One of the oft-noted problems with the Drake Equation was the many ways it assumed that alien worlds would look, not just like Earth, but mid-twentieth century earth including our proclivity for constantly pumping out radio signals...
and would continue to look that way between 1000 and 100,000,000 years.
It appears that Earth at least will fall a little short of that range.
“The search for extraterrestrial intelligence [Seti] is changing,” he said. “We have relied in the past almost exclusively on radio telescopes to detect broadcasts from alien civilisations just as our radio and TV transmissions could reveal our presence to them. However, to date, we have heard absolutely nothing.”
Nor should we be surprised, [Oxford University astrophysicist Prof Chris] Lintott argues. “Humanity has already passed its peak radio wave output because we are increasingly using narrow beam communications and fibre-optic cables, rather than beaming out TV and radio signals into the general environment.”
Humanity could become radio-quiet in about 50 years as a result – and that will probably be true for civilisations on other worlds, he added. “They will have gone radio silent after a while, like us. So Seti radio telescopes will need to be augmented with other ways of seeking aliens. We are going to have to be more creative about what we’re searching for in the data and find unusual things that reveal they are the handiwork of aliens.”
Nor is Lintott the first to make this observation.
Regarding the first point, in a 2006 Sky & Telescope article, Seth Shostak wrote, "Moreover, radio leakage from a planet is only likely to get weaker as a civilization advances and its communications technology gets better. Earth itself is increasingly switching from broadcasts to leakage-free cables and fiber optics, and from primitive but obvious carrier-wave broadcasts to subtler, hard-to-recognize spread-spectrum transmissions."
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