Key Takeaways:
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Aliens might not find Earth interesting if life is common throughout the galaxy.
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If life is widespread, aliens might focus on planets with signs of technology, not just life itself.
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Earth’s radio signals have only reached a tiny fraction of the galaxy and were faint at first.
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As our technology advances, our detectable signals will strengthen, increasing the chance of contact.
Why do aliens not communicate with us? Perhaps they find Earth boring.
According to a recent preprint paper uploaded to the arXiv database, intelligent aliens may not find planets that support life to be all that fascinating. Astrophysicist Amri Wandel of The Hebrew University of Jerusalem and study author said in the paper that if life has evolved on numerous planets throughout the galaxy, then aliens are likely more interested in those where there are indications of both biology and technology.
The study investigates the Fermi paradox, which suggests that since the universe is old, intelligent aliens probably would have visited Earth by now since they would have likely developed long-distance space travel. As far as we know, they haven’t, which could indicate that the Milky Way galaxy has no evidence of any other intelligent life.
But other theories have been put forth by experts to explain the missing aliens: Maybe they came to Earth earlier, before humans developed or had the ability to record their visits. Or perhaps there is more to long-distance space travel than is commonly thought. Maybe advanced civilization was developed by aliens too recently for them to reach Earth. Or they’ve deliberately decided not to explore the cosmos. It’s even possible that they’ve killed themselves off.
Wandel presents an alternative explanation in the new paper, namely that life is actually quite common throughout the Milky Way. Aliens probably wouldn’t waste their time sending signals to every planet if many of the rocky planets orbiting in the habitable zone of stars support life; instead, they would probably end up attempting to communicate with alien algae or amoebas.
Intelligent aliens would probably be far more interested in technological evidence if life is common. Still, tech signals might be hard to spot. It is only since the 1930s that Earth has been emitting radio waves, which are detectable from space. Theoretically, approximately 15,000 stars and their planets have been covered by these signals thus far, but that still represents a very small portion of the Milky Way’s 400 billion stars. Moreover, Wandel noted that since Earth began broadcasting off-planet, only stars within 50 light-years have had time to respond because it takes time for any return message from aliens to travel back.
Even worse, according to Universe Today, Earth’s earliest radio signals were probably transmitted unintentionally into space, meaning that after roughly one light-year, they would have become so distorted that extraterrestrials would not be able to tell them apart. (In 1974, Earthlings transmitted the Arecibo message, designed towards the globular star cluster M13, as the first deliberate high-power broadcast to aliens. It’s time to send another, according to some scientists.)
Wandel found that unless intelligent civilizations are very abundant, with more than 100 million technologically advanced planets in the Milky Way, it’s likely that Earth’s signals haven’t reached another form of intelligent life. But as time passes and our planet emits an increasing amount of radio noise, Wandel wrote, the likelihood increases that Earth’s technological signals will be picked up by intelligent people.
He wrote that the results might indicate that intelligent civilizations are not present within approximately 50 light-years of our planet. But intelligent life could still be out there — they’re just waiting for our call.
