(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. If you had a bird’s-eye view, you’d see Brad moving through the crowd with these expanding rings of camera flashes around him, centered on wherever he happens to be.

Inside the material, this is a charged particle moving at a modest speed. It carries an electric field with it — a celebrity aura — and as it passes, it disturbs the atoms and molecules nearby. They stretch and squeeze and twist under the influence of that field, then snap back into place and release a tiny flash of light. These flashes radiate outward in all directions from wherever the particle is.

When the particle is moving slowly, the flashes from all directions are roughly in phase with each other. They overlap and interfere and largely cancel out. You don’t get a coherent glow. Nothing special happens.

But let’s say Brad Bradington is in a hurry.

Maybe he’s late. Maybe he hates crowds. Maybe he really has to pee. Whatever the reason — he leaps out of the limo and absolutely barrels for the entrance. Shoving people. Elbowing through. Zero regard for personal space.

The key: the paparazzi have a reaction time. Before they can snap a picture, they have to KNOW Brad is there. And the speed at which that knowledge travels — the speed at which the information “Brad Bradington is right here, right now” can reach a photographer’s eyes — is the speed of light in this material.

If Brad is moving slower than that speed, everything is orderly. He’s walking, light is running ahead of him, the paparazzi in front have plenty of warning, they fire from all directions, the flashes cancel out, no special glow.

But if Brad is moving FASTER than the local speed of light?

Then the paparazzi directly in front of him have no warning whatsoever. Zero. By the time any light from Brad reaches them, he’s already blown past. They only ever get a shot from behind, or from the side as he’s already gone.

Every single flash — the light released by every atom and molecule disturbed by Brad’s passage — is now entirely behind him. Instead of spreading out equally in all directions and canceling into nothing, they all pile up together. They reinforce each other. They add into a coherent wave, a shock front of light, spreading out behind the particle in a V-shaped cone.

It’s exactly like a sonic boom. When a jet aircraft exceeds the speed of sound, the sound waves it produces can no longer outrun it — they pile up into a pressure shock wave that you experience as a sudden violent crack. Cherenkov radiation is the same phenomenon, with light instead of sound. The particle drags a cone of coherent electromagnetic radiation behind it as it moves.

A sonic boom, but made of light.

A light boom.

THIS is what Pavel Cherenkov saw glowing blue in his bottle of water in 1934. The gamma rays hitting the water were knocking electrons loose and accelerating them to speeds faster than light moves in water — and those electrons were painting a cone of blue light as they went, over and over, billions of times per second, until the whole bottle glowed.

The blue color is not a coincidence, and it’s worth pausing on.

Cherenkov radiation produces light across a range of frequencies, but the intensity increases toward shorter wavelengths — toward blue and ultraviolet. The physics behind this involves the way different frequencies of light interact with a medium, but the short version is: the higher the frequency, the more coherently the radiation adds up, and the stronger the glow. Blue and violet win. Which is why every photograph of Cherenkov radiation you’ve ever seen — reactor pools, particle detectors, medical imaging — has that same particular, eerie, unmistakeable color. Not purple, not white, not green. Blue. Always blue.

Pavel Cherenkov got a Nobel Prize in 1958. Twenty-four years after he stared at a glowing bottle of water and decided, for no good reason except good scientific instinct, that it was worth understanding.

Not bad, Pavel.

In Part 4, we find out what Brad Bradington is actually good for — from the cores of nuclear reactors to a cubic kilometer of ice at the South Pole.

A young great horned owl discovered at the base of a palm tree in Redondo Beach has prompted police to release a public service announcement video to educate residents on how to respond to such fledgling birds.

The owl was brought in by Redondo Beach Animal Services after it was found on the ground, a situation that may appear concerning but is often part of a normal development stage for young owls, according to Redondo Beach Police Det. Evelo, who did not provide her full name.

In the video, Evelo said the goal is to educate the public about what to do when encountering young owls.

“At this age where they have flight feathers or fledging feathers, they’re starting to branch out and learn how to fly and move around,” Evelo said.

She noted that Redondo Beach’s local geography can make this stage more difficult.

“Unfortunately in Redondo Beach we have a lot of palm trees and that’s not a great home for owls because there’s no branches for them to start learning how to fly,” she said. “You’ll find that at this age these owls will actually fall to the ground and that’s where they’ll do all their learning.”

According to the nonprofit Owl Research Institute, this stage is known as fledgling, when young birds leave the nest before they are fully capable of flight and begin exploring their surroundings. During this time, the owls are still under parental care. This period could last weeks.

“Don’t worry, their parents are still taking care of them. You’ll see mom and dad still coming down to feed them,” Evelo said.

The video also advises residents not to approach or touch owl fledgings and to keep pets and children away to avoid stressing the bird.

“Don’t be alarmed if you see them, just leave them where they are,” the detective said.

However, she said anyone who finds a young owl should not hesitate to call the Redondo Police Department Animal Control if it looks like a dog or another animal is going to get to them.