Ask HN: Concepts that clicked only years after you first encountered them?

#1

Post by luuuzeta » Sun, Jan 01, 2023, 1:50 PM UTC

I'm reading Petzold's Code [1], and it dawned on me that I didn't understand logic gates intuitively until now. I took a Computer Architecture course back in college, and I understood what logic gates meant in boolean algebra but not empirically. Petzold clarified this for me by going from the empirical to the theoretical using a lightbulb, a battery, wires, and relays (which he introduces when he talks about the telegraph as a way to amplify a signal).

Another concept is the relationship between current, voltage, and resistance. For example, I always failed to understand why longer wires mean more resistance while thicker wires mean less resistance.

[1]: https://www.codehiddenlanguage.com/

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#2

Post by bsuvc » Sun, Jan 01, 2023, 2:31 PM UTC

Unit testing and using dependency injection to write test-able code.

I'm not sure if it was years, but it wasn't immediate. I just didn't understand why dependency injection was good at first, and not just someone's weird personal code style choice.

I thought it was just people being "Enterprisey" which I'd encountered many times over the years.

Once I committed to unit testing, I realized how necessary it is.

Unfortunately I still encounter customers who haven't bought into it and as a result have untestable code. It's so hard to go back and retrofit testing.

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#3

Post by ergonaught » Sun, Jan 01, 2023, 2:37 PM UTC

Basic music theory.

Almost no one I encountered bothered to actually explain anything. They simply regurgitated things and I guess expected me to somehow intuitively understand something or other.

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#4

Post by sokoloff » Sun, Jan 01, 2023, 2:37 PM UTC

Systems in equilibrium. A lot of my college engineering courses had these (what seemed to me to be) hand-wavy assertions of equality and what seemed like just an assumption that the system would converge to that point.

I was probably in my late 30s or early 40s before I really grokked why that tended to be true. (I could blindly accept and grind through the equations to get the answers in college, but it was decades later that I developed a feel for why.)

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#5

Post by W0lf » Sun, Jan 01, 2023, 2:40 PM UTC

Discrete mathematics and all sorts of its application in real-world (software development) related problems. Also how any given solution to a problem in one problem domain can be transferred to a problem in another unrelated domain. Think Galois theory but waaaay less fancy :-)

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#6

Post by recursivedoubts » Sun, Jan 01, 2023, 2:42 PM UTC

i didn't really understand hypermedia, and, in particular, the uniform interface/HATEOAS until a few years after i started building intercooler.js (htmx predecessor)

https://intercoolerjs.org/2016/01/18/rescuing-rest.html

much later:

https://htmx.org/essays/hateoas/

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#7

Post by ISL » Sun, Jan 01, 2023, 2:43 PM UTC

That professors were thinking real hard about which problem sets to give us in hopes that we would actually learn something.

I don't think I really understood that completely until I started TA-ing.

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#8

Post by robg » Sun, Jan 01, 2023, 2:46 PM UTC

The autonomic nervous system and the adrenal cortex. Homeostasis is taught as a textbook fact, the body reverting to a baseline over time. What’s not taught is how much the impacts of daily life events drive a continuous stress response. Fight or flight is not just a reaction to deadly threats. It’s active every moment of every day to ensure survival. The adrenal cortex is always active, to traffic, your boss and colleagues, relationship struggles, and overall health and wellness like sleep and nutrition. Yes, the system reverts to a baseline over time but how much that baseline varies is obvious in tracking resting heart rate.

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#9

Post by linuxlizard » Sun, Jan 01, 2023, 2:47 PM UTC

Blue Noise dithering based on a HN post from @todsacerdoti. https://news.ycombinator.com/item?id=25633483 At my previous job we had an ASIC hardware block to implement blue noise dithering. No one, even the people who created it, could explain to me how I needed to use it. Years latter, I read their blog post and a light bulb went on.

Re: Ask HN: Concepts that clicked only years after you first encountered them?

#10

Post by linuxlizard » Sun, Jan 01, 2023, 2:51 PM UTC

ergonaught wrote: post #3

Basic music theory. Almost no one I encountered bothered to actually explain anything. They simply regurgitated things and I guess expected me to somehow intuitively understand something or other.

Sadly, mathematics classes are like that as well. Instructors start throwing equations on the board, expecting us to somehow connect it all together. The best math textbook (Theory of Algebra) I ever read had little sections about the person who revealed a particular subject, why they were studying it, and how the subject is used.