Why Nothing Can Outrun Light
▶ DRILLGeorge flips a switch and a signal lights Liza's lamp — cause, then effect. Keep the signal at or below light-speed and everyone agrees on that order, even Vikazooming past. But push the signal faster than light and Vika sees the lamp light up before George flips the switch — the effect before its cause, an answer before the question. The universe forbids that, so the speed of light isn't just fast: it's the limit that keeps cause before effect. Use the Explain it for a kid / a grown-up switch to set the depth.
The big idea — the speed of light isn't just "really fast" — it's the ultimate limit, and here's the deep reason: if anything went faster, a zooming observer could see an effect happen before its cause — an answer before the question, a lamp before the switch. The universe doesn't allow that, so nothing — no object, no signal, no message — can beat light. And remember from "Why You Can't Add Velocities": you can't even reach light-speed by stacking speeds. This is the keystone that holds all of special relativity together.