Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: nospam@de-ster.demon.nl (J. J. Lodder)
Newsgroups: sci.physics.relativity
Subject: Re: New addition to the list of Relativity Critics/Skeptics
Date: Sun, 24 Mar 2024 15:09:18 +0100
Organization: De Ster
Lines: 45
Message-ID: <1qqxcvq.14yja6r18mi9htN%nospam@de-ster.demon.nl>
References: <3dacfdddc9713967b4dd62ef45180f28@www.novabbs.com> <1qqj6wp.1ob5jmyjy6g6dN%nospam@de-ster.demon.nl> <826f3b6ef703d9d1e307600940a6acee@www.novabbs.com> <1qqjdh9.1pen0glzuxdjN%nospam@de-ster.demon.nl> <814a21bed83def7b73667b4ca8932ca2@www.novabbs.com> <1qqolco.zgpjd4v2qwqmN%nospam@de-ster.demon.nl> <c4f4ac26914a109c7ad262a3914f3aff@www.novabbs.com>
Reply-To: jjlax32@xs4all.nl (J. J. Lodder)
Injection-Info: dont-email.me; posting-host="f50263802fb7fa96649fd64de681b5c2";
	logging-data="436780"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+9oCSZUS27RRHHqa+HWFwrfIwwjyP6M6Y="
User-Agent: MacSOUP/2.8.5 (ea919cf118) (Mac OS 10.12.6)
Cancel-Lock: sha1:Ih571A4kPcJtybQ29+PV8urf3Xk=
Bytes: 2779

LaurenceClarkCrossen <clzb93ynxj@att.net> wrote:

> You're mistaken about infinity not being in Euclid's parallel lines
> according to his article:
> 
> "He began by studying Euclid's postulate that a straight line has infinite
> length."
> 
> 
> "THE PARALLEL POSTULATE"
> 
> Author(s): Raymond H. Rolwing and Maita Levine
> 
> Source: The Mathematics Teacher, Vol. 62, No. 8 (DECEMBER 1969), pp. 665-669
> 
> Published by: National Council of Teachers of Mathematics
> 
> Stable URL: http://www.jstor.org/stable/27958258
> 
> I think that the geometries opposed to Euclid do not contradict his
> because they depart from plane geometry. For example, a triangle with
> other than 180 degrees is not on a plane surface, nor are parallel lines
> that diverge or meet. please read the article and see what I mean!
> 
> Euclid's geometry is about plane geometry and the non-Euclidean's are not.

Euclid's 5th postulate can (and was) given as:
===
5. If two lines are drawn which intersect a third in such a way that the
sum of the inner angles on one side is less than two right angles, then
the two lines inevitably must intersect each other on that side if
extended far enough. This postulate is equivalent to what is known as
the parallel postulate. (Wolfram)
===

The domain of Euclidean geometry is the open Euclidean plane.
No actual infinity is involved, [1]

Jan

[1] You can extent Euclidean geometry by adding a 'point at infinity'.
This is called projective geometry, and it is something else.
(and also irrelevant for disproving general relativity)