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But one major
turning point was that the Copernican system leads to the prediction
that Venus will have phases, and those were observed when the
telescope was invented.
I believe that I can see phases of Venus with the naked eye, under ideal conditions. Assuming this is not my imagination merely because I know it to be true, were there any "heretics" that claimed the same thing before the telescope, thus being another observation that drove the requirement of a new model?
Don,
The idea of accuracy historically in science is a moving target. In fact I think it is a moving target among our introductory students, but at least we have statistics for a model as to how to handle it. The Copernican theory was simpler on some calculations then the Ptolemaic model, but it is hard estimate which was more accurate. For example Christopher Clavius, sometimes called the last Ptolemaic astronomer, conceded that some calculation using the Copernican system were easier.
Tycho Brahe being an observer had a good grasp of observation error. He use a technique to subdivide his instruments that he knew was not precise but whose errors were less than what he thought he could measure. He even produced an error table to correct these result if he felt it was necessary.
Kepler of course built his laws on Tycho's data. He found that he could fit the Copernican model with this data to within seven minutes of arc, but he felt that Tycho's observations should be accurate to at least a minute of arc and that motivated him to through out epicycles and uniform circular motion and find another curve that would fit the data.
The deviation of the motions of the planets from Kepler's Laws is at most about fifty seconds of arc. I have wondered what if Jupiter had been more massive so the perturbations were the order of a few minute of arc, would Kepler have found his Laws? He was a real stickler for accuracy. Many astronomers would have been very happy to be within 7 minutes of arc or about one fourth the diameter of the moon.
On 08/02/2007 11:09 AM, chuck britton wrote:
> An Historical Question concerning Occam's Razor -
> Devil's Advocate Hat On:
>
> When did the Copernican Theory of our Solar system become as precise
> as the Ptolmeic Theory?
> Did Newton work out the perturbations required - or am I totally
> bonkers in believing someone who claimed that all the cycles and epi-
> cycles DID give more precise predictions than did Copernicus (and
> Kepler)?
Al Bachman wrote
| My understanding of Occam's Razor is that it guides the
| choice between EQUALLY VALID models.
| If the simpler model makes incorrect predictions then we
| reject it. (Or question the experimental results more stringently!)
This is my understanding as well as to what the current vernacular means
when referencing Occam's Razor. So two models that predict all the data
equally accurately are not necessarily equally valid, given that
"meaning" of Occam's Razor.