seti: the search for extraterrestrial intelligence terry bridges queen’s university
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SETI: The Search for
Extraterrestrial Intelligence
Terry Bridges
Queen’s University
What is SETI?
SETI asks: are we alone in the universe?
SETI scientists are using optical and radio
telescopes to search for signals from alien
civilizations
The Beginning of SETI
1959
How do we search?
Radio waves can travel large distances … but there’s a
lot of radio “real estate” to cover!
One Magic Frequency Hydrogen is the most common element in the universe.
H atoms emit radiation in the radio spectrum at a
wavelength of 21cm and frequency of 1420 MHz
(compare CBC radio at 107.5 MHz)
The “Waterhole”
Water (H20) is also special. OH emits radiation at 1721
MHz. So “waterhole” between 1420-1721 MHz is a
good place to search
SETI Searches: Past and Present
Radio
Project Ozma, 1960: Frank
Drake looks at Tau Ceti &
Eridani
SETI Institute opens in
1985
META, BETA: 1986-1999, 60-70% of sky, using Harvard 26
metre telescope
-- searched 80 million frequencies!
-- dish now dead as is BETA (1999)
-- a good survey to detect rare but powerful transmitters
Project Phoenix: 1993-2004, funded by SETI Institute targeted search of 1000 nearby stars like the Sun used several telescopes including Arecibo and Parkes
Project Serendip: 1997-present piggy-backed onto other telescopes, 150 million freq some of the data goes to SETI@home
Project Phoenix: 1993-2004, funded by SETI Institute targeted search of 1000 nearby stars like the Sun used several telescopes including Arecibo and Parkes
Project Serendip: 1997-present piggy-backed onto other telescopes, 150 million freq some of the data goes to SETI@home
The “Wow” Signal
The Future of SETI:
The Allen Telescope Array Privately funded by Paul Allen and Nathan Mryhrvold
350 x 6m telescopes linked together
Search 100,000 to 1,000,000 stars, at 100 million frequencies
42 dishes now, 350 eventually (if funded!)
The Allen Telescope Array
The Allen Telescope Array
The Allen Telescope Array
Optical SETI look for optical laser pulses: very focused, can travel across
1000s of light-years, easily detected
Several programs around the world (Berkeley, Harvard, Lick,
Mt. Wilson, Australia
Harvard All-
Sky Optical
SETI Project
1.8m
telescope
Sending Signals!
In 1974, Frank
Drake sent a
message to the
globular cluster
M13
The Drake
Message
Can you figure
it out?
Should We Send Messages?
Pro: detecting another civilization would be very exciting
we could learn a lot from an advanced civilization
Con: will they be friendly or nasty?
What if we detect a signal?-- it would be checked carefully by the discovering scientists
-- it would have to be verified by other observatories
-- if real, all astronomers and governments would be notified.
-- how would the public react? Would there be panic?
Probably an internet meltdown …
-- could we figure out what the message says?
-- should we respond to the message?
-- if so, what do we say?
-- what would the long-term implications be?
Fermi-Hart Paradox: “Where are They?”
We have searched for 50 years with no detection: statistically,
probably less than 10,000 broadcasting civilizations
If there are advanced civilizations, would expect one of them to
have colonized the galaxy: so “they” should be here now! Fermi
asked: where are they?
Presumably means there's not many of them ...
Useful Resources
The SETI Institute: www.seti.org
The Planetary Society: www.planetary.org
“Confessions of an Alien Hunter” by Seth Shostak
“If the Universe is Teeming with Aliens …” by Stephen Webb
“Life Everywhere” by David Darling
SETI@home: http://setiathome.berkeley.edu/
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