The What-If Observatory Serious arithmetic for unserious questions. https://whatifobservatory.com/ 2026-11-09T00:00:00Z Atlantis: Plato’s Own Speaker Called Its Ditch ‘Incredible’https://whatifobservatory.com/utopias/atlantis/2026-11-09T00:00:00ZAtlantis is Plato's story, and its ditch has dimensions. Run them: about 10 billion cubic meters of earth, some 59 times a 1913 tally for the Panama Canal.The What-If Observatory Atlantropa: Dam Gibraltar and Let Evaporation Do the Workhttps://whatifobservatory.com/what-if/atlantropa/2026-11-09T00:00:00ZAtlantropa would dam Gibraltar and let evaporation lower the sea. On a 2013 budget, a fixed area and no seepage, 100 to 200 m takes two to eight centuries.The What-If Observatory Brook Farm: By Swift’s List, Hawthorne Subscribed $1,000https://whatifobservatory.com/utopias/brook-farm/2026-11-09T00:00:00ZBrook Farm's books: about $4,000 paid in, $14,500 in mortgages, about $7,000 of building burned uninsured. Hawthorne's $1,000 and whether he got it back.The What-If Observatory What If a Carrington Event Hit Today? The Size Is Disputedhttps://whatifobservatory.com/what-if/carrington-event/2026-11-09T00:00:00ZReadings of the 1859 storm: a doubted −1,760 nT spot value, −850 to −1,050 nT hourly, about 1.4 to 3 times March 1989. Why no damage figure we read holds up.The What-If Observatory Dyson Sphere: Dyson Meant a Swarm, by Wright’s Accounthttps://whatifobservatory.com/estimates/dyson-sphere/2026-11-09T00:00:00ZJupiter spread at 1 AU makes about 6,700 kg per square meter. Dyson wrote of a swarm and said a solid shell could not hold up, as a 2020 review reports.The What-If Observatory Fermi Paradox: Voyager-Speed Ships Could Cross the Galaxyhttps://whatifobservatory.com/estimates/fermi-paradox/2026-11-09T00:00:00ZAt Voyager 1's 16.6 km/s, a non-stop ship would cross a 100,000-light-year Milky Way in about 1.8 billion years, inside Earth's 4.54 billion.The What-If Observatory From the Earth to the Moon: Verne’s Gun, 22,000 g or Morehttps://whatifobservatory.com/old-forecasts/from-the-earth-to-the-moon/2026-11-09T00:00:00ZVerne's 12,000 yards per second over a full 900-foot run averages about 22,000 g. We grade seven of his claims: the crew a hit, the gun a costume error.The What-If Observatory How Many Blocks in the Great Pyramid? 2.3M May Be a Divisionhttps://whatifobservatory.com/estimates/great-pyramid-blocks/2026-11-09T00:00:00ZAbout 2.3 million, per an 1883 footnote that reports no count. Petrie's volume divided by his average stone gives 2.26 million; the division is our inference.The What-If Observatory Hilbert’s Hotel: In Cantor’s Terms, Full Can Still Take Morehttps://whatifobservatory.com/paradoxes/hilberts-hotel/2026-11-09T00:00:00ZHilbert's Hotel is full yet takes one more guest if all move up a room. By Kragh's history, Hilbert told it in 1924–25; Gamow's 1947 book made it better known.The What-If Observatory How Many People Have Ever Lived to 2022? About 117B, Modeledhttps://whatifobservatory.com/estimates/how-many-people-have-ever-lived/2026-11-09T00:00:00ZNobody counted them. A Population Reference Bureau model says about 117 billion births through 2022; our second road gets 58.5 billion since 10,000 BCE.The What-If Observatory Kardashev Scale: 2022 Energy Use Is About 5x the 1964 Type Ihttps://whatifobservatory.com/estimates/kardashev-scale/2026-11-09T00:00:00ZKardashev's 1964 Type I, as Ćirković quotes it, sat near Earth's level: about 4 trillion watts. Humans used about 20 trillion in 2022, 0.73 on Sagan's formula.The What-If Observatory Malthus: His 512 to 10, People to Food, Had No Datehttps://whatifobservatory.com/old-forecasts/malthus/2026-11-09T00:00:00ZMalthus's 1798 sum gives 512 to 10 after 225 years of unchecked doubling. By Our World in Data's estimates, the world grew 8.23 times from 1800 to 2023.The What-If Observatory Moon Closer to Earth: Half as Far, About 8x the Tidal Forcehttps://whatifobservatory.com/what-if/moon-closer-to-earth/2026-11-09T00:00:00ZHalve the Moon's distance and its tidal force on Earth rises about 8 times, its width doubles and its orbit shrinks to 9.66 days. Tide height stays unknown.The What-If Observatory Moore’s Law: Yearly Doubling in 1965? The Sources Disagreehttps://whatifobservatory.com/old-forecasts/moores-law/2026-11-09T00:00:00ZBy later papers, Moore forecast yearly doubling in 1965 and every two years in 1975. From 2,308 transistors in 1971, the two-year pace lands near 2021's count.The What-If Observatory Panopticon: No Prison for Bentham. Accounts Say He Got Paidhttps://whatifobservatory.com/utopias/panopticon/2026-11-09T00:00:00ZBentham's Panopticon was a round prison with one hidden inspector. Britain built another plan; two accounts report £23,000 for him in 1813. His numbers, run.The What-If Observatory