Wertheim is a science journalist, originally from Australia but now based in Los Angeles, who has talked to a whole range of cranks and outsiders to find out what makes them tick for her book Physics on the Fringe. Their motivations might seem relatively benign, but as Wertheim reveals in the podcast, since writing the book she has found their reactions to it to be far from pleasant.

Kaiser, meanwhile, is a historian of science at the Massachusetts Institute of Technology. How the Hippies Saved Physics is about a loose collection of physicists on the west coast of America that made important contributions to quantum-information theory back in the 1970s. At the time these physicists were into some pretty weird stuff, including ESP and occultism, which meant that their work was largely ignored.

Interestingly, however, one piece of work that these researchers did suggested that quantum entanglement could be used for faster-than-light communication. Although this was later proved to be incorrect, finding the flaw in the work led other scientists to develop the “no-cloning theorem”, which states that you cannot create identical copies of arbitrary unknown quantum states. That theorem is now at the heart of quantum cryptography – the idea that you can send messages with absolute secrecy.

Listen to the podcast now to find out more about just why it is so hard to draw the line between science that is crazy enough to be true and science that is just plain crazy.