If a person is lost in the desert, they have two options. They can research civilization, or they can make themselves easy to spot by lighting a fire or writing HELP in big letters. For scientists interested in the question of whether intelligent extraterrestrials exist, the options are much the same.
For more than 70 years, astronomers have searched for radio or optical signals from other civilizations in search of extraterrestrial intelligence, called SETI. Most scientists are convinced that life exists on many of the 300 million potentially habitable worlds in the Milky Way galaxy. Astronomers also believe there is a decent chance that some life forms have developed intelligence and technology. But no signal from another civilization has ever been detected, a mystery called “The great silence.”
While SETI has long been part of mainstream science, METIor extraterrestrial intelligence messaging, has been less common.
I am a astronomy teacher who has written extensively on the search for life in the universe. I also sit on the advisory board of a not-for-profit research organization that design messages to send to extraterrestrial civilizations.
In the coming months, two teams of astronomers will send messages into space in an attempt to communicate with intelligent aliens who may be there listening.
These efforts are like making a big bonfire in the woods and hoping someone finds you. But some people wonder if it is wise to do so.
The first attempts to contact life off Earth were quixotic messages in a bottle.
In 1972, NASA launched the Pioneer 10 spacecraft to Jupiter carrying a plate with a line drawing of a man and a woman and symbols to indicate the origin of the gear. In 1977, NASA continued with the famous gold record attached to Voyager 1 spacecraft.
These spacecraft – along with their twins, Pioneer 11 and Voyager 2 – now all have left the solar system. But in the vastness of space, the chances of these or any other physical objects being found are incredibly tiny.
Electromagnetic radiation is a much more effective beacon.
Astronomers have broadcast the first radio message designed for extraterrestrial ears since the Arecibo Observatory in Puerto Rico in 1974. The series of 1s and 0s was designed to convey simple information about humanity and biology and was sent to the globular cluster M13. Since M13 is 25,000 light years away, you shouldn’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 leaked into space for nearly a century. This ever-expanding terrestrial babble bubble has already reached millions of stars. But there’s a big difference between a focused blast of radio waves from a giant telescope and a diffuse leak – the faint cue from a show like “I Love Lucy” fades to the buzz of radiation left behind by the Big Bang shortly after it left the solar system.
Sending new messages
Nearly half a century after the Arecibo message, two international teams of astronomers are planning new attempts at extraterrestrial communication. One uses a giant new radio telescope and the other chooses a compelling new target.
One of these new messages will be sent from the the largest radio telescope in the world, in China, around 2023. The telescope, 1,640 feet (500 meters) in diameter, will emit a series of radio pulses across a wide swath of sky. These on-off pulses are like the 1s and 0s of digital information.
The message is called “The Lighthouse in the Galaxyand includes prime numbers and mathematical operators, the biochemistry of life, human forms, the location of Earth, and a timestamp. The team sends the message to a group of millions of stars near the center of the Milky Way galaxy, about 10,000 to 20,000 light-years from Earth. While this maximizes the pool of potential extraterrestrials, it means it will be tens of thousands of years before Earth receives a response.
The other attempt targets only one star, but with 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 star TRAPPIST-1. This star has seven planets, three of which are Earth-like worlds in the so-called “Goldilocks Zone”– which means they could harbor liquid and potentially life too. TRAPPIST-1 is only 39 light years away from us, so it could take intelligent life 78 years to get the message and to Earth to get the answer.
The prospect of extraterrestrial contact is fraught with ethical questions, and METI is no exception.
The first is : Who speaks for the Earth? In the absence of any international consultation with the public, decisions about what message to send and where to send it are in the hands of a small group of interested scientists.
But there is also a much deeper question. If you get lost in the woods, being found is obviously a good thing. When it comes to whether humanity should broadcast a message to extraterrestrials, the answer is much less clear.
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Before his death, emblematic physicist Stephen Hawking was candid about the danger to contact extraterrestrials with superior technology. He argued that they could be malevolent and, if they knew the location of Earth, could destroy humanity. Others see no additional risk, since a truly advanced civilization would already know of our existence. And there is interest. Russian-Israeli billionaire Yuri Milner offered $1 million for the best design of a new message and an effective way to convey it.
To date, no international regulations govern METI, so experiments will continue, despite concerns.
For now, intelligent extraterrestrials remain science fiction. Books like “The three-body problemby Cixin Liu offer somber and thought-provoking insights into what successful METI efforts might look like. It doesn’t end well for humanity in the books. If humans ever come into contact in real life, I hope aliens come in peace.