Things that broke because two people measured correctly.https://significant-figures.pages.dev/enhttps://significant-figures.pages.dev/blog/mars-climate-orbiter/https://significant-figures.pages.dev/blog/mars-climate-orbiter/The software aboard the spacecraft was correct. A program on the ground wrote pound-seconds where the specification required newton-seconds, and every thruster firing entered the navigation model 4.45 times too weak.Tue, 15 Sep 2026 00:00:00 GMTspaceflightsoftwarenewton-secondNASAhttps://significant-figures.pages.dev/blog/laufenburg-bridge/https://significant-figures.pages.dev/blog/laufenburg-bridge/Germany measures height from the North Sea and Switzerland from the Mediterranean. The 27-centimetre offset between them was known, drawn correctly, and applied with the wrong sign.Mon, 14 Sep 2026 00:00:00 GMTcivil engineeringvertical datumRhinesurveyinghttps://significant-figures.pages.dev/blog/sncf-platforms/https://significant-figures.pages.dev/blog/sncf-platforms/The trains were built exactly to specification. The specification came from platform dimensions sampled only from platforms built in the previous three decades, and most French platforms are older than that.Sun, 13 Sep 2026 00:00:00 GMTrailsamplingspecificationFrancehttps://significant-figures.pages.dev/blog/vasa-four-rules/https://significant-figures.pages.dev/blog/vasa-four-rules/Four carpenters' rules were recovered from the wreck, all slightly different. Two were marked in Swedish feet of twelve inches, two in Amsterdam feet of eleven. Every one of them was used correctly.Sat, 12 Sep 2026 00:00:00 GMTshipbuildingarchaeologycustomary unitsSwedenhttps://significant-figures.pages.dev/blog/hubble-null-corrector/https://significant-figures.pages.dev/blog/hubble-null-corrector/The mirror was tested. The instrument built to test it had a lens in the wrong place, so the polishing machine stopped at the wrong moment and the test it had to pass was the test that was broken.Fri, 11 Sep 2026 00:00:00 GMTopticsmetrologynull correctorNASA