Henri Poincaré: Potential of an electric mass distributed on the surface of a sphere

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Such is the present state of the question; let us see now what is the goal that I have in view; what would have been most interesting would have been to replace the current calculation methods with other less defective … Read More

Henri Poincaré: Solving Dirichlet’s problem

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Dirichlet’s problem reduces to the search for Green’s functions. Let’s find a function V which inside a surface S satisfies Laplace’s equation and on this surface takes given values. Suppose that we have found a function U which is finite, … Read More

Henri Poincaré: Dirichlet problem

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The Dirichlet problem is always possible; this principle is known as Dirichlet’s principle and the first proof is due to Riemann. If a function V is subject to taking given values at various points of a certain surface, bounding a … Read More

Henri Poincaré: Common properties of mathematical physics

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This rapid review of the various parts of mathematical physics has convinced us that all these problems, despite the extreme variety of boundary conditions and even differential equations, have, so to speak, a certain air of family which it is … Read More

Henri Poincaré: On the Partial Differential Equations of Mathematical Physics – Law of cooling of an isolated solid body in space

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Suppose we are looking for the law of cooling of an isolated solid body in space. It will be a question of finding a function V satisfying the equation dV/dt = kΔV, and which moreover is given for t = … Read More

Henri Poincaré, Mathematical physics: 1 – Dirichlet’s problem

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When we consider the various problems of integral calculus which naturally arise when we want to go deeper into the most different parts of physics, it is impossible not to be struck by the analogies that all these problems present … Read More

Henri Poincaré, The Moral Union

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(This allocution was delivered by Henri Poincaré at the inaugural meeting of the French League of Moral Education on June 26, 1912, three weeks before his death. This is the last time he has spoken in public.) Today’s Assembly brings … Read More

Henri Poincaré, Morality and Science

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In the last half of the nineteenth century, we often dreamed of creating a scientific morality. It was not enough to boast the educative virtue of science, the advantages which the human soul derives for its own perfecting of the … Read More

Henri Poincaré, Reports on Matter and Ether

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(Conference at the French Society of Physics, April 11, 1912.) When Mr. Abraham came to ask me to close the series of lectures organized by the French Society of Physics, I was at first about to refuse; it seemed to … Read More

Henri Poincaré, Quanta hypothesis: Conclusions

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We see what is the state of the question; the ancient theories, which hitherto seemed to account for all known phenomena, have encountered an unexpected obstacle. It seemed that a modification was necessary. A hypothesis was first presented in Mr. … Read More

Henri Poincaré, Quanta hypothesis: The ideas of Mr. Sommerfeld

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Mr. Sommerfeld has proposed a theory which he wants to relate to that of Mr. Planck, although the only connection between them is that the letter h appears in both formulas, and that the same name of quantum of action … Read More

Henri Poincaré, Quanta hypothesis: The new theory of Planck

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Let us go back to less general and more precise problems, for example to the theory of radiation. Mr. Planck has devised an amendment to his first theory, and I would like to say a few words about it. According … Read More

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