Contact popularized the idea of aliens
listening in on our broadcast media.
Sadly, the odds are against it.
Here’s the problem: Space is really big.
You can work through the physics of
interstellar radio attenuation, but the problem is captured pretty well by
considering the economics of the situation: If your TV signals are getting to
another star, you’re wasting money.
Powering a transmitter is expensive, and creatures on other stars aren’t
buying the products in the TV commercials that pay your power bill.
The full picture is more complicated, but the bottom line is that as our
technology has gotten better, less of our radio traffic has been leaking out
into space. We’re closing down the giant
transmitting antennas and switching to cable, fiber, and tightly focused
cell-tower networks.
(from What If?:
Serious Scientific Answers to Absurd Hypothetical Questions by Randall Munroe)
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