Caesium

These contain cesium-137, which biological systems think is calcium.

No, wait a minute.

Cesium...

Cesium, the body thinks, is potassium, and so it gets into your muscles and ultimately causes what's called cesium heart.

It'll burn holes in your heart muscle.

Plutonium isotopes, tritium, some of these can persist for thousands of years.

Now, there's a little bit of like a science thing going on.

Different elements burn at different temperatures, right? Now, the menus are made mostly of cesium.

Cesium burns at an incredibly low temperature.

You don't need to get them that hot.

So we basically just put them sort of near the source four lights up there and they go up in flames.

That's, that's, that sounds good.

Cesium, uh, so the cesium 137, um, there's a electron transition between two energy levels that has a very precise frequency, okay? Very precise.

You can measure...

What's good about that is any lab can get some cesium and measure this, and then define the length of a second in their lab, okay?