So, Is There Life Out There?
If, as was my experience, your first real taste of science fiction was Star Trek, then the concept of alien races is a very familiar one. When I was a kid the show was a must-see. Each week after school I would watch adventures of the Enterprise crew and their encounters with Vulcans, Klingons, Romulans and more.
I know I am not alone in this addiction. For one thing the TV producers would not keep making the shows if the audience did not exist.
Over in the movie world, one of the most successful of all film series - Star Wars - was heavily populated with alien races. In 1979 Ridley Scott made one of the finest sf/horror movies: Alien. The real star of this movie was the eponymous alien creature; the film spawned numerous sequels, books, comics and other products.
This fascination with aliens is not a recent phenomenon, nor has it been confined to the television and motion picture industries. From the early days of science fiction the concept of alien life has been a given. H.G. Wells wrote the first science fiction alien invasion classic, "War of the Worlds" in 1898, opening the floodgates for the efforts of later writers. This mantle was taken up by some of the greats of sf.
Arthur C. Clarke produced one of the great novels of the 20th Century in 1953 – Childhood's End – in which aliens arrive to take control of the Earth. John Wyndham's 1957 novel The Midwich Cuckoos centred upon a small English village taken over by aliens, imposing some difficult choices upon the Human Race. In 1972, Isaac Asimov, although not noted for writing about aliens in his fiction, wrote The Gods Themselves (1972), in which his alien race was split into three distinct sexes. The novel won him both the Hugo and Nebula Awards for best novel. This list could go on.
But science fiction writers cannot lay claim to being the first to dream of alien races on distant worlds. Most early societies believed there were other worlds, although these beliefs were usually religious or supernatural in nature: not so much aliens as demons and gods.
The ancient Greeks were the first to analyse the possibility of life on other worlds, in the 7th Century BC, but the idea was not the prevailing one. The Geocentric Universe (Earth-centred) notion favoured by Aristotle and Ptolemy won the day.
This notion remained the accepted "truth" of the nature of the universe for many centuries, spreading throughout Europe with the Christian Church's expansion. As the Earth-Centric Universe model precluded the existence of other worlds, it would be two thousand years before other worlds once more began to interest mankind, when two events occurred that would shape the entire science of astronomy.
The 16th Century astronomer Nicolaus Copernicus published a revolutionary text called "De revolutionibus orbium coelestium" (On the Revolutions of the Heavenly Spheres). In this he detailed a sun-centred model for the Earth and other planets. Not long after Copernicus, the telescope was invented (credit for the invention is usually attributed to an unknown spectacle manufacturer from Holland).
It was the invention of the telescope that gave the idea of alien life a kick-start. Through the telescope new worlds previously unseen became visible, and some observers began to suspect that there might be systems like ours surrounding other stars. This was not a popular idea though: proposing the idea of other worlds saw some early astronomers condemned as heretics and burned at the stake.
Belief in other worlds supporting life was common. Many leading astronomers and other scientists and thinkers supported the idea of alien life. French astronomer Bernard de Fontenelle wrote a book on the subject in 1686 called "The Plurality of Worlds" in which he expressed the view that all planets would be capable of sustaining life.
William Herschel (the first person since antiquity to discover a planet – Uranus in 1781) believed that the other planets of our solar system, as well as those orbiting other stars, would naturally by inhabited by alien species. "Cosmic Pluralism" was a well-supported idea – gaining followers such as politician Benjamin Franklin and philosopher John Locke.
Herschel's son John, also an astronomer, was to become the victim of a hoax concerning alien life on the Moon in 1835. In August of that year the New York Sun published a series of articles detailing John Herschel's observations from his observatory in South Africa. They alleged that he had seen crystalline hills, active volcanoes, vast forests, a multitude of creatures including bison and unicorns, and the biggest claim of the article: two intelligent species. Herschel was claimed to have announced that he had seen a stone-age equivalent biped-beaver race, living in simple mud-huts and controlling fire, as well as a race of winged humanoids he called the Vespertilio-homo ("man-bat").
This deception would become known as The Great Moon Hoax, and when John Herschel was informed of his part in it, he apparantly took it in reasonable humour.
Belief in extra-terrestrials was still widespread at the start of the modern age, and was famously demonstrated by Orson Welles' radio dramatisation of "War of the Worlds". When it first aired on US radio, mass panic erupted across America. Welles had chosen to dramatise this story in the form of news bulletins announcing the invasion, beginning with the landing of a "huge flaming object" on a farm at Grovers Mill, New Jersey and the destruction of large areas of the United States. As the play progressed, fake bulletins interrupted dance hall tunes giving the latest details of the invasion. It was very well done – too well, you might say – because anyone who had not tuned in at the start of the play would have missed the announcement that what followed was fiction and so could be convinced by the realism.
But it wasn't just the general public that held onto the belief in life on Mars. In the 19th Century an Italian Astronomer, Giovanni Schiaparelli, had drawn maps of the surface of Mars. He drew the surface of Mars containing a network of long straight lines he called "canali".
The Italian word for "canale" means canal, a word that, in English, refers to an artificial construct. Many astronomers, chief amongst them American Percival Lowell, believed these to be irrigation canals, fashioned by Martians to water their crops.
This belief was partly due to translation, and partly due to current events. The Italian word "canale" does mean canal, but it can also means "channel" or "gully" – both natural watercourses. This dual meaning lead to a misunderstanding of Schiaparelli's intent. Also, these observations were being made against the backdrop of major canal building on Earth – the Suez Canal had been completed in 1869 and a first attempt at building the Panama Canal had started in 1880. So astronomers were interpreting their observations in line with their terrestrial experience.
Although this romantic notion of a Martian civilisation had appeal, it did not gain universal support. For one thing, not every person who trained their telescope on Mars saw the supposed canals. E. E. Barnard, discoverer in 1916 of Barnard's Star and recognised as one of the finest observers of his day, saw no such lines. And early in the 20th Century demonstrations were carried out to show that the lines could have been the result of optical illusions, caused by the observations having been made at the very limit of the power of the telescopes being used.
But when the Space Age began there was still a belief in the scientific community that life could be found. Mercury and the moon were quickly shown to be lifeless, but hopes were high for both Mars and Venus when the first space probes were sent.
Throughout the 20th Century there were several theories about what might be discovered when mankind reached Venus. One theory of Venus viewed it as a very Earth-like world, but somewhat behind us in terms of development – similar to the Earth of the Carboniferous Period. Swedish astronomer Svante Arrhenius had been a supporter of this model, but it was quickly shown to not fit the known facts and was discarded by 1940.
Another theory saw Venus as very Earth-like with a rich oxygen atmosphere between the carbon dioxide clouds (which had been detected in the atmosphere of the planet by analysing the spectrum of reflected light). This was also quickly shown to be incorrect – carbon dioxode is denser than oxygen and so would have sunk to the bottom of the atmosphere, rather than remaining in the high altitudes. Another popular theory had Venus as a watery world, with little dry land – its Oceans teeming with life. And the final serious idea was that Venus was a dry, fiercely hot, lifeless rock.
No one, however, had predicted the true conditions that were found when the first of the space probes arrived.
Since the dawn of the Space Age, numerous probes have been sent to Venus and Mars and both planets have proved disappointing in the search for life – although very interesting to scientists in many other ways.
Mars has a very thin atmosphere, no surface water and a highly cratered surface. The dreams of a Martian civilisation ended when the Mariner and Viking missions returned their results. But this is not the end of the chances for life existing on Mars. There could be water trapped under the surface of the Red Planet, and microscopic life may well exist underground, although no incontrovertible evidence for this has yet been found.
Venus is the very embodiment of hell. It is hot: at the surface the temperature exceeds 400°C. The atmosphere is also very dense, ninety times greater than Earth's, and the whole planet is covered in clouds of sulphuric acid.
But these are not the only worlds believed to be capable of supporting life in our solar system. The outer planets themselves, being gas giants, would not be viable home for the kind of life we would recognise, but these planets have moons that are comparable in size to the terrestrial planets. So scientists have turned their gaze towards these worlds.
Two candidates stand out.
Europa, the fourth largest moon of Jupiter, is an ice-covered world. Due to the gravitational forces exerted upon it by Jupiter and the other Jovian moons, it is believed that under the ice is a vast ocean. The presence of liquid water would support the possibility of life on Europa, and it has been suggested that it might be of a similar type to that seen in Earth's oceans surrounding deep-ocean hydrothermal vents.
NASA currently has plans to send a robotic drilling probe to Europa in an attempt to confirm the existence of such an ocean and to analyse its composition.
Saturn's largest moon, Titan, is another possible contender for life. It has the only other nitrogen-rich atmosphere that we know of, consisting of 98.4% Nitrogen, with the remainder being mainly methane with trace amounts of other gases including hydrocarbons. This mix is thought to be similar to that of the early Earth. Since Titan is much further out from the Sun and considerably colder than Earth, it is unlikely that there would have been sufficient energy to cause the necessary chemical reactions for life to begin.
Then there are worlds outside our solar system. We know of the existence of over two hundred Extrasolar Planets, so the formation of solar systems looks common. But what can we do to determine whether there is life out there?
The only chance we would have at our current level of development would be the detection of other civilisations. If there are worlds out there supporting early stages of life, then we have no way of knowing. There would be only two ways we could determine whether another star shines down on a life-bearing planet.
The first of these is the staple of science fiction: the alien race that comes calling; the old "We come in peace" line – or at least we hope it would be peace. The second, and more realistic, is by detecting their transmissions.
Since the 1930s the Earth has been a beacon in space. We have been broadcasting radio and TV programmes, plus other forms of communication into space. If races on other planets have developed civilisation then it is likely that they too would have begun broadcasting. So we need to train our radio telescopes on the sky and search for signals.
The first attempts at discovering life by such means occurred in the 1920s. In 1922 and 1924 all radio stations in the USA were silent for a period, so that their signals would not interfere with any originating from Mars. None were detected.
It was 1960 before the search started in earnest: astronomer Frank Drake, based at Cornell University in the USA, used a 25 metre radio telescope to examine the stars Tau Ceti and Epsilon Eridani. So far, in four and a half decades of searching, we have no proof of alien life. The only signal we have ever apparently received from the skies was detected on August 15th 1977. On that day Jerry Ehman, a volunteer on the SETI project at Ohio State University, observed a very strong signal. His reaction was to draw a circle around the trace and write "Wow!" in the margin. Because of his actions, this has since been known as The "Wow!" Signal.
Although this is the leading candidate for proving the existing of extra-terrestrial life it has never been detected again, even when examining that same region of space. And so, as far as we know, we are still alone. But given the number of stars out there, this surely isn't true!
I. E. Lester continues his exploration of alien life, looking at the possible forms "life" might take on other worlds, and asking the question: does life on other planets have to be anything like life on Earth?
Story Copyright © 2007 by I. E. Lester. All rights reserved.
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About the author
I.E. Lester is a lifelong fan of science fiction, having acquired the bug whilst on a washed-out family holiday as a child when, sheltering from the rain in a seafront kiosk store, the cover on a collection of Isaac Asimov short stories attracted a nine year old eye.
Having worked through all the fiction of Asimov (as well as Heinlein, Clarke, Moorcock, and many others) he moved onto Asimov's non-fiction, encouraging a love of science.
He studied Mathematics and Astrophysics whilst at University and works as a software designer. When not reading sf or factual science, he can often be found watching cricket or rugby, or wandering medieval streets in France or Italy.
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