Half of all money spent on advertising is wasted. But we just don't know which half. In recent years, marketing professionals have been trying to use neuroscience to locate the "buy button" in our brain, which if pressed would make us buy their stuff. It's the holy grail: a way of knowing, in advance, which ads are going to work and are worth spending money on, and which ones would flop. The promise, from both marketers and some neuroscientists, is that our brains can, effectively, be hacked. But does it work? Presenter/producer: Jolyon Jenkins

"Memory athletes" compete to see who can remember the most random numbers in an hour. Or else to memorise decks of playing cards. Memory training is big in China, where there are TV game shows for memory contests, and where parents pay good money to get their children trained in memorisation techniques. Everyone thought the Chinese were invincible, and that we were at the limits of what could be memorised - until 2019 when a group of North Korean teenagers arrived at the world championships, smashed a bunch of records, and returned to Pyonyang. Since then, nothing has been heard of them. What's their secret? And why does North Korea want to dominate the world in this obscure sport? Presenter/Producer: Jolyon Jenkins

Ever since the middle ages, pieces of the True Cross, and other relics such as saints' bones, have been sold to the gullible. But now the trade in bogus relics has moved online, to the fury of traditional Catholics. They are even more alarmed at the sale of "genuine" relics, which is also picking up pace as monasteries and convents close and their treasures come on the market. In theory selling a relic is an offence under Church law, warranting immediate excommunication. But what is a genuine relic, and how its provenance proved? Jolyon Jenkins goes on a deep dive into a world where faith, science and archaeology collide. Producer/Presenter: Jolyon Jenkins, BBC Audio in Bristol

There are millions of planets out there that could contain intelligent life. We can't look at them all, so which should we focus on? Using nothing but statistics, astronomer Fergus Simpson predicts the aliens will be living on small, dim planets, they'll have small populations, big bodies, and will be technologically backward. This goes against many astronomers' working assumption that the earth is typical of inhabited planets - and that our sun is an ordinary star in an ordinary galaxy. Fergus argues that this is an example of the "fallacy of mediocrity" which we fall for time and time again, whether it's in our assumptions about gym membership, taxi drivers, or train overcrowding. Presenter/Producer: Jolyon Jenkins

As telescopes get better, astronomers are seeing more and more things in the night sky. Sometimes they can't explain them. Is it unreasonable to suggest that they might have found evidence of alien civilisation, or at least some form of extra-terrestrial life? Call it right and they could get the Nobel prize. Get it wrong and it could be career suicide. Only those at the very end of their career, with a well-established reputation, can afford to take the chance. Jolyon Jenkins reports on some of the cases where scientists have stuck their necks out, and how badly it can go wrong for them if their findings are less robust than they thought. Producer: Jolyon Jenkins

Jolyon Jenkins investigates reports that people with severe dementia, or who haven't spoken for years, can sit up and have lucid conversations just before they die. Victorians called the phenomenom "lightning before death" and recently it's been described as "terminal lucidity". It seems incredible, but some in the medical community are taking it seriously. Producer: Jolyon Jenkins

Many animals can navigate by sensing the earth's magnetic field. Not humans, though. But might we have evolved the sense but forgotten how to access it? 40 years ago a British zoologist thought he had demonstrated a homing ability in humans. But his results failed to replicate in America and the research was largely discredited. But new evidence suggests that our brains can in fact detect changes in the magnetic field and may even be able to use it to navigate. Jolyon Jenkins investigates, and talks to a Pacific traditional seafarer who has learned to navigate vast distances across the ocean with no instruments, and who describes how, when all else fails, he has been able to access what he calls "the magic". Is the magic still there for all of us, just waiting to be rediscovered? Producer: Jolyon Jenkins

Jolyon Jenkins explores Esperanto, the language designed to bring world peace and harmony. Invented in the late 19th century, Esperanto is simple to learn, with a logical grammar, a vocabulary drawn from European languages, and no irregularities. Its creator, Ludovic Zamenhof, hoped that it would become a second language that everyone could speak, eliminating international misunderstandings. For a while, Esperanto flourished, and there was even a tiny Esperanto-speaking state in what is now Belgium, but both Stalin and Hitler saw it as subversive and tried to crush it. Jolyon tries to learn the language and to discover what remains of those early ideals. He finds elderly Esperantists playing word games in a Cardiff pub, Brazilian spiritists who believe that Esperanto is the language in which the dead converse, and a small Esperanto-speaking enclave in Goma, in the war-torn eastern Democratic Republic of Congo (some of whom learned it under the misapprehension that Esperanto was an organisation that handed out money). Is Esperanto a blindingly obvious and sensible idea, or a ludicrously utopian one? Presenter/producer: Jolyon Jenkins.

Who do you want to read your old emails when you die? Are the dead entitled to privacy?

Jolyon Jenkins attends an international whistling competition in Los Angeles to meet the people who want whistling to be taken seriously as a musical art form. The competition is organised by the "Whistling Diva", Carole Ann Kaufman, herself a former international whistling champion. "If it comes from the heart, it's art," she says. But even though there have been featured whistling instrumentalists, in the big band era for instance, whistling struggles to be thought of as more than a novelty act. Even the whistlers at the convention find it hard to persuade their own families that their talent is worth celebrating. It's even led to the break up of marriages. Occasionally, though, a whistler does make it to the (comparative) big time. Geert Chatrou is a Belgian whistler who won an international competition in 2004. he is now semi-professional and has recorded and performed with symphony orchestras and jazz bands. So - will a new champion emerge this year? Presenter/producer: Jolyon Jenkins.