Thread: "The Great Silence"

Originally Posted by Atmoscheer

Are these probabilities even relevant within the limits of the Milky Way?

You mean the probabilities reflected in the terms of the Drake Equation?

Originally Posted by KT.

I'd like to point out that most people like to assume that if intelligent life is indeed "out there", it is more technologically advanced than that on Earth. But what if all nearby civilizations are developing technologically at relatively the same pace? Or what if we are the smartest kids on the block?

Intelligent life could be quite common in our galaxy. After all, the ancient Egyptians were intelligent but they weren't transmitting radio signals.

You are quite right. However, the Drake Equation specifically deals with civilizations that send detectable evidence of their presence into space (radio transmissions, for instance), not just with intelligent life or alien civilizations in general. From the point of view of the Drake Equation, a "civilization" doesn't count as such until it starts creating some sign that an observer in another star system could use to detect it's existence. But yes, if we built an interstellar space vehicle and flew around checking out planets that are home to tool-using aliens or alien civilizations, we would probably be just as likely (or more likely) to find civilizations that are less sophisticated than us, rather than more sophisticated. It really depends on how long a species survives on average after attaining our current level of technology, which of course we don't know. As Arthur C. Clarke famously said, we'll find "apes or angels" in most cases, rather than anything close to us in technological terms (and even that assumes that technological civilizations tend to develop into some transcendent state and then last for evolutionarily significant time scales; if this isn't the case, then it's just apes that are likely, rather than "apes or angels"). Hominids started using tools about 2.5 million years ago, but for more than 99% of the time since then, the tools didn't even involve metal. An alien spaceship visiting Earth at some random point during that 2.5 million years would most likely find stone-age savages, would have a quite slim chance (less than 1%) of finding bronze-age societies, an even slimmer chance of finding iron-age societies, and a vanishingly tiny chance of finding industrial societies. Even within the context of industrial societies, a couple centuries went by before we started building radio transmitters and receivers. Who knows how long we will keep it up. If we simply looked at planets that are home to life in general, without any stipulation of "tool-using" or "intelligent" or "civilizations", we would be stupendously unlikely to find even apes or angels, going by Earth's biological history. Just unintelligent animals (or whatever).

At any rate, yes it's true that tool-using life or intelligent life won't necessarily be more technically sophisticated than we are at the moment, but the Drake Equation takes that into account. It's an equation for calculating the number of communicating civilizations in the galaxy at a given time, not simply the number of intelligent or tool-using species.