Re: A wave or not a wave ?

[David Bowman <David_Bowman@GEORGETOWNCOLLEGE.EDU>]

Because I'm feeling peevish and am not inclined to substantively disagree
with John's thoughtful post, I thought I would rather pick a nit from it.
It concerns where John wrote:

>         ....  In particular one should not call
>   (d/dt)^2 q + (d/dx)^2 q = 0
> "the" wave equation as if no other wave equations existed.

John's point is well-taken and probably understood by all, but an
apparent typo (which usually heavily plague my posts) has caused the
above equation to be not any kind of wave equation at all, let alone
"the" wave equation.  As written above the equation is a 2-D Laplace
equation in the variables t & x.  Such an elliptic equation does not
support wavelike solutions for q(t,x).  I'm sure that John meant to
write the "+" sign above as a "-" sign.

David Bowman
David_Bowman@georgetowncollege.edu