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[en] The fine structure constant can be approximately expressed as α = (20 var-phi 4)-1 where var-phi is the golden ratio (1 + √5)/2: the discrepancy between the present and the true value of α-1 is lower than 3.4· 10-4. This simple occurrence would be not fortuitous, thus suggesting a hidden physical meaning. A tentative and qualitative explanation is proposed which is based only on symmetry considerations involving both the Von Klitzing resistance and the vacuum impedance
[en] The structure fine constant (α) plays an important role in relativity, quantum physics and electromagnetism. It characterizes the strength of interaction between light and matter as described in the quantum electromagnetic theory. The fact that the value of the inverse of α nears an integer (137) has raised a lot of speculations. According to the Dirac theory, 1/α represents the limit of Z for elements: elements whose atomic number is over 137 cannot exist. Initially α represents the ratio between the electron speed on the first orbit of the relativistic Bohr atom and the speed of light: α = e2/(4*π*ε0*ℎ*c) where e is the elementary charge and ε the vacuum permittivity. The most accurate value of α obtained so far is α = 1/137035999037 (91), its measurement was based on the trapping of ultra-cold rubidium atoms. Recent studies on quasar spectra have shown that the α constant has changed by less than 1/10.000 of percent in 10 billion years. (A.C.)
[en] The fine structure constant α is one of the fundamental constants of nature characterizing the whole range of physics including elementary particle, atomic, mesoscopic and macroscopic systems. This diversity is reflected in a large number of independent and competitive physical methods available for measuring α. Included in this review are high precision determinations of α based on the measurements of the neutron de Broglie wavelength, the quantum Hall effect, the ac Josephson effect, the electron anomalous magnetic moment, and some simple QED bound systems. Also discussed are new promising approaches based on atom beam interference and single electron tunnelling. Possible implications to physics that might arise from the comparison of α's obtained by these methods are explored. (author)
[en] This investigation sheds light on why the fundamental forces in the universe, the fundamental interactions, are so different. The integration of the results from the mathematical optimization process of the optimal power towers with physics shows that there is a fundamental connection between the relative strengths of the interactions, as well as with the number of dimensions in the universe. It enables the derivation and calculation of the value of the fine structure constant that has not been explained for a hundred years. Forecast value: 137.035999100.
[de]Diese Untersuchung beleuchtet die Frage, warum die Grundkräfte im Universum, die Fundamentalen Wechselwirkungen, so unterschiedlich groß sind. Die Verzahnung der Ergebnisse aus dem mathematischen Optimierungsverfahren der optimalen Potenztürme mit der Physik zeigt, dass zwischen den relativen Stärken der Wechselwirkungen ein fundamentaler Zusammenhang besteht, ebenso wie mit der Zahl der Dimensionen im Universum. Sie ermöglicht die Herleitung und Berechnung des seit hundert Jahren unerklärten Werts der Feinstrukturkonstante. Prognosewert: 137,035999100.
[en] The fine structure constant α and the ratio h/mu between the Planck constant and the unified atomic mass are keystone constants for the determination of other fundamental physical constants, especially the ones involved in the framework of the future International System of units. This paper presents how these two constants, which can be deduced from one another, are measured. We will present in detail the measurement of h/mRb performed by atomic interferometry at the Kastler Brossel Laboratory in Paris. This type of measurement also allows a test of the standard model to be carried out with unparalleled accuracy. Our most precise measurement of h/mRb is still the one we have published previously: h/mRb=4.591 359 2729 (57)*10-9 m2s-1. Using the more recent value of Ar(Rb) published by the Atomic Mass Evaluation of 2012, we obtain: h/mu=3.990 312 7193 (49)*10-9 m2s-1. This leads to the following value of α=137.035998996(85)
[en] Precise measurements of various physical quantities are being made with a much improved precision in experiments with trapped charged particles, many of which are reported in this Nobel symposium. In the present paper, these and other precise measurements are placed in the wider context of the successively more accurate determination of the fundamental physical constants which has taken place during the last decades. The role of systems of units of measurement, based on physical constants and the most accurate measurements, is recalled in providing a coherent framework in which the results of experiments made on different occasions and in different fields of physics may be related to one another