Published: 2:17 PM 1/9/2016
Looking for those plausible civilizations won't be easy...
By Dylan Baddour
At a national gathering of astronomers on Wednesday, a Harvard University scientist pinpointed where interstellar civilizations could be thriving in the Milky Way.
Rosanne DiStefano of the Harvard-Smithsonian Center for Astrophysics told a meeting of the American Astronomical Society that "a globular cluster might be the first place in which intelligent life is identified in our galaxy."
The clusters—dense bunches of solar systems—would afford the best opportunity for life to evolve and establish relations with nearby planets.
It comes a half-century after the kick-off of American academics' official Search for Extra Terrestrial Intelligence (SETI), and months after NASA's head of science told a congressional hearing that humanity was "on the cusp" of learning if alien intelligence exists.
Scholarly debate questions whether the clusters even bear planets. In fact only one has ever been found. But spotting distant planets from the Earth is like noting specks of dust drifting on the other side of town; not easy. DiStefano and her colleague, Alak Ray of the Tata Institute of Fundamental Research in Mumbai, argued that there could be planets in the clusters, and that those planets would be well suited to host life.
As scientists understand, temperature is key for the evolution of life. Liquid water seems necessary for the most basic biological processes, and the precious compound exists in its rare liquid state through a tiny temperature range before it is frozen or vaporized. DiStefano's research stipulated that the "just right" range could be most easily found inside globular clusters.
By the nature of their formation, the clusters are old, about 10 billion years old, more than twice the age of Earth's sun. Bright, hot stars die young, and dim warm ones live long. A heavy concentration of low-burning stars could create a warm cosmic ambience nicely suited to liquid H2O.
The clusters' old age also would afford more time for the evolution of advanced organisms.
And the density of old star systems could facilitate interstellar communication between planetary societies, raising the possibility of the long-imagined galactic civilization somewhere in the sky.
"We call it the 'globular cluster opportunity," DiStefano said. "Sending a broadcast between the stars wouldn't take any longer than a letter from the U.S. to Europe in the 18th Century."
Looking for those plausible civilizations won't be easy. SETI methods haven't changed much since 1960, when Frank Drake at the National Radio Astronomy Observatory made humanity's first attempt to detect extraterrestrial technology, turning a massive radio telescope towards targeted worlds in hopes of picking up intelligent communication. But he found only static and cosmic noise.
Later scientists began sending their own targeted radio pings out into the sky with hopes of a response, but none has yet come. DiStefano recommended reaching out to the globular clusters, just to see if anyone is home.