I was watching a meteor shower at quarter to midnight the other night. It's been a while since I've seen shooting stars but even last night's modest display was quite something. I'm always amazed at how many people have never even seen one solitary silver streak - let alone a true meteor storm and to be honest its been too long since I stood under a star lit sky. It set me thinking.
There are conditions required for life. I am not talking about there being sufficient oxygen or water in the atmosphere for life to begin for then only life with which we are familiar is considered. The complexity necessary for life is only found in certain conditions (energetically speaking). Too hot and molecules do not sustain sufficient complexity as chemical arrangements are constantly broken down by the energy present in the surrounding environment, therefore the complexity of life can never emerge. Too cold and reactions are too slow for this complexity to come about, the energy for sustained chemical reaction being unavailable even if considered over billions of years. In the middle of these two extremes is a wide band of conditions where time and energy can combine to provide the complexity and chemical evolution necessary for life. Perhaps there are cold planets where living things reflect their ancestry in their slow, if even perceptible movements. Other environments may exist that have allowed life to emerge where energy is plentiful in the close orbits around stars; where forms may come and go fleetingly (compared to ours), their perpetuation ensured by a rapid and efficient reproductive cycle. Other chemical mixtures may provide other chemical evolutionary trees different from the carbon based chemistry found on Earth, where silicon or some such material has provided the structure for alien life. It may be removed from life on Earth but in the vastness of the universe it seems likely that life has arisen. It is even probable that the place is teeming. We should appreciate that the universe is without boundaries and even in our local organisation of stars the numbers are so great that they lie on the outer reaches of our imaginations. It has been put forward by Professor Fred Hoyle that life may have evolved in outer-space in comets as they undergo cycles of warming and freezing in their stellar orbits but let us consider planets a likely starting place. Until the mid 1990s no planets had been detected outside of our local system and there were those who believed that planets were scarce. With refinements in our technology, the first was detected by its influence on its host star and this has opened the flood gates for such discoveries that are now relatively common. Although we now have evidence, those who previously thought that planets were scarce in the universe have been shown to be comprehensively wrong, which comes as no surprise to many. I would suggest the same will hold true for life.
There has been a noticeable change in attitude in the popular scientific press towards the possibility of extraterrestrial life. Quite what has been responsible for such a major shift is not easy to define but exobiology is not a field that is discussed in whispers anymore. We now know that there are micro-organisms that do not rely on energy from the sun to survive but we have known this for some time. These unusual creatures are found near thermal vents on the ocean floor or in thermal pools in cave systems and recently whole ecosystems containing many unique species have been discovered in subterranean systems in several locations on our planet. It is possible that isolated subterranean pools subjected to the warmth of volcanic energy could provide the potential for life on planets and satellites even beyond the range of the warmth from their own suns. Recently is has been proposed that moons themselves could sustain life for in our own solar system. Jupiter's moon, Europa, has caught the imagination of the scientific community resulting in open speculation on the possibility of life within an ocean beneath its icy covering, warmed by volcanic activity. The scope for life has, it seems, widened considerably in our eyes even though in the real world it has always been the same. It is our perspective that has changed, for we have let our bias of old, concerning our central and unique role in existence, slip away to be replaced by a more rational, logical view of the universe. It would not be surprising if our perspective were to change even more.
Now we are no longer embarrassed to consider life elsewhere in the cosmos can we consider contact with aliens? One of the points to consider in assessing the likelihood of encountering beings from another planet is how long a civilisation needs to exist before it is capable of communicating across the reaches of space. Homo sapiens has been around for a little while but only in the last one hundred years have we achieved this level of technology. How long we will be around for is another question that is open to debate for we have had the capability of destroying our planet for only a short period of time. Will we live together and manage the planet's resources effectively or will our civilisation fall, bought down by our inability to work as one, divided by greed and misunderstanding? Pessimists would argue that if we are typical of advanced life forms then the period of existence when advanced species have the ability to send signals across space to other civilisations, will be very short. If they are right then the universe could indeed be teeming with life as one civilisation after another burns brightly for a moment before surrendering its ability to contact life on other planets through their own poor evolutionary performance. The result would be their isolation, missing the overlap with the time of another ascending civilisation and thus the opportunity for contact with truly alien life forms.
We have been monitoring the skies for evidence of alien civilisation for some years. Clearly space is not filled with the detectable emissions from alien technology for we would have stumbled across them by now. More likely, if detectable civilisations exist, then contact will come via a weak signal from one particular direction in the sky and this act of detection may come with improvements in our receiving technology. It may simply be that we are isolated by distance even though on a cosmological scale life is indeed common in the universe. At the present time it may not be here in our own neighbourhood but it may well have been . Running water may once have been common place on Mars as the river beds, flood plains and delta-like features suggest and where there is (was) water then the probability of life must increase. It is possible as some sort of cosmological irony that it may arise somewhere close to our planet after all trace of human civilisation has gone for we may be isolated in time. We have no way of knowing but it seems that in time and in space we are probably not alone.
Could these civilisations reach us? What are the possibilities with respect to travelling across the vast distances of space. There are several options open to potential space travellers:
1. Create a method of propulsion that can enable interstellar travel within the lifetime of an organism.
2. Create a craft that can travel interstellar distances and place the pilots in stasis during the excessive time periods incurred in sub-light speed travel.
3. Create self sustaining colonies to man interstellar craft such that although one generation may not complete the journey, their space-borne progeny would finish the odyssey.
Before the invention of aeroplanes it was considered by many that flight was impossible. We may be in a similar situation today with respect to manned deep space travel but until it is achieved we cannot know if this is possible (catch 22!). We do know that time travel is theoretically possible and we may perhaps harness this in the future but only time will tell. Such speculation may irritate some parties and so we should take a more conservative approach to predicting our future. Already we have the potential for self supporting colonies and the technology for interstellar travel at sub-light speeds and so point number three is almost a reality.
What of point two? Bacteria are hardy organisms. When the going gets tough some species are able to form structures known as spores that are long lived and highly resistant in unfavourable conditions. Even in recent times scientists have locked away these spores and revived them after periods of tens of years (in 1956 scientists revived spores that had been entombed by Luis Pasteur some 70 years previously). Reports detailed in the scientific press tell of the revival of micro-organisms from more ancient sources. Roger Levesque of the Laval University, Quebec, drilled a 130 metre long ice core from Ellesmere island in the Canadian Arctic that had been preserved at a temperature of approximately -20C. By sterilising the outside of the core and then melting the inner ice in sterile conditions, he was able to revive bacteria from up to 7,000 years ago. Upon analysis of their DNA they were found to be related to, but significantly different from, bacteria living today providing further support for his claims. Researchers at the California State Polytechnic University, San Luis Obispo (U.S.A.), have gone one step further. In isolating a stingless bee from fossilised amber resin dating back at least 25 million years, they claim to have produced bacterial cultures from the contents of its stomach. These claims are again supported by the DNA sequence characteristics and we must face the possibility that some living organisms at least are able to survive in a dormant state for extremely long periods of time.
Do these reports sound ridiculous? It is perhaps one thing to have revived microorganisms but to consider that larger creatures can survive in a state of suspended animation is surely entering the realms of folklore and the supernatural. James Clegg at the University of California has discovered that brine shrimps, when in unfavorable conditions, are able to form cysts that even when kept at room temperature are able to be revived after a number of years. During this period of dormancy there is no detectable metabolism. Energy is not used in this dormant state, which has led to scientists asking whether we need to re-examine our present definition of life. The use of energy has, until now, been deemed to be one of the fundamental properties of living things in order that they can maintain their structure, but the brine shrimps have shown us that we should not presume such things and that it is possible for some organisms to temporarily (over a period of years) suspend what we understand as the property of life. The slowing of human metabolic rates is certainly not in the realms of science fiction although it is true to say the technology required may be some way off but it is a real possibility. Whether the technology is available to alien beings or their physiology is more amenable to such manipulation is pure speculation, nevertheless the prospect is there.
When considering the three options available for interstellar travel our relatively young race is almost at the point of having the technology to embark on such adventures. Will the scientists of the 22nd century find the key to deep space travel in the seed of 20th century science or will we remain planet bound, confined by our minds and our technology? So, if we reject the UFO phenomenon, interpreted as evidence of alien visitation, on the basis of the impossibility of interstellar travel then we are flying in the face of reality. This is perhaps a shock for some.
In short, I have no problem with the belief that there is life elsewhere in the universe. It would not be surprising if the alien equivalent of an Earthly bacterial spore had arrived and survived on planet Earth sometime in our history. I find it feasible that life may have evolved on other worlds to such a stage where the dominant species is capable of interstellar travel using technologies far in advance of our own. Although it may feel uncomfortable, but pursuing the same line of logical thought, it is not beyond the realms of possibility that such species have visited (or will visit) our planet. As for the reports of saucers and aliens.. that's perhaps a different conversation.
The author has worked in academia and the biotech industry for over 20 years. He is a contributor to Natural Insight writing articles on our natural history and the human condition.
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