Humans have faced existential risks since our species was born. Because we are Earthbound, what happens to Earth happens to us. Josh points out that there’s a lot that can happen to Earth - like gamma ray bursts, supernovae, and runaway greenhouse effect. (Original score by Point Lobo.) 

Interviewees: Robin Hanson, George Mason University economist (creator of the Great Filter hypothesis); Ian O’Neill, astrophysicist and science writer; Toby Ord, Oxford University philosopher.