The book ‘Aliens’ is a perfect page turner. Jim-Al Khalili is the editor of this book comprising of a series of essays on the search for extra-terrestrial intelligence by a distinguished group of astronomers, astrobiologists, geneticists, quantum physicists and so on. It takes a view about the present status on the search for aliens. The wonderful book with short and brilliant essays truly captivates the reader.
SETI is a generic acronym meaning ‘Search for Extra-terrestrial Intelligence’. The search started with radio astronomy. It has now expanded to a variety of mind-boggling technologies and space based telescopes for direct viewing of distant planets. Are we alone in this huge universe comprising of a 100 billion galaxies, each again made of at least a 100 billion stars; or are we not? Carl Sagan says that both the thoughts are mind-boggling. If we are the only one in the universe, there is all the more need to truly understand our responsibility in preserving Earth. If we are not, the hope of contact with distant civilizations is exceedingly small and may not be of any real benefit to us. The speed of light is a limiting factor for any reasonable communication strategy.
The major problem which the astrobiologists face is the definition of life. What does it truly mean to be ‘live’? This question has many scientists, philosophers, and religious masters scratching their heads, but the answer is elusive. Plenty of descriptions tell what life does, but what is actually life-well, that is certainly tricky. How does abiogenesis occur, which is the transformation of chemistry into biology? The life forms on earth is composed of some simple chemicals which are also the most ubiquitous in the universe- carbon, oxygen, hydrogen, and nitrogen. The other key elements like sodium, chlorine, calcium, phosphorus, and sulphur form about 1-2% of all the atoms in the cell. We are carbon based and the universal solvent is water. Life finally is driving forward of matter, energy, and information based on evolutionary principles. Again this is defining life with regards to its properties. The evolution based definition of life has put humans at some sort of an important branch of the evolutionary tree where we are endowed with consciousness, and the ability to wonder about our place in the cosmic scheme of things.
Many of the searches for an alien intelligence is now focussed on finding exoplanets in distant stars. Exoplanets are Earth like planets orbiting around a star like our Sun at just the right distance which may allow water to be held. The famous Drake equation predicted how many intelligent species might be out there in our huge galaxy. The most conservative estimate gives rise to a mind boggling number but few writers point out that this may not be the case. The evolutionary accidents which led to the merging of mitochondrial DNA into another bacterium is a huge event which kick started our life on Earth which is almost based on a single unique plan. There have been no alternate mechanism of life discovered as yet. Following this, the conversion to eukaryotes, that is a cell with a nucleus and then multicellularity for cooperative growth give rise to probabilistic numbers which truly approach zero. And then accounting for intelligent awareness forming civilizations may actually mean that this may never occur anywhere else. In fact, the writers surmise that if the entire evolution was replayed, we would not have been there. Added to evolution, certain lucky events like elimination of dinosaurs due to a huge asteroid impact played a key role in the bursting forth of humans in the scheme of living beings populating the Earth. If the asteroid had not hit earth some sixty million years ago, the dinosaurs would be still roaming around with no science, arts, religion, languages, clashes, and wars. The extremely rare possibility of the life as we know arising has led to speculations that life may not have gone beyond simple bacteria in many planets. In which case, it may be futile to communicate with them.
Humans are arrogant and they do not want to communicate with other species on earth to any extent. Similarly, an alien species intelligent enough to reach a point where it can send signals into space or even visit us may simply be not interested in communicating with a lowly human species. Maybe, we need to evolve further to be truly start a communication channel and speak for earth as a whole. We are too self-centered in our approach to other species and even alien definitions.
There are delightful chapters on the depiction of aliens in our science fiction and movies; and how they have been horribly wrong, barring a few exceptions. The fact is, we have no clue about the composition of alien life and our imagination and creativity have been mostly anthropocentric in their depiction. Many of the aliens are humanoid or like the animals we are exposed to! Some of them resemble dogs with human features. Aliens have been depicted as ugly, sweet, friendly, monstrous, greedy, helpful, useful, and dangerous; and it is a measure of human creativity on the various hues they have taken. All the depictions may be wrong. Aliens may have no interest in us or the Earth. They may not want minerals from Earth and they may not want to suck human blood to survive. Any species from a far off galaxy capable of reaching Earth may be far too advanced to really care about such things. Their technological powers may be awesome beyond our imagination. Yet, we keep persisting with some well exploited picture of an alien race.
In our solar system, the moons of Jupiter and Saturn hold promise for life as they are endowed with water bodies. The ‘extremophiles’- a group of bacteria surviving under the most extreme conditions of temperature, pressure and chemicals may be abound on these moons. If the moons are also counted in holding potential life, the prospect for finding life increases many fold. Hence, our search may be very limited when we are looking only at Earth type planets. Another confounding factor is, a hugely intelligent civilization may have gone beyond the confines of its own planet or moon and may have moved closer to very high energy sources like huge stars or even black holes. In which case, we are looking for intelligent species at a completely wrong place. Radio astronomy may not be successful here as radio is used for a limited time in the history of scientific advancement, as can be seen from our own planet.
The problem with astrobiology and the search for aliens is we have only one working model of life and to extrapolate it to the rest of the universe is a difficult deed indeed. And the pathetic thing is, we do not know anything about our life too.
Life formed quickly after the formation of Earth. Initially, there was no oxygen. It was in fact a poisonous gas. The evolution of plant life and chlorophyll based respiration lead to a huge outburst of oxygen which killed off most life except a few sturdy ones using oxygen for metabolism. Mitochondrial DNA is presumed to be a bacteria utilising oxygen which got incorporated into another bacteria. This symbiotic cell is the precursor of the entire life on Earth as we know. It is the LUCA (Last Unidentified Common Ancestor). Oxygen and ozone are produced by living organisms and their presence in the atmosphere is a biosignature for the presence of life. Alien detecting technology also consists of looking for such biosignatures. Unfortunately, we do not know whether all life is composed of the same elements and uses the same material to reproduce and evolve. Working with a sample size of 1 is truly a difficult proposition.
The last chapter raises the final possibility that intelligent life may be completely artificial. Chemistry becoming biology and then back to chemistry utilising physics all the time. Interestingly, quantum physics are invoked now to explain photosynthesis and energy production in the eukaryotic cell. Artificial Intelligence is something which is expected to happen in a few centuries from now. Self-replicating machines made of the strongest material with a complete endowment of intelligence and awareness will perhaps make life immortal and indestructible. This is serious science and not in the realms of science fiction. The prediction is in a few centuries from now. The thought is that an advanced civilization might have already achieved this state and they may have permanently moved out of the planet of their origin. Their place may be in colonies very close to high energy sources like the huge stars and black holes. They may have even bent the rules of physics. Hence, the suggestion comes that we might want to probe events in space which do not seem to obey the laws of physics. A new signature for alien intelligence may be breaking the rules of physics.
Anyway, humans still haven’t evolved to the extent of dealing with Earth as a whole. We are too selfish, arrogant, and have a huge propensity to shoot first and ask later. We cannot even live at peace with our own neighbours and fellow human beings of a different colour, race, religion, or creed. Our equation with other species on Earth is purely of exploitation and their extinction in our thirst for survival.
Anyway, the search for aliens has led to some profound questions about our own life, its roots and its purpose. It has led to some great scientific advancements too. We don’t know what life is; we don’t know what constitutes alien intelligence; we don’t know what they are capable of; we don’t know where to look for them; we don’t know what to look out for; we don’t know why we need to look out for them. Yet the human mind doesn’t stop. We have to fill our life with some purpose. Alien searching may or may not be worth it.The jury is still out on this. This book is a must read for every lover of science and humanity.
RANDOM MUSINGS 