It's true.

Well actually it’s the other way around. The reason imaginary numbers were invented was to solve a problem we’d been crying over for centuries.

Then, as in most cases, solving one problem opens the door to millions of other problems like why in the fuck does the universe use these imaginary numbers we made up to solve cube roots?

Why is i a core part of the unit circle with like e^i*pi ? “Oh that’s because i is just perpendicular to the real number line” ?! Say that sentence again, how the fuck did we go from throwing sharp sticks to utterly deranged sentences like that? More importantly why do utterly deranged sentences like that accurately describe our universe and what is the next ludicrous math concept we’re going to discover is integral to the function of the universe?

how the fuck did we go from throwing sharp sticks to utterly deranged sentences like that? More importantly why do utterly deranged sentences like that accurately describe our universe and what is the next ludicrous math concept we’re going to discover is integral to the function of the universe?

You need 3Blue1Brown in your life.
Funny how imaginary numbers were invented to solve cube roots, but the most common give example (& definition) uses square root.

Imaginary is a poor name for them because it implies they dont exist. Complex numbers[/component] is more appropriate

Complex numbers ≠ Imaginary numbers
- Imaginary numbers are any number multiplied by the square root of negative 1, a complex number has both a real and imaginary part. 10+i is complex, 10*i is imaginary.
the name seems to be an unfortunate choice that stems from their historical usage as “a means to an end”. i.e, they were first used as part of a method to find some solutions to cubic equations. this method would require algebraic manipulations of complex numbers, but the ultimate goal was to discover a real root. the complex roots would be discarded once a real root was found (if it existed).

the wikipedia article attributes the name to Descartes:

… 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.

which i think helps to highlight how skeptical the people at that time were about the existence of the “imaginary” numbers.

source: memories of my first complex analysis class, and https://en.wikipedia.org/wiki/Complex_number#History

i’d strongly recommend reading the history section of that wikipedia page to anyone interested in the topic, it has some pretty fun history
The Italian Bombelli in 1572 seemed to toy with both concepts but called imaginary numbers “quantità silvestri” (silvestri meaning ‘wild’) and complex numbers “numeri complessi”. Interesting the imaginary is a quantity and the complex is a number, but maybe old Italian didn’t have that distinction.

I suppose Descartes would agree with you, he first coined the term “imaginary” because he didn’t think they’d serve much purpose. Euler made use of them and continued using the term. Complex number is a complex - a number with a real and an imaginary component.
- A wild number appeared!
Well it's true, they don't exist
- There are concepts in nature they describe as well as real numbers describe other concepts. They definitely exist.

Imaginary numbers are as real as negative numbers.

Are they as real as real numbers though?
- I imagine
Unless you're referring to the set of Real Numbers, in which case they're not real.
Why stop there? They're just as real as any number.
- Exactly!
  But why stop there? They're just as unreal as any number.
  
  Some might say they are even about the same amount of number as any number.

Fine, then you figure out what the square root of a negative number actually is!

My calculator says they are an "error".
- https://www.wolframalpha.com/input?i=sqrt(-25)
  
  No idea why it doesn't just say 5i lol.
Serious question because I am math-challenged.

What things are we able to quantify by finding the square root of a negative number aside from square roots of negative numbers?
- Electrical engineers use them for calculating AC-circuits. In a DC circuit, you only have to worry about how much volt and amperes are in each part of the circuit. In an AC circuit, you also have to worry about the phase, cause the voltage goes up and down. The phase means where in that up and down you are.
  
  The complex number is interpreted as a point on a 2-dimensional plane; the complex plane. You have the "normal" number as 1 axis, and orthogonal to that the imaginary axis. The angle of the vector to that point gives the phase.
  
  They can be generally used for such "wavy" (ie periodical) processes. But I think this particular field of electrical engineering is the main application.

Hate to break it to you, but all numbers are imaginary.

I'm not sure I agree with this... it's like if no one is around to hear a tree fall, does it make a sound?
- All numbers are imaginary
  
  They are a logistical concept, invented with the purpose of counting and calculating quantities.
  
  Strictly speaking "Math" doesn't exist in nature.
  
  Circles are not round because of Pi. A triangle's sides are not consistent because of the Pythagorean theorem. A thrown ball doesn't travel in a parabola because of Algebra.
  
  Math is a tool CREATED to understand natural phenomena. Though its logistical power is so strong that it can be stretched to understand almost everything that can be measured.
  
  If a tree falls in the woods it vibrates the air at an audible frequence. Your ears absorb the vibrations and send a signal to your brain that we understand as sound. But the tree never makes a sound. The tree exists and interacts with the environment. Your brain interprets some of those interactions as sound.
  
  You can think of the numbers as the sound. You can understand them clearly, but they're just an interpretation of a natural phenomena.
- I always thought the tree falling in the forest thing was an inpenetrable koan from the depth of ancient philosophy, but it's actually a pretty simple tool to highlight the difference between sound as a physical thing and sound as perception, two related but different concepts for which we only use one word, hence the confusion.
- https://m.youtube.com/watch?v=ymGt7I4Yn3k
  
  Its a bit long but I think its the best explanation of the Russel paradox. Essentially, numbers really aren't what we think they are.
  
  Just thought it might be interesting to someone at least.

Imaginary numbers are the proof that even in mathematics you can discover stuff even though you don't understand what you have found. Complex numbers encode rotation.

Yup. When you have a circuit that is not purely resistive the inductive or capacitive load causes the voltage and current to not be in phase. It looks like ohms law is being violated. However the missing part of the energy is in the imaginary component to be returned latter.
- But that is hardly a 'natural occurence' of complex numbers - it just turned out that they were useful to represent the special case of harmonic solutions because of their relationship with trig functions.
Ever since I went down a particularly nasty rabbit hole and came out with a tenuous grasp on quaternions, imaginary numbers started feeling very simple, familiar and logical.
- Yeah. The thing that made me "get" quaternions was thinking about clocks. The hands move around in a 2d plane. You can represent the tips position with just x,y. However the axis that they rotate around is the z axis.
  
  To do a n dimensional rotation you need a n+1 dimensional axis. So to do a 3D rotation you need a 4D axis. This is bassicly a quat.
  
  You can use trig to get there in parts but it requires you to be careful to keep your planes distinct. If your planes get parallel you get gimbal lock. This never happens when working with quats.

https://lemmy.blahaj.zone/post/15648655

I wrote a piece about why imaginary numbers are actually important. It's in german though.

To sum it up, to every polynomial equation, there exists at least one solution to it, if you allow complex numbers to be solutions.

I used that text as a little test for the AIs at DDG. Here's from Claude 3 Haiku.

Here is the translation to English:

Complex Numbers and Polynomials

Something that hardly anyone knows is that complex numbers, in addition to their application in Complex AC Calculations (known to HTL students), also have a second, important use.

In mathematics, there is often the problem of finding a number x for a given function f(x) such that f(x) = 0 holds.

This is often the case for polynomials, as many important mathematical functions can be well approximated by polynomials.

The Fundamental Theorem of Algebra states that if we allow x to be a complex number, then there is always a solution to the problem such that f(x) = 0.

Restriction: but the polynomial must not consist of only a constant term, i.e., f(x) = 5 would be inadmissible. The x must appear at least once in the polynomial. Otherwise, there are really no restrictions :-)

PS: In the example given in the image (f(x) = x^2 + 2 = 0), a solution would be approximately x = √2 i ≈ 1.4 i.

Then I asked: "Please make it understandable to a general audience and phrase it like a pop-science author would."

Here is the translation in a more accessible, pop-science style:

The Hidden Power of Complex Numbers

Most people think complex numbers are just some obscure math concept, useful only for electrical engineers. But these mysterious numbers actually have a hidden superpower - they can solve all sorts of important math problems.

You see, in math, we often want to find a number x that makes a function f(x) equal to zero. This comes up a lot when working with polynomials - those nice, smooth equations made up of powers of x.

The problem is, sometimes there just doesn't seem to be any real number x that does the trick. That's where complex numbers swoop in to save the day!

The Fundamental Theorem of Algebra proves that as long as we allow x to be a complex number (a number with both a real and imaginary part), then there will always be a solution that makes f(x) equal to zero. No exceptions!

So complex numbers unlock the ability to solve all kinds of polynomial equations that would be impossible with just regular old real numbers. It's like they have a secret mathematical superpower.

Of course, there is one small catch - the polynomial can't be a simple constant, like f(x) = 5. It has to actually contain the variable x somewhere. But other than that, complex numbers can tackle any polynomial problem you throw at them.

So the next time you see an imaginary number like √(-1), remember - it's not just some weird math trick. It's a powerful tool for solving important equations. Complex numbers may seem strange, but they're secretly the heroes of the math world!
- oh wow, the second one is actually impressive. :)

And THEN the imaginary numbers started EATING ALL THE CATS AND DOGS

OP, you need to watch this video. https://youtu.be/cUzklzVXJwo

Spoiler

Imaginary numbers exist in nature.

Is that number with us in this room right now?

Imaginary numbers: proof that mathematicians don't understand branding.