🚀 go-pugleaf

On May 9, 9:00 am, Pentcho Valev <pva...@yahoo.com> wrote:
> In 1902, in "La Science et l'hypothèse", Henri Poincaré, in order to
> justify non-Euclidean geometries, presented a parabole. Bidimensional
> creatures live on a disk. The disk is heated under its center so that
> the temperature is high at the center and decreases towards the
> periphery. The creatures use rigid measuring rods in order to
> determine the geometry of their world. They know nothing about the
> heater and accordingly discover that the ratio of the circumference
> and the diameter is greater than pi. The creatures conclude that
> Euclidean geometry cannot be true on the disk.
>
> Albert the Plagiarist (aka Divine Albert) also wanted to create a non-
> Euclidean geometry but did not know that Poincare's parabole had
> nothing to do with the rotating disc thought experiment. So, by
> appropriating Poincare's result without much ado, Albert the
> Plagiarist created a problem which is usually referred to as the
> Ehrenfest paradox and has four solutions, each of them (except the
> fourth) being offered as a consequence of Einstein's 1905 false light
> postulate:
>
> 1. Ehrenfest: The ratio of the circumference and the diameter of the
> rotating disk, as judged by a non-rotating observer, is smaller than
> pi.
>
> 2. Einstein: The ratio is greater than pi.
>
> 3. M. Strauss (Int.J.Theor.Phys. 11, 107, 1974): The ratio is equal to
> pi.
>
> 4. The rest of the scientific world: Who cares.
>
> Needless to say, Ehrenfest's solution is the correct one, in the sense
> that it is the only VALID consequence of Einstein's 1905 false light
> postulate. Still initiated Einsteinians know that, if Einsteiniana is
> to be eternal, they should explicitly worship Einstein's solution, no
> matter how idiotic it is. From time to time some naive non-initiated
> Einsteinian "repeats the common mistake" and refers to the truth but
> initiated Einsteinians correct him immediately:
>
> http://journals.ucfv.ca/jhb/Volume_3/Volume_3_Howard.pdf
> Don Howard: "In his discussion of Einstein’s "rotating disk" thought
> experiment, an important step on the road to general relativity's
> implication of spatio-temporal curvature, Isaacson repeats the common
> mistake of claiming that the circumference of the disk contracts,
> while the diameter does not, yielding a ratio of circumference to
> diameter less than π (p. 192). In fact, it is the yardstick used to
> measure the circumference that contracts, yielding a circumference
> seemingly larger than for the stationary disk and thus a ratio of
> circumference to diameter greater than π. For a careful discussion,
> see John Stachel, “The Rigidly Rotating Disk as the ‘Missing Link’ in
> the History of General Relativity,” in Einstein and the History of
> General Relativity, Don Howard and John Stachel, eds. (Boston:
> Birkhäuser, 1989), 48-62."

Albert the Plagiarist's breathtaking logic:

http://www.bartleby.com/173/23.html
Albert the Plagiarist: "Moreover, at this stage the definition of the
space co-ordinates also presents unsurmountable difficulties. If the
observer applies his standard measuring-rod (a rod which is short as
compared with the radius of the disc) tangentially to the edge of the
disc, then, as judged from the Galileian system, the length of this
rod will be less than 1, since, according to Section XII, moving
bodies suffer a shortening in the direction of the motion. On the
other hand, the measuring-rod will not experience a shortening in
length, as judged from K, if it is applied to the disc in the
direction of the radius. If, then, the observer first measures the
circumference of the disc with his measuring-rod and then the diameter
of the disc, on dividing the one by the other, he will not obtain as
quotient the familiar number pi = 3.14 …, but a larger number, whereas
of course, for a disc which is at rest with respect to K, this
operation would yield pi exactly."

Albert the Plagiarist explicitly states that the measuring-rod applied
tangentially is contracted but implicitly assumes that circumferential
elements on the rotating disk are not contracted, and so manages to
obtain Poincare's result. John Norton, the cleverest Einsteinian,
explicitly assumes that circumferential elements on the rotating disk
do contract and again obtains Poincare's result. Bravo Norton bravo
John:

http://philsci-archive.pitt.edu/archive/00000960/
Why Thought Experiments Do Not Transcend Empiricism
John D. Norton 2002
"(D1) In Euclidean geometry, the measured circumference of a disk is
pi times its diameter. (Premise)
(D2) The geometry of a non-rotating disk is Euclidean. (Premise)
(D3) The motion of a radial element on a rotating disk is
perpendicular to its length, so that (according to special relativity)
the length is unaltered. (Premise)
(D4) The motion of a circumferential element on a rotating disk is
along its length, so that (according to special relativity) the length
is contracted. (Premise)
(D5) Therefore the measured circumference of a rotating disk is more
than pi times the measured diameter. (From D2, D3, D4)
(D6) Therefore the geometry of a rotating disk is not Euclidean. (From
D1, D5)"

Pentcho Valev
pvalev@yahoo.com