A new study suggests there have been at least 10 billion alien civilizations in the universe since the Big Bang, that Earth's human beings are not the only intelligent life form to have arisen in the universe. For those who are particularly hopeful that alien civilizations exist, the study lends encouragement that the ongoing search for extraterrestrial life -- and, by extension, for the even more difficult find, intelligent alien life -- just might one day yield positive results. But, as with most aspects cosmological, the findings are relative...
Space.com reported May 5 that scientists have mathematically calculated two major probabilities: 1) It is extremely unlikely that Earth is the first habitable world to have developed a technological civilization and 2) there have been at least 10 billion alien civilizations that have existed over time within our universe. The study, authored by the University of Rochester in New York's Adam Frank and the University of Washington's Woodruff Sullivan, not only suggests that humans are not alone but that it is highly unlikely, at least when viewed through a mathematical probability lens, that the universe may be and has been teeming with life.
In fact, according to the study, there is a one in 10 billion trillion chance that humanity is the first technologically advanced species to arise in all the universe. Frank, a professor of physics and astronomy and the study's lead author, noted in a statement that the implication is that "other intelligent, technology-producing species very likely have evolved before us."
"Think of it this way: Before our result, you'd be considered a pessimist if you imagined the probability of evolving a civilization on a habitable planet was, say, one in a trillion. But even that guess — one chance in a trillion — implies that what has happened here on Earth with humanity has in fact happened about 10 billion other times over cosmic history."The number of possible alien civilizations -- 10 billion -- suggests that humanity has had plenty of company -- but only relatively speaking. That immense number is somewhat misleading when it comes to actually searching and finding alien civilizations, given that the universe is an estimated 13.8 billion years old, is filled with an estimated 100 billion galaxies, and even the closest stellar body to Earth is more than four light years away.
Finding alien life, at least mathematically, should be an exponentially easier task, even if the parameters of said living organisms only exist as humans are able to perceive it. Alien civilizations, the outgrowth of alien life progressing to produce and manipulate technologies, would be far less likely.
In fact, Frank and Sullivan admit that, when considering the vast amount of space and the billions of years that have passed since the Big Bang, it could very well be that Earth just might be home to the only extant technological species. And even if humanity is not alone in the universe at present and there are younger or older alien civilizations currently in existence, there is no guarantee that those civilizations are anywhere near advanced enough to discover and/or contact anytime soon -- given Earth's present technological state.
Frank also noted in the statement that "it is astonishingly likely that we are not the only time and place that an advanced civilization has evolved." Sullivan concurred, stating pointedly that the universe is more than 13 billion years old.
"That means that even if there have been 1,000 civilizations in our own galaxy, if they live only as long as we have been around — roughly 10,000 years — then all of them are likely already extinct. And others won't evolve until we are long gone. For us to have much chance of success in finding another 'contemporary' active technological civilization, on average they must last much longer than our present lifetime."Space.com parenthetically highlighted the fact that Sullivan's reference to humanity's 10,000 years of civilized existence is qualified by the fact that humans have only been capable sending radio waves and other electromagnetic signals for barely more than a century. The implication is that humanity has had just a few years -- again, relatively speaking -- to transmit and receive signals to and from the universe, an extremely narrow window through which to detect -- or possibly be detected by -- alien civilizations that might exist.
Frank and Sullivan used a modification of the old standard, the Drake Equation, to reach their conclusions. Astrophysicist Frank Drake himself told Space.com in a 2015 interview that via his equation, "one in every 10 million stars will have a detectable signal" that might suggest the presence of an alien civilization and that astronomers would likely need to study at least a million stars, each one for days, to actually detect alien life.
The scientists also used current astronomical observation data from instruments like the Kepler Space Telescope that suggests that about 20 percent of all stars play host to planets that orbit in the "habitable zone," narrowing the output to worlds where liquid water is present.
The study was published in the journal Astrobiology. According to Adam Frank, the findings are the first time there has ever been an empirical answer provided for the question of whether or not alien civilizations have ever developed prior to civilization developing on Earth.
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