this post was submitted on 02 Aug 2026
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[–] Klear@piefed.world 124 points 1 week ago (3 children)

It's more complex than that...

[–] devaly@ani.social 56 points 1 week ago (1 children)
[–] LemmyPlaceDN@europe.pub 29 points 1 week ago (1 children)
[–] Neverclear@lemmy.dbzer0.com 5 points 1 week ago

Let's get to the root of all this negativity

[–] sundray@lemmus.org 8 points 1 week ago* (last edited 1 week ago) (1 children)
[–] davad@lemmy.world 91 points 1 week ago (8 children)

I've always thought "imaginary" vs "real" was an unfortunate naming convention.

I don't know about other fields, but electrical engineering uses imaginary numbers with AC circuits and changing electrical fields. Since electricity moves as waves, imaginary numbers let you represent what's coming 90 degrees later in a compact way.

[–] FishFace@piefed.social 30 points 1 week ago (2 children)

Yeah, I think it causes unnecessary difficulties. I actually think they're introduced at a time when you could instead teach them as two-dimensional vectors with pointwise addition and a special multiplication and division rule, and prove that (0, 1)×(0, 1) = (-1, 0) using that rule, so that sqrt(-1, 0) = (0, 1).

Then you can establish a convention that you write (a, b) as a + bi (and i = (0, 1)).

This is too abstract for younger students, but nowadays I don't think they learn complex numbers anyway, and I think it would be less spooky for the older students.

[–] andros_rex@lemmy.world 9 points 1 week ago (3 children)

Imaginary numbers are typically introduced in a high school “algebra 2” course in my neck of the woods, like junior year unless you are accelerated or held back. I feel like it’s really common for them to not be taught well - the naming is something that occasionally trips up the teachers.

The teaching of them is something that really interests me - they’re the kind of thing that triggers the “when am I ever going to use this?”/rants about not learning how to do taxes. You can talk about the relevance to electronics, but DC electronics is already hard enough for most to comprehend.

I like to connect it to rotation. Show them the pattern of powers of i with physical movement - quarter turns.

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[–] sangeteria@lemmy.ml 7 points 1 week ago (1 children)

Also tbf, rational numbers are just the lattice modded out by the equivalence relations (a, b) ~ (c, d) iff ad = bc, and the equivalence classes just happen to form an ordered field. If you show an undergrad math/science student this esoteric definition of rationals, the motivation of "2D numbers" makes a lot more sense. Of course, please don't show this to an elementary or middle schooler, a high schooler might be able to handle this if they're passionate about math.

[–] FishFace@piefed.social 5 points 1 week ago

Of course, please don’t show this to an elementary or middle schooler, a high schooler might be able to handle this if they’re passionate about math.

Lol, I was thinking this as I was reading.

The neat thing about complex numbers defined this way is that you don't need to understand quotient spaces because under addition ℂ is already isomorphic to ℝ²!

[–] iusemybrain@sh.itjust.works 22 points 1 week ago* (last edited 1 week ago) (1 children)

don't forgot signal processing. Complex number theory is used a lot when it comes down to Fourier transforms of discrete or continuous functions.

but yea the naming convention of "imaginary numbers" is pretty bad, we did the same thing for negative numbers (we called it imaginary) when people couldn't comprehend of a negative quantity.

negative numbers are defined from a conservative system, basically a gain/loss relationship: if I have 2 apples and I give away 1 to a friend, I have 1 apple left, that loss -- that apple I gave to a friend -- is the negative quantity. For imaginary numbers, we don't really have a way to comprehend an imaginary quantity; what does it mean that I have sqrt(-1) apples.

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[–] feddylemmy@lemmy.world 22 points 1 week ago (1 children)

Carl Friedrich Gauss would agree with you on the naming. He thought the confusion/mistery around imaginary numbers was due to naming. He said +1, -1, and root(-1) should have been called direct, inverse, and lateral units.

[–] DaleGribble88@programming.dev 9 points 1 week ago

Lateral numbers is my preferred term

[–] a1tsca13@lemmy.world 12 points 1 week ago (1 children)

And in optics, the "real" portion of a material's refractive index represents scattered light and the "imaginary" part represents absorbed light.

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[–] IAmNorRealTakeYourMeds@lemmy.world 10 points 1 week ago (1 children)

Not just electricians.

3d graphics are all about about quaternions (4d version of imaginary numbers).

[–] Snazz@lemmy.world 7 points 1 week ago (1 children)

Quaternions are useful, but no means necessary or intrinsic to 3d graphics.

They are useful for describing rotations in 3d space, but the same can be done with a matrix, or even Euler angles. It’s just a more calculations.

That said, basically all the major game engines use quaternions, so unless you are creating your own 3d renderer, you have to learn at least the basics about them.

Quaternions really shine at spherical interpolation (Slerp - yes thats the real terminology) between two rotations.

[–] blackbelt352@lemmy.world 9 points 1 week ago

I'd say Quaternions are necessary purely because they avoid gimbal locking common with 3 axis Euler rotations.

I know in Blender all other rotation options are really just quaterinions under the hood. But an advantage Euler rotations have over quaternions is continuous rotation. I can set 2 key frames with linear extrapolation and have them just continue along each axis forever. Everything quaternion ideally should be bounded to the 4d unit circle.

[–] BCsven@lemmy.ca 8 points 1 week ago

Yep, it is bad naming. I took it in highschool but it didn't really make sense till I saw how it described electric fields with the wave 90 degrees into the flat page.

[–] omega_x3@lemmy.world 6 points 1 week ago (2 children)

Electrical engineers also use them as a simple way of solving differential equations with laplace transforms. Much easier as long as you don't care about what happens at infinity.

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[–] NaibofTabr@infosec.pub 56 points 1 week ago* (last edited 1 week ago)

Just one more axiom bro and it will all make sense... just one more I swear it's consistent... BRO I just NEED one more conjecture and it will BE complete... tHe pRincIPles ARe sOLid BrO jUST TruST mE!

[–] yesman@lemmy.world 46 points 1 week ago (8 children)

It's not like the regular numbers behave themselves. Have you ever heard a coherent, non-self referential definition of the number 3?

[–] arctanthrope@lemmy.world 22 points 1 week ago (1 children)

the only numbers that actually exist are 0 and 1. everything else is a reference to those

[–] spicehoarder@lemmy.zip 4 points 1 week ago (1 children)

I can define zero as the absence of 1. But also 1 itself is a reference to the infinitely fractional 0.00...1 and I'd consider that a different number to the whole number 1

[–] arctanthrope@lemmy.world 11 points 1 week ago

that doesn't actually exist in the standard number system; there is no single real number that's immediately next to 0, you can always get closer. some number systems have infinitesimals, but real numbers don't. and any very small real number with a terminating decimal expression is simply the inverse of a very large number, which is simply a long string of 1+1+1+1+1...

[–] gezero@sopuli.xyz 21 points 1 week ago (1 children)
[–] protist@retrofed.com 9 points 1 week ago (8 children)
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[–] ProfessorScience@lemmy.world 15 points 1 week ago (2 children)
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[–] QuantumSparkles@sh.itjust.works 10 points 1 week ago (4 children)
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[–] anise@awful.systems 9 points 1 week ago (1 children)
[–] WilloftheWest@feddit.uk 9 points 1 week ago (3 children)

That would be 2. 3 would be {{},{{}},{{},{{}}}}.

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[–] howdy@lemmy.ml 27 points 1 week ago (4 children)

men will invent new fields of mathematics before going to therapy

[–] SomethingBurger@jlai.lu 8 points 1 week ago (2 children)

Well, new fields of mathematics are useful.

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[–] DigDoug@lemmy.world 19 points 1 week ago (1 children)

Practically everything people say about imaginary numbers you could also say about negative numbers.

Also... wrong about what?

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[–] Kolanaki@pawb.social 16 points 1 week ago (1 children)

All numbers are imaginary. So are words.

[–] expatriado@lemmy.world 5 points 1 week ago (1 children)

for real, which is imaginary

[–] Kolanaki@pawb.social 5 points 1 week ago

Especially for solipists.

[–] TheTechnician27@lemmy.world 12 points 1 week ago

They're just closure-minded.

[–] Battle_Masker@lemmy.blahaj.zone 11 points 1 week ago (2 children)

alright wise guy, what IS the square root of -1 then?

[–] nibbler@discuss.tchncs.de 6 points 1 week ago (4 children)

alright wise guy, what IS -1divided by 0 then?

[–] NateNate60@lemmy.world 5 points 1 week ago (1 children)

-1 / 0 can be defined to be a special new number, ⭐.

This system of numbers is actually mathematically consistent and has all the properties that a number system should have. But using simple algebra, you can prove that in this new number system, ⭐ = 0. And then you can also prove that all other numbers equal zero.

This number system is known as the zero ring, and it's the ring where the only number is 0 and the following operations are defined:

  • 0 + 0 = 0
  • 0 - 0 = 0
  • 0 × 0 = 0
  • 0 ÷ 0 = 0
  • 0^0 = 0

All other symbols, including 1, 2, and ⭐, are just alternative labels for 0 in this number system. In other words, defining division by zero is essentially the equivalent of reality collapsing in mathematics.

So yes, you can validly define division by zero. You just get degenerate mathematics if you do. So be careful what you wish for.

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[–] uriel238@lemmy.blahaj.zone 10 points 1 week ago

This is a thing that mathematicians do. Rather than just assume you can't divide by zero they'll go ahead and try and see what happens.

[–] RobotToaster@mander.xyz 10 points 1 week ago (2 children)
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[–] DarrinBrunner@lemmy.world 6 points 1 week ago (2 children)

Physicists (only because I watch Sabine, and this is what she says they do)

[–] gezero@sopuli.xyz 18 points 1 week ago

That's the face I make when someone mentions she is watching Sabine (only because I watch prof Dave)

[–] ivanafterall@lemmy.world 4 points 1 week ago (1 children)

Sabine is a little nutty ngl, I had to unsubscribe. She huffs her own farts way too much.

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[–] Agent641@lemmy.world 5 points 1 week ago

All numbers are imaginary

[–] A_Chilean_Cyborg@feddit.cl 5 points 1 week ago (1 children)

Then, when those numbers appear IRL, what do you do then huh??

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[–] MuteDog@lemmy.world 5 points 1 week ago (2 children)

I feel like this is why physicists came up with dark matter/energy

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