Final answer:
Louis de Broglie predicted that all matter can behave as waves as well as particles.
Step-by-step explanation:
Louis de Broglie predicted that all matter can behave as waves as well as particles. This prediction is known as the wave-particle duality, which is a fundamental concept in quantum physics. De Broglie's hypothesis was later confirmed by experiments, establishing a key principle in understanding the behavior of matter at the atomic and subatomic levels.
Learn more about Wave-particle duality