Physicists have been wondering whether the fine structure constant is really a constant, i.e. whether it always had the same value over the history of the universe, as some theories had been suggested which implied this not to be the case. First experimental tests of this question, most notably examination of spectral lines of distant astronomical objects and of the Oklo natural fission reactor, have not hinted any changes. Recent improvements in astronomical techniques brought first hints in 2001 that in fact might change its value ...

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Fine-structure constant, Fine-structure constant - Physical interpretation, Fine-structure constant - Is the fine structure constant really constant?, Fine-structure constant - Anthropic explanation, Fine-structure constant - Numerological explanations

Read more here: » Fine-structure constant: Encyclopedia II - Fine-structure constant - Is the fine structure constant really constant?

See also:

Fine-structure constant, Fine-structure constant - Physical interpretation, Fine-structure constant - Is the fine structure constant really constant?, Fine-structure constant - Anthropic explanation, Fine-structure constant - Numerological explanations

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As a dimensionless constant which does not seem to be directly related to any mathematical constant, the fine-structure constant has long been an object of fascination to physicists. Richard Feynman, one of the founders of quantum electrodynamics, referred to it as "one of the greatest damn mysteries of physics: a magic number that comes to use with no understanding by man." Towards the end of his life, the physicist Arthur Eddington constructed numerological "proofs" that was an exact integer, even relating it to the Eddington number, his ...

See also:

Fine-structure constant, Fine-structure constant - Physical interpretation, Fine-structure constant - Is the fine structure constant really constant?, Fine-structure constant - Anthropic explanation, Fine-structure constant - Numerological explanations

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Arnold Johannes Wilhelm Sommerfeld (December 5, 1868 – April 26, 1951) was a German physicist who introduced the fine-structure constant in 1919. Arnold Sommerfeld was born in Königsberg where he studied mathematics and physical sciences at its university. After receiving his doctorate in 1891 he changed to the University of Göttingen, where he received a professorship in 1896. He became professor of mathematics at the University of Clausthal-Zellerfeld in 1897 and of technical engineering at the University of Aachen in 190 ...

Including:

• Arnold Sommerfeld - External link

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Alpha may refer to: Alpha (letter), a letter in the Greek alphabet. α may be used as the symbol for: Angle of attack in aerodynamics In physics Fine-structure constant, a fundamental physical constant Alpha particle, form of particle radiation H-alpha, or H-α, an emission line created by hydrogen atoms In Bayer designation, the typically brightest star in a constellation The significance level in stati ...

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The cerebellum (Latin: "little brain") is a region of the brain that plays an important role in the integration of sensory perception and motor output. Many neural pathways link the cerebellum with the motor cortex—which sends information to the muscles causing them to move—and the spinocerebellar tract—which provides feedback on the position of the body in space (proprioception). The cerebellum integrates these two functions, using the constant feedback on body position to fine-tune motor movements. Because of this 'upda ...

Including:

• Cerebellum - General features
• Cerebellum - Development and evolution
• Cerebellum - Anatomy
• Cerebellum - Divisions
• Cerebellum - Deep nuclei
• Cerebellum - Cortical layers
• Cerebellum - Peduncles
• Cerebellum - Blood supply
• Cerebellum - Dysfunction
• Cerebellum - Lesions of the cerebellum
• Cerebellum - Ischemia and thrombosis
• Cerebellum - Theories about cerebellar function
• Cerebellum - Cerebellar modeling

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The coupling constant comes into its own in a quantum field theory. A special role is played in relativistic quantum theories by coupling constants which are dimensionless, ie, are pure numbers. For example, the fine-structure constant, (where e is the charge of an electron, ε0 is the permittivity of free space, ℏ is Dirac's constant and c is the speed of light) is such a dimensionless coupling constant that determines the strength of the electromagnetic force on an electron. However, in di ...

See also:

Coupling constant, Coupling constant - Fine structure constant, Coupling constant - Gauge coupling, Coupling constant - Weak and strong coupling, Coupling constant - Running coupling, Coupling constant - Beta-function, Coupling constant - Landau pole and asymptotic freedom, Coupling constant - QCD scale, Coupling constant - Charge colour charge etc, Coupling constant - String theory

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(Sources for this section: [1], [2], [3], [4], [5]) The nuclear strong force holds together the particles in the nucleus of an atom. If the strong nuclear force were slightly weaker, by as little as 2%, multi-proton nuclei would not hold together and hydrogen would be the only element in the universe. If the strong force were slightly stronger, by as little as 1%, hydrogen would be rare in the universe and elements heavier than iron (elements resulting from fusion during the explosion of supernovae) would also be rare. See also:

Fine-tuned universe, Fine-tuned universe - Nature of the constants, Fine-tuned universe - Meaning of universe, Fine-tuned universe - Known physical constants and possible examples of fine tuning, Fine-tuned universe - Explaining fine-tuned universe, Fine-tuned universe - Naturalism and the fine tuning argument, Fine-tuned universe - Naturalistic fine-tuned universe arguments, Fine-tuned universe - Ikeda-Jefferys argument

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The quantity Λ is called the QCD scale. The value is known pretty accurately to be This value is to be used at a scale above the bottom quark mass of about 5 MeV. The meaning of ΛMS is given in the article on dimensional regularization. ...

See also:

Coupling constant, Coupling constant - Fine structure constant, Coupling constant - Gauge coupling, Coupling constant - Weak and strong coupling, Coupling constant - Running coupling, Coupling constant - Beta-function, Coupling constant - Landau pole and asymptotic freedom, Coupling constant - QCD scale, Coupling constant - Charge colour charge etc, Coupling constant - String theory

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In a non-Abelian gauge theory, the gauge coupling parameter, g, appears in the Lagrangian as (where G is the gauge field tensor) in some conventions. In another widely used convention, G is rescaled so that the coefficient of the kinetic term is 1/4 and g appears in the covariant derivative. This should be understood to be similar to a dimensionless version of the electric charge d ...

See also:

Coupling constant, Coupling constant - Fine structure constant, Coupling constant - Gauge coupling, Coupling constant - Weak and strong coupling, Coupling constant - Running coupling, Coupling constant - Beta-function, Coupling constant - Landau pole and asymptotic freedom, Coupling constant - QCD scale, Coupling constant - Charge colour charge etc, Coupling constant - String theory

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The beta function of a quantum field theory measures the running of a coupling parameter. It is defined by the relation For most theories the beta-function is positive, ie, the coupling increases as k increases (as the scale on which the theory is observed becomes shorter). This is also the case in quantum electrodynamics (QED). At low energy, ie, long distances, one knows that α=1/137 (approximately). At the scale of the Z boson, ie, ab ...

See also:

Coupling constant, Coupling constant - Fine structure constant, Coupling constant - Gauge coupling, Coupling constant - Weak and strong coupling, Coupling constant - Running coupling, Coupling constant - Beta-function, Coupling constant - Landau pole and asymptotic freedom, Coupling constant - QCD scale, Coupling constant - Charge colour charge etc, Coupling constant - String theory

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In quantum field theory, since the size of the interaction term is absorbed into the notion of the coupling constant (more correctly coupling parameter, since it runs), the word charge is freed up for another use. One says, for example, that the electrical charge of an electron is -1 and that of any observable particle is an integer multiple of this. The notion of charge is now exactly the same as the representation of the gauge group to which the particle belongs. Thus the colour charge of a quark is fixed at 4/3 since it belongs to the fundamental representation of SU(3), and the colour charge o ...

See also:

Coupling constant, Coupling constant - Fine structure constant, Coupling constant - Gauge coupling, Coupling constant - Weak and strong coupling, Coupling constant - Running coupling, Coupling constant - Beta-function, Coupling constant - Landau pole and asymptotic freedom, Coupling constant - QCD scale, Coupling constant - Charge colour charge etc, Coupling constant - String theory

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In relativity, c defines the relationship between metres and seconds, so every measurement that contains units of metres or seconds has the possibility of being affected. Planck units shows the interconnectedness of units and constants. If c changes (outside of the already known variations allowed in quantum theory), then there would be at least a few profound changes to other constants, equations, or ideas. Here are some possibilites: the energy and/or mass of all particles would have to change: See also:

Variable speed of light, Variable speed of light - Possibility of variations in c, Variable speed of light - Detecting variations in c, Variable speed of light - Implications of variations in c, Variable speed of light - History and current research, Variable speed of light - Experiments that modify c, Variable speed of light - Varying c in quantum theory

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In the 1930s, Paul Dirac and others began investigating the consequences of natural constants changing with time. For example, Dirac proposed a change of only 5 parts in 1011 per year of G (in the force of gravity) but Richard Feynman showed in his famous 1961 lectures (vol 1, chapter 7) that geological evidence indicates the gravitational constant most likely could not have changed this much in the past 4 billion years based on geological and solar system observations (although the observations themselves may ...

See also:

Variable speed of light, Variable speed of light - Possibility of variations in c, Variable speed of light - Detecting variations in c, Variable speed of light - Implications of variations in c, Variable speed of light - History and current research, Variable speed of light - Experiments that modify c, Variable speed of light - Varying c in quantum theory

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We noted that QED is weakly coupled at long distances, but the coupling increases at short distances. This increase was first noticed by Lev Landau who showed that QED becomes strongly coupled at high energy, and in fact the coupling becomes infinite at asympototically high energy. This phenomenon is called the Landau pole. In non-Abelian gauge theories, the beta function is negative, as first found by Frank Wilczek, David Politzer and David Gross. As a result the coupling decreases at short distances. Furthermore ...

See also:

Coupling constant, Coupling constant - Fine structure constant, Coupling constant - Gauge coupling, Coupling constant - Weak and strong coupling, Coupling constant - Running coupling, Coupling constant - Beta-function, Coupling constant - Landau pole and asymptotic freedom, Coupling constant - QCD scale, Coupling constant - Charge colour charge etc, Coupling constant - String theory

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One can probe a quantum field theory at short times or distances by changing the wavelength or momentum, k of the probe one uses. With a high frequency, ie, short time probe, one sees virtual particles taking part in every process. The reason this can happen, seemingly violating the conservation of energy is the uncertainty relation which allows such violations at short times. The previous remark only applies to some formulations of QFT, in particular, canonical quantization in the int ...

See also:

Coupling constant, Coupling constant - Fine structure constant, Coupling constant - Gauge coupling, Coupling constant - Weak and strong coupling, Coupling constant - Running coupling, Coupling constant - Beta-function, Coupling constant - Landau pole and asymptotic freedom, Coupling constant - QCD scale, Coupling constant - Charge colour charge etc, Coupling constant - String theory

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Fine-Tuning comes with caveats. The fact that a universe with different physical constants might be inhospitable to life as we know it does not necessarily mean that it is inhospitable to any form of life. Currently, there is no way of experimentally determining if a universe allows for life or not. Further, most of this universe, especially the interstellar vacuum, appears to be devoid of life; other physical constants may ...

See also:

Fine-tuned universe, Fine-tuned universe - Nature of the constants, Fine-tuned universe - Meaning of universe, Fine-tuned universe - Known physical constants and possible examples of fine tuning, Fine-tuned universe - Explaining fine-tuned universe, Fine-tuned universe - Naturalism and the fine tuning argument, Fine-tuned universe - Naturalistic fine-tuned universe arguments, Fine-tuned universe - Ikeda-Jefferys argument

Read more here: » Fine-tuned universe: Encyclopedia II - Fine-tuned universe - Explaining fine-tuned universe

That life as we know it would not be possible if the physical constants of the universe were even slightly different from what they are and may appear to be "fine-tuned" is an uncontroversial position within the mainstream scientific community. But conclusions drawn from that observation or appeals to the improbability of life that some intelligence intentionally "fine-tuned" the universe for life are not widely accepted. There is controversy over whether such conclusions can even be considered within natural scien ...

See also:

Fine-tuned universe, Fine-tuned universe - Nature of the constants, Fine-tuned universe - Meaning of universe, Fine-tuned universe - Known physical constants and possible examples of fine tuning, Fine-tuned universe - Explaining fine-tuned universe, Fine-tuned universe - Naturalism and the fine tuning argument, Fine-tuned universe - Naturalistic fine-tuned universe arguments, Fine-tuned universe - Ikeda-Jefferys argument

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A Bayesian probabilistic discussion by mathematician Michael Ikeda and astronomer William H. Jefferys argues that the traditional reasoning about intelligent design from the presence of fine-tuning does not properly condition on the existence of life and is also based on an incorrect reversal of conditional probabilities: it is an example of the prosecutor's fallacy, which in this form erroneously claims that if fine-tuning is rare in naturalistic universes, then a fine-tuned universe is unlikely to be naturalistic. (In this context, "naturalistic ...

See also:

Fine-tuned universe, Fine-tuned universe - Nature of the constants, Fine-tuned universe - Meaning of universe, Fine-tuned universe - Known physical constants and possible examples of fine tuning, Fine-tuned universe - Explaining fine-tuned universe, Fine-tuned universe - Naturalism and the fine tuning argument, Fine-tuned universe - Naturalistic fine-tuned universe arguments, Fine-tuned universe - Ikeda-Jefferys argument

Read more here: » Fine-tuned universe: Encyclopedia II - Fine-tuned universe - Ikeda-Jefferys argument

Both popular and professional research articles in cosmology often use the term "universe" when they really mean "observable universe". The reason for this is that unobservable physical phenomena are scientifically irrelevant; that is, they cannot affect any events that we can perceive, and therefore, it is argued, effectively do not exist (physicists say "causally do not exist"). They also cannot be measured, and therefore hypotheses about parts o ...

See also:

Fine-tuned universe, Fine-tuned universe - Nature of the constants, Fine-tuned universe - Meaning of universe, Fine-tuned universe - Known physical constants and possible examples of fine tuning, Fine-tuned universe - Explaining fine-tuned universe, Fine-tuned universe - Naturalism and the fine tuning argument, Fine-tuned universe - Naturalistic fine-tuned universe arguments, Fine-tuned universe - Ikeda-Jefferys argument

Read more here: » Fine-tuned universe: Encyclopedia II - Fine-tuned universe - Meaning of universe