Quality (physics)
Overview
 
In response theory
Green's function (many-body theory)
In many-body theory, the term Green's function is sometimes used interchangeably with correlation function, but refers specifically to correlators of field operators or creation and annihilation operators....

, the quality of an excited system is related to the number of excitation frequencies to which it can respond. In the case of a homogeneous, isotropic system, the quality is proportional to the FWHM
Full width at half maximum
Full width at half maximum is an expression of the extent of a function, given by the difference between the two extreme values of the independent variable at which the dependent variable is equal to half of its maximum value....

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Quotations

Admiration for a quality or an art can be so strong that it deters us from striving to possess it.

Friedrich Nietzsche, Mixed Opinions and Maxims, aphorism 370, “The Danger in Admiration,” (1879).

It is the quality of the moment, not the number of days, or events, or of actors, that imports.

Ralph Waldo Emerson, Speech, January 1842, at the Masonic Temple in Boston, repr. in The Dial (1843) and Nature, Addresses, and Lectures (1849).

It’s the quality of the ordinary, the straight, the square, that accounts for the great stability and success of our nation. It’s a quality to be proud of. But it’s a quality that many people seem to have neglected.

Gerald Ford, Time Magazine|Time (January 28, 1974)

Much of what passes for quality on British television is no more than a reflection of the narrow elite which controls it and has always thought that its tastes were synonymous with quality.

Rupert Murdoch, Address, 1989, to the Edinburgh Television Festival. quoted in Guardian (London, Jan. 1, 1990).

One cannot develop taste from what is of average quality but only from the very best.

Johann Wolfgang von Goethe, Conversations with Eckermann (February 26, 1824).

One shining quality lends a lustre to another, or hides some glaring defect.

William Hazlitt, Complete Works, vol. 9, ed. P.P. Howe (1932). Characteristics, no. 162 (first published anonymously in 1823).

People of quality know everything without ever having learned anything.

Molière, Les Précieuses Ridicules, sc. 9 (1659).

So cheat your landlord if you can and must, but do not try to shortchange the Muse. It cannot be done. You can’t fake quality any more than you can fake a good meal.

William S. Burroughs, The Western Lands, ch. 2 (1987).

Social improvement is attained more readily by a concern with the quality of results than with the purity of motives.

Eric Hoffer, Reflections on the Human Condition, aph. 25 (1973).

The measure of your quality as a public person, as a citizen, is the gap between what you do and what you say.

Ramsey Clark, International Herald Tribune (Paris, June 18, 1991).

 
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