Re: Binary stars

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

As I recall  there were no dipoles in the semi-classical
(Bohr, 1913) model of orbiting. All orbits are circular,
but only those orbits for which the angular momentum
is an integer of h_bar are allowed. Wasn't the model
with several L, for a given n, introduced later?

What rule did I violate by allowing circular motion of
two particles, and by calculating the necessary speeds?
What would you do, Jack, to calculate v semi-classically
from L=0?

I guess you would say it is not possible. Yet many
predictions of semi-classical models are in good
agreement with experimental facts. Look at Rutherford
scattering, for example, or Balmer's series. Sure it does
not explain everything. But we know, more or less,
when not to use it (when lambda becomes comparable
or larger than "sizes of our systems".

Yes, this model is very primitive by today's standards,
but it is better than nothing. Would you agree that it is
not a bad idea to try a semi-classical model first and
then to decide what to do next?

Many of us never advanced above the simple Bohr's
theory. What is wrong in trying to use the tools we
have? Teaching an introductory physics course is not
the same thing as contributing to progress of science.
It is an exercise of thinking about word phenomena
in terms of models, old and new.

Jack Uretsky wrote:

> l=1 is a dipole.  But I mis-spoke, of course; l= 0
> is spherical, not circular.  I stand by the rest.