As invisible as radio signals then.
Now now... Let's be fair...
Radio broadcasts to everyone.
Light you can block off to a single direction.
Oh wait, directional radio antennas exist. Nevermind, yes. Exactly like radio waves.
alt Hacker News
Now now... Let's be fair...
Radio broadcasts to everyone.
Light you can block off to a single direction.
Oh wait, directional radio antennas exist. Nevermind, yes. Exactly like radio waves.