce a different result in
the moving frame, simply my moving its location, thus making
the laws of physics dependent on location. Further, the events
A' and B'' have a relationship to one another specified by the
supposed nonsimultaneity effect between the frames. If the
initial distance AB is large enough, we will therefore have a
faster than light connection between the accelerations and
their results in the moving frame. Again, if we have a third
identical acceleration of a ship, C, placed initially to the left
of A, then both A' and B'' will be different, and C' will be the
same as A'. All this is completely impossible to reconcile
with the known working of the laws of physics, in that their
results are not dependent on location, and there is no faster
than light connecting principle by which experiments might
modify one another's results.
This is why I have argued before that the Lorentz transformation
equations cannot be simple spacetime coordinate transformations,
and SR cannot be a spacetime theory. I therefore suggested that
SR is properly a theory of light, rather than spacetime, and the
transformation equations are relationships created by the working
of light, and not of spacetime. It follows, also, that Lorentz
invariance is a feature of interactions involving lightspeed bosons,
and not a property of spacetime coordinate transformations.
The result, therefore, in the experiment, must be that AB ends
up as A'B', and the string does not stretch or break. The distance
A'B' will appear length contracted in the stationary frame only if
it is measured by sending a pulse of light along it, and not
otherwise.
Alen |
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xray4abc
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| Posted: Mon Jul 14, 2008 8:13 pm Post subject: Re: Are SR effects real or not? Simplified case. |
|
|
On Jul 12, 11:59 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
There is another thread in sci.physics.relativity entitled "Are
'observed' SR effects real?" I have trouble following the discussion,
as maybe you do too. I prefer to phrase the question in a way that to
me is much clearer.
The following thought experiment is an old problem, not original with
me, but I will not give any reference to it just yet. Just think
about it and draw your own conclusion. I'll post my explanation in
about a week.
*****************
Imagine two rocket ships at rest, one behind the other at a distance
x0, in intergalactic space. Let's tie a light string between the two
ships -- so light that it cannot affect the motion of the ships.
Let both ships be aimed at a distant galaxy that is on the line
connecting the ships. The ships synchronize watches and fire their
identical rocket engines at the same time.
Theorem: According to either classical mechanics or relativistic
mechanics, as the two ships accelerate, they keep a constant distance
between them with respect to (w.r.t.) their intial rest frames.
-------------------------------
Proof:
1) According to Newton, the position of a ship under constant
acceleration is given by x=t*t in some units. In an obvious notation,
the equations of motion are
x1 = t*t + x0,
x2 = t*t,
so
x1-x2 = x0.
2) According to Einstein, the position of a ship under constant proper
acceleration is given by x=cosh(t). The equations of motion will be
x1 = cosh(t) + x0,
x2 = cosh(t).
so
x1-x2 = x0.
QED
-------------------------------
But what about the string? When the ships are moving at almost the
speed of light, the string must have tried to contract a lot. But it
is constrained to stay at a fixed length x0. Sooner or later it will
reach its breaking point and will snap!
Do you believe this? Does the string break or not? Is the Lorentz-
Fitzgerad contraction real or not real?
Uncle Ben
|
I vote : NO, for both questions
I am pursuing a simple view of special relativity theory , which is
like:
Person A considers Person B dumb (because he does not have same
understanding of things as B does). Still, based on his perception of
B,
he could have a pretty good capacity of predicting the expected
behaviour of B in some situations and use it for personal benefit.
Of course, the same could apply for person B relative to person A!
The above, refers to my opinion on what you have said in this
thread:
things how they are SEEN and things how they ARE.
What these mean in terms of SRT one should see easily.
Best regards, LL |
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Uncle Ben
Guest
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| Posted: Mon Jul 14, 2008 10:14 pm Post subject: Re: Are SR effects real or not? Simplified case. |
|
|
On Jul 12, 11:59 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
There is another thread in sci.physics.relativity entitled "Are
'observed' SR effects real?" I have trouble following the discussion,
as maybe you do too. I prefer to phrase the question in a way that to
me is much clearer.
The following thought experiment is an old problem, not original with
me, but I will not give any reference to it just yet. Just think
about it and draw your own conclusion. I'll post my explanation in
about a week.
*****************
Imagine two rocket ships at rest, one behind the other at a distance
x0, in intergalactic space. Let's tie a light string between the two
ships -- so light that it cannot affect the motion of the ships.
Let both ships be aimed at a distant galaxy that is on the line
connecting the ships. The ships synchronize watches and fire their
identical rocket engines at the same time.
Theorem: According to either classical mechanics or relativistic
mechanics, as the two ships accelerate, they keep a constant distance
between them with respect to (w.r.t.) their intial rest frames.
-------------------------------
Proof:
1) According to Newton, the position of a ship under constant
acceleration is given by x=t*t in some units. In an obvious notation,
the equations of motion are
x1 = t*t + x0,
x2 = t*t,
so
x1-x2 = x0.
2) According to Einstein, the position of a ship under constant proper
acceleration is given by x=cosh(t). The equations of motion will be
x1 = cosh(t) + x0,
x2 = cosh(t).
so
x1-x2 = x0.
QED
-------------------------------
But what about the string? When the ships are moving at almost the
speed of light, the string must have tried to contract a lot. But it
is constrained to stay at a fixed length x0. Sooner or later it will
reach its breaking point and will snap!
Do you believe this? Does the string break or not? Is the Lorentz-
Fitzgerad contraction real or not real?
Uncle Ben
|
At 6:00 PM my time Monday, July 14 we have a vote of
Yes 1 (Dono )
No 3 ( Sue, Alen, xray4abc)
Snarl 1 (Androcles)
Uncommitted 2 (PD, Martin)
No is ahead. Anhybody else brave enough to vote?
Ben |
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