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FUNDAMENTAL PHYSICS

fundamental physical constant
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A fundamental physical constant is a physical constant dimensionless and therefore takes the same value in any system of units. That makes these physical constants the only strictly universal constant (Although sometimes the constant term applies fundamental physical constants are not strictly universal and depend on the chosen system of units).
Table of Contents [hide ]
1 Difference between physical constants and mathematical constants
2 The problem of the number of fundamental physical constants
3 Examples of fundamental physical constants

4 External links / /

constant difference between the physical and mathematical constants [edit ]
Although both mathematical constants as fundamental physical constants are dimensionless and therefore independent of the system of units, the latter differ from the first that can only be determined by experiment and can not be expressed in terms of mathematical constants.

The problem of the number of fundamental physical constants [edit ]
The number of independent fundamental physical constants reflect scientific advances and certain advances in theoretical physics have shown that certain fundamental constants are really combinations of other physical constants and therefore these advances have reduced the number of physical constants. Moreover, the growing list of fundamental constants when a new experiment is a new relationship between physical phenomena. The number of independent fundamental physical constants is an open question.
physicists strive to provide elegant theories that can reduce the observed phenomena previously known phenomena, sometimes these theoretical works show that it is possible to reduce the number of principles and fundamental constants needed to explain the phenomena. The number of physical constants depends on the unit system, which is why theoretical physicists often use the unit system natural (or system of Planck units) where the number of physical constants is minimal, since the only physical constants that appear in natural units are precisely the fundamental physical constants. Also in the systems of natural units all physical quantities are to be dimensionless.
In the current state of knowledge, after the discovery that neutrinos are endowed with mass and neglecting the angle θ, John Baez (2002) is clear that the standard model requires 25 constants to explain the phenomena fundamental physical, including:
The fine structure constant.
Constant strong coupling.
The ratio between mass expressed several fundamental particles and the Planck mass : six ratios for the masses for the six types of quark (u, d, c, s, t, b), six ratios for the masses for leptons (e, μ, τ, νe, νμ, ντ), a ratio for the Higgs boson , and two more ratios for the bosons mass of the electroweak theory (W, Z).
The four parameters in the matrix of Cabibbo-Kobayashi-Maskawa, which describes how quarks can "oscillate" between different varieties. Four other parameters
matrix Maki-Nakagawa-Sakata, describing the same for neutrinos.

Examples of fundamental physical constants [edit ]
The fine structure constant best known example is the fundamental constant, this constant is involved in determining the magnitude of the electromagnetic interaction between fermions and photons, in simple terms The fine structure constant determines how strong the electromagnetic interaction, compared with others. Currently influenced by any generally accepted theory explains why it takes the value taken. Experimental value is: Where is the

electron charge, is Planck's constant Racionalidada is the speed of light in vacuum, and is the vacuum permittivity.

External links [edit ] General

NIST fundamental physical constants
John Baez, 2002, "Fundamental Constants How Many Are There? ."
Simon Plouffe. " A search for a Mathematical expression for mass ratios using a large database. "
Values \u200b\u200bof fundamental constants. CODATA, 2002.
variability of fundamental physical constants
"Michael Murphy's Research ." Institute of Astronomy, University of Cambridge.
Webb, John K., " Do the laws of Nature change with time? ". The University of New South Wales, Australia.
Artículos
Bahcall, J.N., C L Steinhardt, and D Schlegel, 2004 " Does the fine-structure constant vary with cosmological epoch? " Astrophys. J. 600: 520.
Martins, J.A.P. et al., 2004, " WMAP constraints on varying α and the promise of reionization, " Phys.Lett. B585: 29-34.
Marion, H., et al. 2003, " A search for variations of fundamental constants using atomic fountain clocks, " Phys.Rev.Lett. 90: 150801.
Olive, K.A., et al., 2002, " Constraints on the variations of the fundamental couplings, "Phys.Rev. D66: 045022.
Uzan, JP, 2003," The fundamental constants and Their variation: observational status and Theoretical Motivations, "Rev.Mod.Phys. 75: 403.
Webb, JK et al., 2001, "Further Evidence for cosmological evolution of the fine-structure constant," Phys Rev. Lett. 87: 091 301.
Scientific American Magazine (June 2005 Issue) Inconstant Constants - Do the inner workings of nature change with time?
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