Until now, we ourselves are the only example of the existence of intelligent life in the Universe. We have already launched a bunch of different probes, sent many powerful telescopes into the deepest depths of space - but all to no avail. And what if the main problem is not that we may not be looking there, but when we do it.
The upcoming article in the scientific journal Cosmology and Astroparticle considers an option in which life as we know it may not need stars like our Sun. And instead, it can appear on planets orbiting much more compact and dim stars. If we think for a minute about the fact that life can really exist around such stars, it turns out that the universe can become much more habitable than it is now.
"We used to think that humans are the most common form of life, simply because that's the only thing we know right now," says lead study and article author Avi Loeb of Harvard University.
"Therefore, among people there was an opinion that life could only appear around stars similar in characteristics to our Sun."
But there are many other stars in the universe. Much smaller than the Sun, much dimmer than the Sun, but much more common and equally suitable candidates. They are often referred to as the low-mass class of stars.
Although they produce less light and heat than our Sun, they still have characteristics that allow them to create potentially habitable zones around them, where the ones inside the planet would be able to maintain liquid water. Such stars not only more often than others (than the class of stars to which our Sun belongs, for example) are found in the Universe, but also have a longer life cycle, which is more than 1000 times longer than the life cycle of our star.
Using this information, Loeb calculated that the emergence of life around one of these low-mass stars in the distant future would have a better chance than the emergence of life in our time on a planet like Earth, orbiting a sun-like star.
"If we assume that life should have appeared near a low-mass star, the same as on Earth, then the chances of the actual appearance and development of life in 10 trillion years, and, more importantly, the detection of this life will be a thousand times greater than now.", says Loeb.
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Proxima Centauri is a low-mass star just 4 light years from us
But what if we do not live in these trillions of years? We are here and now, near the Sun. This is the only place where there is life. How can this issue be resolved? Most likely, there is a completely logical explanation for this. Perhaps we just started looking too early.
In other words, at the moment we may be truly alone in the universe. Simply because we appeared before everyone else. If this hypothesis is correct, then the real spread of life in the Universe has not even begun and, most likely, will not begin for several trillion years after us.
There is another explanation, which takes into account all the available facts. Perhaps there is something in space that does not allow life to appear and develop even in technically habitable zones.
“We still believe that we are the center of the biological universe. That we are actually alone or special in this sense or in terms of intelligence,”says Loeb.
“If in the end it turns out that life in the Universe of our level is actually rare or even in its infancy, it will be a great surprise to me, because, no matter how you look, we are not special and clearly do not fit the role center of the Universe.
To understand which of these two explanations is correct, we must first find out if life is possible near low-mass stars. And that doesn't necessarily take trillions of years. Loeb believes the answer can be found within the next decades or so.
By analyzing the composition of the atmosphere of planets close to low-mass stars, scientists can search for biomarkers that will indicate whether these planets are capable of supporting life. If the search continues to show no signs of life, then most likely something is wrong with these low-mass stars. Perhaps their frequent outbreaks or other features simply force them to remain completely "sterile".
But if it turns out that these planets are really capable of supporting life, but it will not be on them, then the most likely answer to this will be that we ourselves appeared too early in this universe to look for neighbors.
NIKOLAY KHIZHNYAK