We are not that unique afterall.
Are we alone in the universe? Let alone, in our galaxy? That is a question most of us have asked ourselves, and its answer could result in us feeling rather optimistic or extremely pessimistic.
Although this question seems like one that will always remain a mystery, it hasn’t stopped scientists from trying to figure it out. And they do this using the famous Drake equation (as seen in the image below), which is a way to estimate the number of active extraterrestrial civilizations in the universe.
Adam Frank and Woodruff Sullivan’s new equation (blue) simplifies the classic Drake equation (yellow). Photo credit: University of Rochester
Now, according to a new paper published in the journal Astrobiology, recent discoveries of exoplanets combined with a broader approach to answering this question has allowed researchers to conclude that, unless the odds of advanced life evolving on a habitable planet are immensely low, then humankind is not the universe’s first technological, or advanced, civilization.
"The question of whether advanced civilizations exist elsewhere in the universe has always been vexed with three large uncertainties in the Drake equation," said Adam Frank, professor of physics and astronomy at the University of Rochester and co-author of the paper, in a press release.
For a long time astronomers have known how many stars exist, but they didn’t know how many of those stars had planets that could host life, how often life might evolve and lead to intelligent beings, and how long any civilizations might last before becoming extinct.
"Thanks to NASA's Kepler satellite and other searches, we now know that roughly one-fifth of stars have planets in 'habitable zones,' where temperatures could support life as we know it. So one of the three big uncertainties has now been constrained," explained Frank.
However, how long civilizations survive is still an absolute unknown. Frank and his co-author, Woodruff Sullivan of the astronomy department and astrobiology program at the University of Washington, discovered they could eliminate that term completely by expanding the Drake equation. "Rather than asking how many civilizations may exist now, we ask 'Are we the only technological species that has ever arisen?'” explained Sullivan in the release.
Using this method, Frank and Sullivan calculated how unlikely life would be if there has never been another example of intelligent life among the universe’s twenty billion trillion stars, or even among just our own Milky Way galaxy’s hundred billion.
The results? Less than one in ten billion trillion. "To me, this implies that other intelligent, technology producing species very likely have evolved before us," said Frank. And when the equation is scaled down to include just our galaxy, the numbers are not as extreme.
However, the universe is more than 13 billion years old. "That means that even if there have been a thousand civilizations in our own galaxy, if they live only as long as we have been around -- roughly ten thousand years — then all of them are likely already extinct," explained Sullivan. "And others won't evolve until we are long gone."
According to Frank and Sullivan, their result has practical applications. Humanity is currently facing a crisis in sustainability and climate change — a critical point other civilizations may have faced — so scientists can use this information to model and simulate the problem to get a sense of what leads to a long-lived civilization and what doesn’t.
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