"Sometimes I think we're alone in the universe, and sometimes I think we're not. In either case the idea is quite staggering".
Arthur C. Clarke
The above quote is really quite profound. Indeed it is not only Mr Clarke that has wondered such a thing. Most people through history, philosophers and scientists alike, normally just phrase the question that lies at the heart of the statement: Are we alone?
I recently attended a Science and Technology Facilities Council Summer School in Astrobiology and it was this basic premise which drove the entire week. Before I continue it would be best to describe exactly what the topic of Astrobiology is.
Astrobiology is a subject which has arisen to enclose the diverse range of investigations within science that have relevance to discovering life beyond the planet Earth. That said it concentrates a great deal with life on Earth so that we can first understand how it arose here and therefore have a better understanding of the conditions required on alien worlds for life to begin eleswhere. It is therefore a multidisciplinary subject which requires excellent communication between separate specialists to acquire a coherent picture of the possibility of finding life beyond our own planet.
As we looked into what we currently understand had to be ‘just right’ for life to arise here it became more and more bewildering. The Earth itself had to have the correct ingredients within its infancy; the Sun had to be a decent brightness with a good lifetime; the Earth had to be the correct distance from the Sun and the solar system even had to inhabit the correct region of the Galaxy. Looking at the Earth itself we see it was pelted with rock for much of its lifetime depositing further materials which would later become important, geological processes took root shaping the landscape, then changing it again and again. From here we could proceed to the complexity of the chemistry that had to occur for the simplest carbon molecules to form which would later become the raw building blocks of life. Even this does not bring us to life as the mechanism of how these disparate entities combined to form a biological construct that could not only gather its own energy but also reproduce itself is still beyond us. It would be easy to dismiss this incomprehensible story as mere witchcraft, never happen again blind luck - to ultimately conclude that lightning could not possibly strike twice in the same universe and say all the species on Earth are truly alone in Space.
We however, currently live in an extremely exciting time in terms of the scientific study for life beyond the Earth. Investigations into planetary science within the Solar System are turning up evidence that liquid water (an important requirement for life upon the Earth) may have existed upon Mars and still exists upon the icy moons of the gas giants. Research into the detection of planets beyond our star system (see the blog of 14/08/07) has already identified over 200 worlds orbiting alien stars with the belief that the discovery of an Earth like planet orbiting a Sun like star is just around the corner (best bet is to check the COROT space telescope pages). Biologists have also discovered wonderfully hardy life forms existing in the harshest conditions we know of on our own planet allowing the speculation that extraterrestrial life could exist in more extreme environments than previously considered while chemists are also playing a major role in unravelling the multifaceted pathways of how simple chemical compounds go on to form life. It is worth remembering what we find conceptually exhausting to comprehend nature may carry out without too much bother.
Unfortunately all areas of the investigation are ongoing so true quantitative evidence of what is required for life elsewhere is incomplete. This leaves the door wide open for some truly wild speculation of life in the Universe, which is good in its own way. As one person has previously said: It is best to be totally liberal in formulating a hypothesis and completely conservative when testing it.
The outcome of the summer school was a much more complete understanding of the situation concerning the requirements for life, the current advances within each field and a true sense of excitement as we appreciated what truly is a fascinating region of ongoing work.