MILKY WAY FULL OF DEAD CIVILIZATIONS, SCIENTISTS THEORIZE

Most of the alien civilizations that ever dotted our galaxy have probably killed themselves off already, Rafi Letzter reported for Space.com.

That's the takeaway of a new study, published to the arXiv database, which used modern astronomy and statistical modeling to map the emergence and death of intelligent life in time and space across the Milky Way.

Their results amount to a more precise 2020 update of a famous equation that Search for Extraterrestrial Intelligence (SETI) founder Frank Drake wrote in 1961.

The Drake equation, popularized by physicist Carl Sagan in his "Cosmos" miniseries, relied on a number of mystery variables — like the prevalence of planets in the universe, then an open question.

This new paper, authored by three Caltech physicists and one high school student, is much more practical. It says where and when life is most likely to occur in the Milky Way, and identifies the most important factor affecting its prevalence: Intelligent creatures' tendency toward self-annihilation.

The authors looked at a range of factors presumed to influence the development of intelligent life, such as the prevalence of sunlike stars harboring Earth-like planets; the frequency of deadly, radiation-blasting supernovas; the probability of and time necessary for intelligent life to evolve if conditions are right; and the possible tendency of advanced civilizations to destroy themselves.

Modeling the evolution of the Milky Way over time with those factors in mind, they found that the probability of life emerging based on known factors peaked about 13,000 light-years from the galactic center and 8 billion years after the galaxy formed.

Earth, by comparison, is about 25,000 light-years from the galactic center, and human civilization arose on the planet's surface about 13.5 billion years after the Milky Way formed (though simple life emerged soon after the planet formed).

In other words, we're likely a frontier civilization in terms of galactic geography and relative latecomers to the self-aware Milky Way inhabitant scene.

But, assuming life does arise reasonably often and eventually becomes intelligent, there are probably other civilizations out there — mostly clustered around that 13,000-light-year band, mostly due to the prevalence of sun-like stars there.

WEEKLY FEATURE : JOSE MARI CHAN AND THE CHRISTMAS ANTHEM