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ASTRO BOY
2013-Jan-20, 09:34 AM
In 1920 two notable Astronomers/Cosmologists had what was referred to as "The Great Debate"
The two, Harlow Shapley and Heber D. Curtis were the two involved....
There debate was as follows:

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http://apod.nasa.gov/diamond_jubilee/1920/cs_why.html

Although the `Great Debate' is important to different people for different reasons, it is a clear example of humanity once again striving to find its place within the cosmic order. In the debate, Shapley and Curtis truly argued over the ``Scale of the Universe," as the debate's title suggests. Curtis argued that the Universe is composed of many galaxies like our own, which had been identified by astronomers of his time as ``spiral nebulae". Shapley argued that these ``spiral nebulae" were just nearby gas clouds, and that the Universe was composed of only one big Galaxy. In Shapley's model, our Sun was far from the center of this Great Universe/Galaxy. In contrast, Curtis placed our Sun near the center of our relatively small Galaxy. Although the fine points of the debate were more numerous and more complicated, each scientist disagreed with the other on these crucial points.

A partial resolution of the debate came in the mid-1920's. Using the 100 inch Hooker Telescope at Mount Wilson, then the largest telescope in the world, astronomer Edwin Hubble identified Cepheid variable stars in the Andromeda Galaxy (M31) . These stars allowed Hubble to show that the distance to M31 was greater than even Shapley's proposed extent of our Milky Way galaxy. Therefore M31 was a galaxy much like our own. In the 1930s, the further discovery of interstellar absorption combined with an increased understanding of the distances and distribution of globular clusters ultimately led to the acceptance that the size of our Milky Way Galaxy had indeed been seriously underestimated and that the Sun was not close to the center. Therefore, Shapley was proved more correct about the size of our Galaxy and the Sun's location in it, but Curtis was proved correct that our Universe was composed of many more galaxies, and that ``spiral nebulae" were indeed galaxies just like our own.

Another reason the `Great Debate' is important is captured nicely in the book Shu, F., 1982, The Physical Universe, An Introduction to Astronomy, (University Science Books, Mill Valley, California) p. 286: "The Shapley-Curtis debate makes interesting reading even today. It is important, not only as a historical document, but also as a glimpse into the reasoning processes of eminent scientists engaged in a great controversy for which the evidence on both sides is fragmentary and partly faulty. This debate illustrates forcefully how tricky it is to pick one's way through the treacherous ground that characterizes research at the frontiers of science."

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Transcripts of the `Great Debate' at.....

http://apod.nasa.gov/diamond_jubilee/1920/cs_nrc.html



My thoughts are as follows.....

At that period in time the belief was also that the Universe was static, a belief that troubled the great Einstein so much, that he "fudged" his own equations with a CC to align with the belief of the day.

All this less than 100 years ago.

It shows that then as well as today, the top minds in cosmology, sometimes had highly conflicting views and interpretations of the nature of the Universe and space/time.
A fact we can all take some solace in

What other great cosmological debates have there been, both present and past?
Hoyle, Bondi and Gold much later were to defend "at all costs" the "Steady State" theory of the Universe...Not sure if there was any "great" debate on the issue, but would be surprised if there wasn't.

Any others?

publiusr
2013-Jan-20, 07:58 PM
Well, with the idea of a multiverse that has always been budding off--the steady-staters have found a new home

ASTRO BOY
2013-Jan-20, 09:17 PM
Einstein and Bohr also had much talked about debates on quantum mechanics did they not?

ASTRO BOY
2013-Jan-20, 09:19 PM
Well, with the idea of a multiverse that has always been budding off--the steady-staters have found a new home

A bit about that debate here.....

http://homepages.paradise.net.nz/rochelle.f/Bohr-v-Einstein.html


The debate between Bohr and Einstein over the interpretation of quantum theory began in 1927 at the fifth Solvay Conference of physicists and ended at Einstein’s death in 1955. The most active phase of the debate ran from 1927 to 1936 when Bohr replied to the EPR paper written by Einstein and two colleagues.

ASTRO BOY
2013-Jan-20, 09:21 PM
more discussion on Einstein/Bohr debate......

http://www.youtube.com/watch?v=2rv4INpgJ2g

mapguy
2013-Jan-22, 06:47 PM
It is indeed fascinating to think that we've only known for less than a century that we live in just one galaxy, and that "spiral nebulae" are actually separate galaxies, and that there are billions of them in the universe. Makes me wonder what kinds of things will be common knowledge after another century, when people will look back at us and say, "Wow, imagine living in 2013, when they didn't even know that!"

Of course, there have been many other "debates" over the centuries, as humans have struggled to comprehend the size of our universe, and the nature of our planet within it. For example, we used to think the Earth was flat; we used to think all celestial bodies orbited around us; we used to think the Sun was a different kind of object than the stars we see at night (this was shown to be incorrect only about 170 years ago, as a result of Friedrich Bessel's use of parallax to calculate the distance to a nearby star).

ASTRO BOY
2013-Jan-22, 07:06 PM
It is indeed fascinating to think that we've only known for less than a century that we live in just one galaxy, and that "spiral nebulae" are actually separate galaxies, and that there are billions of them in the universe. Makes me wonder what kinds of things will be common knowledge after another century, when people will look back at us and say, "Wow, imagine living in 2013, when they didn't even know that!"

Of course, there have been many other "debates" over the centuries, as humans have struggled to comprehend the size of our universe, and the nature of our planet within it. For example, we used to think the Earth was flat; we used to think all celestial bodies orbited around us; we used to think the Sun was a different kind of object than the stars we see at night (this was shown to be incorrect only about 170 years ago, as a result of Friedrich Bessel's use of parallax to calculate the distance to a nearby star).



Well put....

We have barely scraped the surface, and I'm sure the future will hold many surprises for humanity...
The Universe is a weird wonderful and timeless place....and big, I mustn't forget big!