Aliens will be dead before we get their signals, Drake equation update suggests | Science News

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We probably won’t hear from aliens. But by the time we do, they’ll be dead.

A new Drake Equation calculation suggests ghost signals haunt parts of the Milky Way

By
12:00pm, March 12, 2018
animation of signals from alien civilizations

CAN YOU HEAR ME NOW?  Electromagnetic signals (blue circles) from alien civilizations will continue traveling through the Milky Way even after the aliens are gone. The appearance of a doughnut hole represents when a civilization dies out.

If signals from an alien civilization ever reach Earth, odds are the aliens will already be dead.

In an effort to update the 1961 Drake Equation, which estimates the number of detectable, intelligent civilizations in the Milky Way, physicist Claudio Grimaldi and colleagues calculated the area of the galaxy that should be filled with alien signals at a given time (SN Online: 11/1/09).

The team, which includes Frank Drake (now a professor emeritus at the SETI Institute in Mountain View, Calif., and the University of California, Santa Cruz), assumed technologically savvy civilizations are born and die at a constant rate. When a civilization dies out and stops broadcasting, the signals it had sent continue traveling like concentric ripples on a pond. Part of the Milky Way should be filled with these ghost signals.

If the civilization lasted less than 100,000 years

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