Earthlings talk a lot about the possibility of life on other planets throughout the universe, but astrophysicists say in a new study that humans may have dozens of extraterrestrial neighbors in our own galaxy — the Milky Way.
The new study, published Monday in “The Astrophysical Journal,” shed light on just how many planets in our slice of the galaxy could be home to past, current and future alien civilizations, as well as the bleak future that could be in store for us.
“There should be at least a few dozen active civilizations in our galaxy under the assumption that it takes 5 billion years for intelligent life to form on other planets, as [it did] on Earth,” said the University of Nottingham’s Christopher J. Conselice in a statement. “The idea is looking at evolution, but on a cosmic scale. We call this calculation the Astrobiological Copernican Limit.”
There are two variations on the Astrobiological Copernican Limit. To have a “weak” limit suggests that at least 5 billion years are needed for a habitable planet to develop life, whereas a “strong” limit refers to the possibility of life arising in a period of 4.5 billion or 5 billion years.
Scientists use characteristics of our own planet, such as our metal-rich environment, as a guideline for pinpointing other habitable homes in our galactic neighborhood.
They also rely on the detection of signals, including radio waves from satellites and TV, to investigate otherworldly civilizations. Based on the fact that Earth has been beaming radio transmissions for the past century, it is speculated there could be more than 36 counterparts to the human race within our galaxy.
However, the nearest distance to any potentially habitable planet in the Milky Way is 17,000 light-years away, which makes even communicating with them a currently impossible feat.
The new study relates to Fermi’s paradox, a longstanding conundrum of astronomy that asks how there can be a lack of evidence of extraterrestrial civilizations when the probability of other life is so high in the universe. Named for Italian-American physicist Enrico Fermi, the contradiction is often cited as an argument against active alien lifeforms that live long enough for people to discover them.
Researchers believe their findings may indicate how long humans can hope to exist before our own civilization reaches oblivion.
“Our new research suggests that searches for extraterrestrial intelligent civilizations not only reveals the existence of how life forms, but also gives us clues for how long our own civilization will last,” professor Conselice said.
“If we find that intelligent life is common, then this would reveal that our civilization could exist for much longer than a few hundred years; alternatively, if we find that there are no active civilizations in our galaxy, it is a bad sign for our own long-term existence. By searching for extraterrestrial intelligent life — even if we find nothing — we are discovering our own future and fate.”
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