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To: Physicist
Mathematical truth: seven cannot be factored into integers other than itself and one. Mathematical formalism: multiplication is commutative.

Ah, now I see what you mean. Multiplication could have been defined so that it is not commutative. And indeed, matrix multiplication is not.

On the other hand, primality appears to be an intrinsic property of the integer seven. I cannot imagine how one could "redefine" seven to make it composite. (Unless one wanted to redefine multiplication to make that true.)

Still, I have my doubts. As Kronecker said, "God created the whole numbers; everything else was man's handiwork." Integers suffice if all we are going to do is count things. However, if we also want to measure things, we need more sophisticated mathematics. And the further we get from the integers, the more formalism is found in our mathematics. Thus we decide that multiplication of scalars is to be commutative, because it is more useful that way.

When I said that reality is more fundamental than mathematics, I was thinking that nature is always richer in detail than our mathematics. Mathematical modeling is difficult; invariably, we are forced to omit things from our models. Even the "laws" of physics turn out to be, on closer examination, merely good approximations.

100 posted on 12/06/2001 5:28:56 PM PST by Logophile
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To: Logophile
As Kronecker said, "God created the whole numbers; everything else was man's handiwork."

That was a hilarious quote for many reasons.

Kroncker was not very pleased with Cantor creating notations to differentiate between different "infinities". Yet religious people at the time (and many still today) felt no hesitation in discussing God as infinitely wise or infinitely loving or infinitely whatever. Presumably Cantor's response would be to ask if that was referencing the infinite number of integers or infinite number of real numbers or the infinte number of integers taken to the power of the infinite number of integers.

So religion and Cantor's mathematics seemed to be interested in the same subject. ;-)

A brief comment on your metaphysics of mathematics discussion (and an interesting one it has been :-) )--

To be useful in the world we inhabit mathematics should set an outer bound of what is possible in physics but ultimately I would suggest that it is asking too much of mathematcs to try to have it address the issues that concern metaphysics.

Example: If we lived in a virtual world like in the movie "The Matrix" (showing on cable this weekend, btw) the mathematics would have to define what was possible in the matrix. It might or might not be relevant to the "outside' universe.
130 posted on 12/08/2001 1:21:59 PM PST by cgbg
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