Reality has a surprising amount of detail (2017)
johnsalvatier.org110 points by vinhnx 5 days ago
110 points by vinhnx 5 days ago
The first time I built a freestanding bookshelf, I put a lot of effort into making the feet level and the back straight and at a right angle to the feet. Once I put it up against the wall I'd built it for, I realized I'd solved completely different problem than the problem I really had. I needed crooked bookshelf, since the wall was totally tilted.
In the end I screwed some wall shelves in and called it good enough.
One of my first real DIY projects during a summer in college nearly 20 years ago was replacing the rotted out basement bulkhead doors on the ~120 year old house I grew up in. I took measurements of the old ones, bought some nice tongue-and-groove cedar and high-quality hardware, and built the new doors in the garage. When they were fully assembled, I carried them over to install on the old stone frame. I took off the old ones, put mine in their place...and they didn't fit properly at all.
Momentarily baffled, I realized that, despite appearances, the old frame was actually not square, in fact it was a parallelogram. I'd measured the height and width and assumed it was square. The previous (experienced) carpenter who'd built the doors I was replacing had clearly noticed this, and simply allowed for the misalignment in his design. He built perfectly square-appearing doors that mounted to the not-square frame. I had to go back and rework mine considerably for them to fit without looking ridiculous. They're still there and holding up well, but I also still think of this lesson on a regular basis in my day to day life now.
I feel this in my soul. I thought I could replace a door in a day, but months of fiddling, I discovered by frame is not only a parallelogram but it literally shifts by over an inch between seasons. (~100yr old house 2nd floor)
That’s why most doors come prehung in a jamb. Just add shims and then cover them with trim.
A related thing that took me a while to accept when I started woodworking is that wood moves, a lot.
If you built the bookshelf in wood, it will be expanding, contracting and shifting over time with temperature and humidity variation throughout the day and season. And asymmetrically depending on the grain.
The straight right angles won't stay that way, and it's better to design such that they change in complementary ways, rather than remain perfect.
Coincidentally just had this realization last night. Leaned a piece of furniture against the wall, realized the ~perfectly straight/level edge didn't lean smoothly against the wall -- the wall is not perfectly straight!! :-O
I recognized this submission from its title but did not remember what it was about. For some reason this anecdote reminded me. Yes now I know it's about the man who built staircases with his father.
I can never look at staircases the same.
> If you’re a programmer, you might think that the fiddliness of programming is a special feature of programming, but really it’s that everything is fiddly, but you only notice the fiddliness when you’re new, and in programming you do new things more often.
I think I'm drawn to programming because the fiddliness is tractable, and fixable.
In which other domain can I:
* introspect the relevant processes/state, step by step
* snapshot/undo
* fix niggles, once and for all, and for everyone; and get their fixes too
* probe and test my inputs and outputs, checking for quality. Get notified if a part changes in a way that breaks me.
And the only tool I need is a commodity general purpose PC.
When I try woodwork, or even electronics, I'm struck by much friction is in even simple tasks: tools, parts, lead time, safety, space, physical effort, cost, ...
I think this is a very common sentiment among a lot of people, including me.
And also that’s why AI tools create mix reactions. A couple of months ago a post went viral which was really insightful on what I was originally drawn to cs.
Unless you have endless budget, many things can be one-shot. You can't do a test run first, or roll back a cut if the length is too short. You can patch misplaced nail holes, or re-dig a hole (messing up filling a hole with concrete is another matter) and hope you don't kill a tree transplanting it, but the end result isn't clean.
The best I could do with woodworking in the end to approximate programming was live with wasting some timber, leave a lot of margin on the main cuts and size all the pieces as a whole.
Until the next OS update...
With wood you are up against nature. With software you are up against corporations and comities.
(2017) with a few significant past discussions:
https://news.ycombinator.com/item?id=16184255 - Jan 19, 2018
https://news.ycombinator.com/item?id=22020495 - Jan 11, 2020
https://news.ycombinator.com/item?id=29429385 - Dec 3, 2021
https://news.ycombinator.com/item?id=38407851 - Nov 24, 2023
https://news.ycombinator.com/item?id=43087779 - Feb 21, 2025
Related, amazing read about Meccano teaching you reality-based work, in contrast with Lego:
https://contraptions.venkateshrao.com/p/truth-in-inconvenien...
I think we have all written some code that looks bulletproof to us. We run a set of tests with all the inputs we can think of, and it passes with flying colors (after several iterations of course).
Then we give it to someone else and it fails on their first or second attempt. They simply tried to use it in a way that we did not anticipate. It doesn't mean that we are dumb for not thinking of those possibilities; it just means that we did not think of every one of them.
I have read this article already and "reality has a surprising amount of detail" has become a phrase for me. But, I read it again today because the writing is so good. This guy is a gifted writer.
This sentence is the exact reason laying people off and replacing them with AI doesn’t work.
The fact that machine learning can learn highly detailed patterns is the very reason why AI is so useful. So what you’re saying doesn’t really make much sense
> The fact that machine learning can learn highly detailed patterns is the very reason why AI is so useful.
AI doesn't deal with reality, it deals with tokens. This is why all those vibe-coded harnesses, little more than glue between various text IO interfaces, are several hundreds of thousands of source lines of code.
It's why a SOTA model took 100kSLoK to write a C compiler to compile one specific project.
It's why, when I asked for a simple markdown -> ansi escape codes converter (for terminal output) in Python, SOTA Claude and SOTA ChatGPT both give me +- 150 SLoC when my own LUT-based version came to under 10 lines of code + a LUT.
Reality has a surprising amount of detail, but LLMs don't exist in reality, they exist in a virtual world made up off tokens.
Do you exist in reality? Or just in a virtual world made up of sensory signals? Do you have access to the Ding an sich any more than a (multimodal) LLM?
> Do you exist in reality?
Yes.
> Or just in a virtual world made up of sensory signals?
No, definitely reality. Things affect my thought whether I sense them or not.
How would you know? You have no external frame of reference; a virtual world of sensory signals would be identical from your perspective. (I agree that "reality" is the most parsimonious explanation by far, btw, but that's never been the point of the simulation thought experiment.)
I think the more interesting corollary of this article is that if we're living in a simulation, it's an impossibly, improbably detailed one. I really want some compute time on the HPC that's running it.
In the spirit of the article, what detail in the decision making of layoffs might you be missing?
I expect there's a lot of detail that I'm unaware of relating to running a company (planning; risk; legal; ...) that might make a decision foolish to me, but make sense if given more context.
Lovely article!
Contemplating the details of a thing is really satisfying. At times I find myself sitting there and trying to decompose the astonishing amount of work, research, both evolutionary and revolutionary progress that has gone into reaching the current level of something. Buying myself a coffee and stare at the local ferry and acknowledge that someones life's work went into figuring out how to make the paint stick to metal.
Naturally the other point also sticks.. I too often get stuck on the details. :P
Tell me about it, I maintain an open source project in the civil engineering space and it's ... detailed.
My favorite post on HN. Upvote it everytime. Use this phrase so often now.
Really generally shitty collision detection and detail. It's just that when you notice, it rolls back and adds resources until you think it's fine.
Such a great read. This sentence is particularly chilling:
> you could be intellectually stuck right at this very moment, with the evidence right in front of your face and you just can’t see it.
Reality does not have amount of details, it is infinite in all directions. Its only that we perceived certain amount of details, some more some less. One can spend their whole life mastering a single aspect and there always will be room to improve.
This is not my field, but are we sure that reality is not quantised at some level?
Infinite is a very big claim.
One of my favourite essays. xkcd has a good take too 1741-Work
This has always been the fun part of programming to me. I know most people hate it, but I really don’t mind being on-call (ok I hate being woken up) and fixing weird bugs that users run into. All these small edge cases that people run into because reality is odd. Of course I’m in scientific programming so that probably colors my view.
It’s always a little disappointing to me when I think I’ve run into something unique but it ends up being user error or something.
I echo this. The kind of entropy that real users bring has been refreshing to face as a founder.
Being a founder has a lot of SRE like activities. Fortunately I used to actually like troubleshooting and hence love being a founder but I know a lot of people quit this path because of the "suprising amount of details" in reality!
Based on what is the level of detail to reality suprising? To me suprising means mysteriously or improbably unexpected. Why should we expect reality to be simple. Note complex and simple are somewhat subjective. The human brain evolved to just sufficient baseline level be able to handle the level of complexity of reality. So why would it be unexpected that humans find realty complex when our brains are calibrated just enough to handle it.
Good read
a good read indeed! Makes me think about my use of coding agents differently, as the main thing they do is deal with a lot of details that matter to the execution but don't matter to me personally enough to figure them out. Would love to see this author's more recent take as this was written pre-LLMs taking over the world.....
That sort of abstraction has always existed, it's just been a matter of hiring experts or labor from other humans. Reality still has a surprising amount of detail. You deal with it by engaging directly, delegating to someone else to engage with, or just brute force your way to a crooked staircase.
When you hire someone to work on the stairs for you, you /hope/ they know what they're doing, especially if you don't have the skills yourself to judge their work. Same for an agent.
An ancient article that now looks even cheesier. It's so hard to make those goddamn stairs. So complex, such wisdom.