When a person gets lost in the wild, they have two choices. They can search for civilizations or be easily identified by making a fire or writing HELP in large letters. For scientists interested in the question of whether intelligent aliens exist, the possibilities are similar.
For over 70 years, astronomers have been searching for radio or optical signals from other civilizations in search of extraterrestrial intelligence, called SETI. Most scientists are confident that life exists on many of the 300 million potentially habitable worlds in the Milky Way. Astronomers also believe that some life forms have evolved intelligence and technology. But signals from another civilization have never been detected, a mystery dubbed “The Great Silence.”
While SETI has long been a part of mainstream science, METI, or the transmission of extraterrestrial intelligence, is less common.
I’m an astronomy professor and have written extensively on the search for life in the universe. I also serve on the advisory board of a non-profit research organization that designs messages to be sent to extraterrestrial civilizations.
In the coming months, two teams of astronomers will send messages into space to try and communicate with intelligent aliens who may be listening out there.
These efforts are like making a big campfire in the woods and hoping someone finds you. But some people wonder if it’s wise to do it at all.
Early attempts to contact life beyond Earth were unworldly messages in a bottle.
In 1972, NASA launched the Pioneer 10 spacecraft toward Jupiter carrying a plaque with a line drawing of a man and woman and symbols showing where the spacecraft came from. In 1977, NASA followed suit with the famous Gold Disc attached to the Voyager 1 spacecraft.
These spacecraft – as well as their twins Pioneer 11 and Voyager 2 – have all now left the solar system. But in the immensity of space, the chances of finding these or any other physical objects are fantastically slim.
Electromagnetic radiation is a much more powerful beacon.
Astronomers broadcast the first radio message designed for extraterrestrial ears in 1974 from Arecibo Observatory in Puerto Rico. Designed to convey simple information about humanity and biology, the series of ones and zeros was sent to the globular cluster M13. Since M13 is 25,000 light years away, don’t hold your breath for an answer.
In addition to these deliberate attempts to send a message to extraterrestrials, wayward signals from television and radio broadcasts have been seeping into space for nearly a century. This ever-expanding bubble of terrestrial chatter has already reached millions of stars. But there’s a big difference between a focused burst of radio waves from a giant telescope and a diffuse leak — the faint signal from a show like “I Love Lucy” fades beneath the hum of radiation left over from the Big Bang shortly after it did left the solar system.
Almost half a century after the Arecibo message, two international teams of astronomers are planning new attempts at extraterrestrial communications. One uses a giant new radio telescope and the other chooses a compelling new target.
One of these new messages will be broadcast from the world’s largest radio telescope in China sometime in 2023. The 500 meter diameter telescope will transmit a series of radio pulses across a wide swath of sky. These on-off pulses are like the ones and zeros of digital information.
The message is called “The Beacon in the Galaxy” and contains prime numbers and mathematical operators, the biochemistry of life, human forms, the location of the earth and a timestamp. The team broadcasts the message to a cluster of millions of stars near the center of the Milky Way, about 10,000 to 20,000 light-years from Earth. While this maximizes the pool of potential aliens, it means it will be tens of thousands of years before Earth has an answer.
The other attempt only targets a single star but has the potential for a much faster response. On October 4, 2022, a team from the Goonhilly satellite earth station in England will send a message to the TRAPPIST-1 star. This star has seven planets, three of which are Earth-like worlds in the so-called “Goldilocks Zone” – meaning they could harbor liquid and possibly life. TRAPPIST-1 is only 39 light-years away, so it could be as little as 78 years before intelligent life gets the message and Earth gets the answer.
The prospect of alien contact is fraught with ethical issues, and METI is no exception.
The first is: Who speaks for the earth? As there is no international consultation with the public, the decision on what message to send and where to send it lies in the hands of a small group of interested scientists.
But there is also a much deeper question. Of course, if you get lost in the woods, being found is a good thing. When it comes to whether humanity should send a message to extraterrestrials, the answer is much less clear-cut.
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Before his death, the famous physicist Stephen Hawking spoke openly about the dangers of contacting extraterrestrials with superior technology. He argued that if they were given Earth’s location, they could be malevolent and could destroy humanity. Others see no additional risk, since a truly advanced civilization would already be aware of our existence. And there is interest. Russian-Israeli billionaire Yuri Milner has bid $1 million for the best design of a new message and an effective way to deliver it.
So far, there are no international regulations for METI, so experiments continue despite concerns.
Intelligent aliens remain in the realm of science fiction for now. Books like Cixin Liu’s The Three-Body Problem offer murky and thought-provoking perspectives on what the success of METI efforts might look like. It doesn’t end well for humanity in the books. If humans ever make contact in real life, I hope the aliens come in peace.
By Chris Impey, Distinguished Professor of Astronomy at the University, University of Arizona
This article was republished by The Conversation under a Creative Commons license. Read the original article.