Re: Seeing In The Dark thread
- From: oriel36 <geraldkelleher@xxxxxxxxx>
- Date: Wed, 26 Sep 2007 13:05:44 -0700
On 26 Sep, 01:22, Mike Simmons <ms...@xxxxxxxxxxx> wrote:
On 25 Sep 2007 22:22:02 GMT, Margo Schulter wrote:
There's a fine article that I found on the Web which, along with the famous
Shapley-Curtis debate, may give people an idea of how the issue of "external
galaxies" stood in the years immediately preceding Hubble's great discovery:
"The Problem of Island Universes" by Hector Macpherson (1919)
<http://adsabs.harvard.edu/abs/1919JRASC..13..360M>.
Nice article. I particularly like learning history not from modern books
but from the writings of the time. There's no interpretation involved here
-- the author is describing the evidence and theories of the time without
benefit (or hindrance) of the knowledge we have when looking back. It's
the best way to really learn what the state of the science was at the time.
What this discussion says to me as an amateur astronomer, with your remarks
providing much enrichment, is that many people may be involved in the
formulation, testing, refinement, and ultimate demonstration of a hypothesis
like that of island universes or external galaxies, with everyone involved
sharing in the beauty and honor of it all -- and not least, of course,
Hubble with his decisive demonstration.
That's exactly right. There is no one huge step that takes us from
ignorance to enlightenment as Oriel sees things.
Convince yourself of what you wish,I asked,who other than Hubble
determined that external galaxies exist in order to affirm that we
exist in one ?.I happen to enjoy Hubble's observation,reasoning and
conclusion and if you do not then suit yourself.
Hubble made a huge step
-- far greater than any other single observation and greater than most
other whole research projects -- but if taken alone without the benefit of
fore-knowledge based on others' work his finding couldn't be interpreted so
definitively.
Mike Simmons
I looked at how Copernicus used the data of the Ptolemaic astronomers
to replace the Sun's position between Venus and Mars with that of the
Earth and wonder how in the hell Newton managed to replace the
argument with a hypothetical observer on the Sun and it is still
defended by people who call themselves astronomers -
" For to the earth planetary motions appear sometimes direct,
sometimes stationary, nay, and sometimes retrograde But from the sun
they are always seen direct ," Newton
The periodic times argument is one of the oldest in astronomy,the
Ptolemaic astronomers knew it and the Copernican astronomers used it
to infer that the Earth has an orbital motion between Venus and Mars
-
Epitome Of Copernican Astronomy by Johannes Kepler
Finally by what arguments do you prove that the centre of the Sun
which is at the midpoint of the planetary spheres and bears their
whole system - does not revolve in some annual movement,as Brahe
wishes,but in accordance with Copernicus sticks immobile in one
place,while the centre of the Earth revolves in an annual movement.
Argument 10
" The 10th argument,taken from the periodic times, is as follows; the
apparent movement of the Sun has 365 days which is the mean measure
between Venus' period of 225 days and Mars' period of 687
days.Therefore does not the nature of things shout out loud that the
circuits in which those 365 days are taken up has a mean position
between the circuits of Mars and Venus around the Sun and thus this is
not the circuit of the Sun around the Earth -for none of the primary
planets has its orbit arranged around the Earth,as Brahe admits,but
the circuit of the Earth around the resting Sun,just as the other
planets,namely Mars and Venus,complete their own periods by running
around the Sun." Johannes Kepler
The Copernican astronomers never resorted to hypiothetical observers
on the Sun,they simply reworked the Ptolemaic data to replace the
Sun's position with the Earth and then apply axial rotation as the
cause of the daily cycle.You see,the insight of Copernicus had a
distinguished background,far more distinguished that Hubble's great
discovery that some of the nebula were seperate stellar islands.
Insights are individual achievements,for all the data collected by
many it takes an individual to make the huge leap into productive
working principles.If you cannot give Hubble credit then that is
fine,you come from a great tradition for diluting astronomical
discoveries be they that of Hubble,Copernicus ,Kepler,Roemer ect and
what can I say when nobody has actually called you on it.
Tell me what do you think of Newton's approach to and resolution of
retrogrades ?.
.
- References:
- Seeing In The Dark thread
- From: oriel36
- Re: Seeing In The Dark thread
- From: Mike Simmons
- Re: Seeing In The Dark thread
- From: Margo Schulter
- Re: Seeing In The Dark thread
- From: Mike Simmons
- Seeing In The Dark thread
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