# Re: Problem with Fermi-Walker Transport in the Physics FAQ file

On Jul 31, 4:05 am, Dono <sa...@xxxxxxxxxxx> wrote:
On Jul 30, 11:00 pm, "John M. Dlugosz" <11lrha...@xxxxxxxxxxxxxx>
wrote:

I'm editing some of the Physics FAQ files, some just to fix the 10-
year-old converted HTML, general copyediting, and such. But when the
muse descends ...

In the page on "Bell's Spaceship Paradox", my initial effort was to
supply all the illustrations that are left to the imagination of the
reader. I'm also expanding and clarifying the text.

My draft in progress can be seen at <http://www.dlugosz.com/files/
PhysFAQ-edit/Relativity/SR/spaceship_puzzle.html>.

My question to the group concerns Figure 4. I followed the
instructions in the original text, seen in the paragraph before the
figure, and the two lines intersect! Based on the following
paragraph, that should not happen, and the ship that starts out on the
right should remain on the right, but draw ever closer in the lab-
frame.

What is going on here? Clearly the "K" in this formula is not at all
related to the "k" used earlier, since the directions say "K>1" and
the earlier "k" is the x-distance between ships in the lab-frame at
launch. The units of space would make ">1" nonsense (one what?).

In the Figure, the vertical height is 1 unit (-0.0325 through 0.9625)
and the function iterates over t in that range. K=2. The original
curve (and the left curve here) is the same function with K=1. Now,
on the left curve, as with all the previous figures, note that the
hyperbola appears just a few pixels right of the t axis. The function
as written would give an x intercept of 1, so the illustration would
have to be as wide as it is tall before you even start to see the
curve. The two ships differ in their starting position, so the curves
are shifted left by a different constant x for each ship. In Figure
4, the right curve is also shifted left to the same starting position
as the second ship is always drawn at, though the natural position of
the stated function is even farther right (intersects the x axis at
x=K).

Is that an issue? The text does NOT say that the ships have to be a
minimum distance apart to begin with, so I should think not. Point
is, there is something that the text is not explaining, or perhaps a
simple error in a symbol somewhere.

Could someone who understands this please take a close look at it?

Thanks,
--John

John

I couldn't see the page in cause, the link malfunctioned. Either way,
wiki provides a reasonable (not the bset) explanation here:

http://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox

<<
-Analysis
In the following analysis we will treat the spaceships as point masses
and only consider the length of the string. >>
http://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox#Analysis

The Laue Langevin falling neutron experiment,
Tajamar&deMatos detected London moment
Gravity probe B analysis to-date
and molecular dynamics simulations should
prompt some skepticism in the *physics* community
where gravitational/inertial interactions are treated
as a point particle.

http://www.aip.org/pnu/2002/573.html
http://www.esa.int/SPECIALS/GSP/SEM0L6OVGJE_0.html
http://einstein.stanford.edu/
http://www.research.ibm.com/grape/grape_ewald.htm

Induction forces are quite good at mimicking
point sources like radiation forces... but they are not
the same in many respects.

<< If gravity is an electrostatic induced dipole-dipole
force between the fundamental particles of normal matter,
then it cannot be shielded because all matter, whether
charged or not, will participate. And herein lies the
difficulty for antigravity devices. >>
http://www.holoscience.com/news.php?article=r4k29syp
http://www.chem.purdue.edu/gchelp/liquids/inddip.html
http://www.mypage.bluewin.ch/Bizarre/GRAV.htm

IMHO the whole Bell paradox piece should be moved
to a group whose interest is mathematical-games
because experiments to-date do not support its
assumptions as relevant to the world that physicists
study.

If the paradox has any value, it is a demonstration of
how to use the semantic-oprerator when dedication to
sloppiness or adherence to a popular myth preclude
the use of correct 3 to 4 space transforms.

http://en.wikipedia.org/wiki/Gauge_fixing
http://arxiv.org/abs/physics/0204034

"Relativistic particle dynamics"
http://farside.ph.utexas.edu/teaching/em/lectures/node126.html
<< if you know about complex numbers you will
notice that the space part enters as if it were imaginary

R2 = (ct)2 + (ix)2 + (iy)2 + (iz)2 = (ct)2 + (ir)2

where i^2 = -1 as usual. This turns out to be the
essence of the fabric (or metric) of spacetime
geometry - that space enters in with the imaginary
factor i relative to time. >>
http://www.nrao.edu/~smyers/courses/astro12/speedoflight.html

Sue...

.