Sara Seager: Search for Planets and Life Outside Our Solar System | Lex Fridman Podcast #116

Sara Seager explains how astronomers detect planets orbiting other stars and how she hopes to find signs of life by reading the gases in their atmospheres, the focus of her revised version of the Drake equation. She walks through the engineering megaprojects that could make this possible, including the Starshade, a solar gravitational-lens telescope, and Breakthrough Starshot's laser-driven nanocraft. The conversation turns deeply personal as she discusses losing her husband Mike to cancer, how that reshaped her life's mission, and how she rediscovered hope. She closes with book and film recommendations and advice on building a meaningful career.

• Only about a dozen to two dozen nearby stars are realistic candidates to study in detail for life.
  00:14:30
• Seager recast the Drake equation into her own equation focused on detecting biosignature gases rather than radio-broadcasting civilizations.
  00:21:13
• The most common type of planet known so far is a 'mini-Neptune' between Earth and Neptune in size, with no counterpart in our solar system.
  00:35:14
• From far away, humanity has built nothing detectable, even an alien civilization probably couldn't tell if we destroyed ourselves.
  00:45:35
• As a scientist she gets contacted constantly by people claiming aliens are already here, including an alien-abduction couple who took her to lunch.
  00:48:13
• She speculates that sending instructions to print humans at a destination may be easier than physically transporting people across interstellar distances.
  00:59:02
• After her husband Mike's terminal diagnosis she devoted the rest of her life to finding another Earth and proving we are not alone.
  01:22:25
• Seager's number-one book recommendation for everyone is the young-adult novel 'The Giver,' which had a profound impact on her.
  01:30:18

• Proxima Centauri, the nearest star to Earth, appears to host an Earth-mass planet in its habitable zone.
  00:14:30
• The idea of using a gas as an indicator of life elsewhere has been around for almost 100 years, centered on oxygen.
  00:26:26
• Cyanobacteria re-engineered Earth's entire atmosphere to 20 percent oxygen, nearly poisoning everything else alive at the time.
  00:44:34
• Some estimates suggest as many as one in five Sun-like stars could host a true Earth-like planet.
  00:54:55
• The Starshade concept was first conceived in the 1960s and revisited every decade until it became buildable.
  01:01:36
• The Starshade's flower-petal shape is a mathematical solution to light diffraction, blocking a star 10 billion times brighter than its planet.
  01:02:38
• Breakthrough Starshot would accelerate gram-scale 'star chips' on laser-pushed sails to a twentieth the speed of light.
  01:09:53
• Seager's mantra for hard problems: take a big crazy idea, break it into smaller crazy ideas, list them, and knock them out one at a time.
  01:12:29
• A telescope sent 500 times the Earth-Sun distance could use the Sun as a gravitational lens to image distant planets.
  01:08:18

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