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Re: continuous spectra



IOW Heisenberg uncertainty is irrelevant?

bc

Also, the continuousness of a "line" is the same as the continuousness of the spectrum of
a "hot" solid or a "free" electron neutralizing an ionized atm. Or are they like pigs?

"John S. Denker" wrote:

At 02:48 PM 5/11/00 -0400, GARY HEMMINGER wrote:
The question has arisen in one of my classes - are continuous
spectra truly continuous?

Then at 11:12 PM 5/11/00 -0500, Ludwik Kowalski wrote:

I think the spectra are really continous. Why do you doubt?

I agree with Ludwik.

To be even more explicit: All spectra are continuous under all
circumstances. The things we call "lines" are resonances. They have a Q
which might be large but cannot be infinite. Off-peak transitions are
always possible.

To continue, at 02:48 PM 5/11/00 -0400, GARY HEMMINGER wrote:

I'm wondering about this from both a
theoretical and practical point of view.

OK....

Does theory say that there
are an infinite number of wavelengths emitted in the visible range for
example by a black body,

Yes.

Nitpickers note that "infinite" means the usual thing, namely that there is
no meaningful finite upper bound.

Is the limited resolution of our equipment an issue?

It doesn't change the underlying physics.

OTOH suppose the frequency resolution is poor and the noise floor is high.
Then a Q of 1000 will be indistinguishable from a Q of ten zillion. The
center of the resonance can't be resolved and the "wings" of the resonance
are lost in the noise. Such an instrument might fool you into not caring
about the off-peak behavior of your resonances.