# 19.068 pi/lambda

From: Humanist Discussion Group (by way of Willard McCarty willard.mccarty_at_kcl.ac.uk>
Date: Fri, 3 Jun 2005 07:08:18 +0100

Humanist Discussion Group, Vol. 19, No. 68.
Centre for Computing in the Humanities, King's College London
www.kcl.ac.uk/humanities/cch/humanist/
www.princeton.edu/humanist/
Submit to: humanist_at_princeton.edu

Date: Fri, 03 Jun 2005 07:04:48 +0100
Subject: Origins of words/expressions "pi / lambda"?

Thu, 2 Jun 2005 (07:21 +0100 UTC) "Jim Marchand" queried

>When I was an undergraduate, majoring in chemical engineering, we used to
>ask "What's new?" To which the answer was: "Pi over lambda." Now I am a
>retired linguist working on the origin of words and expressions, and I
>cannot remember what that is the formula for. I know we are not scientists,
>but does someone know? It would fit in so well in my present chapter.

propagation constant
1. n. [Geophysics] ID: 984

A property of a sinusoidal plane wave equal to twice pi divided by the
wavelength. Also known as the wavenumber, the propagation constant is
fundamental to the mathematical representation of wavefields. It is the
spatial equivalent of angular frequency and expresses the increase in the
cycle of the wave (measured in radians) per unit of distance. In
nondispersive media, the wavespeed is the ratio of the angular frequency to
the propagation constant. The propagation vector has magnitude equal to the
propagation constant and points in the direction the wave is traveling.

Waves propagating across a plane are a marvelous metaphor for constancy in
the midst of change. Heraclitus "change is real" comes to mind.

```--
Associate Professor of English, Morehead State University
Making meaning one message at a time.
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Received on Fri Jun 03 2005 - 02:20:21 EDT

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