Assuming we one day contact aliens, how will we communicate with them? 

Amy Adams communicates with aliens in Arrival trailer 

In the film, Amy Adams plays a linguist who is recruited by the military to determine whether the aliens that have arriveed on Earth are friendly or hostile.

 The problem with radio telecommunication

We have two options: face-to-face communication or long-distance communication. The former requires either extraterrestrials to visit us or vice versa. But this seems highly unlikely given the huge distance that exists between us and other solar systems. The other involves sending radio signals. But how would we communicate to an alien specie in a manner that it would understand?  Communication will be a huge barrier to bridge. It’s a bit much to expect that extraterrestrials—assuming that they possess sensory organs and brains reasonably compatible with ours—would comprehend our language. 

In 1974, astronomers transmitted a three minute message from the Arecibo Observatory in Puerto Rico aimed at a cluster of stars 25,000 light years away.  The message was sort of a binary communication used by computers. When translated into a graphic, however, the code depicts the shape of the Arecibo telescope, our solar system, the DNA molecule, a figure of a human among others. So far, that message has only travelled a tiny fraction of the distance that it might have to cover to reach an alien civilization, presuming there is one in the distant star cluster that is listening. This shows the limitation of attempting to communicate via radio. By the time the message get delivered to a recipient and revert back, the sender could easily forget about it. Or in the worst-case scenario our species might get extinct.

An Aerial view of the Arecibo Observatory in Puerto Rico

According to an estimate there are 100 billion galaxies in the universe, housing millions of solar systems and planets. Some planets might support complex organic molecules — proteins and nucleic acids — and nothing else. While other planets might harbour simple, single-celled organisms. Though there are chances that life can flourish in some planets but it has to be intelligent enough to signal their presence to us. If they don’t do that, then we’re not going to find them. For example, if the extraterrestrials are a form of marine species living in a distant planet, they will never transmit their location to us.

What to say to them? 

For a moment let’s assume that we managed to get through extraterrestrials or they came to us, we still have to find a medium to communicate. Instead of spoken and written language, some have suggested using mathematics or illustrations of scientific principles to communicate. But researchers Guillermo A. Lemarchand and Jon Lomberg in a 2011 essay called, “Communication with Extraterrestrial Intelligence” argues that following the above mentioned approach is based on the assumptions that the alien mind organizes ideas and perceptions in a fashion similar to ours, which may or may not be the case. Another idea is to create a montage of sounds that is associated with life on earth—such as the sounds of humans, animals, rivers—in a bid to create an audible sort of “cognitive map” that will explain the nature of our species to them.

Threat factor

Physicist, Stephen Hawking warns that if extraterrestrials with more advanced technology than ours visited Earth, they could exploit or exterminate us. But, whatever the odds that are stack against us, we will never stop in our endeavour to look for the unknown. Hunting for an alien life in the vast expanse of universe is equivalent to playing a lottery—you will never win if you don’t play.