The lack of signals from other advanced civilizations is actually very bad news for humanity and modern civilization.
On Earth, civilisations are short-lived. The Roman Empire lasted less than a thousand years, and the Mayan civilization-about two millennia. And the more advanced a civilization is, the less it exists. How much of ours is left? With such irresponsibility and the pace of consumption, we must think, not for long.
The same thing can happen on other planets. And, most likely, it does. Their short lives may explain why we haven’t detected a single signal from an alien intelligence yet.
According to recent calculations, there should be several dozen worlds in the Milky Way galaxy with civilizations developed enough to send messages to space. But these worlds are probably so far away that the signals of their inhabitants do not reach the Earth or fly through space for thousands of years. By the time the signal is received, the civilization that sent it will no longer be on that distant planet. Or we won’t be here. “We can imagine a galaxy where intelligent life is common, but communication is unlikely,” say Tom Westby and Christopher Conselis.
The analysis by Westby and Conselice of the University of Nottingham in England is based on a slightly modified Drake equation proposed almost 60 years ago. Frank Drake has identified factors that, in principle, allow us to estimate how many intelligent civilizations can exist in the galaxy.
Westby and Conselis started with the assumption that it takes 5 billion years for intelligent and technologically advanced life to develop on the planet, just like on Earth. Then it remains to find out how many stars are old enough and how many planets are in their Goldilocks zones.
Thus, in their new CETI equation, Westby and Conselis showed that the number of intelligent civilizations depends on how many stars are in the galaxy and how many of them are more than 5 billion years old.
It turned out that some factors do not limit the prospects for detecting alien life. For example, almost all the stars in our galaxy are older than 5 billion years, and their average age is almost 10 billion years.
Some stars should be excluded due to the lack of basic elements in them. Of the remaining stars, probably only 20 percent have planets in the Goldilocks zone.
Since there are more than 200 billion stars in the galaxy, there must therefore be billions of potentially civilizational worlds. But before stating this, one more important exception must be made.
It is safe to say that a civilization capable of sending signals can last 100 years. On Earth, radio waves were discovered in 1865 by the Scottish physicist James Clerk Maxwell. They learned to use them in 1895, when the Russian physicist Alexander Popov created the first radio transmitter.
With this set of assumptions, taking into account that the average life expectancy of an advanced civilization is 100 years, there should be only 36 sufficiently advanced civilizations in our galaxy today.
Our nearest neighbor is likely to be about 17,000 light-years away, “making it impossible to exchange data or even detect these solar systems with modern technology,” Westby and Conselis write. In the most optimistic case, the nearest civilization should be within 300 light-years of us.
“The lifetime of civilizations in our galaxy is unknown, and this is by far the most important factor in the CETI equation,” Westby and Conselis note.