Stephen predicted with Roger Penrose that the densest objects in our Universe, black holes, emit radiation. Radiation is energy that moves from one place to another, like light and sound waves.

While researching theoretical physics at the University of Cambridge, Stephen was diagnosed with an early-onset, slow-progressing form of motor neurone disease that over many years made it increasingly difficult for him to move. This didn’t stop his amazing contributions to science, however. He also wrote several children’s books with his daughter, Lucy, that combine science and adventure. They are about a young boy named George, who learns about the universe by travelling around it.