orm 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.
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.