North Korea changes nuclear posture: what it means

This is the moment a nuclear reactor awakens for the first time. When the core powers on, it fills with a deep blue glow that rises through the water. It looks unreal, but it’s pure physics. That light is Cherenkov radiation. It happens when charged particles from nuclear fission move through water faster than light can travel in that medium. The particles break the “light speed limit” for water and shed energy as that signature blue glow. The effect was discovered in the 1930s and it lets us li