Posted on 09/09/2003 11:40:31 AM PDT by Mr. Silverback
The January 1994 Bulletin of the American Academy of Arts and Sciences has a "stated meeting report" by Owen Gingerich entitled "Circles of the Gods: Copernicus, Kepler, and the Ellipse," which is quite interesting. At the end there's a note saying that Mr. Gingerich ended his lecture showing a cartoon in which Kepler announces, "The orbit of the planet is elliptical," while three of his puzzled contemporaries muse, "What's an orbit?" "What's a planet?" and "What's elliptical?"
Yes and no. A model's validity is dependant on how close it manges to get us to understanding how our external, objective reality actually works. Their validity may be deductive-nomological or inductive-statistical, but either way, they serve as a kind of truth statement that help us understand the connections and relationships between seemingly disparate phenomena. We can never say for certain, however, that any model is ever complete.
Also instead, of viewing models as constructs, I prefer to see them as mental structures which are part of the cognitive apparatus which helps guide us through the external world. And here is my problem with the whole Anthropic Principle, which is itself a none-too subtle attempt at reviving the old Ptolemic conception of Man being at the centre of the universe. Instead of viewing the universe as being as attuned to us, it's more accurate to say that we are attuned to the universe. Our cognitive, perceptual and communicative faculties, whether through adaptation or exaptation, have evolved to help us make sense of the universe.
You can use the Earth as your frame of reference. In fact, one of my orbit classes at NASA did exactly that. We used the Earth as a frame of reference instead of the sun when we described the celestial sphere. (It described the Sun orbiting the Earth in that reference frame.)
Phil V spaketh thusly:
"...just as long as they're not hold overs from the 70s. There were a lot of smart pills from that era that were tried by dumb-shits like me.
I hate the term "centrifugal force". There is no such thing. For example, what you "feel" (being forced towared the outside of the turn) as a car is rounding a curve and what is described as centrifugal force, is nothing more than your mass trying to continue in a strait line. (see Newtons three laws). The real force is actually in the directon towards the turn (center) and is called centripetal force.
I do remember something about an assistant of Copernicus being responsible for bringing the book to publication, and for doing something Copernicus did not authorize him to do.
But in any event, the earth-centric system was actually a better predictor of planetary motion than was the Copernican model of a sun-centered system--the larger inaccuracies caused by the Copernican were, I believe, based on the erroroneous idea that planetary orbits were circular.
But the chief advantage of the Copernican model was the far simpler calculations needed to compute planetary movement--albeit at the price of being less accurate.
So actually, those who favored the earth-centered soloar system had the weight of evidence on their side, as calculations based on formulas associated with that system more accurately fit astronomical observations.
(I believe there was famous debate about this in those days. A Cardinal Bellarmine, arguing on behalf of the Church, won the argument for the earth-centered model on just those grounds: The Earth-centered model fit the evidence better.)
I suppose the Copernican model might have been made more exact in its results by adding additional calculations, but then it might have been just as complex as the earth-centric model, and there would be no reason to think it better in any respect.
I think it wasn't until Newton and eliptical orbits that Copernicus' ideas were fully vindicated.
This entire episode taught me more about the flawed human concept of genius than it did about astronomy: If Copernicus publically insisted that the sun was indeed the center--he was a fool whom subsequent science made lucky.
And so today he is hailed as a visionary genius.
But tommorow?
Just who is hailed as a genius to which generation of men--is a very subjective judgement.
Genius is just fashionable thinking.
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