Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: WM Newsgroups: sci.math Subject: Re: Incompleteness of Cantor's enumeration of the rational numbers (extra-ordinary) Date: Sun, 5 Jan 2025 13:04:59 +0100 Organization: A noiseless patient Spider Lines: 41 Message-ID: References: <98519289-0542-40ce-886e-b50b401ef8cf@att.net> <8e95dfce-05e7-4d31-b8f0-43bede36dc9b@att.net> <53d93728-3442-4198-be92-5c9abe8a0a72@att.net> <9c18a839-9ab4-4778-84f2-481c77444254@att.net> <8ef20494f573dc131234363177017bf9d6b647ee@i2pn2.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Sun, 05 Jan 2025 13:05:00 +0100 (CET) Injection-Info: dont-email.me; posting-host="cfe6170884cd9660d3ba2d6ea153e630"; logging-data="1037648"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19zlAqdlZ2og0hYGJrU5HYqVvLXP5wGT48=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:0pS7M825kPEuzTD36YOpOfgCSEo= Content-Language: en-US In-Reply-To: Bytes: 3063 On 05.01.2025 12:28, Alan Mackenzie wrote: > WM wrote: > The set of these prime gaps is infinite, without qualification. Euclid > could have told you that. Euclid did not believe in actual infinity. The prime gaps have no upper limit. > >> Finally, the most familiar example is this: The (magnitudes of) natural >> numbers are potentially infinite because, although there is no upper >> bound, there is no infinite (magnitude of a) natural number. > > There are no "actual" and "potential" infinity in mathematics. It has been exorcized by those matheologians who were afraid of the problems introduced to matheology by these precise definitions. > The > notions are fully unneeded, and add nothing to any mathematical proof. > There is finite and infinite, and that's it. > > When I did my maths degree, several decades ago, "potential infinity" and > "actual infinity" didn't get a look in. They weren't mentioned a single > time. That has opened the abyss of nonsense to engulf mathematics with such silly results as: A union of FISONs which stay below a certain threshold can surpass that threshold. > > The only people who talk about "potential" and "actual" infinity are > non-mathematicians who lack understanding, and pioneer mathematicians > early on in the development of set theory who were still grasping after > precise notions. All mathematicians whom you have disqualified above are genuin mathematicians. What you