directors, Michael Duffy, Lyndon Bruce, Declan Healy ; executive producer, Jacqueline Smith ; series producer, Catherine Abbott ; BBC Studios, the Science Unit, Scotland
Ken Burns presents ; a film by Barak Goodman ; directed by Chris Durrance and Barak Goodman ; a production of Florentine Films, Laura Ziskin Pictures and WETA Washington, D.C. in association with Ark Media