On today\u2019s podcast, the World Health Organization redefines \u2018spread through the air\u2019 for diseases; AI used to mix coffee in Finland; all about \u2018young\u2019 and \u2018younger\u2019 followed by a discussion on \u2018younger than\u2019; then, part one of \u2018A Princess of Mars\u2019 by Edgar Rice Burroughs on American Stories.