Hi George,
>-----Original Message-----
>From: george murphy [mailto:gmurphy@raex.com]
>Sent: Wednesday, January 23, 2002 2:02 AM
>To: Glenn Morton
>
> You've read Whewell & I only summaries of him, & I don't
>want to dispute
>your basic point about the tendentious character of his argument.
> But in the mid-18th century "the nebulae" included a
>number of different
>kinds of objects. There were some objects that did indeed consist
>of individual
>stars with or without other "nebulosity"
>that are within the Milky Way, like the Orion Nebula. But there
>were others
>like M31 that we now know to be external galaxies but that
>couldn't be resolved
>into stars at that time. The latter are the ones that had been
>hypothesized to
>be "island universes" by some, but this claim was disputed by others. It's
>really this "island universe" idea that was being debated &, as I
>noted, the
>debate wasn't settled till ~70 years after Whewell wrote.
> I'll be out of touch for ~1week. (Some will say I have
>been for a long
>time!)
I will answer you and await your response when you get back, if you care to
respond. From what I recall of my time as an astronomy major in college
(many years ago and quickly and forcibly moved to physics) the controversy
about the galaxies which Hubble solved was NOT whether or not they were
collections of stars--that was settled prior to Whewell for all except
Whewell. What the issue was, concerned the location of these collections of
stars. Where the nebulas within the Milky Way or outside of it? That is
what Hubble solved. Since all my astronomy books are locked up in a Houston
storage vault, I can only offer this as support:
" In the early 1920's Hubble played a key role in establishing just what
galaxies are. It was known that some spiral nebulae (fuzzy clouds of light
on the night sky) contained individual stars, but there was no consensus as
to whether these were relatively small collections of stars within our own
galaxy, the 'Milky Way' that stretches right across the sky, or whether
these could be separate galaxies, or 'island universes', as big as our own
galaxy but much further away. "http://www.netlabs.net/hp/tremor/hubble.html
And even in the great 1920 debate between Shapley and Curtis, where Shapley
was arguing against the nebulae being outside of our galaxy, Shapley
acknowledged that there were stars in the nebula and used this as an
argument in his favor saying:
"c. If our galaxy approaches the larger order of dimensions, a serious
difficultly at once arises for the theory that spirals are galaxies of stars
comparable in size with our own: it would be necessary to ascribe impossibly
great magnitudes to the new stars that have appeared in the spiral nebulae.
"http://antwrp.gsfc.nasa.gov/htmltest/gifcity/cs_nrc.html
THus I respectfully submit the issue in the 20's was not whether the nebulae
were stars but how far the stars were!
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