With 200 billion trillion stars in the Universe and 13.7 billion years since it all began, you may be wondering where all the alien civilizations are. This is the basic question behind the Fermi Paradox, the tension between our suspicions about the potential for life in the Universe and the fact that we have found a single planet with an intelligent species inhabiting it.
A new paper looked at the paradox from a new angle and concluded that the simplest explanation might be the best; we may be entirely the only intelligent civilization in our galaxy.
The paper begins with a thought experiment proposed by the physicist Edwin Jaynes in 1968. Imagine walking into a laboratory and finding a row of large beakers filled with water, into which you will put “substance X” to see if it dissolves .
In such a scenario, you would expect the substance to dissolve either close to 100% of the time or close to zero% of the time. Either this substance dissolves in water at room temperature or it doesn’t.
If it dissolved about half the time, it would mean that small variations in temperature and pressure in the lab were enough to change the result, and that the conditions were in fact “fine-tuned” for the substance to dissolve. We can apply the same kind of reasoning to the hunt for life and alien civilizations.
A rather bleak conclusion
“Consider an ensemble of Earth-like planets in the cosmos—worlds with similar gravity, composition, chemical inventory, and climatic conditions,” the team writes in the paper, which has not yet been peer-reviewed.
“Although there will certainly be small differences in space, we should reasonably expect life to appear either almost all the time under such conditions, or almost never. As before, it would seem artificial for life to appear in about half of the cases – again motivated from a fine-tuning perspective.”
We don’t have enough information to use this reasoning at lower levels of life, such as microbial life. Microbial life may appear in almost all cases, or it may appear almost never.
“We just don’t have enough data about planets and exoplanets to know either way, although if we look at our planet, we know that multicellular life has only been around for about 600 million years, which may suggest that the jump from in single cells to multicellular life is rare,” explains the author of the paper, David Kipping.
The only intelligent civilization in our galaxy
We also cannot use our own existence as evidence that we live in the scenario where intelligent species are abundant. We might just be on one of the very rare worlds where life has arisen.
Although potential Dyson spheres and other signs of advanced extraterrestrial civilizations were looked for, these all turned out to be natural phenomena.
If we were in a galaxy where intelligent life almost always appears, then you would expect to see signs of alien civilizations throughout the galaxy, as the team pointed out using a modified Drake equation. We simply don’t see it, which leads us to conclude that we are in the scenario where we are in a galaxy where intelligent life almost never appears, rather than one where it is abundant, he writes IFLScience.
That’s a pretty bleak conclusion, but the team says there are still possible reasons to be optimistic about the scenario where intelligent life appears infrequently but spreads rapidly when it does.
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Source: www.descopera.ro
