Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: definition of "wave"



At 10:29 PM 1/26/00 -0500, John Denker wrote:
(a) Standing waves are not exactly *propagating* disturbances, but still I
call them waves.

To get standing waves don't you need two interfering waves.

(c) I do _not_ like to use the word "wave" to describe solutions to the
diffusion equation. The don't propagate very well, but that doesn't settle
the issue, because of the previous two examples. Sigh. I suppose one
could consider them to be grossly overdamped waves, but that seems like
stretching a point.

The diffusion equation is what mathematician call a parabolic differential
equation (like Schrodinger's equation). Although their solutions change in
time, the speed of propagation is infinite. By that is meant, if you have
say a very long pipe and some chemical is inserted in one end, immediately
at the other end the mathematical solution says some of the chemical will
appear. In the case of Schrodinger's equation this is why it isn't
consistent with special relativity.

Gary

Gary Karshner

St. Mary's University
San Antonio, Texas
KARSHNER@STMARYTX.EDU