4 ms·

You don't think making an antenna that can detect an LED shining in a flat miles away is crazy because pockets are transparent?

• swiley 7y ago
  No. Amateur radio operators have done it, and it’s not difficult to imagine how one would.
  • StavrosK 7y ago
    Indeed, nothing is difficult to imagine how to do if the method is common knowledge.
  • burnte 7y ago
    That doesn't make it any less amazing.
• lolc 7y ago
  In darkness our eyes can easily detect a 1W LED from kilometers away.
  • StavrosK 7y ago
    But can they distinguish a specific 300 mW LED in a stadium with tens of thousands of other LEDs next to it?
    • pcnix 7y ago
      If it were a different color, yes. If each of them were a different color, your eye would still be able to, as long as you had enough focus. So the analogy holds pretty well.
    • swiley 7y ago
      My understanding is that healthy human eyes are able to detect individual photons.