SETI or the Search for Extra Terrestrial Intelligence has been a series of ongoing experiments with the aim of discovering intelligent nonhuman civilisation. These experiments have varied in complexity and sophistication as time has gone on. As such an experiment increases, so too does its requirement for resources, and its justification of itself. Included here is a brief history of the SETI program and its objectives, some of the methods and technologies involved, and some of the prime arguments levelled against it. Further investigation into the arguments is put forward, looking at the allegation that SETI may be defined as ‘bad science’.
Mankind has long been fascinated with the notion of something unlike himself ‘out there’ (Boss 1998). For the ancient civilisations, such as the Romans, Chinese, and Inca, a new civilisation could be found simply by travelling in one direction long enough. China, India, and the Middle East were all strange new cultures with different ways and rituals to Europeans. Yet mankind still yearned to travel further. The Americas were discovered and colonised, with catastrophic results for the local inhabitants (Osorio 2008). Over time, the world became known to itself. In this, man’s views began to turn to the heavens. For a long time, the heavens had been populated by intelligent life of sorts in many cultures. Gods, demons, and angels resided there (Wolf 2001). The ancient Babylonians had even identified a place where one of their deities, Oannes, came from, which was the star Sirius (Hitching 1978). Sirius is the brightest object in the night sky, not counting the moon or planets (Maran 1999). As a result it is not surprising that it became a magnet for other speculations about the night sky. The Dogon tribe of South America believe that they came from it and that greater intelligent beings reside there (Hitching 1978).
Modern public speculation on extraterrestrial intelligence began after the 12th of July, 1947, when a pilot, Kenneth Arnold, had a sighting of what would now be termed unidentified flying objects (Spencer 1991). This was widely reported and fired the public imagination with similar sightings being reported globally. The great interest in UFOs and speculation to their origins led the physicist Enrico Fermi to create his Fermi Paradox: If life is so simple and so boundless, and space is so big, where is everyone? (Sample 2007). This paradox became the model for some speculation, but especially influenced a young astronomer called Frank Drake. Drake began work to see if he could defeat the paradox. Amongst his early achievements was Project Ozma, set up in 1960. Named for L. Frank Baum’s princess of Oz (Sneath 1970), project Ozma went on to be the effective prototype for the passive SETI program. It consisted of the use of an 85-foot radio telescope, to scan the heavens for interstellar radio transmissions. It was not successful, save for some anomalous transmissions that were likely the work of military manoeuvres nearby (SETI Institute).
Drake also devised what is now known as the Drake Equation (Cirkovic 2004), which is used by some to speculate as to the possibility of other civilisations. This equation is as follows:
N = R* x fp x ne x fl x fi x fc x L
Where N = Number of potential civilisations
R* = Rate of star formation in our galaxy
fp = The fraction of those stars that have planets
ne = The average number of life supporting planets per star
fl = The fraction of those planets that have life
fi = The fraction of those with life that has intelligent life
fc = The fraction of those with intelligent life that are detectable by methods such as radio telescopy
L = The length of time these civilisations radiate their signals into space.
While a useful tool in the estimation of alien civilisation, the Drake Equation can be used by detractors of SETI to show that it is not good science. The reason for this is that most of the parameters are speculation. We are only aware of R* with any certainty currently. fp and ne are only just being calculated now, with numbers extremely variable, largely due to the presence of a water atmosphere. The remainder of the equation is arbitrary numbers which can be raised or lowered to any degree, as we only have a single example of a life sustaining planet, our own.
SETI today can be divided into two different groupings: Passive and Active. Active SETI is involved with attempts to directly contact alien civilisation. This is difficult due to the large distances between the stars, and the speed of radio waves. Examples of Active SETI include the Arecibo Message, which was beamed from the worlds largest radio telescope at Arecibo in 1974 (Drake and Sobel 1992), and golden records containing information about the earth carried by the voyager probes (NASA 2009). It appears however that most active SETI measures are better designed to create public awareness, than as an actual science endeavour itself. With space being so vast, it is extraordinarily unlikely that a small probe would be picked up, particularly between the stars, by a journeying extraterrestrial.
A more scientific approach is to listen. Passive SETI research stemmed from the original Project Ozma, and has continued in various forms to this day. The use of radio telescopes to search the sky for far-off signals continues to be the best practise we currently have, and the most likely method of detecting other life forms that use similar technology. As radio waves travel at the speed of light, the messages would suffer from time dilation. This means that a hypothetical alien SETI, operating on a planet 40 light years away, would be receiving ‘I Love Lucy’ (Scheffer 2004). The aim of the experiment, however, is to successfully receive an alien signal, regardless of age.
During the early years of searching, there have been more than one moment of excitement. In 1967, Bell and Hewish thought that they had found consistent repeated broadcasts from a star that they christened LGM-1, short for ‘little green men’. This was found not to be an attempt at interstellar communication, but the first discovered pulsar (Dawkins 2007). The next notable moment was the ‘Wow’ signal of 1977 from Ohio State University’s Big Ear radio antenna. Due to the strength of the signal and other parameters, it is often stated to be the most likely actual extraterrestrial signal (Gray and Marvel 2001). This signal was never repeated, though, and suggestion today is that it was an earth-based signal, reflected from space debris.
A question often asked of SETI researchers is ‘how do you know where to look’? With such a broad scope of radio frequencies to scan, it must appear to be a very difficult undertaking. This has been simplified somewhat with the discovery in 1951 of the ‘Water Hole’. This is a range of frequencies on the 21cm wavelength, from 1420 to 1660 megahertz (Gray and Marvel 2001). It is the band between the Hydrogen line, and the nearest hydroxyl spectral line. Thus, the combination of the name is H2O, or ‘water’. At these frequencies, there is very little background noise or radiation, a very good place to look for artificial radio transmissions.
SETI as it now exists, checks all of these frequencies across as much of the sky as it is able. Radio telescope time is purchased through its offices, or dedicated radio telescopes for SETI are being constructed. The largest of these, the Allen radio telescope array, has only recently activated its forty-two antenna first stage (RF Globalnet 2007). Each stage afterwards will continue to increase its sensitivity. The processing of the data is done via computer, and through such initiatives as SETI@home, which allows a home computer to process packages of the SETI data, then mail it back (Seti@home 2009).
SETI is not without its detractors. It has been suggested that SETI is an example of ‘bad science’ (Dewdney 1997). Those that argue against SETI point to the Drake equation, and its uncertainties. Much of the Drake Equation, it is argued, is without merit, for in order to accurately make an estimate on the last four parameters, extraterrestrial life would have had to already been discovered. With the discovery of intelligent extraterrestrial life, the Drake Equation is no longer required, and therefore cancels out its own existence.
This is quite true. However, it is to be recalled that the Drake Equation is merely a theoretical model, into which any numbers may be inputted. This will give a potential likelihood of extraterrestrial civilisation based on available information. In this, it is similar to other theoretical population models which are in common use in population studies, such as the Lotka-Volterra equation (Korobeinikov and Wake 1999). The point of the exercise is to simply gain an understanding of what is theoretically possible, not to be misinterpreted with what is actually there.
Another common detraction of SETI is its cost, in time, money, computing power and radio telescope time. This may also be robustly rebuffed, as in a similar manner to many other scientific endeavours; SETI is privately funded through donations, with support but no funding from NASA (Paulson 2003). SETI reduces its cost on processing time by the popular SETI@home initiative, and currently is developing its own radio telescope arrays, such as the Allen telescope specifically for its needs.
The next detraction comes in the form of the Fermi paradox, discussed before. If there are civilisations out there, then why are they silent? To this end, there are several possible answers. It may simply be that we are not listening hard enough, that our equipment is not sensitive enough, or that we are receiving their signals, but not realising them for what they are. The likelihood of an alien language resembling a terrestrial one would be very small indeed (Sneath 1970). Another possibility is that radio is not a common medium and it is we who are the aberration, or perhaps are not advanced enough to use whatever the common medium is.
A final detraction that SETI is not science comes from scientific principles. SETI is attempting to prove something that may well be negative, based on an assumption that life is common in the universe. This may well be quite correct, however the SETI experiment has not been ongoing for very long, and it may require quite a long time to get an answer of any sort. Radio, as stated before, travels only at the speed of light. In 1901 Marconi sent the letter ‘S’ in morse code across the Atlantic. This would indicate that the furthest a civilisation could be from us, detecting our transmissions and replying, would be 218 years. We as a species have been more or less civilised for several thousand years, but have only had radio for this scarce fraction of our history. Could it be possible that extraterrestrial intelligence has not yet developed to answer us? Or could it be that their answer is on its way right now, speeding towards us at the speed of light? Even if there is nothing at all right now, the sky is vast, and has not been fully covered by SETI. In this, we can say that the experiment has not yet been concluded. Only once all radio bands within the 21cm range have been covered, over all stars in the sky, can we say that there is nothing there, and even then, only within the parameters of the experiment.
It can be seen, then, that our concept of life in the universe has gone from abstract thinking, to amateur experimentation, to a systematic and scientific method rigorously searching the sky for specific signals. We have sent out messages digitised in radio waves, and inscribed on probes. They all say the same thing: We are here, we are waiting, and we want to meet you. In searching for further civilisations, mankind continues its quest everlasting that has fired the imaginations of explorers and scholars since time immemorial. We use the latest technologies, and the some of the finest minds continue to refine the parameters of what we are searching for. While arguments persist over the nature of the science involved, it can be seen here that when viewed as a long-term experiment, with defined requirements for success or failure, and specific protocols, then it certainly cannot be defined as anything but the application of science in that purest of pursuits: The advancement of knowledge through contact with other minds.
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