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Uncle Ben
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 Posted: Wed Jul 16, 2008 1:47 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 15, 8:36 pm, Dono <sa...@comcast.net> wrote:
| Quote: |
On Jul 15, 7:10 am, Uncle Ben <b...@greenba.com> wrote:
That is all we need. If the lead rocket fires first, it must stretch
the string.
This is not what happens in the Bell problem statement.If your problem
statement were correct, the problem would reduce to a trivial one. You
keep trying to peddle your reductionist view of the problem. What
happens in reality is presented here:
http://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox#Analysis
Try reading what Bell REALLY said and try understanding it.
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I took your assignment and read the Wiki article again. The first
paragraph under the heading "Bell's thought experiment" reads as
follows;
-------
"In Bell's version of the thought experiment, two spaceships, which
are initially at rest in some common inertial reference frame are
connected by a taut string. At time zero in the common inertial frame,
both spaceships start to accelerate, with a constant proper
acceleration g as measured by an on-board accelerometer. Question:
does the string break - i.e. does the distance between the two
spaceships increase?"
-------
Aside from the ambiguous form of the question at the end, (yes, the
string breaks; no, the distance between the two spaceships does not
increase w.r.t. the launch frame; yes, the distance between the
spaceships does increase w.r.t. an inertial frame moving along with
the spaceships near the critical break time), that is EXACTLY the
problem I stated and solved. If you disagree, please explain.
Uncle Ben |
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Dono
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| Posted: Wed Jul 16, 2008 4:07 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 15, 6:32 pm, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
I have no particular interest in being faithful to Bell's problem
statement.
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That was an interesting problem.
| Quote: |
I posed the problem that I wanted to pose.
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Yours is a trivial one.
| Quote: |
I wanted it to
be simple but to challenge the idea that SR was just a matter of
perspectives and not something that deals with real times, lengths,
masses, etc.
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If this is what you wanted, you are going the wrong way about it.
Trivial exercises will not cut it. Besides, you have repeatedly tried
to dumb down the original Bell problem as to bring it to your level of
understanding while criticisizing the original problem since you were
unable to understand it.
| Quote: |
For one who is well grounded in SR, the problem is easy,
but it has plagued the minds of many of my physicist aquaintances and
students.
|
No, your dumbed-down version could not have stumped anybody. I can see
how Bell's paradox could stump people but not your version. |
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Dono
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| Posted: Wed Jul 16, 2008 4:10 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 15, 6:47 pm, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 15, 8:36 pm, Dono <sa...@comcast.net> wrote:
On Jul 15, 7:10 am, Uncle Ben <b...@greenba.com> wrote:
That is all we need. If the lead rocket fires first, it must stretch
the string.
This is not what happens in the Bell problem statement.If your problem
statement were correct, the problem would reduce to a trivial one. You
keep trying to peddle your reductionist view of the problem. What
happens in reality is presented here:
http://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox#Analysis
Try reading what Bell REALLY said and try understanding it.
I took your assignment and read the Wiki article again. The first
paragraph under the heading "Bell's thought experiment" reads as
follows;
-------
"In Bell's version of the thought experiment, two spaceships, which
are initially at rest in some common inertial reference frame are
connected by a taut string. At time zero in the common inertial frame,
both spaceships start to accelerate, with a constant proper
acceleration g as measured by an on-board accelerometer. Question:
does the string break - i.e. does the distance between the two
spaceships increase?"
-------
Aside from the ambiguous form of the question at the end, (yes, the
string breaks; no, the distance between the two spaceships does not
increase w.r.t. the launch frame; yes, the distance between the
spaceships does increase w.r.t. an inertial frame moving along with
the spaceships near the critical break time), that is EXACTLY the
problem I stated and solved. If you disagree, please explain.
Uncle Ben
|
You "solved" it by claiming that the two rockets don't take off
simultaneously (contradicted by the problem statement).
You claimed that you solved it by saying that the lead rocket takes-
off before the trailing rocket. WRONG.
Read again the wiki page, including the solution. |
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Dono
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| Posted: Wed Jul 16, 2008 4:13 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 15, 6:47 pm, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
that is EXACTLY the
problem I stated and solved. If you disagree, please explain.
Uncle Ben
|
You are contradicting your earlier post that says that you have no
interest in the original Bell paradox. Now, you claim that this is
exactly the problem that you solved (you didn't really solve
anything).
So, which one is true? Are you just trolling? |
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Uncle Ben
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| Posted: Wed Jul 16, 2008 4:38 am Post subject: Re: Are SR effects real or not? Simplified case. |
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Dono said in part:
| Quote: |
You "solved" it by claiming that the two rockets don't take off
simultaneously (contradicted by the problem statement).
You claimed that you solved it by saying that the lead rocket takes-
off before the trailing rocket. WRONG.
|
This is the second time you have spoken loosely about whether two
events are simultaneous. The first time, in private communication, I
chided you for not specifying that the simultaneous firing was w.r.t.
the launch frame, which you had neglected to say. You responded saying
"obviously that is what I meant," and I went along with you. But since
you have now not only done it again but have chastised me for making a
mistake, I have to conclude that you do not take seriously the
relativity of simultaneity.
I have stated in the problem that the rockets take off simultaneously
w.r.t. the launch frame. Then in the solution I said let us consider
things w.r.t. the "final frame" by which I mean the inertial frame in
which the lead rocket is moving slowly at the time of breakage
(actually at any time after launch). The rockets do not fire
simultaneously w.r.t. the final frame. The lead rocket takes off first
w.r.t. the final frame.
From your earlier discussions, I assumed that you were a sophisticated
relativist. But if you think there is a contradiction between
simultaneity of two events w.r.t. the launch frame and non-simltaneity
of the same two events w.r.t. the final frame, then I have to alter my
opinion.
And since your tone has also changed from one of respect to one of
sarcasm, I think we had better end this corresondence.
Uncle Ben |
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Uncle Ben
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| Posted: Wed Jul 16, 2008 4:39 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 16, 12:13 am, Dono <sa...@comcast.net> wrote:
| Quote: |
On Jul 15, 6:47 pm, Uncle Ben <b...@greenba.com> wrote:
that is EXACTLY the
problem I stated and solved. If you disagree, please explain.
Uncle Ben
You are contradicting your earlier post that says that you have no
interest in the original Bell paradox. Now, you claim that this is
exactly the problem that you solved (you didn't really solve
anything).
So, which one is true? Are you just trolling?
|
No, I mention your Wiki post because you claim that I solved a
different problem. I don't care who first proposed it, it is the
problem I wanted to discuss.
Ben |
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Dono
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| Posted: Wed Jul 16, 2008 4:47 am Post subject: Re: Are SR effects real or not? Simplified case. |
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Then, your "solution" is plain wrong.
Uncle Ben wrote:
| Quote: |
On Jul 16, 12:13�am, Dono <sa...@comcast.net> wrote:
On Jul 15, 6:47�pm, Uncle Ben <b...@greenba.com> wrote:
�that is EXACTLY the
problem I stated and solved. �If you disagree, please explain..
Uncle Ben
You are contradicting your earlier post that says that you have no
interest in the original Bell paradox. Now, you claim that this is
exactly the problem that you solved (you didn't really solve
anything).
So, which one is true? Are you just trolling?
No, I mention your Wiki post because you claim that I solved a
different problem. I don't care who first proposed it, it is the
problem I wanted to discuss.
Ben |
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Dono
Guest
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| Posted: Wed Jul 16, 2008 4:51 am Post subject: Re: Are SR effects real or not? Simplified case. |
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You ARE trolling.
The two rockets take off simultaneously in the launcher frame and also
in the common rocket frame since, at launch, the two frames are
coincident. Find another hobby.
Uncle Ben wrote:
| Quote: |
Dono said in part:
You "solved" it by claiming that the two rockets don't take off
simultaneously (contradicted by the problem statement).
You claimed that you solved it by saying that the lead rocket takes-
off before the trailing rocket. WRONG.
This is the second time you have spoken loosely about whether two
events are simultaneous. The first time, in private communication, I
chided you for not specifying that the simultaneous firing was w.r.t.
the launch frame, which you had neglected to say. You responded saying
"obviously that is what I meant," and I went along with you. But since
you have now not only done it again but have chastised me for making a
mistake, I have to conclude that you do not take seriously the
relativity of simultaneity.
I have stated in the problem that the rockets take off simultaneously
w.r.t. the launch frame. Then in the solution I said let us consider
things w.r.t. the "final frame" by which I mean the inertial frame in
which the lead rocket is moving slowly at the time of breakage
(actually at any time after launch). The rockets do not fire
simultaneously w.r.t. the final frame. The lead rocket takes off first
w.r.t. the final frame.
From your earlier discussions, I assumed that you were a sophisticated
relativist. But if you think there is a contradiction between
simultaneity of two events w.r.t. the launch frame and non-simltaneity
of the same two events w.r.t. the final frame, then I have to alter my
opinion.
And since your tone has also changed from one of respect to one of
sarcasm, I think we had better end this corresondence.
Uncle Ben |
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Uncle Ben
Guest
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| Posted: Wed Jul 16, 2008 5:17 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 16, 12:38 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
From your earlier discussions, I assumed that you were a sophisticated
relativist. But if you think there is a contradiction between
simultaneity of two events w.r.t. the launch frame and non-simltaneity
of the same two events w.r.t. the final frame, then I have to alter my
opinion.
|
Dono apparently doesn't accept the following statement:
"So we see that we cannot attach any absolute signification to the
concept of simultaneity, but that two events which, viewed from a
system of co-ordinates, are simultaneous, can no longer be looked upon
as simultaneous events when envisaged from a system which is in motion
relatively to that system."
A. Einstein, 1905 "On the electrodynamics of moving bodies", Part I,
Sec. 2. |
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Uncle Ben
Guest
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| Posted: Wed Jul 16, 2008 5:27 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 16, 12:51 am, Dono <sa...@comcast.net> wrote:
| Quote: |
You ARE trolling.
The two rockets take off simultaneously in the launcher frame and also
in the common rocket frame since, at launch, the two frames are
coincident. Find another hobby.
|
The common rocket frame is accelerated, and the clocks will not go at
the same rate. You can do it that way, but I did another way using
only inertial frames.
My analysis involves an inertial frame in which the lead rocket is
momentarily at rest or moving slowly at break time. That is what I
call the "final frame"
The firings are not simultaneouse w.r.t. the final frame.
See A. Einstein quoted in message 51. |
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Tom Roberts
Guest
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| Posted: Wed Jul 16, 2008 8:30 am Post subject: Re: Are SR effects real or not? Simplified case. |
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Uncle Ben wrote:
| Quote: |
On Jul 15, 10:28 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
You MUST use more precise language. [...]
No, what SR says is that length of a ruler is RELATIVE, not absolute.
This means that the ruler will have different lengths with respect to
different frames of reference.
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Please re-read what I wrote above. You persist in using inappropriate
(imprecise) language.
When you say "length of a ruler", if you mean WHAT ONE MEASURES then you
are correct, but that is NOT what that phrase means to most people. To
most people that phrase refers to THE length of the ruler (note emphasis
on "the", implying a SINGULAR quantity) -- this is an intrinsic property
of the ruler, and in SR when one speaks carefully (precisely) one calls
it the proper length of the ruler. But most people are not experts, and
do not understand the distinction, and thus hear "THE length of the
ruler" when you meant to say "the MEASURED length of the ruler".
Many of the confusions around here are due to inappropriate and
ambiguous language by people who should know better. Like yourself (you
seem to understand the basics of SR).
Of course some of the confusions around here are due
to pure, unadulterated idiocy.
Tom Roberts |
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Sue...
Guest
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| Posted: Wed Jul 16, 2008 8:41 am Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 16, 1:27 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 16, 12:51 am, Dono <sa...@comcast.net> wrote:
You ARE trolling.
The two rockets take off simultaneously in the launcher frame and also
in the common rocket frame since, at launch, the two frames are
coincident. Find another hobby.
The common rocket frame is accelerated, and the clocks will not go at
the same rate. You can do it that way, but I did another way using
only inertial frames.
|
Unless you have surplus bottle of massive light particles
left over from the 1800's why fool with clocks at all?
http://en.wikipedia.org/wiki/Emitter_theory
Equal length cables will set off the rockets simultaneously
for both electromagnetic and inertial frames.
| Quote: |
My analysis involves an inertial frame in which the lead rocket is
momentarily at rest or moving slowly at break time. That is what I
call the "final frame"
The firings are not simultaneouse w.r.t. the final frame.
|
If they were simultaneous in one inertial frame, they will be
simutaneous in all inertial frames.
~~~Einstein's relativity principle 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
Sue...
| Quote: |
See A. Einstein quoted in message 51. |
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Uncle Ben
Guest
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| Posted: Wed Jul 16, 2008 12:30 pm Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 16, 1:17 am, Uncle Ben <b...@greenba.com> wrote:
| Quote: |
On Jul 16, 12:38 am, Uncle Ben <b...@greenba.com> wrote:
From your earlier discussions, I assumed that you were a sophisticated
relativist. But if you think there is a contradiction between
simultaneity of two events w.r.t. the launch frame and non-simltaneity
of the same two events w.r.t. the final frame, then I have to alter my
opinion.
Dono apparently doesn't accept the following statement:
"So we see that we cannot attach any absolute signification to the
concept of simultaneity, but that two events which, viewed from a
system of co-ordinates, are simultaneous, can no longer be looked upon
as simultaneous events when envisaged from a system which is in motion
relatively to that system."
A. Einstein, 1905 "On the electrodynamics of moving bodies", Part I,
Sec. 2.
|
Here is a link to Einstein's famous 1905 paper "On the
electrodynamics of moving bodies" in translation as archived on the
net and availabile to everyone. Part I is on kinematics, and within
it is Section 2 on simultaneity.
http://www.fourmilab.ch/etexts/einstein/specrel/www/
(I thank Androcles for providing the link to me, although we disagree
on almost everything.) |
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PD
Guest
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| Posted: Wed Jul 16, 2008 12:46 pm Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 15, 10:30 pm, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
| Quote: |
Uncle Ben wrote:
On Jul 15, 10:28 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
You MUST use more precise language. [...]
No, what SR says is that length of a ruler is RELATIVE, not absolute.
This means that the ruler will have different lengths with respect to
different frames of reference.
Please re-read what I wrote above. You persist in using inappropriate
(imprecise) language.
When you say "length of a ruler", if you mean WHAT ONE MEASURES then you
are correct, but that is NOT what that phrase means to most people. To
most people that phrase refers to THE length of the ruler (note emphasis
on "the", implying a SINGULAR quantity) -- this is an intrinsic property
of the ruler, and in SR when one speaks carefully (precisely) one calls
it the proper length of the ruler. But most people are not experts, and
do not understand the distinction, and thus hear "THE length of the
ruler" when you meant to say "the MEASURED length of the ruler".
Many of the confusions around here are due to inappropriate and
ambiguous language by people who should know better. Like yourself (you
seem to understand the basics of SR).
Of course some of the confusions around here are due
to pure, unadulterated idiocy.
Tom Roberts
|
To put Tom's point more colloquially, an given ruler at any given
moment has got thousands of physical lengths, each of them
corresponding to the physical length measured in a different reference
frame.
It so happens that the maximal length out of all those thousands will
be the one measured in the frame in which the ruler is at rest. But
there is nothing physically special about that frame, compared to
other frames, so there is nothing *physically* different about the
physical length of the ruler measured in that frame. There is the
*habit* of calling this particular length in this particular frame the
"proper length", but that is just an adjectival prefix that denotes
that this is the rest frame and the maximal length -- nothing more.
PD |
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Uncle Ben
Guest
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| Posted: Wed Jul 16, 2008 12:57 pm Post subject: Re: Are SR effects real or not? Simplified case. |
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On Jul 16, 8:46 am, PD <TheDraperFam...@gmail.com> wrote:
| Quote: |
On Jul 15, 10:30 pm, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
Uncle Ben wrote:
On Jul 15, 10:28 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
You MUST use more precise language. [...]
No, what SR says is that length of a ruler is RELATIVE, not absolute.
This means that the ruler will have different lengths with respect to
different frames of reference.
Please re-read what I wrote above. You persist in using inappropriate
(imprecise) language.
When you say "length of a ruler", if you mean WHAT ONE MEASURES then you
are correct, but that is NOT what that phrase means to most people. To
most people that phrase refers to THE length of the ruler (note emphasis
on "the", implying a SINGULAR quantity) -- this is an intrinsic property
of the ruler, and in SR when one speaks carefully (precisely) one calls
it the proper length of the ruler. But most people are not experts, and
do not understand the distinction, and thus hear "THE length of the
ruler" when you meant to say "the MEASURED length of the ruler".
Many of the confusions around here are due to inappropriate and
ambiguous language by people who should know better. Like yourself (you
seem to understand the basics of SR).
Of course some of the confusions around here are due
to pure, unadulterated idiocy.
Tom Roberts
To put Tom's point more colloquially, an given ruler at any given
moment has got thousands of physical lengths, each of them
corresponding to the physical length measured in a different reference
frame.
It so happens that the maximal length out of all those thousands will
be the one measured in the frame in which the ruler is at rest. But
there is nothing physically special about that frame, compared to
other frames, so there is nothing *physically* different about the
physical length of the ruler measured in that frame. There is the
*habit* of calling this particular length in this particular frame the
"proper length", but that is just an adjectival prefix that denotes
that this is the rest frame and the maximal length -- nothing more.
PD- Hide quoted text -
- Show quoted text -
|
And to add yet another liquistic comment:
If you measure it, it is real.
It is a cop-out to qualify cetain results in relativity as "apparent"
or "measured" as if measurement was a lesser way to truth. It is
because the writer is still not qjuite accepting the results as real
in the back of his mind, or he thinks the reader wont accept it and he
is hedging his bets.
That is why I always state it outright that, for example, the length
w.r.t. frame f "IS" so-and-so, not "appears to be". Length is defined
relative to a frame of reference. Doubters, get over it!
Ben |
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