Henri Poincaré, Quanta hypothesis: Quanta of action

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The new design is seductive by a certain side; for some time the tendency has been to atomism, matter appears to us as formed of indivisible atoms, and the electricity is no longer continuous, it is no longer divisible to … Read More

Henri Poincaré, Quanta hypothesis: More on quanta of energy

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Statistical equilibrium can only be established if there is exchange of energy between the resonators, otherwise each resonator would retain its initial energy, which is arbitrary, indefinitely, and the final distribution would obey no law. This exchange could not be … Read More

Henri Poincaré, Quanta hypothesis: Quanta of energy

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The explanation of these phenomena must be sought without making a clean sweep of the principles of Thermodynamics; above all, we must admit the possibility of statistical equilibrium, otherwise nothing would remain of Carnot’s principle; we cannot admit, in Thermodynamics, … Read More

Henri Poincaré, Quanta hypothesis: The law of radiation

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Physicists did not at first concern themselves with these difficulties, but two new facts changed the face of things; the first is what is called the law of black radiation. A perfectly black body is one whose absorption coefficient is … Read More

Henri Poincaré, Quanta hypothesis: Thermodynamics and probability

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Let us go back to the kinetic theory of gases; the gases are formed of molecules which circulate in all directions with great velocities; their trajectories would be rectilinear if from time to time they did not collide each other, … Read More

Henri Poincaré, Quanta hypothesis

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One wonders if Mechanics is not on the eve of a new upheaval; recently a meeting was held at Brussels, attended by some twenty physicists of various nationalities, and at each moment they might have been heard to speak of … Read More

Henri Poincaré, Mathematics and logic

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A few years ago, I had the opportunity to expose some ideas about the logic of the infinite; on the use of the infinite in Mathematics, on the use made of it since Cantor; I explained why I did not … Read More

Henri Poincaré, The logic of infinity: An overview

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The antinomies to which certain logicians have been led come from the fact that they could not avoid certain vicious circles. It happened to them when they considered finite collections, but it happened to them much more often when they … Read More

Henri Poincaré, The logic of infinity: The use of infinity

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Is it possible to reason about objects that can notbe defined in a finite number of words? Is it even possible to talk about it knowing what one is talking about, and by saying something other than empty words? Or … Read More

Henri Poincaré, The logic of infinity: The memory of Mr. Zermelo

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It is in a totally different direction that Mr. Zermelo is seeking the solution of the difficulties we have pointed out. He tries to establish a system of axioms a priori, which must allow him to establish all the mathematical … Read More

Henri Poincaré, The logic of infinity: Axiom of reducibility

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Russell introduces a new axiom which he calls axiom of reducibility. As I’m not sure I fully understood his thought, I will let him speak. “We assume, that every function is équivalent, for ail its value to some predicative function … Read More

Henri Poincaré, The logic of infinity: The memory of Mr. Russel

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Russell published in the American Journal of Mathematics, vol. XXX, under the title Mathematical Logics as Based on the Theory of Types, a memoir in which he relies on considerations quite similar to those which precede. After recalling some of … Read More

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