To wonder what extra-terrestrial beings look like is presupposing their existence. But as some say – Absence of evidence is not evidence of absence. Besides, it is hard to fight for or against an abstract idea, much easier if we confine it to a form.
Believers in alien life range from fanatics to serious thinkers. It is an idea that has deep roots and is a recognizable concept by many across the globe. And it has huge opposition too.
Ancient beliefs and popular culture
The belief that creatures exist elsewhere in the universe has been a common theme in our history. ‘People who lived in the stars’ or divine beings with exaggerated humanoid features appeared sometimes in myths and legends. With enhanced intelligence and special powers, these were the aliens of bygone eras. While some stories told of godly, kind creatures, others talked of ferocious beasts that landed from the skies. Some even claim that the archaic ideas of gods have roots in alien appearances! But it is more likely that ancient man realized the vastness of the star-decked sky above him and dreamt up people living in stars, moon and comets to dispel his loneliness and pictured them as his reflection.
About a century and half ago, there came a new wave of literature: science fiction. It was between the pages of these creations that extra-terrestrial beings were deemed to be bizarre odd-looking creatures, significantly different from us.
The hysteria of alien sightings since in the last century has lead to another popular image of aliens: a little grey ‘man’ with huge eyes, large head and small stature. Though branded as urban legends, this image is the most popular amongst supposed escaped alien hostages.
Today science is empowering us to venture further into space, and with each new space odyssey, with each new communicating device invention, we are coming a step closer to reaching out and maybe finding some life-form in the vast universe around us, if it exists. So can science prepare us enough to recognize them if we do?
Will life elsewhere mimic Earth’s Carbon based life?
Astrobiology is not just a quest for life beyond Earth – it is a branch of science looking at life’s origins on Earth too – and the possible routes it may take in future. It is essential to know how life on our planet came about, to guess how it may have come about elsewhere in the universe. One of the major assumptions here is that life there too is carbon-based.
This drives scientists to look for planets that have water, Earth-like atmosphere and such because carbon-based life was possible due to these characteristics. Also this narrows down the search to star systems where the stars are neither too large nor small. This is because larger stars are likely to die soon and origin of life which seems to be a complicated process of trial and errors takes a longer time than that. Smaller stars on the other hand may be counter-productive to our idea of life which thrives and exists because of the optimum heat of the sun.
Maybe these assumptions are wrong – what if life is not carbon-based everywhere? Is this line of thought flawed? Perhaps, but without this assumption, we don’t have much to go forward with. Moreover carbon based life has many merits which sparks a hope that these merits worked wonders in other places too.
An organism has so much to do – eat, grow, replicate. Maybe move around too. So, even the simplest of organisms is, in a way, a complex system of molecules. For such complexity to be stable, you need a good backbone – like carbon.
This backbone also needs to be a little flexible to allow rearrangements and variability. Carbon can perform all of this without much trouble. Remember that the bonds that an atom form depend on the number of electrons in its outermost shell. An atom tries to reach the stable number of 8. Carbon has four electrons can thus form 4 bonds to reach stability. Now imagine that one of these is a bond with another carbon, which too can bind to any 4 atoms. This can lead to a chain of carbon atoms, bonded to each other and a host of other elements. So Carbon has been the atom of choice for Earthly beings.
Since carbon-based life everywhere is assumed to need similar conditions as Earth, we can imagine that the evolutionary routes may be similar. Similar, not same. And applying our planetary observations, we hazard a guess that a denser environment would lead to horizontal life-forms while a planet with sparse environment will prompt vertical life-forms. Even plant-like forms – if they exist –can use say read band of light and may paint their planet red the way our declining forests are green!
Our entertainment industry has given us a wide range of space neighbors – differently colored, with exotic appendages. But most of these tend to have a semblance of two eyes, four limbs (or more) and are generally bilaterally similar, like us.
Isn’t it a little too bigoted to imagine them like this? Even if life is carbon-based, our height, our location, our limb structure has as much to do with the gravity on our planet and the earth’s terrain. Even if life originated on a planet X due to its similarity to Earth, it won’t be the same as our unique blue planet. Also even ‘life on Earth’ isn’t just us humans – there is a mind-boggling variety here. Maybe other planets have rich bio-diversity too?
And so it is safe to assume that life if it exists will be exotic, to the very least. Remember, this planet may also be at an earlier or advanced stage of life as compared to Earth – and so life may be too primitive to respond to our searches or too advanced for us to recognize.
Non carbon based life – a possibility?
Most of our assumptions about life beyond our planet tend to focus on the availability of water, and carbon. That’s understandable – there’s an abundance of carbon based life on Earth – it’s difficult for us to comprehend life, with all its consciousness, depending on any other element. While we keep emphasizing on our carbon-based existence, we need to remember that we (as all other life on Earth) are in fact made up of several elements. It is carbon’s presence in the DNA of all life forms that gives us the carbon-based life moniker. In some academic circles, it is believed that our assumption that life will be carbon-based everywhere, and the consequential searches we perform for similar hospitable environments, is flawed. We call it carbon-chauvinism.
Remember that the way our elements behave and come together to form bonds is because of the conditions that our world presents – the unique pressure, temperature and all the other factors together allow for the existence of our elements in the way they do today. It is likely that elements other than carbon may be the front runners elsewhere. The ability to bond to several other elements simultaneously still seems good and so the best element like carbon in this regard – solicon – is the most famous Carbon replacement in science fiction. Remember Horta of Janus VI planet in Star Trek?
Germanium and Lead fall in this category too, but due to their large sizes, such bonds are too unstable. But there are a horde of other elements to consider. In fact, our own fellow organisms living in conditions so extreme that they seem unworldly, are known to employ lethal substance like arsenic in their metabolic processes. It is then not hard to imagine that elements like phosphorus with its chain forming ability can too be a recipe for life when the existing conditions are dissimilar.
In such scenarios, the idea of water as solvent can take a toss too. Water’s got some unique properties placing it at the centre of life on Earth – it is both an an electron donor and accepter, has lower density in its solid form, allowing aquatic life to flourish even in cold conditions. It is also a damn good solvent – making it the elixir of carbon-based life as we know it, so much so that major space explorations focus on its discovery in other celestial places. But if life were to be based on other elements and other conditions, solvents like ammonia or harsh chemicals like Hydrogen Fluoride may work out too.These elements and solvents are not without problems. But the main argument in their favor is that their chemistry as we understand it is based on our planetary conditions. Of course, we have to start somewhere!
Revisiting the definition of life
Consider this – dust particles when suspended in plasma show a unique behavior! Not only do they organize themselves into helical structures that can replicate themselves; these structures can interact with one another to form a more stable structure. These are in fact the properties that we assign to the living! This phenomenon was demonstrated by Vadim Tsytovich and his colleagues nearly a decade ago. Will this force us to reconsider the definition of life?
Machines, AI and Aliens:
While search for alien life goes on, back home too life is taking on a new meaning. With one step in genetic engineering to enhance our bodies and another in increased mechanic reliability, we are looking at amazing future human evolution scenarios.
Related: What’s next in human evolution?
Even other organisms being sucked into the industry that is genetic manipulation. Such prospects can help widen our imagination – such advancements may have occurred in other pockets of universe too! Maybe they are at a stage of existence which is unrecognizable to us!
The rate at which life originated and then evolved into its current state of being is rather fast when compared to cosmic time scales. But consider the speed of evolution at which technology and machines made by us have evolved. Moore’s law is almost like Planck time in the scale of cosmic things – doubling our technology’s capabilities every 18 months. When we do get to the point of creating an artificial superintelligence, it may leapfrog billions of years of evolution in a matter of hours. Life on Earth may soon be partially, or completely robotic.
With no empirical data to show otherwise, we may assume that if life exists somewhere it may follow similar paths. Then it is not too far-reaching to assume that machines may be out there too or may develop by the time or if we make that coveted contact.
So what should we believe in organic life forms similar to us? Or microscopic life flourishing in strange conditions? Or digitized structures? Or assemblies of elements yet unknown to us and hence undetectable? Or superior humanoid beings busy fighting their own battles (at least that is what Marvel and DC have us believe)? Or is Earthly life a unique quirk in the endless universe with no parallel, alone and marvelous?
Science’s leaps into future and glances at our origin may present us with answer if it is there, the least we can do is prepare for the day it does. Food for thought: if proven that life exists outside the confines of Earth and resembles us; we may have a chance to survive even if our horrible devastation of the beautiful blue planet is irreversible.
Disclaimer: Though this article is filled with pictures, a reminder is in order: all of these images are limited to our current understanding and cinema-based aesthetic value. As cited again and again, alien life can mean anything from microscopic beings to giant machines and a lot of other things that may be beyond our comprehension