Description:
Discussion sur les mathématiques.
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Question trigo...
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Bonjour à tous,
J'aurais besoin d'aide : je connais les 4 longueurs d'un quadrilatère (au début je pensais avoir des trapèzes, mais apparemment ce n'est pas acquis), et je voudrais savoir les angles. Y-a-t-il une méthode pas trop compliquée ?
C'est pour un bricolage en papier de soie dans la classe de mon gamin !... more »
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THE PROTECTIVE BELT OF SPECIAL RELATIVITY
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[link] "Relativity and Its Roots" By Banesh Hoffmann, p.92: "There are various remarks to be made about this second principle. For instance, if it is so obvious, how could it turn out to be part of a revolution - especially when the first principle is also a natural one? 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. If it was so obvious, though, why did he need to state it as a principle? Because, having taken from the idea of light waves in the ether the one aspect that he needed, he declared early in his paper, to quote his own words, that "the introduction of a 'luminiferous ether' will prove to be superfluous."... more »
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fr.sci.maths
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Archive-Name: fr/chartes/sci.maths
WWW-Archive-Name: <[link]>
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= Conseils d'utilisation du groupe fr.sci.maths =
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EINSTEIN'S 1905 THIRD ASSUMPTION
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In 1905 Einstein deduced special relativity from two explicit assumptions - the principle of relativity is valid and the speed of light is independent of the speed of the light source. Yet there was a third assumption, implicit and obviously idiotic:
Assumption 3: The motion of the observer changes the wavelength of light. As the observer starts moving towards the light source with speed v, his motion shifts the wavelength from L to cL/(c+v) so that the product:... more »
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Conjecture des deux corps finis
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Que pensez vous de cette publication inédite parue récemment et dont je suis l'auteur principal?
[link] L'annexe de la publication concerne les étapes du chiffrement effectué à l'aide de l'algorithme SED lequel est constitué de deux corps finis avec des trinômes caractéristiques primitifs différents. Le fichier "ALGOSEDC1.PDF" (voir $) concerne les étapes du chiffrement pour l'algorithme constitué à l'aide de deux corps finis réalisés avec deux polynômes caractéristiques primitifs différents. Le fait de la restitution du bloc clair après le déchiffrement confirme la faisabilité de l'existence d'une quasi infinité d'algorithmes de chiffrement issus de la conjecture des deux corps finis.... more »
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SCIENCE IN A MESS
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[link] "In 2010 Stephen Hawking, in The Grand Design, announced that philosophy was "dead" because it had "not kept up with modern developments in science, particularly physics". He was not referring to ethics, political theory or aesthetics. He meant metaphysics, the branch of philosophy that aspires to the most general understanding of nature – of space and time, the fundamental stuff of the world. If philosophers really wanted to make progress, they should abandon their armchairs and their subtle arguments, wise up to maths and listen to the physicists. This view has significant support among philosophers in the English-speaking world. Bristol philosopher James Ladyman, who argues that metaphysics should be naturalised, and who describes the accusation of "scientism" as "badge of honour", is by no means an isolated case. But there could not be a worse time for philosophers to surrender the baton of metaphysical inquiry to physicists. Fundamental physics is in a metaphysical mess and needs help. The attempt to reconcile its two big theories, general relativity and quantum mechanics, has stalled for nearly 40 years."... more »
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recherche l'équation d'une courbe
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bonjour,
sur l'excellent site "mathcurve", il est question de courbes bicylindrique.
en partant de l' quation cart sienne donn e sur la page : <[link]>
j'essaye de tracer une de ces courbes "utilis e par le joaillier... more »
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