darrelj@sdcrdcf.UUCP (12/17/84)
Basically, Occam's razor os a principle for deciding between theories or
explanations, both of which explain all of a set of observations. The
principle says "use the simplest explanation which works".
Example: there have been two major explanations put forward to
explain the apparent motion of the other planets in the solar system.
Copernicus held that the Earth is at the center of the universe, and that
the other planets moved in epicycles (sort of little curliques) to account
for the apparent reversal of direction at regular intervals.
Keppler held that the Sun was the center of the solar system (and provided a
formula which related distance from sun to velocity). In his explanation,
the retrograde observations fall out of the fact that the Earth is also
moving back and forth in its orbit.
Keppler's laws are much simpler than the wheels within wheels (within
wheels) needed in the Copernican universe, thus by Occam's razor, it's the
prefered theory. (Now, of course, we have additional observations, such as
Gallileo's of the moons of Jupiter, which required Keppler's laws as the
only explanation
--
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
...{allegra,burdvax,cbosgd,hplabs,ihnp4,orstcs,sdcsvax,ucla-cs,akgua}
!sdcrdcf!darrelj
VANBUER@USC-ECL.ARPArcb@rti-sel.UUCP (12/19/84)
Come on guys! Lets get this definition right! Occam's Razor: When considering the relative merit of two theories, the one that requires the least degree of assumption is the better of the two. Least_degree := assumption_count * assumption_probability ^ 2 assumption_probability is the probability that an assumption could be true. The assumption that the observer exists has a very high probability. The assumption that UFO's exist has a very low probability. Randy Buckland Research Triangle Institute ...!mcnc!rti-sel!rcb
darrelj@sdcrdcf.UUCP (12/20/84)
As a couple of kind and discreet (i.e. no public inferno, or even private
inferno) correspondents have pointed out, I mislabelled (and over
simplified) those with whom various theories of the universe are identified.
The Earth-centered system is the Ptolemeic theories as laid out in
"Almagest". The first (influential) heliocentric theories were those of
Copernicus in "De revolutionibus orbis". Kepler further simplified the
smaller corrections in orbits by proposing eliptical rather than circular
orbits with little epicycles.
William of Occam was an English scholastic philospher of the 14th century.
Aknowledgements to presley and rivers (and the pocket encyclopedia I should
have checked the first time).
--
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
...{allegra,burdvax,cbosgd,hplabs,ihnp4,orstcs,sdcsvax,ucla-cs,akgua}
!sdcrdcf!darrelj
VANBUER@USC-ECL.ARPAgino@voder.UUCP (Gino Bloch) (12/22/84)
[use Occam's razor to remove this line]
> Copernicus held that the Earth is at the center of the universe, and that
Copernicus held that the SUN is the center of the universe; the guilty party
(-:-) was Ptolemy of Alexandria.
Merry Christmas or whatever, see you next year.
--
Gene E. Bloch (...!nsc!voder!gino)
Extend USENET to omicron Ceti.baba@spar.UUCP (Baba ROM DOS) (12/24/84)
"Entities should not me multiplied beyond necessity."
is the best English translation I can offer.gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (12/26/84)
> "Entities should not me multiplied beyond necessity."
Change "me" to "be" and I'll second the motion.biep@klipper.UUCP (J. A. "Biep" Durieux) (01/02/85)
>Basically, Occam's razor os a principle for deciding between theories or >explanations, both of which explain all of a set of observations. The >principle says "use the simplest explanation which works". > Example: there have been two major explanations put forward to >explain the apparent motion of the other planets in the solar system. >Copernicus held that the Earth is at the center of the universe, and that >the other planets moved in epicycles (sort of little curliques) to account >for the apparent reversal of direction at regular intervals. >Keppler held that the Sun was the center of the solar system (and provided a >formula which related distance from sun to velocity). In his explanation, >the retrograde observations fall out of the fact that the Earth is also >moving back and forth in its orbit. >Keppler's laws are much simpler than the wheels within wheels (within >wheels) needed in the Copernican universe, thus by Occam's razor, it's the >prefered theory. (Now, of course, we have additional observations, such as >Gallileo's of the moons of Jupiter, which required Keppler's laws as the >only explanation > Darrel J. Van Buer, PhD [] I've always heard and read it this way: Copernicus came up with the idea that the sun (which he deified, according to some of his writings) was the centre of the universe, celes- tial bodies rotating faster as they were closer to this "source of light and power". Tycho Brahe, while using the same mathematical model, held that the earth was the centre, around which the sun rotated, the other planets rotating around the sun (so he could explain, what C. couldn't, why there wasn't a continuous east wind, and why a stone thrown in the air didn't bend to the west. This are problems of planet rotation around their own centre, not around the sun, of course). Kepler, who had learnt the Copernican conception, became an assistant of Brahe. When the latter died, he took over the work. Brahe had recorded incredible accurate observations of the celestial bodies, which Kepler held behind when Brahe's family took the heritage. The major improvement K. made to C.'s system was getting rid of the idea that all orbits had to consist of circles (and epicycles). After years of working he realized that the shape of the orbits had to be the same as the shape of the chapel he had been passing by every day when going to his observatory: an ellips. Then he found his two famous laws: 1) A planet moves in an ellipse with the sun in one of the centres; 2) The line from the sun to a planet sweeps equal surfaces in equal times. Nine years later he found his third law: 3) The squares of the revolution times of the planets are proportio- nal to the cubes of their mean distances. Kepler, too, deified the sun. -- Biep. {seismo|decvax|philabs}!mcvax!vu44!botter!klipper!biep I utterly disagree with everything you are saying, but I am prepared to fight to the death for your right to say it. --Voltaire