The search for microscopic aliens

Astrophysicist and TED Fellow Sarah Rugheimer searches for aliens -- but not the cartoony green kind. She's looking for extraterrestrial microbes by studying how these single-celled organisms emit gases, which could reveal evidence of them throughout the cosmos. Wondering if we're really alone in the universe, Rugheimer identifies two big hurdles to confirming life on another world and offers insight into what finding it might mean for us.