Transcript big_idea_-_life_beyond_earthx

Big Idea:
Life Beyond Earth
Chris Impey
Department of Astronomy
University of Arizona
Evidence that
planet and moon
habitable locations
are abundant
Evidence that
ingredients for life
are widely available
in time and space
What We Know
(and don’t…)
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.
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 ~1021 terrestrial planets in traditionally
defined habitable zones in the observable universe.
Biomarkers
Adaptive
Optics at
the 6.5m
Magellan
Close et al.
Courtesy: Laird Close
GMT Primaries and Adaptive Secondaries
Coronagraphs will yield an even higher
contrast in reflected light from a planet.
Olivier Guyon, GMT simulation, University of Arizona
Historical Perspective (GMT Era)
GMT
MagAO
Courtesy: Laird Close
GMT can discover Habitable Earths Around Nearby, Cool, Stars
calibration gain currently
Best
on AO images
GMT (see HR8799obtained
inner planet detection)
Targets
GMT calibration floor estimate
with TODAY's technology
RAW contrast
reached in labs
Scaled to GMT diffraction limit
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.
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
In 20 years, all PW pulsed lasers
and Arecibos emitting detected
out to 1kpc (spanning 108 stars)
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
We’re on the cusp of technological
maturity: “ancestor” simulations of
1035 ops or 0.1c galactic exploration
10,000 processors
working for a year
Around
2050
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.
Responses to Fermi
They don’t exist
They are very rare
They are unrecognizable
They are inscrutable
They don’t care
They created us
Galaxy
Colonizing
Civilization
Optimistic Scenario:
The Great Filter lies behind.
Advanced life like us is rare.
Galaxy
Colonizing
Civilization
Pessimistic Scenario:
The Great Filter lies ahead.
We’re rare & we’re in trouble.
Galaxy
Colonizing
Civilization
Technology Analogy
is to
as
is to
?
Evolution Analogy
is to
as
is to
?
They Are Among Us
Salvation and Damnation
THE END