Discovery and Invention
The moments the world worked differently.
Eratosthenes with two shadows. Hipparchus with the precessing sky. Koch and the cholera bacillus. The Antikythera bronze. Maimonides at the Cairo court.
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Galileo Galilei was tried by the Roman Inquisition in 1633 for advocating that the Earth orbits the Sun. What was his sentence?
Galileo recanted his Copernican views publicly under threat of torture and was sentenced to house arrest. He spent the last nine years of his life at his villa at Arcetri near Florence, where he continued working on physics and mathematics in private; his *Two New Sciences* (the foundational work of modern mechanics) was written under house arrest and smuggled out for publication in the Dutch Republic in 1638. He went blind in 1638 and died at Arcetri on 8 January 1642. The Inquisition had burned Giordano Bruno in 1600 for related heretical positions; the Catholic Church formally rehabilitated Galileo in 1992.
The tomb of the Egyptian pharaoh Tutankhamun was one of the few royal tombs to survive ancient looting substantially intact. Who found it, and when?
Carter — financed by his patron Lord Carnarvon — had been excavating in the Valley of the Kings for five years without major success when one of his Egyptian workers found a stone step at the foot of an earlier tomb on 4 November 1922. The tomb was the substantially-intact burial of Tutankhamun (reigned c. 1332–1323 BC), a minor 18th-dynasty pharaoh who had been almost completely forgotten. Schliemann excavated Troy (in modern Turkey, not Egypt). Champollion decoded hieroglyphics. Petrie was an Egyptologist of an earlier generation but did not find Tut.
The Antikythera mechanism — the corroded bronze object that turned out to be a 2,000-year-old planetary computer — was recovered in 1900 from where?
Greek sponge divers under Dimitrios Kontos took shelter from a storm in the lee of Antikythera island in April 1900 and made a routine seabed inspection of the anchorage. One of them, Elias Stadiatis, brought up a single bronze arm. The first state recovery operation began in November 1900 and continued for ten months, eventually producing the mechanism, several substantial bronze and marble sculptures (the Antikythera Youth, the Antikythera Philosopher), substantial glassware, and thousands of ceramic amphorae. The wreck dates to approximately 60 BC. The mechanism was identified as something more than corroded bronze in 1902.
Archimedes is supposed to have run naked through Syracuse shouting *Eureka!* — 'I have found it!' — after a sudden insight came to him while bathing. What had he figured out?
King Hiero II had commissioned a gold crown but suspected the goldsmith of substituting some silver. Archimedes realised in the bath that an object's volume could be measured by the water it displaces — and that comparing the displacement of the crown with that of a pure-gold reference of the same weight would reveal the fraud. The story comes from Vitruvius (writing about 250 years later) and may be embellished. The Eureka technique is now substantially recognised as a real Archimedean principle (the law of buoyancy), independently developed in his treatise *On Floating Bodies*. The mirror/burning-glass war machine is a separate (and probably apocryphal) story from the siege of Syracuse.
Around 240 BC the chief librarian of Alexandria measured the circumference of the Earth using two shadows and a piece of arithmetic. The two shadows were on the same day — the summer solstice — at?
Eratosthenes knew that on the summer solstice, the sun was directly overhead at Syene (modern Aswan), because it lit the bottom of a deep well. At Alexandria on the same day, a vertical pole cast a shadow at an angle of about 7.2 degrees. Since 7.2° is one-fiftieth of a circle, the distance between Alexandria and Syene had to be one-fiftieth of the Earth's circumference. He knew the distance (about 5,000 stadia, by professional surveyors who measured it by counting camel paces). The arithmetic gave a circumference of approximately 250,000 stadia — about 40,000 km, within two percent of the modern value. He had no instruments more complex than a pole.
The French geologist Alfred Lacroix arrived at the destroyed Caribbean city of Saint-Pierre six weeks after Mount Pelée had killed 28,000 people in two minutes. He spent four years reconstructing what had happened. What did he name the previously-unrecognised phenomenon he identified?
Lacroix coined *nuée ardente* — the modern technical term is *pyroclastic density current* — for the fast-moving, ground-hugging cloud of superheated gas and ash that had killed Saint-Pierre. His 1904 book *La Montagne Pelée et ses Éruptions* is the foundational text of modern volcanology. Plinian columns had been recognised since Pliny the Younger's account of Vesuvius in 79 AD; lahars and calderas were already named features. The substantive Lacroix contribution was identifying — for the first time, on observational evidence — that horizontal pyroclastic flows existed and could be the principal killing mechanism of a volcanic eruption.
The Laki fissure in Iceland erupted for eight months from June 1783, releasing a sulphur cloud that killed about 23,000 people in Britain alone. How much of Iceland's own population died in the subsequent famine?
Approximately 10,000 of Iceland's roughly 49,000 inhabitants died — a 21% population reduction in a single year, the worst proportional natural-disaster mortality of any European country in the post-medieval period. The cause was famine, not direct gas exposure: sulphate fallout on Icelandic pasture killed 80% of the sheep, 50% of the cattle, and 50% of the horses, collapsing the island's agricultural economy. The Danish Crown, which administered Iceland, briefly considered evacuating the surviving population to Jutland.
The Lighthouse of Alexandria — the Pharos — was one of the Seven Wonders of the Ancient World. About how tall was it, and how long did it stand?
Built under Ptolemy II Philadelphus around 280 BC at the entrance to Alexandria's harbour. Estimated height between 103 and 118 metres — the tallest human-built structure in the world for most of its existence. A series of medieval earthquakes (956, 1303, 1323 AD) progressively destroyed it. The Mamluk Sultan Qaitbay used its remaining stones to build a citadel on the same site in 1480; the Qaitbay Citadel still stands. The lighthouse design — multiple stepped tiers (square base, octagonal middle, cylindrical top) with a fire and reflector at the summit — set the template for the entire subsequent European lighthouse tradition.
On the morning of 30 June 1908, an asteroid or comet fragment exploded above the Siberian taiga. How large was the area of forest the blast flattened?
About 2,150 square kilometres of forest were flattened in a radial pattern — roughly the area of greater London, or about a third the area of Rhode Island. The blast left no crater because the object exploded in the atmosphere at about 5–10 km altitude rather than impacting the ground. About 80 million trees were flattened. The first scientific expedition (Leonid Kulik's, 1927) reached the site nineteen years after the event because the Russian Revolution and its aftermath had occupied substantial governmental attention in the interval. The Chelyabinsk meteor of 2013 was about a thirtieth the size of Tunguska.
On the morning of 30 June 1908 something exploded several kilometres above the Siberian taiga with the force of a hydrogen bomb. The first scientific expedition to reach the site arrived how long afterward?
Kulik reached the Tunguska blast zone in 1927. The Russian Empire had bigger problems in 1908 (it was running out of money and political legitimacy), then the First World War, then the Revolution, then the Civil War. Kulik found about 2,150 square kilometres of forest flattened in a radial pattern around a central point — but no crater. The explosion is now understood as an airburst of a stony asteroid or icy comet roughly 50–60 metres across at about 5–10 km altitude. The 2013 Chelyabinsk meteor was a much smaller version of the same phenomenon.
Sponge divers off the small Greek island of Antikythera in 1901 brought up a corroded lump of bronze about the size of a shoebox. It took 120 years to admit what it actually was.
The Antikythera mechanism uses about 35 interlocking bronze gears to model the motion of the sun, moon, and (probably) the five visible planets, with a complete eclipse-prediction system based on the Saros cycle. The shipwreck dates to roughly 60 BC; the mechanism was probably built around 100 BC, in the eastern Mediterranean Greek scientific tradition associated with Hipparchus of Rhodes. Nothing of comparable mechanical sophistication is known until medieval Islamic astronomical instruments more than a thousand years later. The original existence of such a device was so improbable that the academic mainstream took most of the 20th century to accept it.
Around 130 BC, Hipparchus of Rhodes produced the first comprehensive Greek catalogue of stellar positions. Roughly how many stars did he catalogue?
The Hipparchian catalogue contained approximately 850 stars, with positions in ecliptic coordinates accurate to about one degree and brightnesses on a 1-to-6 magnitude scale (the direct ancestor of the modern stellar magnitude system). The catalogue itself was lost; it survives substantially through inclusion in Ptolemy's *Almagest* (c. 150 AD), where Ptolemy substantially preserved Hipparchus's data with minor updates. A 2022 multispectral imaging project at St Catherine's Monastery in Sinai recovered fragments of the original Hipparchian Greek text from a palimpsest — the first direct recovery of any portion of the catalogue. Telescopes were 1,700 years in the future.
Robert Koch identified the cholera bacterium in 1883 in Alexandria and confirmed the finding in Calcutta a few months later. But an Italian had identified the same comma-shaped organism nearly 30 years earlier, and been ignored. Who?
Pacini described the comma-shaped *Vibrio* in cholera victims at Florence during the 1854 outbreak — the same outbreak that drove John Snow's investigation of the Broad Street pump in London. He published in Italian in a regional medical journal and was ignored by mainstream European medicine for 30 years. The bacterium's formal name was retroactively changed to *Vibrio cholerae* Pacini 1854 by the International Committee on Bacteriological Nomenclature in 1965. Leeuwenhoek (1632–1723) saw bacteria 150 years too early to know what they were. Pasteur was Koch's living rival, not a cholera-priority claimant. Galileo was an astronomer, dead 200 years.
Johannes Kepler arrived at the University of Tübingen as a 17-year-old scholarship student in 1589. Which of his teachers privately taught him that the Copernican heliocentric system was correct — at a time when the Lutheran consistory's official curriculum required teaching the Ptolemaic geocentric system?
Maestlin was the senior Tübingen astronomer from 1583 to 1631. He officially taught the Ptolemaic system in public lectures and in his standard textbook, while privately teaching Copernicus to selected advanced students in tutorial. Kepler's 1596 *Mysterium Cosmographicum* — the first explicit Copernican defence by his generation — was dedicated to Maestlin. Melanchthon was a Lutheran reformer of the previous generation, died 1560. Tycho Brahe never went to Tübingen and was substantively hostile to Copernicus. Galileo was three years younger than Kepler and never taught him.
The Aachen dancing mania of 1374, the Strasbourg dancing plague of 1518, the Tanganyika laughter epidemic of 1962, and the Pokémon Shock of 1997 are now all classified as the same clinical phenomenon. What's the modern medical name?
*Mass psychogenic illness* is the term preferred in current WHO and American Psychiatric Association literature. The older terms — *mass hysteria*, *collective madness*, *epidemic conversion disorder* — are now considered partially or wholly stigmatising. The clinical pattern is consistent across the seven-century case series: an outbreak of physical symptoms (dancing, twitching, fainting, laughing, etc.) that spreads through a connected social group under sustained collective anxiety or stress, cannot be explained by organic pathology, and self-limits when the affected individuals are separated from each other or from the triggering environment.
The Archimedes Palimpsest is a 13th-century Greek prayer book whose vellum pages were originally scraped Archimedes manuscripts. Some of the works it preserves — including the *Method of Mechanical Theorems* — exist nowhere else. Who identified the underlying Archimedes text, and when?
Heiberg traveled to the library of the Metochion of the Holy Sepulchre in Istanbul in 1906 after seeing a single photographic reproduction of a few pages of the prayer book. He identified the underwriting as Archimedean within hours, photographed substantial portions of the manuscript, and published the substantive content in 1910. The manuscript disappeared during the First World War, resurfaced at a Christie's auction in 1998, and was bought by a anonymous private collector for $2 million. The collector loaned it to the Walters Art Museum in Baltimore, where multispectral imaging recovered substantially more of the underwriting than Heiberg's photographs had captured. Schliemann excavated Troy, not Constantinople libraries. T. L. Heath translated Greek mathematical works but didn't find the palimpsest.
The very slow westward drift of the celestial coordinate system relative to the fixed stars — the *precession of the equinoxes* — was first detected around 130 BC by an astronomer comparing his own star measurements with records from 150 years earlier. Who?
Hipparchus noticed that the stars had shifted about 2 degrees relative to the equinox points since the older Alexandrian observations. He was about 30 percent low on the rate but the discovery itself was the first detection of any systematic motion of the whole celestial sphere — caused, as we now know, by the Earth's axis wobbling like a top on a 26,000-year cycle. Aristarchus had been earlier (3rd century BC) and proposed heliocentrism — also correct, also ignored. Eratosthenes was the librarian. Ptolemy lived three centuries after Hipparchus and preserved most of Hipparchus's work in the *Almagest*.
An enormous volcanic eruption around 1257 left a substantial sulphate-aerosol signal in both Greenland and Antarctic ice cores — about twice the Tambora 1815 signal — and produced an unusually cold European summer in 1258. The source volcano was identified in what year?
Identified in October 2013 by a team led by the French geographer Franck Lavigne, using converging evidence from tephra geochemistry (the glass-shard composition in polar ice matched Lombok pyroclastic deposits), radiocarbon dating, an 18th-century Old Javanese chronicle (the *Babad Lombok*) that records a catastrophic mountain eruption in the kingdom of Pamatan dated to roughly the right period, and climate-model consistency between the eruption magnitude and the recorded 1258 European cold summer. The mountain (Samalas) was approximately 4,200 metres tall before the eruption; about 1,700 metres of its vertical profile was removed in May 1257. The crater is now the Segara Anak caldera on Lombok.
On the evening of 11 November 1572, the 25-year-old Tycho Brahe walked back from his uncle's alchemical laboratory and looked up at the constellation Cassiopeia. He saw something that, by the medical-physical theory of the day, was not supposed to be possible. What was it?
A new star — what we now call a Type Ia supernova, SN 1572 — appeared in Cassiopeia and remained visible for sixteen months. Aristotelian cosmology held that the celestial sphere above the moon was unchanging; a new star above the moon was, by the prevailing theory, impossible. Tycho's parallax measurements demonstrated that the star sat well beyond the moon, demolishing the Aristotelian unchanging-heavens doctrine on observational grounds. His pamphlet *De Nova Stella* (1573) was one of the foundational publications of European astronomy. The other answers describe imagined celestial phenomena rather than the actual 1572 event.
King Frederick II of Denmark built Tycho Brahe an extraordinary research observatory, paid for by approximately 1% of total Danish state revenue per year. Where?
Tycho was granted the small island of Hven (about 4.5 km long) in 1576. He built the main observatory complex *Uraniborg* between 1576 and 1580, with a secondary underground observatory *Stjerneborg* added in 1584. He worked there for 21 years and produced the most accurate pre-telescope astronomical observations ever made. He fell out of royal favour after Frederick's death (1588) and the regency of the young Christian IV; he left Hven in 1597 and died in Prague in 1601. Uraniborg was demolished progressively after his departure. Hven became Swedish in 1658.
In 1620 the seventy-four-year-old mother of the great astronomer Johannes Kepler was arrested for witchcraft in the Duchy of Württemberg. The trial dragged on for six years. Who served as her lead defence lawyer?
Kepler personally took on his mother's case, returned from his observatory at Linz multiple times to represent her, and wrote the surviving 128-page legal brief in his own hand. She was acquitted in October 1621 after fourteen months of formal trial proceedings and six years of accumulated accusations. The trial documents — including Kepler's brief and the prosecution's catalogue of complaints from neighbours — are some of the most complete surviving records of a 17th-century German witchcraft case. Katharina died six months after the acquittal, broken by the imprisonment. Galileo never wrote about her. The Catholic Church had limited authority in Lutheran Württemberg.
Saladin's senior court physician at Cairo — a man who fled the Almohad persecution in Córdoba as a teenager, ended up in Egypt by way of Morocco and Palestine, and on the side wrote the most influential medieval Jewish philosophical work ever — was?
Maimonides served Saladin's vizier Al-Qadi al-Fadil and later Saladin's son Al-Afdal. His *Guide for the Perplexed* (c. 1190) is the major work of medieval Jewish philosophy. Avicenna had been dead for 130 years by then (980–1037) and lived in Persia, never Cairo. Averroes was a contemporary of Maimonides — also from Córdoba, also a doctor — but he stayed in Andalusia and served the Almohad rulers there. Al-Razi (c. 854–925) was even earlier, the great Persian physician and freethinker.
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