Chinese team tackles a century-old puzzle in physics: can we travel back in time?

Chinese researchers have proposed a simple yet powerful theory to explain one of physics’ oldest puzzles: why time only moves forward and why travelling to the past remains impossible. Physicist Cai Qingyu and his team at Hainan University in southern China have developed a fresh explanation at the quantum level for why we cannot unscramble an egg or grow younger, even though the laws of physics perfectly allow time to go backwards. Unlike earlier theories, their framework does not rely on...