It is fanciful to think that many such life forms like those on Earth exist in the Universe and those have given rise to the myriads of stories about aliens to us.
Earth was once considered to be the center of the Universe with humans being the epitome of perfection but are we really that? When we do not know the facts, we tend to generalize things and try to bring them into our own thought to make things easy for us to understand. But those principles that we hold sacred may not hold for other forms of life. We tend to straight jacket life into a particular familiar pattern.
We initially assumed that earth was the center of the Universe which is today exploded to bits by newer findings over the millennia. Today we know that earth is but a tiny speck of dust moving in space, utterly insignificant in the Universes’ scheme of things.
That is why in our way of thinking and definitions we search for life, and thus far our search has not yielded anything that can be remotely considered as life as we define it anywhere else than on the earth.
Earth teems with life whether it is in the steaming pools coming in from the earth by way of sulfur springs or even in the frozen wastes of Antarctica. Life started fairly recently as per Geological time scale, yet it abounds everywhere on earth.
But the in the past, earth has been radically different from the climate and atmosphere on the earth we have today. Initially it had been a lava covered rock with a poisonous atmosphere, a world of oceans with bare microbial life, later a steaming tropical planet with huge dinosaurs and finally came the cave dwelling humans. It passed through many stages and life as we know slowly evolved.
Now, technically life cannot be an accident that occurred only on earth. It should have also occurred elsewhere but mankind searches for life that is akin to it as per its definition. Movies portray aliens like lizards with horrendous looking features looking exactly akin to our physical structure with a head, a torso, hands and feet.
Is it necessary for life to resemble the way we look? It may look like a sphere, or a cylinder or a block which uses other ways to move than hands and legs. Its physiology may be utterly different from us and its internal organs need not resemble ours in any way.
When we search for life, we essentially search for life as we know on earth in an anthropomorphic way. Perhaps that is why we are failing to spot life elsewhere. The way other forms of life perceive and communicate may be totally different from ours.
We use radio waves for communication, so we send out radio waves into the Galaxy hoping that if there is life elsewhere they would be spotted by them. What if they do not use radio waves for communication and use some other principles that is unknown to us (say Z waves)? What if they find the principle being used by them is the most appropriate for long distance communication and radio waves are not perceived by them at all. Hence, just like us, they would be looking only in the Z waves for interstellar transmission and not through Radio waves. Similarly another civilization on another planet may be using a third principle which is unknown to both us as well as the 2nd civilization mentioned above. Organisms in different planets because of their evolution may perceive things differently from us and their organs register something else which we cannot. They in turn may not be able to perceive what we do.
This may well be the reason we are not finding another civilization. We look for life forms and perception resembling our own, with also the same mistake being committed by them. That is why we cannot find each other.
It is both improbable and impossible to assume that we are alone in this Universe. Therefore the only logical explanation is difference of methods and perception that is foxing us all. Now is this barrier of perception insurmountable? As of today that appears to be so. Our planet is only about 450 crore years old and there would be planets as old as 1000 crore years (Big Bang about 1400 crore years ago). In the evolutionary ladder civilization on such planets should be crores of years ahead of us, yet no contact yet, so is it that the communication barrier is insurmountable?
