HowItActuallyWorks

Everyday mechanisms, explained with sources. One diagram, one myth checked, every week. Wrong? We correct it publicly.

Columns

• One Mechanism, One Diagram — One everyday mechanism, explained with one self-made diagram.
• MythCheck — A common claim, checked against evidence, with a clear verdict.
• Monthly Curiosity Archive — A monthly index of that month's posts, with a short review.

Pinned Manifesto Thread

• Manifesto
• How to read this account, and how corrections work
• The three columns
• What mechanism have you always wanted explained?

Sources — Tidal Locking: Why the Moon Always Shows the Same Face

Post: Tidal Locking thread, post 1 (with diagram) · post 2

• NASA Science — Tidal Locking: supports that the Moon spins once in the same time it takes to orbit Earth, so the same side always faces us.
• Astronomy — Why does the same side of the Moon always face Earth?: supports that Earth's gravity acting on the Moon's tidal bulges produced torque that slowed the Moon's spin until rotation matched revolution.

Sources — Airplane Windows: Why Are Airplane Windows Round?

Post: Airplane Windows thread, post 1 (with diagram) · post 2 · post 3

• BYU Design Review — The Reason for Round Windows: The de Havilland Comet: supports the mechanism that stress concentrates at rectangular window corners and repeated pressurization can lead to fatigue cracking.
• Aerossurance — Comet Misconceptions: supports the careful Comet account used in the thread — one break-up traced to an antenna aperture and a tank-test failure to an escape-hatch corner, not a passenger window as the sole confirmed cause.

Sources — Water Molecules: How Many Water Molecules Are in a Glass of Water?

Post: Water Molecules post (with diagram)

• Water molar mass ≈ 18.015 g/mol; Avogadro constant exactly 6.02214076×10^23 /mol (SI definition). Calculation: 250 g / 18.015 g per mol ≈ 13.88 mol; 13.88 × 6.02214076×10^23 ≈ 8.36×10^24, stated as about 8×10^24. 250 g is a typical glass; a smaller glass gives a smaller count.

Sources — MSG: Is MSG Actually Harmful?

Post: MSG thread, post 1 (with diagram) · post 2

• FDA — Questions and Answers on Monosodium glutamate (MSG): supports that added MSG is “generally recognized as safe”; in studies with self-identified sensitive individuals given MSG or a placebo, scientists have not been able to consistently trigger reactions; a typical serving of a food with added MSG contains less than 0.5 g, while the mild, short-lived symptoms noted by FASEB were tied to 3 g or more consumed without food.

Sources — Mercator Projection: Why Greenland Looks as Big as Africa on Maps

Post: Mercator thread, post 1 (with diagram) · post 2

• CIA World Factbook — Greenland: supports Greenland total area 2,166,086 sq km (stated in the thread as about 2.17 million km2).
• Encyclopaedia Britannica — Africa: supports Africa total land area approximately 30,365,000 sq km (stated in the thread as about 30.4 million km2); the ratio 30,365,000 / 2,166,086 ≈ 14.02 is calculated from these two figures and stated as about 14 times.
• Encyclopaedia Britannica — Mercator projection: supports the mechanism that the Mercator projection is conformal (preserves local angles), was designed for navigation, and distorts area increasingly toward the poles.

Corrections Log

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Correction format: Correction: original post date, original claim, what was wrong, corrected claim, and source. Original posts are not deleted for corrections; the correction is posted publicly and linked.