LE MONDE SCHIZOPHRÈNE D'EINSTEINIANA

http://www.rehseis.univ-paris-didero...JUMEAUX_A4.pdf
LE PARADOXE DES JUMEAUX
Jeudi 16 juin et vendredi 17 juin, 9h-13h
Université Paris Diderot, salle Klimt, 366 A
"Revenu à la Terre ayant vieilli de deux ans, il sortira de son arche
et trouvera notre globe vieilli de deux cents ans"
ALLER 16 juin
9h Accueil des participants
9h15 Elie DURING et Alexis de SAINT-OURS
Introduction : Histoire d'une fable relativiste
9h30 Jean-Marc LÉVY-LEBLOND
(Université de Nice)
Peut-on déparadoxifier les jumeaux ?
10h30 Alexis de SAINT-OURS
(Université Paris-Diderot / REHSEIS)
Accélération et asymétrie
11h30 Thierry GRANDOU
(Université de Nice / CNRS)
Sur l'origine du paradoxe de Langevin
12h30 Discussion générale
RETOUR 17 juin
9h Point d'étape
9h30 Jean-Pierre LUMINET
(Observatoire de Paris / CNRS)
Si ce n'est toi c'est donc ton frère
10h30 Philippe LOMBARD
(Irem de Lorraine / Archives Poincaré)
Paradoxe des jumeaux et relativité générale
11h30 Elie DURING
(Université Paris Ouest-Nanterre)
En quel sens les jumeaux sont-ils "contemporains" ?
12h30 Discussion générale

Les conclusions du séminai

http://luth2.obspm.fr/~luminet/jumeaux_VF.pdf
Si ce n'est toi c'est donc ton frère ?
Jean-Pierre Luminet
"La vitesse de la lumière dans le vide est la même pour tous les
observateurs, quel que soit leur état de mouvement - il s'agit d'un
fait observé dont Einstein est parti pour construire sa théorie. (...)
L'observateur « en mouvement » se considère, lui, au repos, et voit
l'autre système se mouvoir par rapport à lui. Il voit donc les
horloges de l'autre système ralentir (donc le temps s'allonger) et ses
distances rétrécir. Jusqu'ici, il n'y a pas paradoxe, même s'il paraît
curieux que chacun puisse voir l'autre plus « jeune » et plus petit
qu'il ne se voit lui-même. (...) Prenons maintenant deux horloges qui
sont synchronisées dans le même système de référence. Que se passe-t-
il si l'une des deux part à bord d'un vaisseau spatial et revient au
terme d'un long voyage ? Einstein montre, dans son article de 1905,
qu'à son retour l'horloge voyageuse retarde sur l'horloge au repos.
Autrement dit la symétrie est brisée, les deux points de vue ne sont
pas équivalents. (...) Prenons deux jumeaux dont l'un part vers une
planète lointaine à une vitesse proche de celle de la lumière. A son
retour, le voyageur lit sur sa montre qu'il est parti six ans, alors
que son frère resté sur terre a vieilli de quarante ans. (...) Y a-t-
il pour autant violation du principe de relativité ? Non..."

Mais ce sont les vieilles élucubrations de la "fable relativiste",
Jean-Pierre Luminet. Rien de nouveau? On n'a pas discuté de l'article
de Peter Hayes?

http://homepage.ntlworld.com/academ/...elativity.html
What is wrong with relativity?
G. BURNISTON BROWN
Bulletin of the Institute of Physics and Physical Society, Vol. 18
(March, 1967) pp.7177
"A more intriguing instance of this so-called 'time dilation' is the
well-known 'twin paradox', where one of two twins goes for a journey
and returns to find himself younger than his brother who remained
behind. This case allows more scope for muddled thinking because
acceleration can be brought into the discussion. Einstein maintained
the greater youthfulness of the travelling twin, and admitted that it
contradicts the principle of relativity, saying that acceleration must
be the cause (Einstein 1918). In this he has been followed by
relativists in a long controversy in many journals, much of which ably
sustains the character of earlier speculations which Born describes as
"monstrous" (Born 1956). Surely there are three conclusive reasons why
acceleration can have nothing to do with the time dilation
calculated:
(i) By taking a sufficiently long journey the effects of acceleration
at the start, turn-round and end could be made negligible compared
with the uniform velocity time dilation which is proportional to the
duration of the journey.
(ii) If there is no uniform time dilation, and the effect, if any, is
due to acceleration, then the use of a formula depending only on the
steady velocity and its duration cannot be justified.
(iii) There is, in principle, no need for acceleration. Twin A can get
his velocity V before synchronizing his clock with that of twin B as
he passes. He need not turn round: he could be passed by C who has a
velocity V in the opposite direction, and who adjusts his clock to
that of A as he passes. When C later passes B they can compare clock
readings. As far as the theoretical experiment is concerned, C's clock
can be considered to be A's clock returning without acceleration
since, by hypothesis, all the clocks have the same rate when at rest
together and change with motion in the same way independently of
direction. [fn. I am indebted to Lord Halsbury for pointing this out
to me.] (...) The three examples which have been dealt with above show
clearly that the difficulties are not paradoxes) but genuine
contradictions which follow inevitably from the principle of
relativity and the physical interpretations of the Lorentz
transformations. The special theory of relativity is therefore
untenable as a physical theory."

http://www.informaworld.com/smpp/con...ent=a909857880
Peter Hayes "The Ideology of Relativity: The Case of the Clock
Paradox" : Social Epistemology, Volume 23, Issue 1 January 2009, pages
57-78
"This first appearance of what has become known as time dilation in
Einstein's work requires careful attention. In particular, anyone who
assumes that the special theory deals only with uniform movement in a
straight line and is thus a precisely delineated subset of the later
general theory, will wish to explore why Einstein extends his
conclusions to polygonal and circular movements. It is by no means "at
once apparent" that what is true for a straight line is true for a
polygon, nor that what has been "proved" for a polygon applies to a
circle. The principle of relativity introduced at the outset of the
1905 paper implicitly limited the special theory to reference frames
moving at a constant speed in a straight line with respect to one
another. In later work, Einstein explicitly stated that the special
theory applied only to a reference frame "in a state of uniform
rectilinear and non rotary motion" in respect of a second reference
frame, in contrast to the general theory that dealt with reference
frames regardless of their state of motion (Einstein 1920, 61).
Acceleration, therefore, would appear to be the province of the
general theory. A polygon, however, would seem to necessarily involve
acceleration whenever there is a abrupt alteration in the direction of
travel. Even more confusingly, a circular path, far from allowing
movement at a "constant velocity", has a velocity that continually
changes. Einstein, it is argued, wished to minimise the significance
of acceleration - as he did not mention acceleration at all in the
passage, he could hardly be said to do otherwise (Essen 1971, 13).
With respect to the transition from the straight line to the polygon,
this assumption is corroborated by comments Einstein made in 1911 when
he said that the larger the polygon the less significant the impact of
a sudden change of direction would be.
Einstein 1911: "The [travelling] clock runs slower if it is in uniform
motion, but if it undergoes a change of direction as a result of a
jolt, then the theory of relativity does not tell us what happens. The
sudden change of direction might produce a sudden change in the
position of the hands of the clock. However, the longer the clock is
moving rectilinearly and uniformly with a given speed in a forward
motion, i.e., the larger the dimensions of the polygon, the smaller
must be the effect of such a hypothetical sudden change." (Einstein et
al. 1993, 354)
(...) The argument that the prediction of time difference between a
moving and a stationary clock violates the principle of relativity is
well known. Certainly, it must have become known to Einstein, for in
1918 he created a dialogue in which "Kritikus" voiced exactly this
objection (Einstein 1918). In response to this criticism, Einstein
underwent a volte-face, reversing his reasoning in 1905 and 1911. The
sudden change in direction of the moving clock, far from having
unknown effects that needed to be minimised, was now said to provide
the entire explanation for the change. Instead of imagining a moving
clock travelling in a huge polygon or circle to make sudden changes in
direction as insignificant as possible or the journey as smooth as
possible, Einstein imagined an out and back journey. He then explained
that the slow-down in the moving clock occurred during the sudden jolt
when it went into reverse. (...) Given Einsteins argument in 1918, it
seems inescapable that his 1905 prediction of time dilation was not,
in fact, a "peculiar consequence" of his forgoing account of special
relativity (Einstein 1923, 49). When it is also remembered that in
1904 Lorentz deduced the existence of "local time", it is reasonable
to conclude that the prediction that the clocks would end up showing
different times can be reached without entering into Einstein's
reasoning on the special theory at all. The supporters of Einstein,
however, generally maintain that one needs to move beyond the special
theory to the general theory to understand why the times shown by the
clocks would be different. However, as Einstein's prediction preceded
the general theory, this argument is problematic (Lovejoy 1931, 159;
Essen 1971, 14). It has been seen that: (a) in 1911 Einstein
explicitly rules out the ability of the special theory of relativity
to say what happened if the moving clock suddenly changed direction,
and (b) in 1918 Einstein tacitly admitted that his explanation of the
clock paradox in 1905 was incorrect by transforming the polygonal or
circular journey of the moving clock into an out and back journey. If
the general theory is necessary to explain the clock paradox, then
Einstein must have (a) predicted the effects of acceleration in 1905
even though he did not incorporate them into his theory for another
decade, and (b) hidden his intuition by describing a journey that
discounted their significance. (...) There is, nonetheless, some
divergence about how to resolve the clock paradox amongst mainstream
scientists and philosophers who address the issue. The majority
suggest that (a) the general theory is required to resolve the paradox
because like "Kritikus" they have deduced - quite correctly - that it
cannot be explained by the special theory. However, a minority believe
that (b) the paradox can be explained by the special theory because
they have deduced - again quite correctly - that it is incredible to
suppose that only the general theory can explain a prediction
ostensibly arising from the prior special theory. Each deduction,
considered in isolation, is allowable within the mainstream; what is
not permitted is to bring the two of them together to conclude that
( c) neither the special nor the general theory explains time
dilation. (...) The prediction that clocks will move at different
rates is particularly well known, and the problem of explaining how
this can be so without violating the principle of relativity is
particularly obvious. The clock paradox, however, is only one of a
number of simple objections that have been raised to different aspects
of Einstein's theory of relativity. (Much of this criticism is quite
apart from and often predates the apparent contradiction between
relativity theory and quantum mechanics.) It is rare to find any
attempt at a detailed rebuttal of these criticisms by professional
physicists. However, physicists do sometimes give a general response
to criticisms that relativity theory is syncretic by asserting that
Einstein is logically consistent, but that to explain why is so
difficult that critics lack the capacity to understand the argument.
In this way, the handy claim that there are unspecified, highly
complex resolutions of simple apparent inconsistencies in the theory
can be linked to the charge that antirelativists have only a shallow
understanding of the matter, probably gleaned from misleading popular
accounts of the theory. The claim that the theory of relativity is
logically consistent for reasons that are too complex for non-
professionals to grasp is not only convenient, but is rhetorically
unassailable - as whenever a critic disproves one argument, the
professional physicist can allude to another more abstruse one.
Einstein's transformation of the clock paradox from a purported
expression of the special theory to a purported expression of the much
more complicated general theory is one example of such a defence. A
more recent example is found in Alan Sokal and Jean Bricmont's
scornful account of Henri Bergson's attempt to investigate the clock/
twin paradox. Like "Kritikus", Bergson argued that the asymmetric
outcome of the paradox was incompatible with the principle of
relativity. Like Einstein, Sokal and Bricmont explain that Bergson has
failed to recognise the asymmetric forces of acceleration at work.
They go on to claim that the special theory tells us what happens
under these circumstances and that the general theory only laboriously
leads to the same conclusion. The suggestion that to vindicate this
claim would be laborious functions in the same way as Einstein's
elusive "calculations"; that is, it is not an explanation but an
explanation-stopper. Sokal and Bricmont do not demonstrate how either
the special theory or the general theory explain time dilation. Nor do
they explain how their claim can be reconciled with Einstein
explicitly limiting the special theory to objects travelling at a
uniform velocity, nor account for why the circular journey of 1905
became the out and back journey of 1918. (...) Einstein's theory of
relativity fails to reconcile the contradictory principles on which it
is based. Rather than combining incompatible assumptions into an
integrated whole, the theory allows the adept to step between
incompatible assumptions in a way that hides these inconsistencies.
The clock paradox is symptomatic of Einstein's failure, and its
purported resolution is illustrative of the techniques that can be
used to mask this failure. To uncover to the logical contradictions in
the theory of relativity presents no very difficult task. However, the
theory is impervious to such attacks as it is shielded by a
professional constituency of supporters whose interests and authority
are bound up in maintaining its inflated claims. Relativity theory, in
short, is an ideology."

Pentcho Valev