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Why Aliens Are Not Calling us?

We’ve been trained by television and movies to admit the possibility of intelligent life somewhere else in the universe. “Of course there’s intelligent life out there; I saw it last week on Star Trek.” We’ve witnessed it all, from the cute and cuddly ET to the fanged horror of Alien.

But is it possible that we’re not all by ourselves in the universe? And if intelligent life is out there, why haven’t they communicated with us yet?

The first individual to talk about this question in an organized way was Frank Drake, who created the Drake equation to forecast the number of extra-terrestrial civilizations in the galaxy. His equation is rather complex, but here’s an easy form of his argument.

First, let’s total how many stars are in the galaxy. To quote one of my predecessors, “Billions upon billions!” And how many of those stars have planets? Until now, we actually didn’t know. But over the past 20 years, astrophysicists have made extraordinary development in finding planets around other stars. We now know that many stars have planets circling them

Could beings in fact live on any of those planets? Many of them are just huge balls of gas, or else too hot or too cold to comprise liquid water, which is the foundation of all life on Earth. But a few of them do appear to be at the correct temperature. These are the Goldilocks planets: not too hot and not too cold for liquid water. (And that’s deprived of even seeing the likelihood that exotic forms of life could live without water.)

Now we enter darker territory. How probable is it that life will evolve on a possibly habitable planet? We don’t know the answer, but life on Earth got going soon after the creation of our solar system, and it has stuck itself into every accessible place, no matter how hostile.

Colonies of strange beings flourish in continuous darkness near deep ocean vents, where superheated sulphur-rich water discharges from under the ground. Radiation-resistant bacteria lie favourably in levels of radioactivity that would rapidly kill a human being. And then there’s the Tardigrade, which appear like a microscopic eight-legged teddy bear that can live in liquid nitrogen or boiling alcohol. So the likelihood of life emerging on inhabitable worlds appears very high.

Another prospect is that intelligent life inevitably destroys itself. Until recently, our choices for total self-destruction were restricted to nuclear weapons. But we are on the verge of increasing our fleet to contain genetically engineered viruses.

And consider the threats posed by nanomachines, tiny self-replicating robots encoded to convert matter into more robots. Picture a tiny robot, no larger than the width of a human hair, programmed to deliver some useful function, designed to build a copy of it, using materials from its environment. Now you have two machines, and both can make copies, giving us four machines. But what if this development got out of control? The nanomachines could quickly devour the entire Earth, transforming it, along with everyone on the planet, into “grey goo.” British astrophysicist Martin Rees debates these and other disastrous possibilities in his book, Our Final Hour. Have all our possible alien guests surrendered to self-destruction?

Or is it probable that the galaxy actually does contain other forms of intelligent life, but something stops contact with us? Here we enter the land of more hypothetical ideas. (Translation: when a researcher says “hypothetical,” it in fact means “a very stimulating concept that’s only one step removed from total nonsense.”)

Among the more hypothetical prospects: maybe the galaxy is a dangerous place, full of robotic probes sent out by unfriendly ETs to wipe out any rivalry, so everyone else is in hiding. Maybe we actually should not have put a thorough description of the location of our solar system on our own space probes. It’s a bad notion to reach out and attempt to touch ET when we might get a call from the Alien instead.

An even stranger proposal is that superior civilizations have decided not to communicate with lesser creatures such as ourselves, so that we live in a kind of intergalactic zoo, with a “Do not talk to the animals” board.

Some have even proposed that we live in a huge computer simulation, Just like The Matrix.

A lengthier list of prospects (along with a sceptical discussion) has been assembled by astrophysicist Milan Ćirković.


Without more data, the Fermi paradox will continue, for now, unsettled, and many of the suggested solutions will have to be categorized as “speculative.” And now you know precisely what that means.