Sending radio messages to extraterrestrial civilizations, broadcasting our presence in the universe, hoping to hear back. It sounds like something out of sci-fi and maybe a little silly.
But, you know that here at Astrocenter, we love all things sci-fi!
METI stands for Messaging Extraterrestrial Intelligence. It's exactly as it sounds and similar to SETI (Search for Extraterrestrial Intelligence) in its goal to contact other civilizations in the universe.
Humanity does have a precedent with attempting to directly contact ETs. The Golden Records, currently speeding away from the Solar System at more than 30,000 mph, are records stored in the Voyager I and II spacecraft. They carry information about human civilization and our culture for potential intercepters to find. The New Yorker story linked above is a wonderful glimpse into how the project came to be.
However, METI is much more efficient than any physical medium; electromagnetic waves travel at the speed of light. Let's look at the advantages and disadvantages in turn.
Advantages of METI
No worries about missing each other.
The Milky Way galaxy is big, and it's existed for 13.6 billion years. We'd have to be pointing
our radio telescopes at the right time to the right place to pick up extraterrestrial signals. Given how far the signals would be traveling to reach Earth, even a small angular displacement means an incredibly large spatial displacement over longer distances. (Imagine using a long stick to try and pick up something - you'd have to make really minute adjustments to get the stick in the right spot.)
With METI, you can simply send out signals wherever, whenever. More broadcasting to different areas of space means more chances that the signals will be picked up by a lucky listener.
Better chances of contact.
By broadcasting, we can let other civilizations know that we're ready and willing to make first contact.
We're already doing it (sort of).
Plot twist: METI's been a thing. Way back since the '30s.
How? Ever since the advent of radio and TV, all of those electromagnetic signals have been spreading to the universe in an ever-expanding sphere. That means theoretically, any one of our sitcoms or Superbowls could be picked up by an alien observer if they had a strong enough telescope. If that's the case, why not keep on doing it?
Disadvantages of METI
The Dark Forest
You're a hunter, creeping through a dark forest. You don't know what monsters lurk in the shadows, so you don't make a sound; announcing your presence will mean certain death.
That's how the Dark Forest theory, proposed by sci-fi author Cixin Liu, sees the universe. Interstellar diplomacy is nonexistent, and civilizations would rather exterminate potential threats than attempt to contact them. In such a world, broadcasting is akin to screaming and waving your torch in a beast-filled forest.
Here's the thing, though - many scientists say interstellar war is not a valid concern. There's not much on Earth a spacefaring civilization would want that they couldn't get from other, less genocidal options like icy moons for water. And unless the civilization is really advanced, any physical object traveling in space is bound by the speed of light. In that case, why even bother invading Earth?
There's also a logical argument against the risks of starting purposeful messaging.
"[I]f they’re that advanced, then they can be presumed to have large antennas and sensitive radio receiving equipment, and to have had such technologies for a while," says Seth Shostak, a senior astronomer at the SETI Institute. "That means that irrespective of their personal natures, they can detect the transmissions we’ve already sent into space... In other words, it’s entirely too late to worry about giving away our position."
Concluding thoughts
So there you have it. It's got both pros and cons that may be outweighed by one or the other, depending on what you prioritize. But what do you think?
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Sci-fi/science works about METI:
Contact by Carl Sagan
The Dark Forest by Cixin Liu
Extraterrestrial by Avi Loeb
More sources about METI:
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