We have a special guest on the show today - Stephen Schwartz. Stephen is an expert on nuclear weapons; he has been studying nuclear weapons policy, particularly in the US, for decades. His book - The Atomic Audit - was the first ever survey of the true financial cost of nuclear weapons; he has been the editor and publisher of the Bulletin of the Atomic Scientists, who manage the famous Doomsday clock and publish scholarly and popular literature on existential threats including nuclear weapons. He edited the Non-Proliferation review, and is currently an Adjunct Professor at Middlebury - he also runs an excellent social media feed on Twitter @AtomicAnalyst where he keeps us all up to date on nuclear weapons and political developments. I was delighted to have him on the show: we sat down for an interview about nukes in the modern era and under Trump, the real financial cost of nuclear weapons, the biggest risks that they pose, dispelling nuclear myths, and what we can do to help keep our society safer from these risks. I also find out why he tried to position his college to stock up on suicide pills in the 1980s. I hope you enjoy.

You can follow us on Twitter @physicspod, we have a Facebook page if you're still on that website, and you can always contact us with your comments, questions, and concerns via the contact form over at www.physicspodcast.com; I read everything and respond to everything that makes sense, and if you want to tell me what you'd like to hear from the show, I'd love to hear it. You can donate to the show via links on the website to help us cover hosting costs and in case you think it's worth a few dollars, pounds, yen or euros for hours of free, independent content. If you don't want to go through the hassle of doing that, though, please do tell as many people as you can about the show. When we come back, there's going to be an overview of the series that we're just emerged from. Episodes include the apocalypses that didn't happen, the ways we might hope to avoid them in the future, and where to go next.