Next time you drive on a freeway, look up to see how many power lines you pass under. Most people never notice these, even on common commuter routes. But once you perceive one, you’ll be seeing them all over the place. What else works this way?
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Noticing little kids in strollers works the same way. Once you have your own, its hard not to notice other kids.
If you have the right radio receiver, you can hear the power lines as you pass under them.