Q. What's going on these days to throw a whole new light on the old Frank Drake equation for estimating the probability of alien civilizations in space?
A. That well-known equation (1961) argues for a galaxy full of sentient life, yet no artificial signal has been detected and we wonder why, says Huntsville, Ontario letter-writer Grant Hallman in “Scientific American” magazine. The implicit assumption is that such a civilization would emit radio signals we could both detect and recognize during its entire lifespan, but here on Earth, we can already see the failure of that assumption in two ways:
First, after less than a hundred years of beaming transmissions, the day of the 50-kilowatt broadcast antenna is ending, as our communications technology advances to coaxial, fiber-optic, and short-range low-power systems. Even geosynchronous satellite communication is aimed down, “parsimoniously covering only a portion of Earth's surface.”
Second, every broadband medium is moving to a digital format with data compression, which removes redundancies — that is, any recognizable pattern in the signal — in favor of compact digital code.
“I can only conclude,” Hallman writes, “that we could be sitting in the midst of a ‘Galaxy-Wide Web' of alien chatter, which to us, without the algorithms to decode it, appears like noise.”
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