Sunday, November 15, 2009

The unit of silence: a dirac

Several famous physicists have their name attached to a unit. Isaac Newton and his work on classical mechanics is memorized with the SI unit of force: the newton (symbol: N). From newton derives the unit of energy, Nm, which is named the joule (symbol: J) after James Prescott Joule. The list goes on. Paul Dirac, known for his work on the hydrogen atom and the spin of the electron and memorized with the Dirac delta function, also has “his” unit: a dirac (symbol unknown). But this is a unit of a somewhat different kind [1]:
Paul Dirac was a unusual person. Perhaps because Dirac's father demanded that his young son use French rather than his native English to converse with him, the young Dirac adopted the habit of silence during his childhood simply because he could not express his thoughts in French. Whatever the reason, the adult Paul Dirac was a man of silence. Dirac's silence was so intense that it inspired a little levity among physicists. In physics, the units given to physical quantities like time or length are important. Physicists, clearly in jest, have defined the unit of silence as the dirac.
A few diracs—at least microdiracs— would suit everybody well at times!

Keywords: physics, units, history, humans, parents, childhood, solitude, silence, humor

John S. Rigden: Hydrogen • The Essential Element. Harvard University Press, Cambridge, Massachusetts and London, England, Third Printing 2003; p. 88-89.

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