Why Is SETI Not An Interstellar Switchboard?

Monolith by highdarktemplar on DeviantArt.
Monolith by highdarktemplar on DeviantArt.

On reading an article in The Daily Galaxy today, I was interested by what the author had to say. In a nutshell, the article pointed out that it is a big mistake to believe we are the only intelligent life in the Milky Way.

Why is that?

The only reason given was that there are billions of stars, it is therefore foolish to think we are the only example of an advanced species. Unfortunately, there is no evidence to suggest that we aren’t the only intelligent life form in our galaxy. Just because there are hundreds of billions of stars possibly with billions of habitable planets does not constitute evidence that we’re not alone. That’s what science is all about, formulating a theory and then gathering the evidence. Simply saying, “There’s lots of stars, therefore there must be an intelligent species out there,” doesn’t cut it.

Dr Frank Drake toiled with this idea to eventually arrive at the famous Drake Equation, a concept I have never felt at ease with:

At first glance, we could say that the Drake equation really is nonsense (after all, how can any equation predict more than one intelligent civilization in our galaxy, when we only have experience of one: us), and that we are the only kids on the Milky Way block. — from If There’s an Alien Race Living on our Doorstep, Why Can’t We Hear Them?

How can you arrive at the conclusion that we are not the only intelligent life in the galaxy simply because there are a lot of stars?


What can we expect ET to look like?
What can we expect ET to look like?

It is true that the Milky Way contains billions of stars, of which a high percentage probably have exoplanets not dissimilar to Earth orbiting them. There’s every chance that a smaller percentage of those Earth-like terrestrial exoplanets have some kind of basic life form slivering around (or indeed swimming, flying, walking or ‘talking’). Also, there’s the chance that some of these exoplanets have nurtured something that we’d consider to be ‘intelligent.’

Now this is where things start to get a bit tricky.

There are massive international efforts under way to find any kind of extraterrestrial life. We’re toasting soil samples on Mars in the hope of finding the biological signature, and we’re using full-blown antennae scouring the skies for any organized signal from an intelligent alien species. However, whether we are looking for microbial life in the Solar System or something a little more sophisticated beyond, our search for extraterrestrial life is based on only one model: Earth.

It’s all very well saying that we should be looking for other possible forms of life, but if we have no experience of it, how do we know what to look for?

It’s a similar question to, “What is beyond a black hole’s event horizon?” We have no idea, because we cannot experience it, the physics of our Universe simply do not apply beyond an event horizon.

There are a lot of ideas, theories and conjecture but at the end of the day, we have to assume ET will have some trait we are familiar with.

When looking for intelligent extraterrestrials we make the assumption that these civilizations have progressed in a similar way to us, eventually transmitting radio signals (perhaps even laser beacons) to communicate on their home world, between planets with their own kind, or even reaching out into the cosmos, signalling their presence to other life forms capable of receiving interstellar signals.

We’ve been leaking radio signals into space for the last century and we are constantly communicating with our planetary probes. There’s every chance that if there’s an intelligent alien (with a radio receiver) within 100 light years, we may have already been detected. We are also being a bit more proactive these days, using programs such as Messaging Extraterrestrial Intelligence (METI) to make our presence known. (But what should we be saying?)


The Arecibo radio antenna, used by SETI
The Arecibo radio antenna, used by SETI

Unfortunately, apart from one isolated case, the Search for Extraterrestrial Intelligence (SETI) has drawn up blanks, we don’t think we’ve heard anything in the cosmos that’s originated from an alien.

On this single null result, we could jump to the conclusion that there is no other form of ‘intelligent’ life in our galaxy. Say if the ‘Rare Earth‘ theory is correct, and we are indeed the only form of intelligent life in our galaxy? But there are other explanations. What if ET is signalling via another method? What if there is some interstellar mechanism that is hindering (or even blocking) the transmission of electromagnetic communications? All these questions are valid as there is no scientific evidence to support otherwise. It’s very quiet out there, a fact that is bugging scientists quite a bit, and this problem been dubbed the Fermi Paradox.

The Milky Way is very old, in fact, the oldest star in our galaxy has been burning for 13.2 billion years (compare that with the age of the Universe at 13.74 billion years); you’d logically think that something resembling an intelligent civilization would have popped into existence in that time. If they did, surely we’d have detected them by now, wouldn’t we?

Actually, this spawns yet another debate: Have ancient interstellar alien civilizations come and gone? Was there a frenzy of intelligent life popping up all over the galaxy in the billions of years that our Sun was a proto-star surrounded by a proto-planetary disk? If old alien intelligence has since become extinct, our few thousand years as an evolving civilization is a mere spark in universal time scales. Could it be that we’ll have to wait until we can actually visit interstellar destinations first-hand to do the SETI equivalent of an archaeological dig, looking for alien artefacts? Perhaps SETI should be changed to the Search for Extraterrestrial Artefacts (SETA), where we’d have to look for evidence of alien civilizations past.

Dyson Microcosm by justravelin on DeviantArt

There’s another factor to consider. What if an advanced extraterrestrial civilization simply isn’t transmitting? If this is the case, perhaps we should consider a Search for Extraterrestrial Technology (SETT). In this case we could look for alien megastructures, searching for the stuff of science fiction. These structures could include examples of Dyson Spheres, huge alien-made hollow spheres containing a star; a means to harvest all the stellar energy for a vastly advanced civilization.

These are all options, and we shouldn’t close any possibility, no matter how extreme they may be.


There’s a reason why we haven’t received a signal via SETI, but we have no idea about what it could be. We really could be alone in the Milky Way. But then again, there’s a huge number of reasons why we might not be receiving a message from an intelligent species.

SETI may not be an interstellar switchboard, but the reasons for this are far from obvious. The theory that we are alone is just as valid as the theory that we are actually a part of a vast interstellar ecosystem. Until we have scientific evidence, we can’t say either way.

Could Active-SETI Learn From… Twitter?


The Search for Extraterrestrial Intelligence (SETI) has been an ongoing endeavour for the last 50 years. Detecting radio communications from an alien civilization would be the most profound event in mankind’s history; its effect would change the way we view our origin and our place in the Universe. It could mean that far from “being alone” we could be existing in a cosmic ecosystem, where life is more common than not and advanced extraterrestrial civilizations are no longer science fiction. A positive SETI signal would affect us globally; science, religion, society, daily life would alter radically.

Unfortunately, SETI is currently drawing up blanks. Apart from one or two inconclusive signs, it looks like we live in a dead part of the galaxy. Life As We Know It™ is an Earth-only affair. Who knows, we might be searching for another five decades and still be no closer to answering the question “are we alone?

Not to be too downhearted, scientists have been trying to make our presence felt by reversing SETI; we’ve been Messaging Extraterrestrial Intelligence (METI, a.k.a. “Active-SETI”) ever since we attached a plaque depicting the human form and a handy galactic map to Earth to the side of the Pioneer probes in the 1970s. Now we send a variety of radio signals to the stars in the hope of attracting ET’s attention.

But what signal do we send? Do we send a message with only good stuff from Earth? Or should we send a more gritty message, detailing our flaws as well as achievements? What actually makes a “good” METI signal in the first place?

Perhaps SETI could take some advice from the evolving social media scene, after all, when done right, there’s no more efficient way of conveying a clear message via 140 characters or less…
Continue reading “Could Active-SETI Learn From… Twitter?”

If There’s an Alien Race Living on our Doorstep, Why Can’t We Hear Them?

An alien civilization could be transmitting, but we can't hear them (© Steve Swayne via Flickr)

As I was watching Battlestar Galactica last night, I was thinking about the lack of alien civilizations in the show. To be honest, I tire easily of humanoid alien beings with curiously shaped heads synonymous with Star Trek et al., so I’m loving the fact a far-off human colony created their own evil race, the Cylons. So far, so good, I’m getting sucked into BSG (will it be as good as, or even better than Bablyon 5? That has yet to be seen, but it looks promising).

These thoughts took me back to an Astroengine article I wrote in November with my usual gripe about our obsession for looking under rocks on Mars (The Search For Life, What’s the Point?). I reached the conclusion that I’d much rather be pottering around in an empty cosmos, devoid of life, than bumping into an angry neighbour who wants to probe/assimilate/hybridize me. Science fiction musings I know, but it isn’t that far from some of the conclusions that could arrive from using the famous Drake equation that underpins our incessant search for intelligent extraterrestrial life.

Today, I was referred to some research addressing the Fermi Paradox, although we haven’t heard from our extra-terrestrial neighbours yet, doesn’t mean they’re not transmitting. The galaxy could be teeming with intelligent aliens, but we just can’t hear them
Continue reading “If There’s an Alien Race Living on our Doorstep, Why Can’t We Hear Them?”

The Search For Life, What’s the Point?

Another mission, another brave “search for life”…

Is it me, or does virtually every robotic foray into space have some ET-searching component attached? In the case of Mars exploration, every lander and rover’s prime directive is find life, evidence of past life, potential for life or the building blocks of life. Even the very first man-made artefact to land (crash) on the planet, the 1971 Soviet Mars 2 mission, was designed to find organic compounds and… any sign of life.

On writing an article yesterday (“Wasteful” Sample Storage Box Removed from Mars Science Laboratory), I started to think that we might just be trying a little too hard and spending too much money on this endeavour. Perhaps there’s another way for us to work out if we are, indeed, an interplanetary (possibly intergalactic?) oasis, or a component of a biological cosmic zoo…
Continue reading “The Search For Life, What’s the Point?”