Cards

One a day. System design, science, history, and whatever else was worth a second look. All 169 of them, newest first.

130 newlywed couples observed in an apartment-shaped lab, where the ones still together six years later had answered each other's small bids for attention 86% of the time against 33% for those who divorced

On LoveOct 4, 2026

A Thousand Small Moments Of Not Being Heard

on-love relationships gottman

The ReAct loop of think, act, observe and repeat feeding each observation back into the context, beside plan-and-execute and reflection, and the loop that fails by never converging

AI SystemsDay 63Oct 4, 2026

Think, Act, Look, Repeat

system-design ai-systems agents

A prompted JSON response wrapped in markdown and a cheerful preamble against constrained decoding that enforces the shape while generating, and the business validation a well-formed response still needs

AI SystemsDay 62Oct 3, 2026

Stop Asking Nicely For JSON

system-design ai-systems llm

A committee approving a ten million pound reactor in two and a half minutes then arguing for forty-five about a bicycle shed, with Parkinson's 1957 observation that we comment where we feel competent

Corporate LifeOct 3, 2026

The £350 Bicycle Shed

corporate-life meetings parkinsons-law

The weak version of leadership in deadlines set without asking and blame travelling down, against the invisible work of clearing obstacles and the one day that asks someone to step out in front

LeadershipOct 2, 2026

Authority Tells People Where To Stand

leadership management teams

Recall@k measuring whether the right passage reached the context and faithfulness measuring whether the answer was supported by it, and a chunking change that improved one number while breaking the other

AI SystemsDay 61Oct 2, 2026

We Can't Improve What We Only Eyeball

system-design ai-systems rag

The inherited script of patriarchy, misogyny and chauvinism, control dressed as protection, an unequal division of work at home, and the cost to a boy taught that feeling is weakness

On Being a ManOct 1, 2026

Strength That Needs An Audience

on-being-a-man patriarchy masculinity

Vector search ranking millions of separately embedded documents by distance in milliseconds, then a cross-encoder reranker reading the query and fifty candidates together and reordering the top five

AI SystemsDay 60Oct 1, 2026

The Top Five Aren't The Best Five

system-design ai-systems rag

A humpback whale surfacing beneath a seal knocked off an ice floe and lifting it clear of hunting orcas, beside 115 recorded encounters over 62 years in which 104 of the animals rescued were strangers

WonderSep 30, 2026

The Whale That Lifted A Seal

wonder humpback-whales orcas

A policy clause cut in half at 500 characters so neither piece retrieves, beside fixed-size, recursive, semantic and parent-document chunking, and the token ranges different content types actually want

AI SystemsDay 59Sep 30, 2026

Where We Cut Decides What We Find

system-design ai-systems rag

A p99 latency spike to 800ms caused by a stop-the-world garbage collection pause, beside generational and concurrent collectors that shrink the stop by spending CPU to avoid it

ConcurrencyDay 58Sep 29, 2026

The Pause Nobody Scheduled

system-design concurrency garbage-collection

A film about queer lives met with sudden concern for children, set against honour killings over caste, the policing of women's bodies, and decades of on-screen harassment that worried nobody

On DorothySep 29, 2026

What Exactly Is Being Protected?

on-dorothy queer-rights tamil-cinema

Three groups of students two weeks after an exercise study, where motivation produced 35%, nothing produced 38%, and one sentence naming the day, time and place produced 91%

How Things Get DoneSep 28, 2026

Deciding When And Where

how-things-get-done habits implementation-intentions

Two threads reading 41 and both writing 42 so one increment vanishes, beside a lock that makes threads queue and a compare-and-swap instruction that retries on collision instead of blocking

ConcurrencyDay 57Sep 28, 2026

Don't Take The Lock. Ask Instead.

system-design concurrency locks

Two boats tied together with neither one anchored, drifting at the same speed, against two anchors set side by side as the picture of a relationship between people who can each hold their own ground

On LoveSep 27, 2026

Drop The Anchor First

on-love relationships self-worth

Four CPU-bound Python threads funnelled into a single lane by the GIL against I/O-bound threads that release it while waiting, with processes and C extensions as the routes to real parallelism

ConcurrencyDay 56Sep 27, 2026

Four Cores, One Lane

system-design concurrency python

A common swift leaving Europe in August and not touching anything solid until the following summer, eating, mating and sleeping in the air, and a scientific name, Apus, that means footless

WonderSep 26, 2026

Ten Months Without Landing

wonder swifts birds

A sequential async method compiled into a state machine that releases its thread at every await and keeps locals on the heap, beside C# rewriting the code and Java rewriting the runtime

ConcurrencyDay 55Sep 26, 2026

The Keyword That Rewrites Our Method

system-design concurrency async-await

A parent and baby out of sync for roughly 70% of their interaction, and Tronick's miss-notice-repair cycle showing that the return, rather than the accuracy, is what builds a secure child

ParentingSep 25, 2026

Good Parents Come Back

parenting attachment repair

Platform threads carrying a megabyte of OS stack each against virtual threads parked on the heap by the Java runtime, letting plain sequential blocking code scale to millions of concurrent requests

ConcurrencyDay 54Sep 25, 2026

Threads That Cost Almost Nothing

system-design concurrency java

Ten thousand threads holding a megabyte of stack each while asleep, against one event loop asking the kernel which sockets have data ready, and the rule that nothing in a handler may ever block

ConcurrencyDay 53Sep 24, 2026

One Thread, Ten Thousand Connections

system-design concurrency event-loop

Water sinking through burning oil to the bottom of a pan past 300°C, flashing to steam and expanding around 1,700 times to blast burning oil upward, against a lid or fire blanket as the actual fix

Kitchen PhysicsSep 24, 2026

Why Water Makes A Pan Fire Worse

kitchen-physics fire-safety steam-expansion

A multi-tenant query missing its tenant filter and returning every customer's rows, the four isolation levels from shared table to cluster per tenant, and row-level security enforcing the filter in the database

SecurityDay 52Sep 23, 2026

One Missing WHERE Clause

system-design security multi-tenancy

A Tamil poem asking where the good we did goes if one small wrong always returns, beside a tally of one remembered wrong against a hundred forgotten kindnesses, and the old line about trusting God and tying the camel

Faith & ActionSep 23, 2026

Where Did All The Good You Did Go?

faith-and-action tamil-thought karma