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Old 18-August-2002, 03:28 AM
Silas Silas is offline
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Because this is an astronomy venue, I will close by calling to your attention that the information content in the Fraunhofer lines of starlight is independent of relative motions of source or observer.
I'm not completely clear what you mean by this...

I'm fond of using the very pronounced double emission lines of sodium as a benchmark, simply because even a rank amateur (me!) can recognize them.

If I see them, I know them. "Oh, wow, hot sodium!"

If I see them, and they're red, I know, "Oh, wow, hot sodium that's moving away from me." If see them, and they're blue, I know, "Oh, wow, hot sodium that's moving toward me."

Is that or is that not "information?"

Silas