Pythagorean said:
The same way clay isn't fundamentally related to any object you decide to model with the clay.
Mathematics is logical clay.
I disagree. Mathematics had its origins in the need to cost effectively solve everyday practical problems. Like knowing how many apples you're bartering for a cow, how to divide a given number of loafs of bread equitably (as near to as possible) between a number of people, computing firing solutions, computing man-hours & labour force requirements, map making, figuring out how many different ways you can arrange stuff, etc.
That is what mathematics is, at its roots. It has its origins in practical necessities. Not pipe dreams about imaginary numbers and such.
Pythagorean said:
The purpose is to be able to make models of reality with accurate logical statements; much like the purpose of making clay is for a sculptor to model. Some "claymakers" (mathematicians) DO just investigate formal rules to play with them, even though they don't have a meaningful physical counterpart.], but a lot of mathematics is driven directly by observation of the physical world.
I would say the purpose is to be able to make verifiable, reasonably accurate predictions about reality from reasonably accurate measurements. I don't think anybody really cares how stuff works as long as it does. I think this thread is evidence enough of that.
Do you see people questioning how irrational numbers can denote physical quantities? Nope.
Jarle said:
Pythagorean put it well. Clay can be used to make sculptures of real things, but the clay itself is in no correspondence with what it imitates. The relation is always inferred from the outside. Furthermore, we don't even have to imitate real things at all.
I don't think the clay analogy is very good. At all. When I want to compute how many apples each of 5 people gets from a trolley cart full of them, I already know each one is bound to get less or all the apples in the cart? How do I know that? Math didn't tell me. It can't tell me.
How do I know no one can get more apples then there were in the cart initially? How do I know I have to divide and not multiply by the number of people? Or add the number of people to the number of apples? Or subtract from?
Nope. Sorry. Maths is just a dumb tool for use in making predictions about reality. It just models reality and does what you tell it to (by analysing the practical problem and deciding what operations to use, how to pipe them). When you tell it to do garbled nonsense the result is pointless.
I know to use division because I know it is the mathematical operation modeled after the action I perform in distributing the apples equitably.
Similarly, I know that by dividing the number of people by the number of apples in the cart I get the number/amount of people each apple gets, after an equitable distribution.
So how is mathematics not firmly rooted in reality? How was it not developed after and for reality (making predictions about it)?
There is nothing beyond that but insanity, as Georg Cantor may have found out if he realized he was going insane.
Jarle said:
It's no secret that we use mathematics for various purposes like physical modeling and that it is developed for these things, but the important point is, which I have stated several times, that mathematics itself does not correspond to these things.
I don't see how you can end on that point. Again, how does addition not correspond to hoarding stuff in reality, for instance?
Jarle said:
Mathematics is the purely formal development and use of strictly formal rules. It cannot correspond to anything.
It is rooted in observations about reality. It corresponds to reality. It went off the rails at some point, when the theoretical eggheads stole it from the engineers of their day.
Jarle said:
However, that mathematics does not correspond to the real world does not imply that we have no motivation for the further development of mathematics, which you seem to suggest.
That is not what I suggest. What I suggest is that mathematicians try to develop practical maths with immediate, fundamental applications once in a while.
And that they try to stop needlessly delving in silliness, like using the complex plane instead of 2D vectors and whatnot.
Jarle said:
How our calculations relates to reality is through an interpretation outside of mathematics.
No. That interpretation took place in the beginning and is what gave ous our particular flavour of mathematics, as you might put it, by defining its axioms. Where a + b does not equal 1 regardless of what a and b are, for instance. That interpretation is defining for and integral to mathematics.
It also takes place in the beginning of every new piece of mathematics developed. Like equations for computing the texture coordinates of the sample point from the texture coordinates of the triangles' tips by weighing these coordinates according to the distance to the sample point.
How could I have known to develop the math necessary for texture mapping, vertex rotations, fish eye lens projection, etc. on my own from scratch if what you say were true? How is it that they're basically the same others came up with long before myself (except I don't use matriceal representation), whose work I didn't have access to at the time?
Jarle said:
So no, mathematics is not necessarily merely formal games without potential applications to reality, and this is because we have motivation for extra-mathematical use. That fact does not change the status of mathematics. At all.
What you're saying is basically that people developed imaginary numbers and group theory before the addition and subtraction of natural numbers for bartering. Abelian groups were just floating around in ethereal existence waiting to be plucked by some mathematician with spare time on their hands before anyone had even learned to count.
Jarle said:
One can, and one do occasionally, but one does not have to... Often we have a constructive application in mind for our use and development of mathematics. And often we don't, applications will often come as a 'side-effect' of the development of new mathematics, and there are many examples of this.
Yeah. Side effects like using complex numbers and the complex plane instead of 2D vectors. Or a Riemann sphere instead of polar projection.
Jarle said:
I never said numbers were symbols, I said numerals were symbols, and they are. And I also said arithmetic is the formal manipulation of these symbols, and I can not see a single argument against that in your comment.
This is semantics. I don't know what you mean by numerals but numbers aren't symbols.
Jarle said:
That mathematics deals only in formality means that the mathematical calculus is used and developed by following strictly formal well-defined rules. It's what I have been saying all along.
What strict, formal, well-defined rules did I follow when I developed my sign() function or fish-eye projection on my own?
Jarle said:
As you can see in the link, we can formalize the use of what we call infinity as a symbol tied to certain rules; much like a number. And what you directly adressed; division of zero can also be formalized as shown. It puzzles me if you cannot see the connection between this and what I said right above the link.
To accomplish what? What do you accomplish by your formalisation of 1/0, infinity? Results based on division by 0, infinity. By hiding under an alias you just postponed the inevitable reckoning until you've done all the calculations you could. In the end, what you're left with is still very much as meaningless as it is still bound to division by 0 or infinity.
Or you can just make up some arbitrary convention like 1/0 = 2 and go from there. Still an exercise in pointlessness every bit as meaningless for making predictions about reality. Which has been the whole point of math since its inception.
Jarle said:
We do have many different algebras as well. Some "useless", in that it has no current obvious application. In 'abstract algebra', addition is defined in many ways for different algebraic systems.
Why must we have a myriad of dud algebras instead of a myriad of
sillyAddition69(a,b) = 1
sillyAddition70(a,b) = a+b/2
sillyAddition71(a,b) = (a-1)×b
etc.
Jarle said:
There is not 'one' algebra in the same way as there is not 'one' geometry.
Of course there is. And you can model and/or contain egghead brain farts inside the one geometry and the one algebra. :)
See above.
Why must I have a whole new (elliptical, hyperbolic) geometry to study curved surfaces (distances on them, angles, etc.)? Can't I model or study curved surfaces in "Euclidian" geometry?
Why do I need the complex plane? Don't I have vectors?
This is exactly what I'm talking about.
Jarle said:
They are all studies of formalized structures. But they can also all have potential application outside of mathematics. That doesn't make them correspondent to whatever they might be used to represent, and it doesn't change the way we use mathematics. The use is always formal, completely rule-governed and without correspondence to physical reality.
I disagree.