Things almost everybody has slightly wrong
Explainers
One named misconception each, in an actual subject.
1 September 2026 · 5 min read
Why Postgres is ignoring the index you just created
You added the index, the query is still slow, and EXPLAIN says sequential scan. The planner is usually right, and the four reasons it overrules you are worth knowing.
1 September 2026 · 4 min read
Docker containers are not lightweight VMs
The comparison is how almost everyone is introduced to containers, and it is wrong in three ways that decide what you can run, what breaks on upgrade, and how strong the isolation actually is.
1 September 2026 · 4 min read
Async does not mean parallel
You made the function async, added await everywhere, and it runs at exactly the same speed. That is the expected result, and the reason is a distinction the word async never makes.
1 September 2026 · 4 min read
HTTPS does not hide which site you are visiting
The padlock means nobody can read what you sent. It has never meant nobody can see where you sent it, and the gap is larger and more visible than most people assume.
1 September 2026 · 4 min read
Git's staging area is not a draft folder
The index is not a list of files you have marked for later. It is a complete snapshot of your next commit, and once you see that, most of Git's confusing behaviour stops being confusing.
1 September 2026 · 4 min read
p < 0.05 does not mean there is a 95% chance you are right
It is the most consequential misreading in applied statistics, it is taught by omission rather than by error, and the correct reading is a single sentence that changes what the number is worth.
1 September 2026 · 3 min read
Correlation does not imply causation — but it implies something
Everybody can recite the slogan. Almost nobody can say what correlation does license, which is a short and genuinely useful list — and it includes one case where the arrow points backwards.
1 September 2026 · 3 min read
A pay rise cannot move you into a bracket that leaves you worse off
Almost everyone believes tax brackets can make a raise cost you money. They cannot, and the arithmetic takes one paragraph. What can cost you money is something else entirely, and it is worth knowing which.
1 September 2026 · 4 min read
Planes do not fly because the air travels further over the top
The explanation nearly everyone was taught contains a step that is simply false, and NASA says so in print. What is odd is that the correct explanation is easier.
1 September 2026 · 4 min read
Microwaves do not work by resonating with water
The resonance story is repeated everywhere, including by people who should know. It is wrong, and the real mechanism explains the things the myth cannot — like why ice barely heats and why there are cold spots.
1 September 2026 · 4 min read
Why an LLM cannot count the letters in “strawberry”
A model that writes competent code fails a task a six-year-old can do. It is not a gap in reasoning — the model is not looking at letters at all, and what it is looking at explains several other oddities too.
1 September 2026 · 4 min read
An LLM is not looking anything up
The intuition that a model queries something when you ask it a question is wrong, and almost every surprise people have about hallucination, cutoffs and confidence follows from replacing it.
Essays
Why courses, tutorials and documentation keep missing their reader.
31 August 2026 · 5 min read
Why every Kafka tutorial starts in the wrong place
Kafka tutorials open with a producer, a consumer and a topic — and never say what problem any of it solves. The result is people who can run the quickstart and still cannot design anything.
31 August 2026 · 4 min read
Tutorial hell is not a discipline problem
You are not stuck in tutorial hell because you lack willpower. You are stuck because following along is a genuinely different skill from building, and no amount of following teaches the other one.
31 August 2026 · 4 min read
The gap between the tutorial and the docs
The tutorial is too basic and the documentation assumes you already know. That gap is not an accident — it is what happens when reference material and teaching material are written by the same people for different readers.
31 August 2026 · 4 min read
Beginner, intermediate, advanced: three words that describe nobody
Course levels sort courses, not people. Where you start and how far you want to go are two independent questions, and collapsing them into one label is why you keep picking wrong.
31 August 2026 · 4 min read
The average student does not exist
In 1950 the US Air Force measured 4,063 pilots to design a cockpit for the average one. Not a single pilot was average. Every course you have ever taken was built for that same person.
31 August 2026 · 4 min read
Learning your second programming language is a different skill
Every guide to a new language is written for someone who has never programmed. If you already have ten years of it, that guide is not just slow — the help itself is what is slowing you down.
31 August 2026 · 4 min read
You didn't lack discipline. The course was the wrong length.
Most people who start an online course never finish it, and the standard explanation — motivation — gets the causation backwards. Abandonment is usually a design fault, and it is usually the same one.
31 August 2026 · 4 min read
Analogies are a loan against understanding
A good analogy gets you moving in seconds. It also has to be repaid, and the courses that lean hardest on them are the ones that never come back to settle up.
31 August 2026 · 5 min read
Every prerequisites list is wrong, in both directions at once
It demands things you will never need and omits the one thing that will actually stop you. Prerequisites are written by people who cannot remember not knowing.
31 August 2026 · 5 min read
The question no course asks you
Nobody teaching you anything at scale has ever asked what you already know. Not because it does not matter — it is the single most useful thing you could tell them — but because they had no way to use the answer.