Monads.
Ask HN: What is the most complex topic you understand?
81–90 of 98 posts
Re: Ask HN: What is the most complex topic you understand?
#82Nothing. Some people don't understand things, that is not the same as understanding nothing. I also understand ashtanga and programming.
The most complicated thing you understand is nothing? As in nothingness? Is that a zen thing? I can tell you one thing I don’t understand. I don’t understand what you’re trying to convey.
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Re: Ask HN: What is the most complex topic you understand?
#83Entropy. It was hard for me to understand this arbitrary rule of things becoming less ordered over time. Was this just a fundamental natural law? The answer is no. Entropy is a logical consequence of probability and time. Why do things become more chaotic over time? Because chaotic configurations have a higher probability of occurring. There are far more disordered configurations of things then there are ordered, thi…
> The thing I don't fully understand yet is heat entropy. Apparently when you take heat into account for everything, the disordered intuition suddenly becomes applicable. So if you have a system becoming more ordered with time, heat must be increasing somewhere to offset this increase in order. Maybe someone can explain this part to me?
You can extract work from order, and can create order with work. Consider this scenario:
We have two kinds of particles and two rooms. If we have one kind of particle per room it is pretty ordered, if we mix everything then it isn't ordered. Now, lets say we have two filters, filter 1 lets particle 1 through and filter 2 lets particle 2 through, but not the others. So we have a wall between the rooms made of these two filters. Particle 1 will just put pressure on filter 1 and vice versa. This way we can let particle 1 push their filter through room 2, which creates work, thus mixing particles a bit. Do the same with particle 2 and now we have mixed both and extracted the work from mixing the particles. We can reverse this process by moving the filters the opposite direction, dividing the particles again and this process will require work to perform.
Exactly how the filter work doesn't matter, as long as it lets through the other particles then the other particles will stabilize and eventually even out the pressure on the sides. It could be slow but it would work. Doesn't have to be perfect either, if probability isn't exactly the same for both particles you can do it over and over until you get the purity on each side you want. We already uses this to enrich uranium for example, so we can make filters for basically anything in theory.
Re: Ask HN: What is the most complex topic you understand?
#84well... programming
Hmm, how do you know you understand programming? I have programmed for 30 years, more than 10 in the area of embedded Linux, mostly user space, but also kernel and boot loader. My code has been running in at least a million devices in the field. However more often than not when I need to look into systemd code, I have the feeling I have no clue how this stuff can possibly work, have I ever learned to program?
Yes you did, and of course you have a deep understanding. However, nobody knows everything about something, even if he studies that something for a lifetime.
Re: Ask HN: What is the most complex topic you understand?
#85Rather than "understand" I'll talk about complex "accomplishments". I once built a computer. I had Alan Clements "Microprocessor Systems Design" for an undergraduate text and built a 68000 based machine with 64M of RAM and ROM. Using discrete ICs on two big Eurorack wirewrap cards was hard work and needed good eyesight and dexterity. Then I wrote a bootloader and kermit-like like RS232 program loader, and finally has…
Amazing. Do you have some docs / resources on this online? How would you go around building a computer out of commodity components today? Do you think compiling everything on own computer results in noticeable increase in performance? Say, distribution provides binaries built on Intel, but I want to run on AMD, does it make sense to recompile binaries on the AMD?
> docs / resources on this online?
Surprisingly the old textbook went to three editions, the last in 1997 [1] It looks as if it may be on archive.org [2], and is definitely in Google Books and LibGen.
> How would you go around building a computer out of commodity components today?
Good question. You could of course retrace my steps using 1980s technology, but I wouldn't advise that. The problem today is physical scale. Most components are surface mount and you really need to build multi layer boards and use a bench microscope to place and solder. Getting anything hand-built to reliably run faster than 100MHz without knowing what you're doing is no fun. Everything I spent a thousand hours building is in a SoC for $1 now.
> Do you think compiling everything on own computer results in noticeable increase in performance?
That's a question to ask Gentoo/Arch users (and BSD people who use Ports). I think yes, because hopefully you'll optimise for the architecture you have. But is is worth it? Given the many hours you'll wait, maybe not at my age :) Do it while you're young and can learn cool things from it.
[1] https://www.goodreads.com/book/show/950048.Microprocessor_Sy...
[2] https://archive.org/details/microprocessor-systems-design-68...
Re: Ask HN: What is the most complex topic you understand?
#86Earlier quoted context omitted.
Amazing. Do you have some docs / resources on this online? How would you go around building a computer out of commodity components today? Do you think compiling everything on own computer results in noticeable increase in performance? Say, distribution provides binaries built on Intel, but I want to run on AMD, does it make sense to recompile binaries on the AMD?
> docs / resources on this online? Surprisingly the old textbook went to three editions, the last in 1997 [1] It looks as if it may be on archive.org [2], and is definitely in Google Books and LibGen. > How would you go around building a computer out of commodity components today? Good question. You could of course retrace my steps using 1980s technology, but I wouldn't advise that. The problem today is physical scal…
There's also the excellent https://www.nand2tetris.org/
From basic computing gates all the way to running tetris. It taught me so much of the lower levels.
Also a comment as a former Gentoo user of 7+ years - the performance is there - 5-15% maybe. I honestly don't think it's noticeable, it never was to me, but what you learn using Gentoo has served me very well.
I moved on as well. I'm too old to deal with fixing things and all the waiting, I just want it to work haha
Re: Ask HN: What is the most complex topic you understand?
#87I've repaired multiple HP 5061 Cesium Beam Atomic Clocks. I've got a very good handle on how they work. I'm fairly good at explaining it to people as well.
Re: Ask HN: What is the most complex topic you understand?
#88Entropy. It was hard for me to understand this arbitrary rule of things becoming less ordered over time. Was this just a fundamental natural law? The answer is no. Entropy is a logical consequence of probability and time. Why do things become more chaotic over time? Because chaotic configurations have a higher probability of occurring. There are far more disordered configurations of things then there are ordered, thi…
Ok, but notice this argument is based on purely probabilistic assumptions and that all micro-states are equally probable to occur and do occur in time. There is still the question whether these assumptions are valid in a given physics system. In physics we know much more about evolution of systems, for example in classical mechanics model of gas, there are deterministic equations of motion which also conserve some qu…
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Re: Ask HN: What is the most complex topic you understand?
#89Semiconductor fabrication process flows. How to start with a bare epitaxial silicon wafer, then process it step by step, until it leaves the fab.
Re: Ask HN: What is the most complex topic you understand?
#90Software programming. Probably not surprising, considering the discussion board I'm posting on.