As Carl Sagan memorably put it, the Drake Equation tells us that only a few worlds out there might have been suitable to support an intelligent civilization. And of that small number, only a "pitiful few" technological civilizations would have been able to "avoid the trap jointly set by their technology and their passions."

In other words, after billions of years of "torturous evolution," an intelligent civilization might finally come about, only to "snuff themselves out in an instant of unforgivable neglect."

So what are the chances that we could make contact with such a civilization via radio signal covering vast expanses of the Milky Way Galaxy? 

Unless more than a few intelligent civilizations could learn to survive their "technological adolescence" without destroying themselves, the chances would be slim to none. 

If we take this pessimistic - or one might simply call it realistic - view, then we might want to rethink our search for evidence of intelligent life in deep space. As Paul Gilster writes in Aeon Magazine:

Interstellar archaeologists are looking for evidence of engineering on scales that dwarf our own. They assume that civilisations eventually build technologies capable of exploiting the energy resources of entire stars. They are building on the early work of the Soviet astronomer Nikolai Kardashev, who, in 1964, set about categorising these futuristic civilisations. His scheme, called the Kardashev Scale, has three types, and so far humanity does not even rate as a Type I — a civilisation that can master the energy resources of its entire planet. A Type II culture can tap all the resources of its local star, and a Type III can harness the energy of an entire galaxy. We do not, of course, know if any civilisation other than our own exists, but Kardashev’s scale offers us a way of approaching the problem of detection: it gets us thinking about what kind of traces these advanced civilisations might leave behind.

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