Study: Probability of extraterrestrials in the Milky Way extremely low
Two researchers have attempted to calculate the probability that we are alone in the Milky Way. The result is quite clear.
(Image: Dotted Yeti/Shutterstock.com)
The probability of two civilizations with highly developed technology existing simultaneously in the Milky Way is so low that another would have to be at least 280,000 years old to exist alongside us now. At least, that is what two researchers from the Austrian Academy of Sciences have calculated, based on their estimates of how many rocky planets with plate tectonics and an atmosphere of nitrogen and oxygen appear to exist. The existence of these two conditions alone suggests that the search for intelligent extraterrestrial life (SETI) is largely futile. If, against all odds, there is an extraterrestrial civilization in the Milky Way, then it is most likely on the other side of the galaxy.
COâ‚‚ content is crucial
Planetologists Manuel Scherf and Helmut Lammer based their analysis on the assumption that the amount of carbon dioxide in an atmosphere is crucial to how long it can be maintained. If there is too little, the gas envelope can escape into space; if there is too much, an irreversible greenhouse effect occurs that no biosphere can survive. To maintain exactly the right amount of CO2, a planet would need plate tectonics. This regulates the amount and ensures that carbon dioxide is trapped in rock and removed from the atmosphere. However, this does not work forever, and at some point there will be so little CO2 on Earth that photosynthesis will no longer be possible for plants.
Depending on the COâ‚‚ content of an atmosphere, it can reach different ages, the two write. However, the longer an atmosphere remains stable, the greater the probability that life and ultimately a technological civilization will develop. Taking all factors into account, a technological civilization on a planet with 10 percent carbon dioxide in the atmosphere would have to be at least 280,000 years old to coexist with another in its galaxy. For ten technological civilizations to coexist in a galaxy, they would have to be ten million years old on average.
Videos by heise
Although the values determined depend on many other factors, this is yet another indication that the search for extraterrestrials could remain unsuccessful for a very long time, or even forever. Nevertheless, Scherf believes that we should not give up. Even if such civilizations were extremely rare, there is only one way to find out for sure, "and that is by searching for them." If we were to find them, it would be the greatest scientific discovery ever. And while there are always calculations that attribute extremely low chances of success to the search, there are also studies that point in a different direction and suggest, for example, that a galaxy could be colonized fairly quickly.
(mho)
