Science Weekly

Dr Chris van Tulleken has been at the forefront of the campaign to change our food system and better regulate the sale of ultra-processed foods (UPF). This year he will be giving the Royal Institution Christmas lectures, Britain’s most prestigious public science lectures, in which he’ll be investigating how food has fundamentally shaped human evolution, the importance of our microbiome – as the extra ‘organ’ we didn’t know we had – and how we can all eat better in future, for the sake of our own health and the health of the planet. Nicola Davis sat down with Van Tulleken to discuss the lectures, the challenge of understanding the impact of UPFs on our health, and his top tip for Christmas dinner. Madeleine Finlay hears from them both in this Christmas special edition of Science Weekly. Help support our independent journalism at theguardian.com/sciencepod

For the past 10 years cosmologists have been left scratching their heads over why two methods for measuring the universe’s rate of expansion provide totally different results. There are two possible solutions to the puzzle, known as the Hubble tension: either something is wrong with the measurements or something is wrong with our model of the universe. It was hoped that observations from the James Webb space telescope might shed some light on the problem, but instead results published last week have continued to muddy the waters. To understand why the expansion rate of the universe remains a mystery, and what might be needed to finally pin it down, Madeleine Finlay speaks to Catherine Heymans, the astronomer royal for Scotland and a professor of astrophysics at the University of Edinburgh. Help support our independent journalism at theguardian.com/sciencepod

On Monday Google unveiled its Willow quantum computing chip. The new chip takes just five minutes to complete tasks that would take 10 septillion years for some of the world’s fastest conventional computers to complete. But despite its impressive power, it’s not clear the chip has any practical applications. So does it bring quantum computing any closer? To find out Ian Sample speaks to Winfried Hensinger, professor of quantum technologies at the University of Sussex. Because of industrial action taking place by members of the National Union of Journalists at the Guardian and Observer this week, you may notice some disruption to the availability of new episodes in your Guardian podcast feeds in the coming days. All the work on this episode was done before the strike action began. For more information please head to theguardian.com. Help support our independent journalism at theguardian.com/sciencepod

Madeleine Finlay speaks to Sophie Scott, a professor of cognitive neuroscience at University College London, to dig into the science of laughter. Sophie explains what exactly laughter is, the many different purposes it serves for humans and animals, and how prioritising it could make us all feel a little better. Help support our independent journalism at theguardian.com/sciencepod

Ian Sample speaks to colorectal surgeon and researcher James Kinross about the miraculous world of our gut microbiome, how modern life is impacting it, and what we can do to look after it Because of industrial action taking place by members of the National Union of Journalists at the Guardian and Observer this week, we are re-running an episode from earlier in the year. For more information please head to theguardian.com. We’ll be back with new episodes soon.. Help support our independent journalism at theguardian.com/sciencepod