Scientists at SETI have been scanning the galaxy around us for the past 50 years, hoping to intercept a signal that would let us know we’re not alone in the galaxy. The premise is a simple one: if intelligent life exists in the universe then it must be curious like we are. As such, someone should be out there broadcasting, and all we need to do is listen in to hear their broadcast. As of yet there have been no confirmed extraterrestrial signals from space, but in August of 1977, SETI recorded one that still makes us wonder today: is it possible someone out there already tried to contact us?

The “Wow! signal”, as it’s come to be done, was a 1420Mhz signal received over a span of 72 seconds on August, 15th, 1977. Jerry Ehman is credited with discovering the signal and circling it. He also wrote “Wow!” next to the find, which is why today it’s called the Wow! signal. So, what are the odds this signal actually was extraterrestrial in nature? And if it was, why haven’t we ever heard it again?

The Science Of Interstellar Communications

With the nearest solar system 4.3 light-years away, interstellar signals take years (sometimes even centuries) to propagate across our galaxy. As this is the case, even if we sent a message to our nearest neighbor and they were listening it would take nearly nine years for us to hear a reply. As most neighboring stars are 20 light-years away or further, the time to complete such a call can be forty years or more. For this reason, we have decided to become listeners rather than broadcasters. But what if other civilizations came to the same conclusion?

For all we know there are thousands of intelligent civilizations out there with their ear to the phone, waiting for someone to call. If this is true, that call might never be placed. But what if someone out there decided to dial out? Where would they call? What would they say? How would anyone know the call was real?

The sad truth is that we have no legitimate answer for any of these questions. For all we know we are being bombarded by incoming calls on a daily basis, but maybe we just aren’t listening to the proper frequency. It’s also possible that we are listening to the proper frequency, but the call is unlike anything we assumed it would be, making it difficult to understand.

The Vegans Called While You Were Out

We can probably safe assume that at least a few intelligent civilizations out there are willing to take a chance and place a call, but if they did, would we receive it? Without any prior knowledge on who to call, a civilization would move the signal around from solar system to solar system and vary the frequency with the hope of hitting one that was being listened to. If this were the case, then the Wow! signal would be the result. So why hasn’t the signal returned?

As there is no immediate feedback to know if a signal reached anyone, the obvious solution would be to broadcast a signal that floated over all frequencies in all directions, keeping it just long enough for any recipient to know they had been contacted. In computerese, this is known as a ‘ping’. The concept is simple: you send out a transmission and then await a response. If the same signal comes back to you then you realize it must have been sent back from an intelligent species: simple and eloquent.

Unfortunately, we can never be certain from where or when a signal originated. In the time it would take us to respond, the alien receiver could be dismantled or the civilization could disappear altogether. For this reason alone, our search needs to focus on the systems nearest to us, as anything further out would have little meaning.

Provided we received a signal in 1977 and then sent one back, it might be 2017 until we get another response. Is SETI willing to wait that long to hear the Wow! signal again? We hope so, but to our knowledge that return ping was never sent by us, which might mean we never hear from that broadcaster again.

The Search Continues

So long as people continue funding SETI, the search will continue; however, how many years are we willing to wait? One signal in fifty years is hardly a success story, but if that one signal could be verified it would change our world overnight. Think about it: what would it be like to actually confirm we aren’t the intelligent life in the universe?

But what if we do confirm a signal? What then? Our recommendation would be a constant broadcast to that portion of the sky, at the same frequency received, with an outpouring of mathematical data. As we assume any alien civilization would be knowledgeable of mathematics, it would become our first universal language. From there, it would be a matter of sending diagrams that would allow them to build a primitive interstellar television, to which we could broadcast more about our species.

Being bright enough to communicate with us this far, they would no doubt create a television to view our transmissions and then a broadcaster to send their own. In doing so, we could send intricate messages back and forth and eventually learn to communicate with one another. Of course, the time lag would prevent any timely conversations. The reason for this is because each message would take years to respond to, possibly making any such banter meaningless.

For instance, if we asked another civilization if they had cell phones they might respond, ‘no’, but by the time we received the signal back they might have already developed the technology. For this reason, all questions would deal more with culture than inventiveness,with the exception being a question of whether they have attained interstellar spaceflight, which could be a prelude to a visitation.

Thirty-three years later, all we know about the Wow signal is that it originated somewhere in the constellation Sagittarius, which encompasses a large region of space (small to our eyes, but large in its interstellar mass). It might have been an anomaly, or it’s possible it was an actual attempt to communicate. One thing is for certain, if the signal ever occurs again we’ll take it much more seriously the second time around!