Scientists have determined how long it takes to establish contact between humanity and aliens

Chinese scientists are trying to understand: if humanity is not unique and other civilizations can also emerge in space, why haven’t we found anyone else? A recent study by scientists offers a bold answer to the question, IFLScience reports.

Previously, researchers have repeatedly tried to find a solution to the Fermi paradox, which raises the question of whether humans are unique in the universe and why we have not been able to establish communication with other civilizations. Now, scientists believe that even if extraterrestrial civilizations do exist, they need to survive for thousands of years to be able to talk to someone else.

Scientists Wenjie Sun and He Gao estimated the number of extraterrestrial intelligent civilizations (CETI — communicating extraterrestrial intelligent civilizations — ed.) using only two parameters

• the probability of life on a planet of the Earth group;
• the stage of evolution of the parent star of the planet on which another civilization will be born.

The researchers created 9 possible scenarios in which CETIs were either rare or common. For example, if CETIs are rare, in order to interact with someone else, civilizations need to survive for 400,000 years before the signal sent reaches its target. The most positive predictions are 2000 years between the sending of a signal by one civilization and its receipt by another.

The authors of the study argue that the reason why humanity has not yet received its «first cosmic greeting» is that our time has simply not yet come. Moreover, the scientists suggest that the lifespan of civilizations is likely to be self-limiting — an effect also known as the doomsday argument.

According to Chinese researchers, the lifespan of a civilization can be limited by many factors, including

• societal problems
• nuclear destruction;
• sudden climate change;
• cataclysms;
• destruction of the world by a comet or asteroid.

Nevertheless, scientists recognize that sooner or later humanity will establish contact with extraterrestrial civilizations. However, scientists believe that this will require much more advanced technologies than those currently available to humanity.