It is indeed true that the search for extraterrestrial life is focused on trying to find life like Earth. Because only those planets that are about as big and heavy as our Earth, and have about the same temperatures, are “habitable”. These are planets with liquid water.
How do we search for life?
One of the methods by which scientists are trying to detect traces of extraterrestrial life is to search for oxygen in the atmosphere of such planets. This oxygen is produced here on Earth by living beings.
You can also look for methane. This gas is also produced in large quantities by terrestrial organisms. In the spectrum of the reflected light of the planet, one can find signs of plant photosynthesis. And so researchers are looking for these “signals” in the atmospheres of distant exoplanets.
But isn’t such an approach an indication of the extreme naivety of astronomers? Or even nonsense? Are we really that arrogant and believe that life everywhere in the universe should look exactly like it does on Earth?
Of course not. Scientists are well aware that life in principle can look completely different. And it is quite interesting, in fact, to imagine life forms living, for example, in the gaseous shell of giant planets.
Or in the atmosphere of a star. Or talk about life that does not require water and carbon. And instead, it is based on silicon. Or imagine that somewhere there is life, consisting only of energy. And existing inside black holes. And so on.
It’s not that astronomers have no imagination. Through their experience, they could probably imagine even more alien lifeforms than the average person. But this is not the main thing. This is a serious, scientific search for this life.
We need to do more than just imagine what life might be like elsewhere. But you also need to find ways to discover this life, if it exists somewhere. But for this we need to know exactly how this life works, how it interacts with the environment and how it affects it. And what effect it can have on the parameters we observe.
At the moment, we know quite well only one kind of life: life on Earth. We understand this type of life well enough to know how it will manifest itself on other planets so that we can find it where it is.
It is useless to imagine any “other” life if we do not know how to find it. We can look for something only if we are sure that, having found it, it will be possible to draw an unambiguous conclusion – the goal has been achieved!
Therefore, it is unfair to demand that astronomers look for “other” life, and not just terrestrial life forms. The fact that researchers do not do this has nothing to do with a lack of imagination.
It would just be pointless. Because we can’t find such “alien” life forms anyway.
And by the way, we are not talking about intelligent beings. The search for intelligent life is a different story. This can happen at any moment. For example, if suddenly an alien spaceship lands on the lawn in front of your house.
The search for intelligent aliens is not anti-scientific (actually, there are many relevant and serious projects on this topic).
However, it is absolutely hopeless. Because while we do not have enough knowledge about life itself. And about how often it can occur in the Universe. And how likely the existence of intelligent life is generally pure speculation.
If we look at the only database we have, ourselves, things look pretty bad. Life has existed on Earth for about 3.5 billion years, and for most of that time it did just fine without intelligence. It only appeared in the last few hundred thousand years. And, very likely, will disappear again in a few hundred thousand years.
Of course, researchers still speculate about the “other” life. This idea is even devoted to a whole science – astrobiology.
Astrobiology explores alternative conceptions of life. And how life can function in a variety of conditions. But so far there is no reliable evidence of the existence of any life that did not originate on Earth. And no one knows how these kinds of life work.
And we just don’t know what to look for at all.