David N. Spergel

Director: Center for Computational Astrophysics, FlatironCharles Young Professor Emeritus, Princeton UniversityCo-Chair: NASA WFIRST Form. Science Working GroupLecturer, “Imagining Other Earths”, Free COURSERA lectureshttps://www.coursera.org/learn/life-on-other-planets How will humanity first discover ET Life?Best guess: BiosignatureWhy we will need to wait for advanced lifeforms to contact us:– Nearby Sun-like stars differ in age by billions of years. Life on […] The post David N.

Science Working Group Lecturer, "Imagining Other Earths", Free COURSERA lectures https://www.coursera.org/learn/life-on-other-planets How will humanity first discover ET Life. Best guess: Biosignature Why we will need to wait for advanced lifeforms to contact us: – Nearby Sun-like stars differ in age by billions of years. Life on nearby exoplanets is likely a billion years older or billion years younger than on Earth – Timescale for technological evolution is much more rapid.

E.g., we now commute primarily through compressed signals on optical fibers. Compressed signals look like noise— can’t eavesdrop on advanced civilizations. There’s a starman waiting in the sky He’d like to come and meet us But he thinks he’d blow our minds There’s a starman waiting in the sky He’s told us not to blow it Cause he knows it’s all worthwhile – David Bowie Q We can detect simpler lifeforms through their biosignatures – Oxygen, Ozone, Methane: signature of active biochemistry – Need to develop the ability to image and characterize the atmospheres of exoplanets – Cosmology drove the design of telescopes for the past century: Hale’s 100in to the James Webb Space Telescope.

Search for the signatures of life will drive the design of telescopes for the next century – WFIRST will be both a powerful telescope for cosmology (Hubble-class telescope with 100x field of view) and for advancing study of exoplanets.