For thousands of years, humans have wondered whether we’re alone in the cosmos. Now, for the first time, we have the technology to investigate. But once you look for life elsewhere, you realize it is not so simple. How do you find it over cosmic distances? What actually is life?

As founding director of Cornell University’s Carl Sagan Institute, astrophysicist Lisa Kaltenegger has built a team of tenacious scientists from many disciplines to create a specialized toolkit to find life on faraway worlds. In Alien Earths, she demonstrates how we can use our homeworld as a Rosetta Stone, creatively analyzing Earth’s history and its astonishing biosphere to inform this search. With infectious enthusiasm, she takes us on an eye-opening journey to the most unusual exoplanets that have shaken our worldview - planets covered in oceans of lava, lonely wanderers lost in space, and others with more than one sun in their sky! And the best contenders for Alien Earths. We also see the imagined worlds of science fiction and how close they come to reality.

With the James Webb Space Telescope and Dr. Kaltenegger’s pioneering work, she shows that we live in an incredible new epoch of exploration. As our witty and knowledgeable tour guide, Dr. Kaltenegger shows how we discover not merely new continents, like the explorers of old, but whole new worlds circling other stars and how we could spot life there. Worlds from where aliens may even be gazing back at us. What if we’re not alone?

Lisa Kaltenegger is the Director of the Carl Sagan Institute to Search for Life in the Cosmos at Cornell and Associate Professor in Astronomy. She is a pioneer and world-leading expert in modeling potential habitable worlds and their detectable spectral fingerprint. Kaltenegger serves on the National Science Foundation’s Astronomy and Astrophysics Advisory Committee (AAAC), and on NASA senior review of operating missions. She is a Science Team Member of NASA’s TESS Mission as well as the NIRISS instrument on James Webb Space Telescope. Kaltenegger was named one of America’s Young Innovators by Smithsonian magazine, an Innovator to Watch by Time magazine. She appears in the IMAX 3D movie “The Search for Life in Space” and speaks frequently, including at Aspen Ideas Festival, TED Youth, World Science Festival and the Kavli Foundation lecture at the Adler Planetarium.

Shermer and Kaltenegger discuss: Carl Sagan and his influence • Sagan’s Dragon • ECREE Principle • how stars, planets and solar systems form • how exoplanets are discovered • Hubble Space Telescope, Kepler Space Telescope, James Webb Space Telescope • The Origin of Life • Fermi’s Paradox: where is everybody (the Great Silence, the Great Filter) • biosignatures • technosignatures • Dyson spheres • Will aliens be biological or AI? • interstellar travel • Kardashev scale of civilizations • how to talk to aliens when we can’t even talk to dolphins • Deities for Atheists, Skygods for Skeptics: aliens as gods and the search as religion • why alien worlds matter.