Weekly. Written by Chiradip Mandal
Every issue takes one guarantee, states it as a machine-checkable invariant, prices it in physics, and hands you the derivation and the lab that make it yours.
That is the whole product. Not a survey, not a diagram to recognise in an interview — a result you can reconstruct on a whiteboard and defend when someone pushes back. It holds to four rules: no product pitches, first principles or nothing, claims that can be checked, and lessons that survive the example being replaced.
Its sibling is the study group, which meets monthly to take a system apart together. Same standards, same people, different form — one is read, the other is argued.
Each issue is roughly 1,400 words in a fixed shape — the claim, its cost, the derivation, the engineering that buys it back cheaply, an assignment, and errata — so you always know where the proof starts and can enter at your own altitude.
| # | Title | Published |
|---|---|---|
| 002 | What a quorum actually buys — R + W > N is a visibility property, not a consistency one; the second inequality nobody checks |
— |
| 001 | Eleven nines, recomputed — the durability figure everyone quotes, rebuilt from the Markov chain, then broken by the term the chain cannot see | — |
This letter lives in git, not in a newsletter platform. Every figure ships with the script that produced it, and every number is reproducible from the repository.
If you can show that a number here is wrong, send the pull request. The fix carries your name in the commit history, permanently. Counterexamples we can’t refute run in the next issue, with attribution. This is the one thing a hosted newsletter cannot offer, and it is the reason the archive is the canonical home rather than the inbox.