How did Google's AlphaZero beat the world's best chess computer?

Google’s AlphaZero, after just four hours of training, last week trounced the highest rated chess engine in the world, Stockfish. How did it do this? 

From Zero to Master in Hours: AlphaZero Accelerates Reinforcement

Deepmind's AlphaZero shows unprecedented growth in AI, masters 3

DeepMind's superhuman AI is rewriting how we play chess

Google's AlphaZero Destroys Stockfish In 100-Game Match

Why Artificial Intelligence Like AlphaZero Has Trouble With the

Google's AlphaZero Destroys Stockfish In 100-Game Match

Computer chess - Wikipedia

AlphaZero - Wikipedia

AlphaZero achievement in chess a quantum leap for artificial