What is the strangest math that turned out to be useful?
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I don't really get 'em. It seems like people often use them as "a pair of numbers." So why not just use a pair of numbers then?
wrote on last edited by [email protected]They also have a defined multiplication operation consistent with how it works on ordinary numbers. And it's not just multiplying each number separately.
A lot of math works better on them. For example, all n-degree polynomials have exactly n roots, and all smooth complex functions have a polynomial approximation at every point. Neither is true on the reals.
Quantum mechanics could possibly work with pairs of real numbers, but it would be unclear what each one means on their own. Treating a probability amplitude as a single number is more satisfying in a lot of ways.
That they don't exist is still a position you could take, but so is the opposite.
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I'm studying EE in university, and have been surprised by just how much imaginary numbers are used
From what I've seen that's one example where you could totally just use trig and pairs of numbers, though. I might be missing something, because I'm not an electrical engineer.
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I mean, quaternions are the weirder version of complex numbers, and they're used for calculating 3D rotations in a lot of production code.
There's also the octonions and (much inferior) Clifford algebras beyond that, but I don't know about applications.
Yeah but aren't quaternions basically just a weird subgroup of 2x2 complex matrices?
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There have been a number of Scientific discoveries that seemed to be purely scientific curiosities that later turned out to be incredibly useful. Hertz famously commented about the discovery of radio waves: “I do not think that the wireless waves I have discovered will have any practical application.”
Are there examples like this in math as well? What is the most interesting "pure math" discovery that proved to be useful in solving a real-world problem?
wrote on last edited by [email protected]Strangest? Functional analysis, maybe. I understand it's used pretty extensively in quantum field theory, although I don't actually know firsthand.
That's a body of mathematics about infinite-dimensional spaces and the operations on them. Even more abstract ways of defining those operations exist and have come up as well, like in Tseirlson's problem, which recently-ish had a shock negative resolution stemming from quantum information theory.
There's constructions I find weirder yet, but I don't think p-adic numbers, for example, have any direct application at this point.
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Oh god, the cringe.
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From what I've seen that's one example where you could totally just use trig and pairs of numbers, though. I might be missing something, because I'm not an electrical engineer.
You can, they map, but complex numbers are much much easier to deal with
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Does this count? Because it really is wtf.
Don't put that cursed shit on mathematicians, lol.
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The following aren't necessarily answers to your question, but he also mentioned these, and they are way too funny to not share:
The Hairy Ball theorem
Cox Ring
Tits Alternative
Wiener Measure
The Cox-Zucker machine (although this was in the 70s and it's rumored that Cox did most of the work and chose his partner ONLY for the name.
)Based Cox.
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There's no such thing as a Nobel Prize in economics. Economists got salty about this and came up with the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel, and rely on the media shortening it to something that gets confused with real Nobel Prizes.
I mean, it's endorsed by the same people. He has a page on their website and everything.
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Look up Wassily Wassilyevich Leontief
Are you talking about the input-output thing? It assumes each sector produces exactly one thing, and is agnostic of growth, change and multiple non-equal possibilities existing. I'm skeptical.
It's not really covered up, either.
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Yeah but aren't quaternions basically just a weird subgroup of 2x2 complex matrices?
wrote on last edited by [email protected]Would that make it less true? Complex numbers can be seen as a weird subgroup of the 2x2 real matrices. (And you can "stack" the two representations to get 4x4 real quaternions)
Furthermore, octonions are non-associative, and so can't be a subgroup of anything (although you can do a similar thing using an alternate matrix multiplication rule). They still show up in a lot of the same pure math contexts, though.
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You can, they map, but complex numbers are much much easier to deal with
wrote on last edited by [email protected]In quantum mechanics, there are times you divide two different complex numbers, and complex multiplication/division is the thing two real numbers can't really replicate. That's how the Bloch 2-sphere in 3D space is constructed from two complex dimensions (which maps to 4 real ones).
It's peripheral, though. Nothing in the guts of the theory needs it AFAIK - the Bloch sphere doesn't generalise much and is more of a visualisation. So, jury's still out on if it's us or if it's nature that likes seeing it that way.
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I mean, it's endorsed by the same people. He has a page on their website and everything.
The same site says things like:
Between 1901 and 2024, the Nobel Prizes and the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel were awarded 627 times to 1,012 people and organisations.
which pretty clearly makes a distinction between the Nobel Prizes and the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel.
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A complex number is just two real numbers stitched together. It's used in many areas, such as the Fourier transform which is common in computer science is often represented with complex numbers because it deals with waves and waves are two-dimensional, and so rather than needing two different equations you can represent it with a single equation where the two-dimensional behavior occurs on the complex-plane.
In principle you can always just split a complex number into two real numbers and carry on the calculation that way. In fact, if we couldn't, then no one would use complex numbers, because computers can't process imaginary numbers directly. Every computer program that deals with complex numbers, behind the scenes, is decomposing it into two real-valued floating point numbers.
That's like saying negative numbers or fractional numbers is just two while numbers stitched together because that's how computers deal with it
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Integration.
Integration was literally developed to be useful
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The same site says things like:
Between 1901 and 2024, the Nobel Prizes and the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel were awarded 627 times to 1,012 people and organisations.
which pretty clearly makes a distinction between the Nobel Prizes and the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel.
wrote on last edited by [email protected]Yeah, you're not wrong about the history. It just still seems like it counts.
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Would that make it less true? Complex numbers can be seen as a weird subgroup of the 2x2 real matrices. (And you can "stack" the two representations to get 4x4 real quaternions)
Furthermore, octonions are non-associative, and so can't be a subgroup of anything (although you can do a similar thing using an alternate matrix multiplication rule). They still show up in a lot of the same pure math contexts, though.
I just think complex vector spaces are a great place to stop your abstraction
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I just think complex vector spaces are a great place to stop your abstraction
Stopping while we're ahead? Never!
/s, but also I'm sort of in this picture.
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Stopping while we're ahead? Never!
/s, but also I'm sort of in this picture.
Well who wants constraints anyway? The most inconvenient constraints in the wrong place can make certain things much more complicated to deal with... Now a nice, sensible normal Hilbert space, isn't that lovely?
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There have been a number of Scientific discoveries that seemed to be purely scientific curiosities that later turned out to be incredibly useful. Hertz famously commented about the discovery of radio waves: “I do not think that the wireless waves I have discovered will have any practical application.”
Are there examples like this in math as well? What is the most interesting "pure math" discovery that proved to be useful in solving a real-world problem?
Riemann went nuts working on higher dimensional mathematics and linear algebra. At the time there was not a clear use case for math higher than like 3 or 4 dimensions, but he drove himself crazy discovering it anyways. Today, this kind of math underlies all of artificial intelligence
