Re: Can anyone describe the differences here?
- From: David <dseppala@xxxxxxxxxxxxx>
- Date: Sat, 17 Jun 2006 04:51:02 GMT
On 15 Jun 2006 07:20:12 -0700, actionintegral@xxxxxxxxx wrote:
In this example (and many similar examples), prior to time t0, there
David wrote:
The situation I'm trying to understand is where two frames agree that
the rod is a certain shape before time t0 and after time t0 one frame
says the rod hasn't changed shape or length while the other frame says
that the rod has changed shape and length.
Please help me try to understand your question. Here is my starting
point:
Any change in shape or simultaneity is caused by the Lorentz
Transformation.
This transformation is assumed remain unchanged for all time prior to
and after t0.
So any disagreement the two frames have will always exist. A contracted
rod will
always be contracted. A slow wristwatch will always be a slow
wristwatch.
There is no time t0 when the frames suddenly begin to disagree.
I apologize if I am not understanding you.
is a straight rod near the surface of a rotating cylinder. The rod
and cylinder have zero relative velocity, and they are both aligned
along the x-axis. Now consider two inertial frames, the rest frame of
the cylinder and an inertial frame moving along the x-axis. In both
of these frames, the rod near the surface of the cylinder is measured
to be a straight line. The observers in the rest frame of the
cylinder measure the unattached rod to be a straight line and
observers in the moving frame measure the unattached rod to be a
straight line.
Now at time t0 as measured in the moving frame, all points of the rod
are attached to the surface of the cylinder parallel to the x-axis. In
this frame, the moving frame observers simply place the straight rod
on to the surface of the cylinder. It remains straight as measured by
the moving frame observers and each point of the rod begins rotating
at a constant rate around the cylinder. The moving frame observers
continue to measure the attached rod as being a straight line.
But according to Einstein, when the moving frame observers
simultaneously placed each point of the rod on to the surface of the
cylinder, the observers in the rest frame observed that one end of the
rod was placed on the surface of the cylinder before the other end.
Since the cylinder is rotating, this means that the rod has to be bent
and shaped into a spiral as it is attached. These rest frame
observers see that the unattached rod was a straight line, and that
the same rod when it is attached is bent into a spiral shape.
I don't understand how the moving frame observers can continue to
measure that the attached rod is still straight yet it doesn't have
all the properties one would expect with a straight rod. I don't see
how the difference in properties is explained using SR physics
concepts.
David
.
- References:
- Can anyone describe the differences here?
- From: David
- Re: Can anyone describe the differences here?
- From: actionintegral
- Re: Can anyone describe the differences here?
- From: David
- Re: Can anyone describe the differences here?
- From: actionintegral
- Can anyone describe the differences here?
- Prev by Date: Re: two rockets, opposite directions, relativity problem
- Next by Date: Re: Since k varies but not G suggests an Eather
- Previous by thread: Re: Can anyone describe the differences here?
- Next by thread: Re: Can anyone describe the differences here?
- Index(es):
Relevant Pages
|
