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Topic: « Monsieur, personnellement, je ne suis pas d'accor
d avec Einstein... »

Replies: 8   Last Post: Oct 8, 2013 8:41 AM

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Pentcho Valev

Posts: 5,006
Registered: 12/13/04
« Monsieur, personnellement, je ne suis pas d'accor
d avec Einstein... »

Posted: Sep 18, 2013 2:21 AM
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Etienne Klein: "Récemment, j'ai eu l'occasion de donner un cours de relativité (et non de relativisme...) à de futurs ingénieurs. Alors que je venais d'effectuer un calcul montrant que la durée d'un phénomène dépend de la vitesse de l'observateur, un étudiant prit la parole : « Monsieur, personnellement, je ne suis pas d'accord avec Einstein ! » J'imaginai qu'il allait défendre une théorie alternative, ou bien réinventer l'éther luminifère, en tout cas qu'il allait argumenter. Mais il se contenta de dire : « Je ne crois pas à cette relativité des durées que vous venez de démontrer, parce que je ne la... sens pas ! » Là, j'avoue, j'ai éprouvé une sorte de choc : ce jeune homme qui n'avait certainement pas lu Einstein avait suffisamment confiance dans son « ressenti » personnel pour s'autoriser à contester un résultat qu'un siècle d'expériences innombrables avait cautionné."

Un vieux homme qui avait certainement lu Einstein mais quand même contestait le fameux résultat:
Herbert Dingle, SCIENCE AT THE CROSSROADS, p.27: "According to the special relativity theory, as expounded by Einstein in his original paper, two similar, regularly-running clocks, A and B, in uniform relative motion, must work at different rates.....How is the slower-working clock distinguished? The supposition that the theory merely requires each clock to APPEAR to work more slowly from the point of view of the other is ruled out not only by its many applications and by the fact that the theory would then be useless in practice, but also by Einstein's own examples, of which it is sufficient to cite the one best known and most often claimed to have been indirectly established by experiment, viz. 'Thence' [i.e. from the theory he had just expounded, which takes no account of possible effects of accleration, gravitation, or any difference at all between the clocks except their state of uniform motion] 'we conclude that a balance-clock at the equator must go more slowly, by a very small amount, than a precisely similar clock situated at one of the poles under otherwise identical conditions.' Applied to this example, the question is: what entitled Einstein to conclude FROM HIS THEORY that the equatorial, and not the polar, clock worked more slowly?"

L'auteur du fameux résultat qui en 1918 recourt à une élucubration ("this is more than compensated by a faster pace of U1 during partial process 3") pour sortir de l'impasse:
Dialog about Objections against the Theory of Relativity, 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."

Etienne Klein sait que le jeune étudiant avait raison et que le fameux résultat est faux mais ne peut faire rien: il veut rester le physicien le plus beau, le mieux habillé, le plus riche et le plus intelligent en France:
- Est-ce que tu m'admires vraiment beaucoup ? demanda-t-il au petit prince.
- Qu'est-ce que signifie admirer ?
- Admirer signifie reconnaître que je suis l'homme le plus beau, le mieux habillé, le plus riche et le plus intelligent de la planète.
- Mais tu es seul sur ta planète !
- Fais-moi ce plaisir. Admire-moi quand même !

Pentcho Valev

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