KINEMATICS AND DYNAMICS IN SPECIAL RELATIVITY

http://philsci-archive.pitt.edu/5243...ity_Frisch.pdf
Principle or constructive relativity
Mathias Frisch, University of Maryland
pp. 3-4: "Brown, as Janssen and others read him, appears to believe
that only an account of the particular forces pushing and pulling the
microscopic constituents of a rod can explain length contraction;
Janssen by contrast, maintains that the structure of Minkowski
spacetime explains the phenomenon and that explanatory advantage of
Einstein's theory over Lorentz's consists precisely in the fact that
the special theory of relativity teaches us that certain phenomena are
independent on the detailed assumptions about the dynamics governing a
particular system. Brown argues that the behavior of rods and clocks
ultimately calls for a dynamical explanation; while Janssen argues
that the explanation is kinematic."

Of course Harvey Brown is right and Michel Janssen wrong but special
relativity is doomed anyway: the prediction that arbitrarily long rods
can be trapped inside arbitrarily short containers can have neither a
dynamical nor a kinematic explanation:

http://math.ucr.edu/home/baez/physic...barn_pole.html
"These are the props. You own a barn, 40m long, with automatic doors
at either end, that can be opened and closed simultaneously by a
switch. You also have a pole, 80m long, which of course won't fit in
the barn. Now someone takes the pole and tries to run (at nearly the
speed of light) through the barn with the pole horizontal. Special
Relativity (SR) says that a moving object is contracted in the
direction of motion: this is called the Lorentz Contraction. So, if
the pole is set in motion lengthwise, then it will contract in the
reference frame of a stationary observer.....So, as the pole passes
through the barn, there is an instant when it is completely within the
barn. At that instant, you close both doors simultaneously, with your
switch. Of course, you open them again pretty quickly, but at least
momentarily you had the contracted pole shut up in your barn. The
runner emerges from the far door unscathed.....If the doors are kept
shut the rod will obviously smash into the barn door at one end. If
the door withstands this the leading end of the rod will come to rest
in the frame of reference of the stationary observer. There can be no
such thing as a rigid rod in relativity so the trailing end will not
stop immediately and the rod will be compressed beyond the amount it
was Lorentz contracted. If it does not explode under the strain and it
is sufficiently elastic it will come to rest and start to spring back
to its natural shape but since it is too big for the barn the other
end is now going to crash into the back door and the rod will be
trapped IN A COMPRESSED STATE inside the barn."

http://www.quebecscience.qc.ca/Revolutions
Stéphane Durand: "Pour mieux comprendre le phénomène de ralentissement
du temps, il est préférable d'aborder un autre phénomène tout aussi
paradoxal: la contraction des longueurs. Car la vitesse affecte non
seulement l'écoulement du temps, mais aussi la longueur des objets.
Ainsi, une fusée en mouvement apparaît plus courte que lorsqu'elle est
au repos. Là aussi, plus la vitesse est grande, plus la contraction
est importante. Et, comme pour le temps, les effets ne deviennent
considérables qu'à des vitesses proches de celle de la lumière. Dans
la vie de tous les jours, cette contraction est imperceptible.
Cependant, si une fusée de 100 m passait devant nous à une vitesse
proche de celle de la lumière, elle pourrait sembler ne mesurer que 50
m, ou même moins. Bien sûr, la question qui vient tout de suite à
l'esprit est: «Cette contraction n'est-elle qu'une illusion?» Il
semble tout à fait incroyable que le simple mouvement puisse comprimer
un objet aussi rigide qu'une fusée. Et pourtant, la contraction est
réelle... mais SANS COMPRESSION physique de l'objet! Ainsi, une fusée
de 100 m passant à toute vitesse dans un tunnel de 60 m pourrait être
entièrement contenue dans ce tunnel pendant une fraction de seconde,
durant laquelle il serait possible de fermer des portes aux deux
bouts! La fusée est donc réellement plus courte. Pourtant, il n'y a
PAS DE COMPRESSION matérielle ou physique de l'engin."

Pentcho Valev

http://hyperphysics.phy-astr.gsu.edu.../bugrivet.html
"The bug-rivet paradox is a variation on the twin paradox and is
similar to the pole-barn paradox.....The end of the rivet hits the
bottom of the hole before the head of the rivet hits the wall. So it
looks like the bug is squashed.....All this is nonsense from the bug's
point of view. The rivet head hits the wall when the rivet end is just
0.35 cm down in the hole! The rivet doesn't get close to the
bug....The paradox is not resolved."

The bug-rivet "paradox" (more precisely, the bug-rivet ABSURDITY, one
of the idiotic consequences of Einstein's 1905 false constent-speed-of-
light postulate) initially acts like the face of Medusa the Gorgon -
on seeing it, Einsteinians get petrified for a while. Then they
somehow recover themselves but enter a phase of irrepressible
bubbling:

http://groups.google.com/group/sci.p...c7f644c331d846
Tom Roberts: "OK. That is a rather bad gedanken, because a) it assumes
seriously impossible properties of the rivet, and b) there is no
inertial frame in which the rivet REMAINS at rest. I have no desire to
discuss it because it is so bad. That's probably why I had forgotten
it. If you want to discuss the pole-barn paradox... (...) My point is:
some things are reasonable to assume in a gedanken, and some are not.
It is reasonable to assume that doors can open and close arbitrarily
quickly, because they need not really be physical doors. But it is not
reasonable to assume a rivet is prefectly rigid, because that is
inconsistent with SR (the speed of sound cannot exceed the speed of
light, which makes a perfectly rigid object impossible). And it is not
reasonable in a gedanken to expect the student to wrestle with
accelerating frames (such as that of the rigid rivet after its head
stops by hitting the wall). Of course in the bug-and-rivet gedanken,
if one does not assume infinitely-rigid rivet and wall, the bug is
always crushed as the rivet and wall disintegrate upon impact. A 10-
gram rivet traveling at 0.9 c would have a kinetic energy comparable
to that of a small atomic bomb."

Pentcho Valev

The following quotation in fact proves that the speed of light is
variable (varies with the speed of the emitter) IF LENGTH CONTRACTION
IS ABSURD:

http://www.amazon.com/Relativity-Its.../dp/0486406768
"Relativity and Its Roots" By Banesh Hoffmann
"Moreover, if light consists of particles, as Einstein had suggested
in his paper submitted just thirteen weeks before this one, the second
principle seems absurd: A stone thrown from a speeding train can do
far more damage than one thrown from a train at rest; the speed of the
particle is not independent of the motion of the object emitting it.
And if we take light to consist of particles and assume that these
particles obey Newton's laws, they will conform to Newtonian
relativity and thus automatically account for the null result of the
Michelson-Morley experiment without recourse to contracting lengths,
local time, or Lorentz transformations. Yet, as we have seen, Einstein
resisted the temptation to account for the null result in terms of
particles of light and simple, familiar Newtonian ideas, and
introduced as his second postulate something that was more or less
obvious when thought of in terms of waves in an ether."

So the crucial question is: IS LENGTH CONTRACTION ABSURD? The
following examples prove it is:

http://math.ucr.edu/home/baez/physic...barn_pole.html
"These are the props. You own a barn, 40m long, with automatic doors
at either end, that can be opened and closed simultaneously by a
switch. You also have a pole, 80m long, which of course won't fit in
the barn. Now someone takes the pole and tries to run (at nearly the
speed of light) through the barn with the pole horizontal. Special
Relativity (SR) says that a moving object is contracted in the
direction of motion: this is called the Lorentz Contraction. So, if
the pole is set in motion lengthwise, then it will contract in the
reference frame of a stationary observer.....So, as the pole passes
through the barn, there is an instant when it is completely within the
barn. At that instant, you close both doors simultaneously, with your
switch. Of course, you open them again pretty quickly, but at least
momentarily you had the contracted pole shut up in your barn. The
runner emerges from the far door unscathed.....If the doors are kept
shut the rod will obviously smash into the barn door at one end. If
the door withstands this the leading end of the rod will come to rest
in the frame of reference of the stationary observer. There can be no
such thing as a rigid rod in relativity so the trailing end will not
stop immediately and the rod will be compressed beyond the amount it
was Lorentz contracted. If it does not explode under the strain and it
is sufficiently elastic it will come to rest and start to spring back
to its natural shape but since it is too big for the barn the other
end is now going to crash into the back door and the rod will be
trapped IN A COMPRESSED STATE inside the barn."

http://www.quebecscience.qc.ca/Revolutions
Stéphane Durand: "Pour mieux comprendre le phénomène de ralentissement
du temps, il est préférable d'aborder un autre phénomène tout aussi
paradoxal: la contraction des longueurs. Car la vitesse affecte non
seulement l'écoulement du temps, mais aussi la longueur des objets.
Ainsi, une fusée en mouvement apparaît plus courte que lorsqu'elle est
au repos. Là aussi, plus la vitesse est grande, plus la contraction
est importante. Et, comme pour le temps, les effets ne deviennent
considérables qu'à des vitesses proches de celle de la lumière. Dans
la vie de tous les jours, cette contraction est imperceptible.
Cependant, si une fusée de 100 m passait devant nous à une vitesse
proche de celle de la lumière, elle pourrait sembler ne mesurer que 50
m, ou même moins. Bien sûr, la question qui vient tout de suite à
l'esprit est: «Cette contraction n'est-elle qu'une illusion?» Il
semble tout à fait incroyable que le simple mouvement puisse comprimer
un objet aussi rigide qu'une fusée. Et pourtant, la contraction est
réelle... mais SANS COMPRESSION physique de l'objet! Ainsi, une fusée
de 100 m passant à toute vitesse dans un tunnel de 60 m pourrait être
entièrement contenue dans ce tunnel pendant une fraction de seconde,
durant laquelle il serait possible de fermer des portes aux deux
bouts! La fusée est donc réellement plus courte. Pourtant, il n'y a
PAS DE COMPRESSION matérielle ou physique de l'engin."

http://hyperphysics.phy-astr.gsu.edu.../bugrivet.html
"The bug-rivet paradox is a variation on the twin paradox and is
similar to the pole-barn paradox.....The end of the rivet hits the
bottom of the hole before the head of the rivet hits the wall. So it
looks like the bug is squashed.....All this is nonsense from the bug's
point of view. The rivet head hits the wall when the rivet end is just
0.35 cm down in the hole! The rivet doesn't get close to the
bug....The paradox is not resolved."

Pentcho Valev

http://www.math.upatras.gr/~weele/fi...aper%2064).pdf
Beyond the pole-barn paradox: How the pole is caught
J.P. van der Weele and J.H. Snoeijer
Mathematics Department, Division of Applied Analysis, University of
Patras, 26500 Patras, Greece
Laboratoire de Physique et Mécanique des Milieux Hétérogènes, ESPCI,
10 rue Vauquelin, 75005 Paris, France, Present address: School of
Mathematics, University of Bristol, University Walk, Bristol BS8 1TW,
United Kingdom
E-mail: ;
"One of the most popular paradoxes of Special Relativity, appearing in
almost every course on the subject, is the pole-barn paradox. It can
be stated as follows: A farmer, who owns a barn 4 m long and a ladder
of length 5 m, would like to fit the ladder inside the barn. To
accomplish this, he plans to use the Lorentz contraction, i.e., the
relativistic effect that objects 'shrink' when moving with constant
velocity with respect to an observer. (...) ...in the farmer's frame
(normal-sized barn, shortened ladder) the ladder is completely inside
the barn between tB and tA. (...) Now we come to the actual catching
of the ladder. Let us assume that the farmer closes the barn at some
moment between tB and tA, when the ladder (in his reference frame) is
inside the barn. (...) The ladder will of course not fit nicely: it
will bend, or break, or poke through the door. But the fact is that it
is caught."

A dynamical explanation? A kinematic explanation? What prevents
scientists from admitting or at least suspecting that this "bend, or
break, or poke through the door", on close inspection, is just absurd
and apply REDUCTIO AD ABSURDUM? If the conclusion (length contraction)
is absurd, then the premise (Einstein's 1905 constant-speed-of-light
postulate) is false.

Pentcho Valev

Albert Einstein and John Norton explain the twin paradox:

http://en.wikisource.org/wiki/Dialog...f_rela tivity
Dialog about Objections against the Theory of Relativity (1918), by
Albert Einstein
"...according to the special theory of relativity the coordinate
systems K and K' are by no means equivalent systems. Indeed this
theory asserts only the equivalence of all Galilean (unaccelerated)
coordinate systems, that is, coordinate systems relative to which
sufficiently isolated, material points move in straight lines and
uniformly. K is such a coordinate system, but not the system K', that
is accelerated from time to time. Therefore, from the result that
after the motion to and fro the clock U2 is running behind U1, no
contradiction can be constructed against the principles of the theory.
(...) During the partial processes 2 and 4 the clock U1, going at a
velocity v, runs indeed at a slower pace than the resting clock U2.
However, this is more than compensated by a faster pace of U1 during
partial process 3. According to the general theory of relativity, a
clock will go faster the higher the gravitational potential of the
location where it is located, and during partial process 3 U2 happens
to be located at a higher gravitational potential than U1. The
calculation shows that this speeding ahead constitutes exactly twice
as much as the lagging behind during the partial processes 2 and 4.
This consideration completely clears up the paradox that you brought
up."

http://www.pitt.edu/~jdnorton/teachi...yon/index.html
John Norton: "Now consider the judgments of simultaneity of the
traveling twin, as shown in the spacetime diagram opposite. Since the
traveling twin is moving very rapidly, the traveler's hypersurfaces of
simultaneity are quite tilted. Two hypersurfaces of simultaneity are
shown in the lower part of the diagram for the outward part of the
traveler's journey. These are the hypersurfaces that pass through the
event at which the clock reads 1 day and just before the turn-around
at the traveler's clock time of 2 days. We read from these
hypersurfaces that the traveling twin judges the stay-at-home twin's
clock to be running at half the speed of the travelers. When the
traveler's clock reads 1 day, the stay-at-home twin's reads 1/2 day;
just before the turn around, when the traveler's clock is almost at 2
days, the stay-at-home twin's clock is almost at 1 day. Then, at the
end of the outward leg, the traveler abruptly changes motion,
accelerating sharply to adopt a new inertial motion directed back to
earth. What comes now is the key part of the analysis. The effect of
the change of motion is to alter completely the traveler's judgment of
simultaneity. The traveler's hypersurfaces of simultaneity now flip up
dramatically. Moments after the turn-around, when the travelers clock
reads just after 2 days, the traveler will judge the stay-at-home
twin's clock to read just after 7 days. That is, the traveler will
judge the stay-at-home twin's clock to have jumped suddenly from
reading 1 day to reading 7 days. This huge jump puts the stay-at-home
twin's clock so far ahead of the traveler's that it is now possible
for the stay-at-home twin's clock to be ahead of the travelers when
they reunite."

Note the statement:

"the traveler will judge the stay-at-home twin's clock to have jumped
suddenly from reading 1 day to reading 7 days"

Is this sane? If yes, does it have a dynamical explanation? A
kinematic explanation? What if nobody cares? Could science be more
dead?

Pentcho Valev

http://www.parabola.unsw.edu.au/vol3...ol35_no1_2.pdf
Parabola Volume 35, Issue 1 (1999)
LENGTH AND RELATIVITY by John Steele
"The Pole in the Barn Paradox. Now we know about length contraction,
we can invent some amusing uses of it. Suppose you want to fit a 20m
pole into a 10m barn. If the pole were moving fast enough, then length
contraction means it would be short enough. (...) Now comes the
paradox. According to your friend who is going to slam the barn doors
shut just as the end of the pole goes in, the pole is 10m long, and
therefore it fits. However as far as you are concerned, the pole is
still 20m long but the barn is now only 5m long: length contraction
must work both ways by the first postulate. How can you fit this 20m
pole into a 5m barn? This paradox is apparently due to Wolfgang
Rindler of the University of Texas at Dallas. Of course the key to
this is relativity of simultaneity. Your friend sees the front end of
the pole hit the back wall of the barn at the same time as the doors
are closed, but you (and the pole) do not see things this way. You are
standing still and see a 5m long barn coming towards you at some
shockingly high speed. When the back of the barn hits the front of the
pole (and takes the front of the pole with it), the back end of the
pole must still be at rest. It cannot 'know' about the crash at the
front, because the shock wave travelling along the pole telling it
about the crash travels at some finite speed. The front of the barn
has only 15m to go to get to the back of the pole, but the shock wave
has to travel the whole length of the pole, namely 20m. The speed of
the barn is such that even if this shock wave travelled at the speed
of light, it would not get to the back of the pole before the front of
the barn did. Hence in both frames of reference, the pole fits inside
the barn (and will presumably shatter when the doors are closed)."

A dynamical explanation? The kinematic explanation is quite
straightforward:

http://www.ias.umn.edu/pdf/TimeandRe...ty-Janssen.pdf
Michel Janssen: "Does Minkowski space-time, thus understood, explain
length contraction and the phenomena examined in this talk? Yes and
no. It explains them by showing they need no explanation."

Pentcho Valev