Alonzo Church's lambda calculus: computation without a machine
In 1936, Alonzo Church tied effective calculation to his lambda calculus. Alan Turing's work reached the same result on a related problem.
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America's 17-year cicadas wait for warm soil to surface
Some periodical cicadas spend 17 years feeding on tree roots, then surface together once the soil warms. Why they keep such long cycles is still unclear.
Al-Azhar: how a Fatimid mosque became a university
Al-Azhar began as a Fatimid mosque in 970. By 988 the state paid 35 scholars to teach there, and it later became a modern university in Cairo.
Alden Global Capital bought US newspapers, then stripped them
Alden Global Capital cut staff and sold real estate at the US papers it bought. A federal inquiry found it probably moved pension money into its own funds.
Employers are retraining staff instead of hiring AI engineers
Job postings for generative AI skills rose 1,848% in 2023, and companies short of engineers to hire are retraining the staff they already have.
A blowout preventer failed to stop the Deepwater Horizon well
A blowout preventer is a seabed stack of valves built to seal a runaway well. On Deepwater Horizon in 2010 it failed. A capping stack later stopped the flow.
Bletchley's Bombe cut Enigma's settings to about a million
Enigma had 158 million million million settings. The Turing-Welchman Bombe cut that to about a million, and helped Bletchley Park find each day's key.
How a breeder reactor makes more fuel than it burns
A breeder reactor turns leftover uranium into plutonium fuel. The US Department of Energy says recycling it could need 100 times less uranium.
A 1606 English law turned a foiled plot into Bonfire Night
A 1605 plot to blow up parliament led to a 1606 law making 5 November an annual celebration, which stayed on the books until 1859.
Banyan roots grow from branches, then thicken into trunks
A banyan drops roots from its branches. Once they reach the soil they thicken into pillars, which is how one tree in India came to cover five acres.
Bell Labs built the first practical solar cell in 1954
Three Bell Labs scientists turned silicon into a 6% efficient solar cell in 1954, more than a century after the photovoltaic effect was first observed.
Bernard Williams used Gauguin to put luck into morality
In his 1976 essay on moral luck, Bernard Williams asked if Gauguin's success could justify leaving his family. Critics say it barely weighs the harm done.
Bessemer's process made steel ten times faster
Henry Bessemer patented a way to turn molten iron into steel with a blast of air in 1855. It cut batch times tenfold and made cheap steel possible.
How a 1992 law turned Britain's polytechnics into universities
The Further and Higher Education Act 1992 gave 34 British polytechnics degree-awarding powers, ending a divide that had run since 1965.
The panopticon was designed so no one had to watch all the time
Bentham's panopticon put a tower inside a ring of cells. Prisoners could not see the watchman, so they had to assume someone was looking, at minimal cost.
Australia's School of the Air: outback lessons by phone
Mount Isa's School of the Air teaches outback children scattered across 800,000 square kilometres by radio, then satellite phone, in daily lessons.
Houthi attacks pushed global shipping around Africa
Houthi attacks in the Red Sea led the biggest container lines onto the longer route around Africa. It adds 10 to 12 days and about $1m in fuel per ship.
Henry Cole sold the first printed Christmas card in 1843
In 1843, a busy London civil servant had no time to write to family and friends, so he commissioned an artist to design a card instead.
Arm position matters more than which arm for blood pressure
Which arm barely changes a blood pressure reading. How you hold it can shift the systolic number by more than 6 points, a Johns Hopkins trial found.
Disneyland's chaotic 1955 opening set the theme park standard
Disneyland opened in Anaheim on July 17, 1955, to forged tickets, broken rides and soft asphalt. It still set the standard for what a theme park could be.
A 30-point credit score rise can cut a US mortgage rate
US mortgage lenders price conventional loans in 20-point credit score tiers. A 30-point rise can cut the rate by 0.25 percentage points or more.
Chicago's steel frame, and the iron mill that came first
The Home Insurance Building carried its floors on a steel and iron skeleton, not its walls. That idea let Chicago build past five storeys.
Half the mining power lets one party rewrite a blockchain
A miner with more than half a blockchain's computing power can build a longer chain, undo its own payments, and spend the same coins twice.
Irish heating oil jumped about €200 a tank in one week
A week of renewed US-Iran fighting added about €200 to a full Irish heating-oil delivery in July 2026, reversing months of falling prices.