XXth century_physics

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"It thus appears that we must abandon the identification of the holes with protons and must find some other interpretation for them. Following Oppenheimer, we can assume that in the world as we know it, all, and not merely nearly all, of the negative-energy states for electrons are occupied. A hole, if there were one, would be a new kind of particle, unknown to experimental physics, having the same mass and opposite charge to an electron. We may call such a particle an anti-electron. We should not expect to find any of them in nature, on account of their rapid rate of recombination with electrons, but if they could be produced experimentally in high vacuum they would be quite stable and amenable to observation. An encounter between two hard γ-rays (of energy at least half a million volts) could lead to the creation simultaneously of an electron and anti-electron, the probability of occurrence of this process being of the same order of magnitude as that of the collision of the two γ-rays on the assumption that they are spheres of the same size as classical electrons. This probability is negligible, however, with the intensities of γ-rays at present available. The protons on the above view are quite unconnected with electrons. Presumably the protons will have their own negative-energy states, all of which normally are occupied, an unoccupied one appearing as an anti-proton. Theory at present is quite unable to suggest a reason why there should be any differences between electrons and protons...„ Paul Dirac (1931)
”The general theory of quantum mechanics is now almost complete... The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble.” Paul Dirac (1929) ”I think that in six months... physics as we know it will be over” Max Born (after Dirac’s paper on the relativistic equation of the electron)
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Physics of the XX th century Part 1
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Physics of the atom and the path to
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Hantaro Nagaoka Nagaoka's atomic mo
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Robert Millikan (1868-1953 (1868 19
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Charles Glover Barkla (1877-1944) d
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John William Nicholson (1911): atom
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Accelerated electric charge radiate
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Attenuation of radiation for rings
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Solvay Conference 1913
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H. Geiger - On the Scattering of th
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Proc. Roy. Soc. 82, 495 (1909)
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In the ”plum-pudding” model of
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"Consider an atom which contains a
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”...considering the enormous vari
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”The wavelengths of the first fou
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Spectral lines were seen as manifes
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In the Bohr’s model spectral line
Page 36 and 37: Bohr found excellent description of
Page 38 and 39: Periodic system of elements accordi
Page 40 and 41: Periodic system of elements accordi
Page 42 and 43: Intra-atomic Charge ”Now, accordi
Page 44 and 45: H. G. J. Moseley, Phil. Mag. 26, 10
Page 46 and 47: ”We have here a proof that there
Page 48 and 49: James Franck Gustav Hertz Franck-He
Page 50 and 51: James Franck Gustav Hertz ”...it
Page 52 and 53: Wojciech (Adalbert) Rubinowicz (188
Page 54 and 55: Solvay Conference 1921
Page 56 and 57: Arthur Holly Compton (1892-1962) Co
Page 58 and 59: Compton’s data [(Phys. Rev.19, 26
Page 60 and 61: Compton effect
Page 62 and 63: The crisis of the quantum theory
Page 64 and 65: Louis de Broglie
Page 66 and 67: Clinton Davisson and Lester Germer
Page 68 and 69: George P. Thomson Electron diffract
Page 70 and 71: Important dates in the development
Page 72 and 73: Heisenberg to Pauli (July 9, 1925)
Page 74 and 75: ”It is well known that the formal
Page 76 and 77: ”In this communication I wish fir
Page 78 and 79: The uncertainty principle
Page 80 and 81: ”I used to take long walks on Sun
Page 82 and 83: ”The fact that the variables used
Page 84 and 85: ”A recent paper by the author may
Page 88: Solvay Conference 1930
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