this post was submitted on 26 Jun 2025
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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?

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[–] mkwt@lemmy.world 71 points 14 hours ago

Non-Euclidean geometry was developed by pure mathematicians who were trying to prove the parallel line postulate as a theorem. They realized that all of the classic geometry theorems are all different if you start changing that postulate.

This led to Riemannian geometry in 1854, which back then was a pure math exercise.

Some 60 years later, in 1915, Albert Einstein published the theory of general relativity, of which the core mathematics is all Riemannian geometry.

[–] Rhynoplaz@lemmy.world 42 points 14 hours ago (2 children)

I work with a guy who is a math whiz and loves to talk. Yesterday while I was invoicing clients, he was telling me how origami is much more effective for solving geometry than a compass and a straight edge.

I'll ask him this question.

[–] Rhynoplaz@lemmy.world 25 points 13 hours ago (1 children)

My disclaimer: I don't know what any of this means, but it might give you a direction to start your research.

First thing he came up with is Number Theory, and how they've been working on that for centuries, but they never would have imagined that it would be the basis of modern encryption. Multiplying a HUGE prime number with any other numbers is incredibly easy, but factoring the result into those same numbers is near impossible (within reasonable time constraints.)

He said something about knot theory and bacterial proteins, but it was too far above my head to even try to relay how that's relevant.

[–] Reverendender@sh.itjust.works 21 points 13 hours ago (1 children)

Tell him I would like to subscribe to his blog

[–] Rhynoplaz@lemmy.world 13 points 11 hours ago

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. 😂)

[–] frezik@lemmy.blahaj.zone 7 points 12 hours ago

Origami can be used as a basis for geometry:

http://origametry.net/omfiles/geoconst.html

IIRC, you can do things that are impossible in standard Euclidean construction, such as squaring the circle. It also has more axioms than Euclidean construction, so maybe it's not a completely fair comparison.

[–] TheBlindPew@lemmy.dbzer0.com 37 points 11 hours ago (3 children)

The math fun fact I remember best from college is that Charles Boole invented Boolean algebra for his doctoral thesis and his goal was to create a branch of mathematics that was useless. For those not familiar with boolean algebra it works by using logic gates with 1s and 0s to determine a final 1 or 0 state and is subsequently the basis for all modern digital computing

[–] Crankenstein@lemmy.world 6 points 5 hours ago

George Boole introduced Boolean algebra, not Charles. Charles, according to this site on the Boole family, he had a career in management of a mining company.

[–] Fleur_@aussie.zone 5 points 2 hours ago

Shoutout to Satyendra Nath Bose who helped pioneer relativity as a theoretical physicist because he didn't want to study something useful that would benefit the British.

[–] Agent641@lemmy.world 4 points 8 hours ago (1 children)

Was he trying to dunk on his professors?

[–] Simplicity@lemmy.world 28 points 13 hours ago (2 children)
[–] raspberriesareyummy@lemmy.world 6 points 9 hours ago (1 children)
[–] VindictiveJudge@lemmy.world 1 points 56 minutes ago

Quake, not Doom. Doom didn't use true 3D rendering and had almost no dynamic lighting.

[–] Sparkega@sh.itjust.works 1 points 1 hour ago

The exact example I also thought of from the question! Well done

[–] four@lemmy.zip 22 points 14 hours ago (2 children)

IIRC quaternions were considered pretty useless until we started doing 3D stuff on computers and now they're used everywhere

[–] theherk@lemmy.world 12 points 13 hours ago* (last edited 12 hours ago) (1 children)

This talk by Freya Holmer on Quarternions is awesome and worth anybody’s time that like computer graphics, computer science, or just math.

[–] khannie@lemmy.world 1 points 7 hours ago

That was a cool watch. Thanks.

[–] iii@mander.xyz 4 points 13 hours ago (1 children)

I wonder if complex numbers predate the discovery of electromagnetism

[–] SwingingTheLamp@midwest.social 7 points 8 hours ago

Yes, mathematicians first encountered equations which could only be solved with complex numbers in the 16th century.

[–] truthfultemporarily@feddit.org 19 points 10 hours ago (1 children)

A brain teaser about visiting all islands connected by bridges without crossing the same bridge twice is now the basis of all internet routing. (Graph theory)

[–] lowered_lifted@lemmy.blahaj.zone 1 points 39 minutes ago

freaking freaky little Russian outpost that one is. Bridges galore

[–] bjoern_tantau@swg-empire.de 18 points 13 hours ago* (last edited 13 hours ago) (3 children)

Complex numbers. Also known as imaginary numbers. The imaginary number i is the solution to √-1. And it is really used in quantum mechanics and I think general relativity as well.

[–] theherk@lemmy.world 7 points 12 hours ago (1 children)

I’m the akshually guy here, but complex numbers are the combination of a real number and an imaginary number. Agree with you, just being pedantic.

[–] bjoern_tantau@swg-empire.de 2 points 12 hours ago (1 children)

Sure, but 1 is a real number. 😜

[–] hornface@fedia.io 3 points 11 hours ago (1 children)

Yes, and 1 is also a complex number.

[–] Whats_your_reasoning@lemmy.world 2 points 7 hours ago (1 children)

Of course, but 1 is the loneliest number.

[–] corsicanguppy@lemmy.ca 1 points 1 hour ago

2 is as bad as 1: it's the loneliest number since the number 1.

[–] Bwaz@lemmy.world 5 points 8 hours ago

It's used extensively in electronic circuit design (where it's called "j", as "i' already meant electronic current).

Also signal processing has i or j all over it.

[–] gigachad@sh.itjust.works 4 points 13 hours ago

Electromagnetics as well.

[–] acockworkorange@mander.xyz 15 points 9 hours ago (1 children)

If I recall correctly, one mathematician in the 1800s solved a very difficult line integral, and the first application of it was in early computer speech synthesis.

[–] Crankenstein@lemmy.world 8 points 5 hours ago

the man you're thinking of is, I believe, George Boole, the inventor of Boolean algebra.

[–] blaue_Fledermaus@mstdn.io 11 points 13 hours ago (1 children)

I've read that all modern cryptography is based on an area (number theory?) that was once only considered "useful" for party tricks.

[–] nsrxn@lemmy.dbzer0.com 7 points 12 hours ago* (last edited 12 hours ago) (1 children)

prime number factorization is the basis of assymetric cryptography. basically, if I start with two large prime numbers (DES was 56bit prime numbers iirc), and multiply them, then the only known solution to find the original prime numbers is guess-and-check. modern keys use 4096-bit keys, and there are more prime numbers in that space than there are particles in the universe. using known computation methods, there is no way to find these keys before the heat death of the universe.

[–] stinerman@midwest.social 7 points 10 hours ago (1 children)

DES is symmetric key cryptography. It doesn't rely on the difficulty of factorizing large semi-primes. It did use a 56-bit key, though.

Public key cryptography (DSA, RSA, Elliptic Curve) does rely on these things and yes it's a 4096-bit key these days (up from 1024 in the older days).

[–] nsrxn@lemmy.dbzer0.com 2 points 6 hours ago
[–] three_trains_in_a_trenchcoat@piefed.social 9 points 12 hours ago (1 children)

Non-linear equations have entered the chat.

Chaos and non-linear dynamics were treated as a toy or curiosity for a pretty long time, probably in no small part due to the complexity involved. It's almost certainly no accident that the first serious explorations of it after Poincare happen after the advent of computers.

So, one place where non-linear dynamics ended up having applications was in medicine. As I recall it from James Gleick's book Chaos, inspired by recent discussion of Chaotic behavior in non-linear systems, medical doctors came up with the idea of electrical defibrillation- a way to reset the heart to a ground state and silence chaotic activity in lethal dysrhythmias that prevented the heart from functioning correctly.

Fractals also inspired some file compression algorithms, as I recall, and they also provide a useful means of estimating the perimeters of irregular shapes.

Also, there's always work being done on turbulence, especially in the field of nuclear fusion as plasma turbulence seems to have a non-trivial impact on how efficiently a reactor can fuse plasma.

[–] dylanmorgan@sh.itjust.works 6 points 11 hours ago (1 children)

A good friend of mine from high school got his physics PhD at University of Texas and went on to work in the high energy plasma physics lab there with the Texas Petawatt laser, and a lot of the experiments it was used for involved plasma turbulence and determining what path energetic particles would take in a hypothetical fusion reactor.

[–] Rhynoplaz@lemmy.world 5 points 11 hours ago (2 children)

Be honest, how many unofficial experiments were there?

You ever just start lasering shit for kicks?

[–] duckythescientist@sh.itjust.works 1 points 48 minutes ago

Probably not as many as we'd like to think. I recently got to run a few days of tests at Lawrence Livermore National Labs with an absurdly massive laser. At one point we needed to bring in a small speaker for an audio test. It took the lab techs and managers about two hours and a couple phone calls to some higher ups to make sure it was ok and wouldn't damage anything. There's so much red tape and procedure in the way that I don't think there's an opportunity to just fuck around. The laser has irreplaceable parts that people aren't willing to jeopardize. Newer or smaller lasers are going to be more relaxed. This one is old enough to be my father, and it's LLNL's second biggest single laser iirc. And they are the lab using lasers for fusion, so they have big lasers.

[–] Hadriscus@jlai.lu 1 points 1 hour ago* (last edited 53 minutes ago)
[–] bacon_pdp@lemmy.world 9 points 14 hours ago (2 children)

Donuts were basis of the math that would enable a planned economy to be more efficient than a market economy (which is a very hard linear algebra problem).

Basically using that, your smart phone is powerful enough to run a planned economy with 30 million unique products and services. An average desktop computer would be powerful enough to run a planned economy with 400 million unique products and services.

Odd that knowledge about it has been actively suppressed since it was discovered in the 1970s but actively used mega-corporations ever since…

[–] evujumenuk@lemmy.world 5 points 13 hours ago (1 children)

That's pretty interesting. Do you happen to have any introductory material to that topic?

I mean, it might even have applications outside of running a techno-communist nation state. For example, for designing economic simulation game mechanics.

[–] bacon_pdp@lemmy.world 4 points 12 hours ago

Well Wassily Wassilyevich Leontief won a Nobel prize in economics for his work on this subject that might help you get started

[–] three_trains_in_a_trenchcoat@piefed.social 5 points 12 hours ago (1 children)

I'd like to read up on this if you have sources

[–] bacon_pdp@lemmy.world 4 points 12 hours ago

Look up Wassily Wassilyevich Leontief

[–] saimen@feddit.org 5 points 2 hours ago

Having watched all the veritasium math videos I feel like all the major breakthroughs in math were due to mathemicians playing around with numbers or brain teasers out of curiosity without a concrete use case in mind.

[–] Arkouda@lemmy.ca 1 points 14 hours ago

How do you define "pure math discovery"?