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terminology: period vs. wavelength

At 01:14 PM 6/29/01 -0400, Michael Edmiston wrote:

The dictionaries are on my side, they specifically say the root of period is
periodus and this specifically refers to a time interval.

Not all dictionaries say so.

Before there was Latin _periodus_ there was Greek
_periodos_ "circuit"
_peri_ "around"
_odos_ "way" (same root as "odometer")
giving no reason to restrict the concept to temporal periods.

But I am completely outnumbered by current-day math professors who are
teaching scads of students that period does not need to be a time interval.

I think most physicists would be perfectly comfortable saying that in a
crystal lattice, the atomic positions are given by a periodic function of X
and Y.

Nonetheless, I still expect students to work problems in context. If I
ask students for the wavelength of a sound wave I expect them to report a


and if I ask for the period of a sound wave I expect them to report a time.

Not so clear.

However, it is certainly an eye-opener to talk to math professors and
realize how much of the terminology used in math classes these days is
stuff I never
heard of, or stuff that is different than the way I learned it and teach it.

To my ears, in this context wavelength is a _more specific_ term than
period, equivalent to "spatial period". But that doesn't make it wrong to
call it a period -- just as it is usually not wrong to call a lawn a lawn,
without specifying what species of grass it is.