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Jack Oughton SETI
There are few subjects to inspire the mind as much as the idea of finding intelligent life amongst the
stars. What would a being from another world look like? What characteristics would we recognize in
it? Would it have a personality? What could we learn from each other?
Throughout human history, the belief in life beyond the creatures of the earth has been consistent,
but harder to define. Ancient superstitions of supernatural beings, clearly identified as intelligent,
though not so commonly believed in today, could be perceived as ‘alien’. Long before the modern
and well developed idea of aliens that we identify with today; influenced by new media and films,
some ancients wrote of men on other worlds. Indeed, many new age spiritual practices blur the line
between spirituality and science on the matter, with many unorthodox belief systems such as
Scientology taking hold in a more liberal intellectual climate. Some with more radical views look back
retrospectively and believe that many of our prophets and old Gods where actually alien beings,
arguing that such complicated creations as the pyramids could not have been created so early
without outside assistancei (Daniken, 1990).
The first known Western thinker to argue for a universe full of other planets and therefore,
extraterrestrial life (the plurality of worlds) is the ancient Greek philosopher Thales. However,
opponents to his theory, Plato and Aristotle, argue that the Earth is unique and that there can be no
other systems of worlds. Eventually their views win this philosophical war, becoming remembered
and seen as more credible, their belief in a unique earth endures. When their philosophy is adopted
by the Church as religious dogma in the early first millennium, the unique earth theory is given a
new centuries long lease of life, and arguments against it, effectively made illegal. Giordano Bruno,
an Italian priest and cosmologer is burnt at the stake for heresy on February 17, 1600. His crimes
include arguing that an infinitely large universe could contain an infinite number of planets, some
which harbour life. Lucian, 800 years after Thales, writes of aliens on the moon in his work, A True
Storyii, but only from what we would consider a fictional perspective. The spread of the telescope
allows people to observe moons orbiting Jupiter, suddenly people realise that the dogma could be
wrong. The subsequent overcoming of the geocentric theory undermines the premise which the
Church has clung to for hundreds of years, and soon esteemed astronomers such as Kepler begin to
suggest the possibility of alien life; “Each planet in turn, together with its occupants, is served by its
own satellites. From this line of reasoning we deduce with the highest degree of probability that
Jupiter is inhabited.”iii After this, the possibility of extra terrestrial life and intelligence is once again
considered in the West.
Thus, the belief in the idea of extra terrestrial intelligence, loosely defined, has persevered (even in
the face of adversity) in some form for far longer than the organized scientific search of today. The
historic debate continues, modern sceptics; proponents of the Rare Earth hypothesisiv claim sentient
life is rare or nonexistent in the universe, while simple microbial life is more common. SETI scientists
and supporters through their actions and arguments have more faith in finding extra terrestrial
intelligence and could be described as modern pluralists.
The Search For Extraterrestrial Intelligence (SETI) is the collective name for a number of activities to
detect intelligent extraterrestrial life. The aim of the SETI projects is to detect extraterrestrial life,
and if possible, communicate with it (Communication With Extraterrestrial Intelligence – CETI, a
branch of SETI’s research).
Probably the most well known SETI organization of today is the SETI Institute, a non-profit
Corporation founded in 1984, and based in California; “The mission of the SETI Institute is to explore,
understand and explain the origin, nature and prevalence of life in the universe”v. However, SETI is
established globally, for example, the SETI League is another non profit corporation based in New
Jersey, and founded in 1994. It has branches worldwide, including a UK divisionvi, which co-ordinates
the research efforts of British amateur radio astronomers. The hugely successful SETI@Home
program has participants with the software installed from over 200 countriesvii.
The origin of the modern SETI era can be placed to 1959. Cornell University physicists Giuseppi
Cocconi and Philip Morrison published an article in Nature, “Searching for Interstellar
Communications” in which they suggested the potential use of microwave signals for interstellar
communication. ETI, they argued, would most likely broadcast at 1420 MHz; the emission frequency
of hydrogen – the most abundant element in the universe. Soon after, in 1960, little known Cornell
University astronomer Frank Drake performed the first modern SETI experiment; Project Ozma.
Drake used the 25 meter radio receiver, the National Radio Astronomy Observatory at Green Bank,
West Virginia, to examine the stars Tau Ceti and Epsilon Eridani at around 1420 MHz, he picked them
because of their relative proximity of 11ly and similar ages to Sol. Though he found no alien signals
he did accidentally detect a secret military transmission. Later that year Frank Drake wrote his now
famous Drake Equation, which allows it’s user to speculate on how many communicable alien
civilizations there may be, which he then presented to the first SETI meeting, held at Green Bank, in
1961. That same year, a paper was published which was the blueprint for future optical SETI
research. (Dr. R. N. Schwartz, 1961)viii. SETI finally had established itself, with operating procedures
to follow and scientific credibility. Arguably the only success SETI had was in 1977 with the ‘Wow
Signal’. A strong, narrowband radio signal detected by Big Ear radio telescope at Ohio State
University. It lasted 72 seconds, but despite recent efforts to find it has not been detected again.
Project SERENDIP (Search for Extraterrestrial Radio Emissions From Nearby Developed Intelligent
Populations): A ‘parasitical’ program that ‘borrows’ the radiotelescope at the National Radio
Astronomy Observatory from other radioastronomical projects. It is able examine 168 million
channels every 1.7 seconds. This parasite operating template has been modelled by other radio SETI
programs, such as SETI Australia based at the 64m Parkes radioscope and Project Starvoice, based
at the 32m Medicina radio observatory, in Italy.
NASA Microwave Observing Program and Project Phoenix: In 1992, the U.S. government funded
NASA’s "Microwave Observing Program (MOP)". MOP was planned as a long-term effort,
performing a search of 800 specific nearby stars, along with nonspecifically directed "Sky Survey",
unfortunately MOP was canceled by congress a year after its start. In 1995 the SETI Institute
resurrected it under the name of Project Phoenix, funded by private sources. Project phoenix ended in
2004, after completing its scan of 800 stars, but found nothing promising.
The SETI process can be broadly divided into 3 parts, the actual detection of evidence of alien life
(‘intelligent’ or not), the analysis of the massive amounts of data involved, and the practical ways of
communicating with this yet undiscovered life.
Detection of ETI: These methods are directly applied to discover possible extraterrestrial
intelligence, either by intentional communicational broadcast, or as a biproduct of their
Radio: Currently the most widely used detection technique used. Radio receivers located at different
points on the earth’s surface scan the skies in search of unusual signals, these signals are then
recorded and sent for analysis to determine if they are worth pursuing further.
Optical: Optical telescopes watch the skies for concentrated pulses of laser light in the visible
spectrum, which could be thousands of times brighter than background starlightix.
Determining suitable planetary candidates for alien life: These are methods used more by
astrobiologists, who are not looking specifically for evidence of alien intelligence, just life. But, using
them in tandem with SETI can give researchers a better idea of where to point their receivers.
Spectroscopic: Though we don’t yet possess the optical ability to observe extrasolar planets directly,
spectroscopic analysis would allow us to determine the conditions upon the planet, and to see if it
was theoretically habitable.
Exoplanetary Wobbles: Minute gravitational influence of planets upon distant stars allow us to
detect the presence of these planets (Struve, 1952).x The distance of these planets from their stars
calculated by this information allows us to decide whether they could be candidates for sentient life.
Communicating: A purely hypothetical field so far, as no alien civilizations have been discovered,
nevertheless a number of messages have been sent in an attempt to make our presence known to
anyone listening. These included the famous 1974 Arecibo Message. A number of communicational
languages are in development: mathematical languages, pictorial systems such as the Arecibo
message, and even algorhythmic computer messages which could be run as self explanatory codes
on alien software.
There are reasons to seek out alien life, beyond the inherent human need to explore and learn. The
indirect benefits of SETI so far have been significant, the SETI Institute itself has a significant
outreach element, engaging people of all ages in a fascinating branch of science, far removed from
unappealing dusty classrooms and chemical formulaexi. SETI is at the bleeding edge of applied
astrobiology and radio astronomy, and through the internet and mass media, SETI has a well
established public presence, with educational cruises, internet podcasts and TV specials.
More directly, SETI is involved in formal education, it has it’s own curriculum at high school level,
Voyages Through Time. SETI researchers also have written textbooks used in classrooms, such as Life
in the Universe, a national best-seller for introductory astrobiology, and Perspectives on Astronomy,
a widely adopted text for introductory astronomy. SETI also trains teachers through Astrobiology
Summer Science Experience for Teachers (ASSET), giving them the knowledge and physical tools to
teach a detailed astrobiology curriculum. SETI encourages undergraduate scientists also with its
Astrobiology Research Experience for Undergraduates (REU) program, in which especially promising
candidates get the chance to work hands on with research institute scientists. SETI’s work as a
member of the NASA Astrobiology Institute (NAI) sees the organization supporting public science
talks, and contributing to the design of science museum exhibits. The SETI Institute understands the
benefits of publicity, and has leveraged its interesting subject matter as a way of capturing public
imagination. Admittedly this is an advantage it has over more ‘academic’ organizations, which do not
take much of an active role in public outreach, and therefore have less public engagement.
Compared with other research subjects, SETI is cheap, it costs the American taxpayer nothing, as it is
entirely privately funded, since 1992, when the American congress ceased it’s funding of the
Microwave Observing Program. SETIs use of ‘grid computing’ means that computational loads
greater than any super computer ( 27.24 teraflops xii)can be processed, without the multimillion
dollar operating costs a supercomputer would bring. By nature, the research costs of most of SETI
are low due to it’s thrifty ethos. Parasitical research programs and public initiatives such as the SETI
league keep costs as low as possible.
The implications of discovering or communicating with alien life would be far reaching, and would
mark one of the most monumental points of human history. From the philosophical stance, it may
bring us closer to an understanding of who we are as a species, our origin and our place in the vast
universe we inhabit. The useful discoveries to be gained from communicating with a species that
could possess technology and knowledge that we do not are limited only to the imagination;
answers to questions that we haven’t been able to answer yet? The insights that could be gained
from interacting with completely alien minds could cause a paradigm shift on the very way humans
perceive everything; questions that we haven’t even asked yet? As technologist and Microsoft co-
founder Paul Allen said while commissioning the new telescope that bears his name, "I like to call
SETI the longest of long shots. But if this array picks up a signal, that would be an amazing thing – a
Problems with SETI
At the moment, one of the main problems facing SETI is the distances involved. The transmission of
the Arecibo, will take 25,000 years to arrive at the stars it was directed at, and a return signal would
take another 25000 years. The immensity of the universe means that any communication, if
theoretically established would literally take years, as the distances between stars are measured in
light years; wave information travelling at the speed of light (which at this time we cannot find a way
to exceed) would take 4.2 years to reach the next nearest star to us (after Sol), proxima centurai.
And by astronomical measures this distance is next to nothing, the Milky Way is thought to be
100,000 light years across, and the ‘nearby’ galaxy, Andromeda, is 2.5 million light years away. Even
if we were to receive a message, there would be no assurance of the continued existence of the
civilization or star system it originated from, and if we could establish communication, it would be
awkward and slow, in the time lag waiting for responses.
Another fundamental, but rather subtle problem SETI faces is the inherent bias we as humans will
have, in searching for alien life, only on the criteria for life which we know about or can imagine.
Carbon chauvinism is a term used by Carl Sagan to describe itxiii, It describes the limits that humans
have in our imagination or perception of alien life, based on our preconceptions born of our earthly
environment. At a philosophical level, an alien species may not fit the criterion for our definition of
life, we may not even recognise it. A sufficiently advanced species may choose not to make itself
known to us, or we may not be fully able to understand or comprehend itxiv. On the flipside of this,
on our planet of the total estimated twenty million different speciesxv, only humans are capable of
interstellar communication. If we do find life on other worlds, are the odds of it being sentient
completely stacked against us?
The radio astronomers make a broad assumption that the alien communicational medium would be
through wave based information, but since it appears that this is essentially impractical for
communication over the distances involved, perhaps an alternate and more efficient technology is
used, that we are not yet aware of and cannot receive.. The human definition of ‘habitable’ is
predicated around carbon based life, and the search criterion for habitable worlds is ones where
liquid water could exist. However, astrobiologists are beginning to propose alternate mediums that
life could develop in. These include and are not limited to ammonia, silicon and hydrogen fluoride.
Extremophile life has been discovered on earth happily subsisting in extremely hostile environments;
such as acidic, extremely hot or areas of high pressure that ‘normal’ life could not survive. This
indicates that our search criteria could be completely wrong, is it possible that life could live
anywhere? Research has proven that certain hardy terrestrial bacteria are able to survive for
extended periods of time when exposed to space. (R. L. Mancinelli, 2008)xvi
Another problem with SETI is the fragmented nature of the human race. Since the invention of the
radio at the end of the 19th century, humanity has been sending out radio transmissions in a variety
of different languages and contexts. The first messages received by hypothetical aliens would make
very little sense and would not communicate in any form an appropriate introduction or first
impression of humans as a species. Do we really want an alien race’s early impressions of us to be
based on the gibbering of the mass media? Have we already presented a terrible first impression?
Although commercial radio signals are relatively weak in comparison with concentrated signals
beamed for interstellar communication, perhaps other civilizations have the technology to listen.
This idea was explored in the film Contact, based on a book written by Sagan, in which an alien signal
to humanity is sent back encoded into Hitler’s opening speech at the Nuremburg Olympics.
If contact is then made with extra terrestrial intelligence, the problem arises of who speaks for earth.
As a species which has not yet outgrown its old habits of tribal warfare and in which the prospect of
self annihilation still remains, would we be ready to communicate reasonably with another species?
We have always reacted badly to new important discoveries that threaten to shake up our well
entrenched world views. A question taken less seriously asks, is revealing our location safe?xvii Would
they be benign or hostile? The lessons of our own history have taught us that when a more
advanced civilization communicates with a more primitive one, the social implications for the less
developed civilization can be disastrous. It’s people and government struggle to come to terms with
a bewildering new technology gap to which they have not had enough time to gradually adapt to.
Also, if the more advanced civilization decides to make war on the weaker, inevitably it prevails. An
example is the Spanish-Aztec wars, in which a few hundred gun wielding, steel armoured
Conquistadores overthrew the most militarily powerful Mesoamerican civilization in less than 2
The Future of SETI:
There have been significant advances in technology over the last 40 years, especially in processing
power. Chances of success today are greatly higher, for example Project Ozma’s detection ability was
1 trillion times less sensitive than the average SETI radiotelescope used today.xviii Moore’s law states
that processing power doubles every 18 months, this combined with a greater distribution of the
SETI@Home project as more people own personal computers, paints a bright future for SETI’s
capacity to both detect and analyse new information. Specific new developments in the SETI
program itself appear promising. In November 2008 NASA will launch the Kepler space telescope,
which will for the first time allow us to detect earth sized exoplanets.
As Morrison and Cocconi argued, in their influential paper; "The probability of success is difficult to
estimate, but if we never search, the probability of success is zero." Though we may be alone, at least
we can say we tried.
Daniken, E. V. (1990). Chariots of the Gods : Was God An Astronaut?. Souvenir Press Ltd.
http://www.sacred-texts.com/cla/luc/wl2/wl211.htm [accessed 08/04/08]
The Internet Encyclopaedia Of Science - http://www.daviddarling.info/encyclopedia/K/KeplerJ.html [accessed 08/04/08]
Ward, Peter D., and Brownlee, Donald, 2000. Rare Earth: Why Complex Life is Uncommon in the Universe. Copernicus Books
(Springer Verlag). ISBN 0-387-98701-0
http://www.seti.org/about-us/ [accessed 08/04/08]
http://www.jsquared.co.uk/seti-uk/ [accessed 08/04/08]
McConnell, Brian; Chuck Toporek (2001). Beyond Contact: A Guide to SETI and Communicating with Alien Civilizations. O'Reilly.
Dr. R. N. Schwartz, P. C. (1961). Interstellar and Interplanetary Communication by Optical Masers. Nature , 205-208.
A. Howard et al., "Optical SETI at Harvard Smithsonian," in Bioastronomy '99 - A New Era in Bioastronomy, G. Lemarchand and K.
Meech, eds., ASP Conference Series 213, pp. 545-552, 2000
Struve, O. (1952). Proposal for a project of high-precision stellar radial velocity work. The Observatory , 199-200.
http://www.seti.org/epo/index.php [accessed 08/04/08]
McConnell, Brian; Chuck Toporek (2001). Beyond Contact: A Guide to SETI and Communicating with Alien Civilizations. O'Reilly.
Sagan, Carl (1973). The Cosmic Connection. Anchor Press / Doubleday: New York
Baird, John C. (1987). The Inner Limits of Outer Space: A Psychologist Critiques Our Efforts to Communicate With Extraterrestrial
Beings. Hanover: University Press of New England. ISBN 0-87451-406-1.
- The Department of Biochemistry and Molecular Biology; biodiversity
http://www.bmb.psu.edu/courses/bisc002_summer03/biodiversity.pdf [accessed 08/04/08]
R. L. Mancinelli, M. R. (2008). Biopan-survival I: Exposure of the osmophiles Synechococcus SP. (Nageli) and Haloarcula SP. to the
space environment. Advances In Space Research , 327-334.
David Brin(2006) Shouting at the cosmos http://lifeboat.com/ex/shouting.at.the.cosmos [accessed 08/04/08]
Horizon – are we alone in the universe? (2007) BBC2