How geoengineering could save us from climate disaster; Have we broken mathematics?; Why exercise reduces cancer risk

Episode 311 Geoengineering could be the best way to avoid catastrophic climate disaster - but there’s a big catch. In the recent Global Tipping Points Conference in the UK, scientists discussed growing concerns that the AMOC may be on the verge of collapsing. This is a system of ocean currents that plays a crucial role in regulating global climate. With the window of action rapidly closing, one climate model suggests geoengineering is the fastest way to stop this from happening. But without global consensus, the team explains how geoengineering could also damage the climate further or even lead to a new kind of warfare. We’re brushing up against the edge of mathematics with the uncovering of a number so large it’s hard to even describe. Busy Beaver numbers are used to describe the longest possible run-times of ‘Turing machines’ - a theoretical model of computation conceived by Alan Turing. These numbers are surprisingly hard to figure out. But after uncovering the fifth Busy Beaver number in 2021, an online community of mathematicians now thinks they’ve figured out the sixth number - and it’s beyond massive. What does this mean for the nature of mathematics? We’ve known for a long time that exercise is a great way of reducing cancer risk - and now we finally know why. A new study suggests changes in the microbiome caused by exercise can reduce tumour growth - and there appears to be one particular molecule that’s doing this good work. Does this mean we could one day use poop transplants as a cancer treatment? Chapters: (00:22) Can geoengineering save us from climate disaster? (16:59) Have we broken mathematics? (25:42) Why exercise reduces cancer risk Hosted by Rowan Hooper and Penny Sarchet, with guests Michael Le Page, Jacob Aron, Claudia Wieners and Marlies Meisel. To read more about these stories, visit https://www.newscientist.com/ Learn more about your ad choices. Visit megaphone.fm/adchoices