Does it take 15,000 litres of water to produce a kilogram of beef?

Does a fall in the UK's healthy life expectancy mean what you think it means?

Tim Harford investigates some of the numbers in the news. This week: Headlines have claimed that “healthy life expectancy” in the UK has fallen by two years. What does this actually mean? A new government report estimates that HS2 will cost almost double its original estimate. We ask where the money’s gone. Chancellor Rachel Reeves has reduced VAT on theme parks, aquariums and other summer fun. But will these savings get passed on to the consumer? And Tim gives a much-anticipated update on his recent marathon. Contributors: Stuart McDonald - actuary at LCP Health Analytics John Burn-Murdoch - Chief Data Reporter for the Financial Times Kate Lamble - journalist and presenter of ‘Derailed: The story of HS2’ Dan Neidle - founder of Tax Policy Associates Credits: Presenter: Tim Harford Reporter / Producer: Lizzy McNeill Producers: Tom Colls, Nathan Gower and John McMinn Production co-ordinator: Brenda Brown Sound mix: Neil Churchill Editor: Richard Vadon

Is the ‘loneliness epidemic’ real?

What does it mean if you say that something is an epidemic? In the case of a virus, it usually means that it is spreading rapidly and that more and more people are getting infected. When a disease isn’t on the rise but is there in a population at a reasonably steady level, we tend to say that the disease is endemic. But what if the thing you’re talking about is not a virus, but a feeling? In 2023, the US surgeon general launched a report called “Our Epidemic of Loneliness and Isolation”, warning of the health harms of being lonely and socially isolated. The idea that there is an epidemic of loneliness didn’t start there - the term was already in use in the US in the 2010s. And it’s a phrase that’s still going strong, popping up in news stories on a regular basis. After that warning from the US Surgeon General, the World Health Organisation launched the Commission on Social Connection, with their director general warning that “more and more people are finding themselves isolated and lonely.” But is it true that loneliness rates are increasing? Is it right to say we’re in the midst of an epidemic of loneliness? It’s hard to find the data that backs up this claim. If you’ve seen a number in the news you think we should take a look at, email moreorless@bbc.co.uk CONTRIBUTOR: Professor Melody Ding, an epidemiologist and population behavioural scientist at the University of Sydney This programme has been edited to correct a minor technical production error on 27/05/2026 CREDITS: Presenter: Tim Harford Reporter: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neill Editor: Richard Vadon

Are refugees more likely to commit crime?

Tim Harford investigates some of the numbers in the news. On the programme: Last week, Annunziata Rees-Mogg took to X to post a claim about the proportion of sex offences in Dorset that are committed by asylum seekers, writing that “asylum seekers make up 0.8% of Dorset’s population and 44% of alleged sex offenses. So unbelievable I had to check.” We checked too, and the number isn’t right. In the last series of More or Less we suggested that nuclear power plant Hinkley C was spending so much on protecting the fish population that it would cost something like £250,000 per fish saved. We’ve had to take a look at that one too. Last year, we looked at a report by the Bible Society based on polling from YouGov. The Quiet Revival suggested that churchgoing was on the rise in the UK, with young men leading the trend. YouGov now have an update on that survey. How many caterpillars does a blue tit chick eat before it leaves the nest? In a recent nature documentary, Sir David Attenborough said the right number was 20,000. We’re not so sure. If you’ve seen a number in the news you think we should take a look at, email the more or Less team: moreorless@bbc.co.uk CONTRIBUTORS: Madeleine Sumption, Director of the Migration Observatory at Oxford University Professor David Voas, Emeritus Professor of Social Science in the UCL Social Research Institute Annette Jäckle, Professor of Survey Methodology at the University of Essex and a Deputy Director of the UK Household Longitudinal Study Dr Malcolm Burgess, Principal Conservation Scientist at the RSPB CREDITS Presenter: Tim Harford Reporter: Lizzy McNeill Producer: Nathan Gower and Josh McGinn Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: James Beard Editor: Richard Vadon

Erdos Problem 1196: Can AI now solve maths that no human can?

It’s said that AI could soon be coming for the jobs of artists, lawyers, and software engineers. But it might now also be threatening a role at the height of academia – are pure mathematicians safe? Last month, a Stanford mathematician woke up to an email, claiming to have the solution to a problem he'd been working on for seven years - a 60-year-old conundrum known as "Erdos Problem 1196". The answer had been generated in just 80 minutes - by ChatGPT. Since the end of last year, AI has been providing solutions to a number of novel maths problems, but Problem 1196 is the first to raise eyebrows within the mathematical community. In this episode, we talk to the mathematicians who've worked on Problem 1196 and find out what the rise of AI could mean for the future of their field. CONTRIBUTORS: Katie Steckles, Mathematician and communicator Jared Duker Lichtman, Szegő Assistant Professor of Mathematics at Stanford University Liam Price, amateur mathematician Credits: Presenter: Charlotte McDonald Producer: Josh McMinn Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O'Neill Editor: Richard Vadon

Why it’s wrong to say vaping is as bad for you as smoking

According to the World Health organisation, smoking kills some 7 million people every year. It is one of the world’s leading causes of preventable death. Because smoking causes lung cancer and other awful health conditions, many smokers switch to vaping - using nicotine-based e-cigarettes. But the World Health organisation is also concerned about vaping. Last year they said 100 million people around the world are now using e-cigarettes, including millions of children, and warned that they were fuelling a new wave of nicotine addiction. But how do the health risks of these two means of getting nicotine into your bloodstream compare? According to a recent headline in the Daily Mail, they’re basically the same. Here’s the headline: “Vaping is linked to lung and mouth cancer in major study, as experts warn: 'It is NOT safer than smoking’” But is vaping really just as bad for you as smoking? CONTRIBUTOR: Professor Lion Shahab, Co-Director of the UCL Tobacco and Alcohol Research Group CREDITS: Presenter: Charlotte McDonald Reporter/producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neil Editor: Richard Vadon