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Re:How the number zero was ‘discovered’ by inopinatus on Thursday December 08, 2016 @12:28PM (#13132099)
We really are quite unkind in naming the numbers, or at least the difficult ones. We call them Zero (via Fibonacci's "zephiram", from the Arabic "sifr" meaning "empty"). Negative (from the Latin "negare", "to deny"). Irrational. And so on, in an escalation of denial: Imaginary. Transcendental. Supernatural. Surreal. There's more than a suggestion here that, on encountering the construction of each, the gut feeling is to reject their right to exist.

(Counterpoint; the ones we like are the ones we can grasp intuitively, and they receive more complimentary names: positive, natural, rational, prime. "integer" is Latin for "complete, sound, healthy")

It won't end, we'll always be discovering new number systems, so perhaps we should reserve terms now. Paradoxical numbers, anyone? Or repugnant?

Re:How the number zero was ‘discovered’ by conistonwater on Thursday December 08, 2016 @01:09PM (#13132536)
My dictionary gives "integer" as

> early 16th cent. (as an adjective meaning ‘entire, whole’): from Latin, ‘intact, whole,’ from in- (expressing negation) + the root of tangere ‘to touch.’ Compare with entire, also with integral,integrate, and integrity.

Indeed, whole numbers is another word for integers, dated in English, but that's what they are called in some other languages like German and Russian.

I also suspect natural is like in natural philosophy: occurring in nature, not like the other meaning of innate, although the two meanings are closely related.

Imaginary is due to Descartes (https://en.wikipedia.org/wiki/Complex_number#History):

> [...] sometimes only imaginary, that is one can imagine as many as I said in each equation, but sometimes there exists no quantity that matches that which we imagine.

It says Descartes didn't like them, but imaginary literally means not occurring in nature, and this was presumably before people accepted mathematical concepts as being as real as anything else.

Transcendental also literally means beyond the algebraic numbers, since that's the definition, that's what they transcend.

Surreal numbers are surreal because somebody (Conway?) needed to attach a prefix to real, and my dictionary says sur- is the same as super-. My dictionary says it is surreal that is the odd word here: a backformation for surrealism, which is some kind of art movement (I wouldn't trust some French painters to get English etymology right, eh? ;)).

Also, what about dyadic, and p-adic, numbers? Ordinal numbers? Hyperreal?

Re:How the number zero was ‘discovered’ by SilasX on Thursday December 08, 2016 @04:56PM (#13134655)
To add to this, "rational number" comes from "ratio" [2], not "rationality".

They look similar because (per [1]) they both come from Latin ratio ("reckoning, accounting"), which derives from reri (think, judge).

[1] http://www.dictionary.com/browse/ratio?s=t

[2] They're the numbers expressible as one integer divided by another.

Re:How the number zero was ‘discovered’ by thefalcon on Thursday December 08, 2016 @05:57PM (#13135088)
I realize not everyone is the same as myself, but I really wish that this etymology was explained when the concept of the rational number was introduced. I have trouble with rote memorization, but little trouble so long as I can derive a thing from first principles. Realizing that rational number comes from ratio seems so obvious in hindsight, but would have been so very helpful to my in-school self oh so long ago.
Re:How the number zero was ‘discovered’ by lawpoop on Friday December 09, 2016 @12:42PM (#13140229)
When I took math in high school, our textbook had little blurbs that pointed out historical curiosities in regards to math. (The only one I remember clearly is an ancient Greek Queen? maybe Middle Ages, who did a lot of work on conic sections. So maybe it's not such an effective teaching tool since I didn't remember who exactly she was or when or where she lived).

Anyway, all the people who said stuff like "When are we going to use X math topic in real life" were even more flummoxed by random math historical facts that weren't going to be on the test.

Anyway, at least for me, I think I passed a point of maturity where I don't feel "bombarded" when I encounter additional information in regards to a math topic. I did poorly in math in high school, and, at the time, I felt that the less information, the better-- I could only integrate so much. But now at my age (almost 40) learning additional historical facts seems to help me understand the topic better.

Re:How the number zero was ‘discovered’ by sedachv on Thursday December 08, 2016 @04:27PM (#13134461)
> this was presumably before people accepted mathematical concepts as being as real as anything else

Maybe as "unreal as anything else" would be a more accurate way to put it. Mathematical realism and even any kind of Platonism have a lot of detractors. I think the attitude change was more due to what is now known as Logicism (https://en.wikipedia.org/wiki/Logicism) and Formalism ( https://en.wikipedia.org/wiki/Formalism_(philosophy_of_mathe... ) when people realized that you did not need to appeal to the physical world to come up with useful things.

Re:How the number zero was ‘discovered’ by schoen on Thursday December 08, 2016 @07:06PM (#13135554)
> but imaginary literally means not occurring in nature

I would be tempted to say "pictured", "in a picture".

https://en.wiktionary.org/wiki/imago#Latin

But imago also has a lot of other meanings, and so "ghostly" and "conceptual" are also possibilities. :-)

Re:How the number zero was ‘discovered’ by agumonkey on Thursday December 08, 2016 @03:39PM (#13134066)
When you think about it, complex numbers are used to describe very natural properties, whereas natural, even though "naturally" simple, are very conceptual and symbolic.
Re:How the number zero was ‘discovered’ by thaumasiotes on Thursday December 08, 2016 @08:41PM (#13135988)
Only the imaginary numbers are named as a slur on the concept.

The quantity zero is empty, so the name is clearly appropriate.

negare is "deny" in classical Latin, but the term "negative number" is much more recent than any form of Latin, and refers to the "taking away" sense of "negative", just as in "negative reinforcement". Negative numbers are related to subtraction.

Supernatural numbers are an extension of the natural numbers. The terminology is pretty straightforward. Also, the word "supernatural" is generally complimentary, not derogatory. Similarly, surreal numbers extend, and are named in reference to, the real numbers.

Irrational numbers can't be expressed as ratios (of integers). It's not the term's fault if you confuse it with another word.

Re:How the number zero was ‘discovered’ by blaze33 on Thursday December 08, 2016 @05:32PM (#13134915)
I guess the naming also comes from the dimension you're looking at them. If you're constrained to one axis they're only positive and negative numbers. The other axis is the imaginary one because you can't possibly conceive it from your dimension. But if you have access to both dimensions there are no longer real or imaginary numbers but only complex ones. Quaternions. Hypercomplex numbers.

Like life, once you get out of a black and white understanding of your world, it's suddenly more complex...

Re:How the number zero was ‘discovered’ by theoh on Thursday December 08, 2016 @06:43PM (#13135418)
What about the happy, amicable, friendly, perfect, "untouchable" etc. numbers? I think you're being selective. Admittedly there reportedly also exist narcissistic and vampire numbers
Re:How the number zero was ‘discovered’ by labster on Thursday December 08, 2016 @04:44PM (#13134572)
Even some natural numbers have bad reputations: 666 is the mark of the Beast, 13 and 4 are unlucky, 1 is the loneliest number, 3's a crowd, and 40 (four tens) are terrible.
Re:How the number zero was ‘discovered’ by geebee on Thursday December 08, 2016 @06:50PM (#13135460)
It's amazing, isn't it? This was one of the best parts of math class.

It's so natural, too. Numbers, you count, 1, 2, 3, 4... it makes so much sense. And of course, rational numbers aren't too hard to grasp within that context. They're expressible with the nice numbers we know.

Even today, there are a lot of people who consider pi a strange, unusual number, an oddity. If they're aware of the square root of two, or euler's constant, they may consider them to be unusual as well.

At least in the US, it isn't until you've studied math for a while that you really do get into the notion of limits. A professor in Calc might talk about this in more depth (maybe when Taylor series come up) or high school geometry might mention that pi isn't actually that unusual. But I honestly don't blame people that this is hard to grasp. It's a long way from the "numbers" you understand from an early age, when you learn to count.

But yeah, it says something that numbers that occur "naturally" are almost never representable as the ratio of two integers. The ratio of a circumference to a radius. The "long" side of a right triangle with "legs" of a single unit. The number whose natural log is 1. Almost every number that took us by surprise, that we didn't invent but were instead required to measure and explain, remarkably, isn't expressible the way we thought numbers would be.

Can I go on a bit here and say that math gets hard the moment almost everything else gets hard, when you get out of your own head and try to see things as they actually are? When I was a kid, I loved "mechanical drawing", because it all looked so good on the page. I drew human creations, cars, houses, everything with nice lines, it all looked so sharp and snappy. And then you try to draw nature... where are the lines? It turns out you can't represent nature very well with lines. You have to draw what isn't there, not what is. The first time this comes up is when you try to draw someone's face.

Same for numbers. Draw a cube, measure the volume. Ok, easy. Draw a cylinder, measure the volume. A little harder, you have to make a good circle, but it can be done. Measure the volume - now you need this strange, "irrational" number that. Now go draw a tree trunk...

Hard. There isn't even a nice circle there. And to actually take the volume or surface area accurately, you need some way to measure the space under the curve, which requires calculus, little squares above and below the line, which can be made smaller and smaller, but they never reach zero. And the limit of the upper and lower sequence isn't an approximation of the number. The limit is the number. And it turns out that it's exceptionally unusual for that limit to be expressible as a ratio of two integers.

It's just unreal, isn't it? Er, I mean, real. ;)