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

Gravity and gravitational tests

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Gravity has a universal character, but its strength rapidly decreases with distance, being the weakest of the four fundamental forces of physics[1]. In the 4th century BC, the Greek philosopher Aristotle considered as the cause of the fall of heavy … 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: 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

Global warming and gender equality are the priorities of Ursula von der Leyen

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Ursula Gertrud von der Leyen (born Albrecht, on October 8, 1958) is a German politician and elected president of the European Commission. She was Germany’s Defense Minister from 2013 to 2019. Member of the center-right Christian Democratic Union (CDU), she … Read More

Henri Poincaré, The logic of infinity: The cardinal number

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We must not forget the preceding considerations when defining the cardinal number. If we consider two collections, we may seek to establish a law of correspondence between the objects of these two collections, so that any object of the first … Read More

Henri Poincaré, Why space with three dimensions – Analysis Situs (Topology)

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Geometers usually distinguish two kinds of geometries, which they call the first of metric and the second of projective; metric geometry is based on the notion of distance; two figures are regarded as equivalent when they are “equal” in the … Read More

Digital Assembly 2019 – Bucharest, Romania, June 13-14

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The Digital Assembly 2019 is a forum for stakeholders to take stock of the achievements of the Digital Single Market Strategy, draw lessons and to exchange views on the contours of a future digital policy. The event is also a … Read More

Philosophy of physics

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(The wave-particle duality, in which we can see how the same phenomenon can be perceived in two different ways, was one of the philosophical problems posed by quantum mechanics.) The philosophy of physics refers to the set of philosophical reflections … Read More

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