Fact or Fiction

Did NASA really spend millions creating a pen that would write in space? Is chocolate poisonous to dogs? Does stress cause gray hair? These questions are a sample of the urban lore investigated in this book, “Fact or Fiction: Science Tackles 58 Popular Myths.” Drawing from Scientific American's "Fact or Fiction" and "Strange but True" columns, we've selected 58 of the most surprising, fascinating, useful and just plain wacky topics confronted by our writers over the years.