SR contraction - Detailed practical twist experiment
DSeppala
see relativistic effects, an identical gedanken experiment can be done
at very long distances. I challange anyone to explain why they think
the experimental result is different at very long distances. If the
experimental results are indeed the same, then Einstein's notions of
space and time don't seem to work.
Experiment at short distance - 10 kilometers.
Two rigid steel disks, each 1 meter in diameter rotate at a
constant rate perpendular to the x-axis, with the x-axis passing thru
the center of each disk. The distance between the disks is 10
kilometers. The disks are very massive and for all practical purposes
will remain 10 kilometers apart throughout this experiment. A soft
solid clay cylinder also 1 meter in diameter spans the gap between the
two steel disks, and rotates at the same constant rate as the steel
disks. The rate of rotation of the disks and the clay cylinder is one
revolution per day. I have a segmented thin steel wire. Each one
kilometer segment is connected to the next segment by a calibrated
device that can increase the tension on the wire segments. The
purpose of each of these devices is to increase the tension on each
segment so that the mechanical effect of increased tension reaches a
steady-state value after traveling only about a kilometer or two.
The segmented wire runs parallel to the surface of the rotating
setup. One end of the segmented wire is attached to the 0 degree
position of the left steel disk at time t0. One day later the other
end of the segmented wire is attached to the 0 degree position of the
steel disk on the right end. The segmented wire therefore makes one
loop around the clay cylinder. Now the tension on the segmented wire
is increased so that the wire approaches a straight line. This causes
the wire to cut through the soft clay until it is laying on the
surface of the cylinder. The friction of the clay surface prevents
the segmented wire from "looping" in any significant way due to the
rotational rate of one revolution per day.
That's the experiment. Now can anyone describe how the results differ
if the length between the two rigid disks, and the length of the clay
cylinder are one light-year instead of 10 kilometers? The rotation
rate remains the same, just the length of the setup has changed. As
the tension of the wire increases, does it cut through the clay to
approach a straight line as it did in the original experiment? If
the answer is no, why not?
If the answer is yes, the results of the two experiments are
independent of the length of the setup. But with long lengths, we can
measure relativistic effects. If the wire cuts through the clay, we
can attach two wires, with wire A atached at 0 degees and wire B
attached simultaneously at 180 degrees on the left disk, and then a
day later, after one revolution of the cylinder, attach the other end
of wire A to 0 degrees of the right disk and wire B to 180 degrees of
the right disk. Now when the tension on these wires is increased, as
these wires cut through the clay, they intersect. But with this same
scenario, there is a frame with velocity V along the x-axis relative
to the setup who views the attachment of the wires at both ends to be
simultaneous events, instead of one day apart. What is this frame's
explanation of why the wires intersect?
David Seppala
Bastrop, TX
eric gisse
[...]
Does the answer matter?
You'll just make a slightly modified scenario and repost in a few days.
Inertial
"DSeppala" <dsep...@austin.rr.com> wrote in message
news:2102ff88-7f31-484e...@k23g2000yqa.googlegroups.com...
Oh dear, here comes another one
> This is a simple practical experiment to do at short distances. To
> see relativistic effects, an identical gedanken experiment can be done
> at very long distances. I challange anyone to explain why they think
> the experimental result is different at very long distances.
Probably because of relativistic effects are more apparent :)
> If the
> experimental results are indeed the same, then Einstein's notions of
> space and time don't seem to work.
>
> Experiment at short distance - 10 kilometers.
> Two rigid steel disks, each 1 meter in diameter rotate at a
> constant rate perpendular to the x-axis, with the x-axis passing thru
> the center of each disk. The distance between the disks is 10
> kilometers.
Its those two disks again
| |
---|-------------|---
| |
A 10km B
> The disks are very massive and for all practical purposes
> will remain 10 kilometers apart throughout this experiment.
OK .. or they just need to be firmly secured
> A soft
> solid clay cylinder also 1 meter in diameter spans the gap between the
> two steel disks, and rotates at the same constant rate as the steel
> disks.
|=============|
---|=============|---
|=============|
A 10km B
where '=' is the tube .. the whole thing spinning
> The rate of rotation of the disks and the clay cylinder is one
> revolution per day.
Fine .. don't think it really matters to much how fast
> I have a segmented thin steel wire.
Gees .. how much more stuff do yiou need here?
> Each one
> kilometer segment is connected to the next segment by a calibrated
> device that can increase the tension on the wire segments. The
> purpose of each of these devices is to increase the tension on each
> segment so that the mechanical effect of increased tension reaches a
> steady-state value after traveling only about a kilometer or two.
Umm .. seems odd, but why not just have them rigid?
> The segmented wire runs parallel to the surface of the rotating
> setup. One end of the segmented wire is attached to the 0 degree
> position of the left steel disk at time t0. One day later the other
> end of the segmented wire is attached to the 0 degree position of the
> steel disk on the right end.
Ooookay
> The segmented wire therefore makes one
> loop around the clay cylinder.
Yeup. In the inertial frame of the ground.
> Now the tension on the segmented wire
> is increased so that the wire approaches a straight line. This causes
> the wire to cut through the soft clay until it is laying on the
> surface of the cylinder.
OK
> The friction of the clay surface prevents
> the segmented wire from "looping" in any significant way due to the
> rotational rate of one revolution per day.
Fine
> That's the experiment.
Doesn't seem to accomplish much
> Now can anyone describe how the results differ
> if the length between the two rigid disks, and the length of the clay
> cylinder are one light-year instead of 10 kilometers?
Won't change at all
> The rotation
> rate remains the same, just the length of the setup has changed. As
> the tension of the wire increases, does it cut through the clay to
> approach a straight line as it did in the original experiment? If
> the answer is no, why not?
It would behave in basically the same way.
> If the answer is yes, the results of the two experiments are
> independent of the length of the setup.
Not in details, but basically the same thing happening.
> But with long lengths, we can
> measure relativistic effects.
There's no relativistic effects in that setup .. nothing is moving fast
enough relative to the experiment
> If the wire cuts through the clay, we
> can attach two wires, with wire A atached at 0 degees and wire B
> attached simultaneously at 180 degrees on the left disk, and then a
> day later, after one revolution of the cylinder, attach the other end
> of wire A to 0 degrees of the right disk and wire B to 180 degrees of
> the right disk. Now when the tension on these wires is increased, as
> these wires cut through the clay, they intersect. But with this same
> scenario, there is a frame with velocity V along the x-axis relative
> to the setup who views the attachment of the wires at both ends to be
> simultaneous events, instead of one day apart. What is this frame's
> explanation of why the wires intersect?
The clay and wires are twisted around as measured in that frame. A straight
line on the surface of the cylinder as viewed from the ground frame will
appear to wrap around the cylinder from a fast moving frame, and vice versa.
Gees .. this is the same experiment as the last one that failed to refute SR
.. only you've added in some clay. Have you nothing better to do than
reword the same experiment over and over and have it shown not to show any
problems? are you related to Henry?
Dirk Van de moortel
00cad6f9$0$15588$c3e...@news.astraweb.com
> "DSeppala" <dsep...@austin.rr.com> wrote in message
> news:2102ff88-7f31-484e...@k23g2000yqa.googlegroups.com...
>
> Oh dear, here comes another one
It's the same one as in 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
2006, 2007, 2008 and 2009.
It is his New Year's card.
Dirk Vdm
DSeppala
> "DSeppala" <dsepp...@austin.rr.com> wrote in message
You missed a critical point in the experiment. In the rest frame as
the tension of the wires is increased, they cut through the clay to
approach straight lines on the surface of the clay. When two wires
are connected with one at 0 degrees and one at 180 degrees and they
cut through the clay, then end of intersecting each other. But from
the point of view of the moving frame that attached them
simultaneously, increasing the tension doesn't shouldn't cause them to
cut through the clay (they are simply straight lines already on the
surface of the clay), and the motion of the 0 degree versus the 180
degree attached wires is identical, just offset, so they should never
intersect. (The purpose of the clay was due to some responders -
outside of this group thinking high rotation rates cause looping of
the wires preventing them from intersecting as they do in the 10
kilometer case).
David
Inertial
Nope
> In the rest frame as
> the tension of the wires is increased, they cut through the clay to
> approach straight lines on the surface of the clay.
Yeup. And that's what the moving observer will observe as well. However,
they will observe the whole apparatus to be twisted.
> When two wires
> are connected with one at 0 degrees and one at 180 degrees and they
> cut through the clay, then end of intersecting each other.
Yeup. And that's what the moving observer will observe as well. However,
they will observe the whole apparatus to be twisted.
> But from
> the point of view of the moving frame that attached them
> simultaneously, increasing the tension doesn't shouldn't cause them to
> cut through the clay (they are simply straight lines already on the
> surface of the clay),
No .. you see? THERE is your mistake.
As already explained, in that frame the wires are measured as straight ..
they are wrapped around the clay
> and the motion of the 0 degree versus the 180
> degree attached wires is identical, just offset, so they should never
> intersect.
Wrong .. you'll end up with exactly the same result. Except the moving
observer will measure the whole setup as twisted.
> (The purpose of the clay was due to some responders -
> outside of this group thinking high rotation rates cause looping of
> the wires preventing them from intersecting as they do in the 10
> kilometer case).
> David
Well. it still doesn't save you. SR still gives you the same results
happening no matter who is looking at it. Changing the frame of reference
you are observing from does not change what happens.
DSeppala
>
> Nope
>
> > In the rest frame as
> > the tension of the wires is increased, they cut through the clay to
> > approach straight lines on the surface of the clay.
>
> Yeup. And that's what the moving observer will observe as well. However,
> they will observe the whole apparatus to be twisted.
The moving frame observers may or may not see the cylinder to be
twisted. True, per Einstein, if the cylinder was initially not
rotating, and the rest frame observers simultaneously started rotating
all points of the disk in an identical fashion, the moving frame
observers would see the entire cylinder having a twist. However, in
this problem the initial conditions of the cylinder are completely
arbitrary. The cylinder could have been put together in segments, one
segment spinning a second, or a century before other segments started
spinning and before all segments are connected. You cannot correctly
assume anything about whether either frame sees the cylinder as being
twisted.
However the moving frame observers do not observe the straight
wire they simultaneously placed on the cylinder to be twisted. The
wire started out as a straight line and continues to be a straight
line (as observed by the moving frame). If they don't see it as a
straight line, which points of the wire do you think had a faster
rotation rate (from the moving frame point of view) when they were all
simultaneously placed (as viewed by the moving frame) on the rotating
cylinder?
David
> you are observing from does not change what happens.- Hide quoted text -
>
> - Show quoted text -
Inertial
>> > You missed a critical point in the experiment.
>>
>> Nope
>>
>> > In the rest frame as
>> > the tension of the wires is increased, they cut through the clay to
>> > approach straight lines on the surface of the clay.
>>
>> Yeup. And that's what the moving observer will observe as well.
>> However,
>> they will observe the whole apparatus to be twisted.
>
> The moving frame observers may or may not see the cylinder to be
> twisted.
No .. they will
> True, per Einstein, if the cylinder was initially not
> rotating, and the rest frame observers simultaneously started rotating
> all points of the disk in an identical fashion, the moving frame
> observers would see the entire cylinder having a twist. However, in
> this problem the initial conditions of the cylinder are completely
> arbitrary.
Doesn't matter .. it will appear twisted in the moving observers frame if it
is not twisted in the stationary frame
> The cylinder could have been put together in segments, one
> segment spinning a second, or a century before other segments started
> spinning and before all segments are connected.
Doesn't matter .. it will appear twisted in the moving observers frame if it
is not twisted in the stationary frame, and vice versa
> You cannot correctly
> assume anything about whether either frame sees the cylinder as being
> twisted.
Yes .. you can
> However the moving frame observers do not observe the straight
> wire they simultaneously placed on the cylinder to be twisted.
It will appear twisted in the moving observers frame if it is not twisted in
the stationary frame, and vice versa
> The
> wire started out as a straight line and continues to be a straight
> line (as observed by the moving frame).
It will appear twisted in the moving observers frame if it is not twisted in
the stationary frame, and vice versa
> If they don't see it as a
> straight line, which points of the wire do you think had a faster
> rotation rate
None, if attached simultaneously
> (from the moving frame point of view) when they were all
> simultaneously placed (as viewed by the moving frame) on the rotating
> cylinder?
This is all basic stuff .. there is no contradiction here .. except in you
insisting that things that SR does NOT say will happen and then claiming
they aren't consistent (which, of course, they aren't, because they are not
what SR predicts)
DSeppala
> "DSeppala" <dsepp...@austin.rr.com> wrote in message
If the wires are twisted in the rest frame, then when the tension is
increased and they cut through the clay the wires will intersect
(criss-cross) - just like they do for short distances. Why does the
moving frame observer say that the straight wires intersect? From his
point of view, the wires remain straight. What does he say is the
cause of the wires to intersect?
Thanks,
David
Inertial
You're still not getting it. The moving frame will see perfectly taut wires
in the rest frame (the frame in whish the wirse do not have any movement
along the axis of rotation) as being curved around the cylinder. The taut
wires will never appear straight in the moving frame.
DSeppala
>
> - Show quoted text -
In the posted problem, the moving frame attached the wire
simultaneously to the left and right disks. (I think you are thinking
the rest framea observers attached the wires simultaneously) They see
the wire as a straight wire rotating about the x-axis. In the rest
frame of the setup, the wire was attached one revolution apart. The
rest frame observers see the wire as looped around the cylinder and
rotating with the cylinder. When this is done with two wires, the
moving frame sees the two wires that were attached simultaneously in
the moving frame rotate as straight lines around the x-axis. In the
rest frame, as the tension of the wires increase, they cut through the
clay and form straight lines on the surface of the clay. When two
wires are attached to the left and right sides, these two wires
intersect as the tension is increased. The moving frame observers
still see the wires as straight lines as the tension is increased.
They do not see the two wires intersect unless one wire undergoes a
different motion than the other wire.
David
Inertial
I know
>(I think you are thinking
> the rest framea observers attached the wires simultaneously) They see
> the wire as a straight wire rotating about the x-axis.
No .. they won't. Unless the wires are NOT rotating with the cylinder until
they are attached.
In that case they will be stragiht in the moving frame and be curved around
the cylinder in the rest frame
> In the rest
> frame of the setup, the wire was attached one revolution apart.
So the write would be curved around the cylinder.
> The
> rest frame observers see the wire as looped around the cylinder and
> rotating with the cylinder.
Yes
> When this is done with two wires, the
> moving frame sees the two wires that were attached simultaneously in
> the moving frame rotate as straight lines around the x-axis.
Yes
> In the
> rest frame, as the tension of the wires increase, they cut through the
> clay and form straight lines on the surface of the clay.
Yes
> When two
> wires are attached to the left and right sides, these two wires
> intersect as the tension is increased.
Yes
> The moving frame observers
> still see the wires as straight lines as the tension is increased.
No .. they will see them bend around the cylinder as the tension is
increased
> They do not see the two wires intersect unless one wire undergoes a
> different motion than the other wire.
The same events will happen in both frames.
DSeppala
no longer on the surface of the cylinder except at the end points.
The moving frame observers do not see the wires bend around the
cylinder, as you state. That would mean that from their point of view
the wire remained on the surface of the clay, instead of cutting
through it.
David
>
> > They do not see the two wires intersect unless one wire undergoes a
> > different motion than the other wire.
>
>
DSeppala
in the middle of the clay cylinder that extends from the left end to
the right end. Now let the moving frame observers simultaneously
attach a wire with a tension T1 to the two end rotating disks and to
the clay surface. Now increase the tension of the wire to T2. The
wire cuts through the clay and is stopped at the x-axis by the steel
rod in the middle of the clay cylinder. Why do the moving observers
say increasing the tension from T1 to T2 causes the wire to always
touch the x-axis at the midpoint of the wire?
If the moving frame observer simultaneously attaches the wire to the
two rotating disks at the end and simultaneously lays the wire flat in
a straight line on the surface of the clay cylinder, why does the
moving frame observer say if the tension starts at T2 the center of
the wire will cut through the clay instead of remaining on the surface
and will stop at the steel rod in the middle of the clay?
Thanks,
David
Inertial
Yes
> It is
> no longer on the surface of the cylinder except at the end points.
Yes
> The moving frame observers do not see the wires bend around the
> cylinder, as you state.
No . .they will .. the wirse started out straight in the moving frame and
bent around in the rest frame
After tension is applied there will be bent in the moving frame and straight
in the rest frame
> That would mean that from their point of view
> the wire remained on the surface of the clay, instead of cutting
> through it.
No
You really need to think about this more clearly
Before they are connected are not rotating with the cylinder and are
straight in the both the moving and rest frames
In the moving frame the two ends of the wire are connected simultaneously
and the wires remain straight on the surface of the cylinder and are now
turning with the cylinder.
In the rest frame one end of each wire are connected to one end of the
cylinder and the wire starts to wrap around the cylinder until the other
ends of each wire are connected
So now
In the moving frame, we have two wires on the surface of the cylinder
rotating with it.
In the rest frame, we have two wires wrapped once around the cylinder
rotating with it
When tension is applied on the wires where they are attached to the ends of
the cylinder
In the moving frame the wires cut through the clay and end up criss-crossed,
and with an overall twist.
In the rest frame they wires cut through the clay and end up criss-crossed
but with no overall twist.
Inertial
> Here's a better way to explain things.
Here we go again.
You do realize that no matter WHAT example you show, SR never predicts
different events occurring just because someone else is looking at them.
They may happen in different orders, but the same events still happen.
All one ends up doing is applying LT between the coordinates of those events
(position in space and time) in one frame to find out what their coordinate
are in the other.
> Let's say there is a steel rod
> in the middle of the clay cylinder that extends from the left end to
> the right end.
OK .. seems like its getting more complicated .. not simpler
> Now let the moving frame observers simultaneously
> attach a wire with a tension T1 to the two end rotating disks and to
> the clay surface. Now increase the tension of the wire to T2.
How does this tension increase? It cannot happen simultaneously throughout
the wire. If the tension is applied simultaneously in the rest frame, then
in the moving frame the tension is applied first at one end and then later
at the other. This is quite a complicated thing to analyze from the moving
frame point of view, even in the rest frame it isn't that easy.
Regardless though .. once you work it out in one frame, apply a Lorentz
transform to see what happens from the point of view of an observer in some
other frame.
DSeppala
>
> - Show quoted text -
Okay, we agree that the wires cut through the clay and get crossed in
both frames.
Now two questions.
1. Why does the moving frame say the wires get crossed when the
tension is increased?
2. If, prior to attaching the wires, the wires are already at that
tension that results in the wires getting crossed, when the moving
frame simultaneously attaches the wires to the left and right disks
and to the surface of the rotating cylinder, what causes some points
on one of the wires to rotate differently then the same points on the
other wire (for the 2 wire case). With the tension devices every 1
kilometer we can adjust the tension very slowly, say over 100 years.
By the way, two physics professors that have been helping me,
believe that the wires never get crossed. They stated that high
rotation velocities cause the wires to "loop" in all frames, so that
they never cross. That is why in this posting I specifically stated
the diameter as 1 meter and the rotation rate as 1 revolution per day,
and used a soft clay rotating cylinder to span the space between the
left and right rotating disks. With these parameters, they haven't
been able to explain why the wires get crossed at a cylinder length of
one meter and 10 kilometers, but not at a length of 1 light-year.
David
Inertial
Because it is seeing the sections of wire and cylinder as they are at
different times in the rest frame
> 2. If, prior to attaching the wires, the wires are already at that
> tension that results in the wires getting crossed,
The tension makes the wires shorter .. if they were at that high tensions
then you could not attach them in either frame without them cutting thru the
clay
> when the moving
> frame simultaneously attaches the wires to the left and right disks
> and to the surface of the rotating cylinder, what causes some points
> on one of the wires to rotate differently then the same points on the
> other wire (for the 2 wire case). With the tension devices every 1
> kilometer we can adjust the tension very slowly, say over 100 years.
>
> By the way, two physics professors that have been helping me,
> believe that the wires never get crossed. They stated that high
> rotation velocities cause the wires to "loop" in all frames, so that
> they never cross.
There is no high rotation velocity ..so its a different problem
> That is why in this posting I specifically stated
> the diameter as 1 meter and the rotation rate as 1 revolution per day,
> and used a soft clay rotating cylinder to span the space between the
> left and right rotating disks. With these parameters, they haven't
> been able to explain why the wires get crossed at a cylinder length of
> one meter and 10 kilometers, but not at a length of 1 light-year.
The length makes no difference
Sue...
> This is a simple practical experiment to do at short distances. To
> see relativistic effects, an identical gedanken experiment can be done
> at very long distances. I challange anyone to explain why they think
> the experimental result is different at very long distances. If the
> experimental results are indeed the same, then Einstein's notions of
> space and time don't seem to work.
It is explained just below the illustration.
http://www.anl.gov/Careers/Education/rube/rubeolive.html
Sue...
[...]
> David Seppala
> Bastrop, TX
eric gisse
[...]
He has been doing these stupid scenarios for more than a decade now. He
learns nothing, and will repeat the exercise a few days to a few weeks after
the last time someone talked to him. Just watch.
DSeppala
millimeter apart, and the moving frame simultaneously attaches them to
positions on the left and right rotating disks and on the surface of
the rotating cylinder 1 millimeter apart, they are initially parallel
(as viewed in the moving frame). When the tension on wire A is
increased indentically and simultaneously with the tension on wire B,
what causes wire B to move differently then wire A as they rotate, so
that they eventually cross?
David
eric gisse
[...]
> If we have two straight wires side by side, called A and B, say 1
> millimeter apart, and the moving frame simultaneously attaches them to
> positions on the left and right rotating disks and on the surface of
> the rotating cylinder 1 millimeter apart, they are initially parallel
> (as viewed in the moving frame). When the tension on wire A is
> increased indentically and simultaneously with the tension on wire B,
> what causes wire B to move differently then wire A as they rotate, so
> that they eventually cross?
> David
Does the answer matter, David? You've had more than a decade of asking
questions *just like this* to figure it out and no such luck so far.
Inertial
Yes .. but not in the rest frame
> When the tension on wire A is
> increased indentically and simultaneously with the tension on wire B,
In which frame? Simultaneously in one is not simultaneously in the other.
I assume you mean the moving frame.
> what causes wire B to move differently then wire A as they rotate, so
> that they eventually cross?
They don't move differently.
Androcles
"eric gisse" <jowr.pi...@gmail.com> wrote in message
news:hi8q3d$2kb$1...@news.eternal-september.org...
> Inertial wrote:
>
> [...]
>
[...]
Androcles
> DSeppala wrote:
>
> [...]
[...]
YBM
That's enough : http://netreport.virginmedia.com
Cut Internet access to this old fart.