Space and Physics
PUBLISHED
The search for extraterrestrial intelligence, or SETI, is an important area of research aiming to find out not only if alien life exists, but in particular if there are advanced technological civilizations out there.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.We spoke with Dr Vishal Gajjar, an astronomer with the SETI Institute, to discuss the work done there and to ask a hotly debated question: Should this search take a more active role? Should we broadcast who we are and where we are to the heavens?
Dr Gajjar had a lot to share with us, and it turns out that we are certainly not being as quiet as a church mouse when it comes to signals spreading through the cosmos.
What does SETI do?
VG: SETI is searching for evidence of technologies. So we are not so keen on trying to decipher or get [messages], we are not really trying to kind of communicate with aliens.
This is a very common public misconception. People think that we are actively trying to send signals and then trying to receive a message back. That's not how it works. The interstellar distances that we deal with are so vast that it is not possible to do two-way communication in a human lifespan. So all this SETI effort is basically what we call a passive activity.
We are searching for technosignatures, not just in radio. We are searching for technosignatures in all possible electromagnetic wave bands.
Is there a consensus on if we should actually be pursuing a more active version of SETI, sending signals out there?
VG: As far as the SETI community goes, we are not so much concerned about sending messages. As I mentioned, we are mostly doing a passive activity.
There is some amount of agreement in the community that actually doing this “METI” (Messaging Extraterrestrial Intelligence) is a bit risky as well, because we are dealing with something unknown here. We don't really have much idea about what kind of possible dangers are out there.
We are a very young civilization, a very young species. We just started producing technology that is possible to detect across interstellar distances. We just shouldn't start shouting. That's the number one reason that I would argue that we should not just start broadcasting right away!
But it is not the only one, right?
VG: That was number one. Number two is who should speak for us, right? I mean, is it me? I should take charge and say, "Okay, I want to talk to aliens, and I'll just start broadcasting! That's not a problem, right?”
When you transmit a signal, you're not transmitting for one person or one nation; you are transmitting for the whole Earth. So who should speak for Earth? There is no consensus on that.
Unless we have such consensus on what exactly we as a species want to send, we shouldn't do it.
Number 3 is that [METI] is, in some sense, unavoidable. We are already doing it to some extent.
We transmit powerful radio waves to Solar System probes, which are exploring the Solar System. We have very powerful communication going across interplanetary space. And they don't just stop there. They keep transmitting in space.
We are already transmitting signals that may be detectable across interstellar distances.
Earth is not radio quiet. Recent analysis suggests that if an alien civilization had radio observatories like the ones that are coming online here in the coming years, they would be able to spot the signals from mobile phone masts up to 10 light-years away.
Even more powerful leakage is coming from airport radars. That signal is a tell-tale sign of a technological civilization for up to 200 light-years. Now, we have not had airport radars for long enough to be detected at that distance, but the fact that we could be discovered like this suggests that maybe we could spot a civilization in a similar way if they were close enough.
Our first evidence of ETs might be their phone calls or air traffic controls.
This interview has been edited for length and clarity. You can listen to the full podcast above and on our podcast page.
