🚀 go-pugleaf

On 7 Μάϊος, 01:49, Pentcho Valev <pva...@yahoo.com> wrote:
> 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)"
>
> Good logic? Bad logic? Does D5 follow from D4? Note that John Norton
> is the cleverest Einsteinian so if his logic (which is Divine Albert's
> logic of course) is bad, let us try to imagine the logic of much
> sillier Einsteinians.
>
> Pentcho Valev
> pva...@yahoo.com

PV, excellent illustration.   Since movement is relative, according to
the man stationary with the disc, the disc is Euclidean, BUT,
according to the man watching the disc outside, it is non-Euclidean.

Einstein would have us believe the disc has two different types of
geometry.