Leah Washington and her new boyfriend Joe Pugh are on their first day out together. They're at Alton Towers theme park, where they've chosen to ride the "Smiler" rollercoaster: a terrifying tangle of track that loops and swoops through a world-record 14 inversions. Leah and Joe are seated right at the front of the train and, as they reach the highest point of the ride, they steel themselves for the drop. But then, quite suddenly, the ride stops.

Down on the ground, the computer system that controls the rollercoaster is warning that another carriage is out on the track, right in the path of Leah and Joe's train. The engineers are certain the computer is wrong...

Algorithms are often faster and cleverer than humans, and they can help us avoid accidents. But computers can make mistakes. When should we trust our own heads, instead of the machine?

For a full list of sources, see the show notes at timharford.com.

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Cautionary Conversation: In the 1920s, a conman convinced America that goat testicles were the secret to male virility. Tim Harford and Dr Kate Lister (Betwixt the Sheets: The History of Sex, Scandal & Society) dive into the bizarre and grisly tale of "Doctor" John Brinkley. This snake oil salesman mobilised the power of radio marketing to build an empire on goat gland transplants and other quack "cures". And Brinkley might have got away with it, were it not for his nemesis: the tenacious Dr. Morris Fishbein.

Find Betwixt the Sheets here: https://podfollow.com/betwixt-the-sheets-the-history-of-sex-scandal-society

For a full list of sources, see the show notes at timharford.com

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Winston Trew has just been arrested for mugging. It's 1972 and the crime has recently made its way to Britain from the United States. Dangerous thugs, replicating their American counterparts, have made the city of London their hunting ground - so Winston's eventual conviction is a win for the police, and for the press.

The problem is, 22-year-old Winston is completely innocent.

Do you have a question for Tim Harford and Rachel Botsman about trust? Please send it in to tales@pushkin.fm.

For a full list of sources, see the show notes at timharford.com.

See omnystudio.com/listener for privacy information.