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Article #5819Re: Lowneheim-Skolem theorem (was: Continuos vs. discrete models)
From: John C. Baez
Date: Fri, 20 Nov 1992 22:04
Date: Fri, 20 Nov 1992 22:04
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1649 bytes
In article <1992Nov17.124233.24312@oracorp.com> daryl@oracorp.com (Daryl McCullough) writes: >columbus@strident.think.com (Michael Weiss) writes: > >>In short: there may be good reasons for radically changing the foundations >>of physics (and there may not-- pace, defenders of the status quo(ntum)!), >>but the Loewenheim-Skolem theorem is not one of them. > >LS doesn't demand that we adopt Paul Budnik's discretized physics, but >I believe it gives us permission to do so. LS shows that there can >never be a demonstration that space-time must be continuous, because >there is no property of an uncountable set that doesn't also hold of >some countable set. I object. Lowenheim-Skolem says there are countable models of the reals; you can go ahead and use these if you like, and I will not object, since this does not affect what *theorems* you can prove about the real numbers. (Theorems, those statements that follow from the axioms, are defined purely syntactically and are utterly independent of a choice of model.) So I am at a loss to think of any sense in which using a countable model of the real numbers makes ones physics more "discrete."
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Newsgroups: sci.physics Path: arc1-ca.pugleaf.net!sparky!uunet!snorkelwacker.mit.edu!galois!riesz!jbaez From: jbaez@riesz.mit.edu (John C. Baez) Subject: Re: Lowneheim-Skolem theorem (was: Continuos vs. discrete models) Message-ID: <1992Nov20.220424.22979@galois.mit.edu> Sender: news@galois.mit.edu Nntp-Posting-Host: riesz Organization: MIT Department of Mathematics, Cambridge, MA References: <1992Nov17.124233.24312@oracorp.com> Date: Fri, 20 Nov 92 22:04:24 GMT Lines: 21