This week’s podcast begins with the welcome news that at least one form of destructive planetary change – a sudden and dramatic reversal of the Earth’s magnetic field – is much less likely than previously thought. As Susan Curtis explains, careful studies of rock samples and beryllium deposits in Antarctic ice cores indicate that the last such reversal took around 22,000 years to complete.

Next up is a discussion of nuclear fusion, and specifically a visit that Tushna Commissariat made to the Plasma Science and Fusion Center at the Massachusetts Institute of Technology (MIT). In 2018, a group of scientists from the MIT centre set up a spin-off company called Commonwealth Fusion Systems that hopes to achieve “net energy gain” in a fusion plasma thanks, in part, to new superconducting magnet technologies. In the podcast, we discuss the emergence of private industry funding for fusion energy and whether this trend will change sceptical views about this low-carbon, low-radioactive-waste form of energy.

Shifting gears from fusion to fission, we return to the subject of the Chernobyl meltdown – a frequent topic in recent podcasts – in an interview with Kate Brown, a historian at MIT who specializes in researching nuclear disasters. Brown contacted us in response to a Physics World interview with epidemiologist Richard Wakefield which, she felt, mischaracterized her book about Chernobyl. On topics such as this, where opinions in the scientific community differ widely, it can be difficult for journalists to strike the right balance, so please send us an e-mail to offer critical (or favourable!) views on our coverage.  We definitely promise to stop consuming Chernobyl-produced vodka (yes, it really exists; no, we’re not actually drinking it) long enough to read and reflect on the feedback.