Big Idea: Life Beyond Earth Chris Impey Department of Astronomy University of Arizona Chris Impey Department of Astronomy University of Arizona

Evidence that ingredients for life are widely available in time and space Evidence that planet and moon habitable locations are abundant

A majority of the biosphere remains to be explored. Over 99% of microbes have not yet been cultured. Only remote sensing through most of the Solar System. A small fraction of habitable planets/moons discovered. A tiny fraction of SETI search space has been explored. What We Know (and don’t…)

Earth Clones

Habitable “Real Estate”:Cryogenic > Terrestrial Dwarfs > Sun-like stars

Several hundred Earth-like worlds discovered since 1995, most of them in the neighborhood of the Sun.

Twenty billion habitable worlds in the Milky Way, some with up to 8 billion years head start on Earth.

There are ~10 21 terrestrial planets in traditionally defined habitable zones in the observable universe.

Biomarkers

Courtesy: Laird Close Adaptive Optics at the 6.5m Magellan Close et al.

GMT Primaries and Adaptive Secondaries

Olivier Guyon, GMT simulation, University of Arizona Coronagraphs will yield an even higher contrast in reflected light from a planet.

Historical Perspective (GMT Era) GMT MagAO Courtesy: Laird Close

RAW contrast reached in labs Scaled to GMT diffraction limit calibration gain currently obtained on AO images (see HR8799 inner planet detection) GMT calibration floor estimate with TODAY's technology GMT can discover Habitable Earths Around Nearby, Cool, Stars Best GMT Targets 19

The Drake Equation 200 billion 100 billion 20 billion 10 billion? 100 million?? 1 to 1 million???

The radio cosmos is quiet. Look for small bandwidth (artificial) pulse sequences. The visual cosmos is noisy. Look for very rapid pulses that outshine the parent star.

In 20 years, all PW pulsed lasers and Arecibos emitting detected out to 1kpc (spanning 10 8 stars ) The search to detect signals from technological civilizations has met with 55 years of silence. But the search capacity (in sensitivity and bandwidth) grows exponentially An approach which avoids any assumption about communication is to search for alien “artifacts”

How long to colonize? Assume 10,000 years per 20 parsec hop Total time to span the Galaxy: 1500 hops x 10,000 years = 15,000,000 years 30,000 pc

10,000 processors working for a year Around 2050 We’re on the cusp of technological maturity: “ancestor” simulations of ops or 0.1c galactic exploration

The Fermi Question As originally phrased by Erico Fermi in 1950, it seems a reasonable proposition that: Our civilization and technology is very young; life forms with much more advanced technology could have remarkable capabilities. A modest extrapolation of current technology allows us mine asteroids or moons, and create probes that could create replicas of themselves and propagate through the galaxy. There are many likely sites for complex life, and plenty of time for technology to develop, billions of years before Earth formed.

They don’t exist They are very rare They are unrecognizable They are inscrutable They don’t care They created us Responses to Fermi

Galaxy Colonizing Civilization

Galaxy Colonizing Civilization Galaxy Colonizing Civilization Optimistic Scenario: The Great Filter lies behind. Advanced life like us is rare. Pessimistic Scenario: The Great Filter lies ahead. We’re rare & we’re in trouble.

Technology Analogy is to ? as is to

Evolution Analogy is to ? as is to

They Are Among Us

Salvation and Damnation

THE END