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robot_socks t1_j69yyg0 wrote

Reply to comment by Wouter_van_Ooijen in ELI5: Why do imaginary numbers even need to exist? by Tharsis101

>For imaginary numbers, for instance to describe both amplitude and phase of waves.

They really drop that one on you out of left field in higher level math/science/engineering classes. One day, they are just like 'remember that imaginary number bullshit from junior high school? Here is what that is actually for.'

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sudoku7 t1_j6a965p wrote

To be fair, Euhler's will mess with people's heads, and it's honestly the answer to this question but it sure isn't ELI5 :).

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Denziloe t1_j6brpho wrote

It's not what it's "actually for", it's one application among many, including their original algebraic origins.

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Genshed t1_j6a7lmv wrote

I didn't learn about imaginary numbers until several decades after leaving college.

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macedonianmoper t1_j6b5xnw wrote

What did you take then? I can't imagine an engineering degree that wouldn't use them, especially if you have any classes on anything electrical

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Genshed t1_j6b7ngm wrote

I can't imagine an engineering degree I could have done.

Background: I went to high school in the late 1970s. We had geometry (Euclid style, not Descartes) and an algebra class for the students who were going to university.

Took an accelerated trigonometry class during summer bridge, and then failed Calculus I three times my freshman year.

That's when I shifted my academic goals from the natural sciences to history. I still retain my youthful enthusiasm for the sciences, which is why I learned about complex numbers in the first place.

Most of my friends view my ongoing efforts to understand mathematics as a charming eccentricity. As my eldest brother put it, paraphrasing Oscar Wilde, 'all logarithms are quite useless.'

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macedonianmoper t1_j6b9mpy wrote

Ah I see, then it's totally understandable, unlike fractions and negatives they don't really serve a purpose for day to day.

Education changes from place to place, I see a lot of people apparently had calculus in highschool while I only started it in college (this was only a few years ago), I did however learn about imaginary numbers in high school

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lunatickoala t1_j6civq4 wrote

It's interesting how "useful day to day" can change so much in context. Logarithms are the basis for how slide rules work so in the time before personal computers when logarithms were more useful then than today.

And while most people don't actively use logarithms in their day to day life, they are incredibly important because human perception is generally logarithmic, not linear. The decibel scale is logarithmic because of this. There's even some evidence to suggest that logarithmic thinking might even be more natural. https://news.mit.edu/2012/thinking-logarithmically-1005

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DigitalSteven1 t1_j6b5gst wrote

We learned about them in like 9th grade. Times change. The mathematics being taught in high school now was university level a decade or two ago.

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gwaydms t1_j6b63rb wrote

We didn't learn imaginary numbers until Algebra 1. Not a lot of us took that in Jr hi. Well, I did, but the excellent teacher we had went to teach at the high school, so we got the world's worst Algebra teacher. I'd ask her a question and be more confused afterward, so I learned to figure things out on my own. I felt bad for the kids who couldn't do that and got no help from our very nice but clueless teacher.

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