(This is Part 3 of a series on Cherenkov radiation — the "light boom." Read Part 1 and Part 2 first.) We have our material — the crowd at the red carpet. We have our star particle — Brad Bradington. We have our paparazzi. Let's watch what happens. Brad steps out of his limo and walks at a nice, relaxed pace. The red carpet is absolutely packed — thousands of fans and photographers, crowding every inch. The people in the middle of the crowd and at the edges can't see the limo from where they're standing. So when Brad appears, only the people right next to him know he's arrived. And what do they do? They scream, they holler, they point their cameras and start snapping pictures. But only the ones nearest to him. The ones further back don't even know he's there yet. As Brad walks slowly down the carpet, word of his presence spreads outward in all directions — a ripple of recognition, expanding like rings on a pond.…