In the early 1900s, physicists were struggling to understand the behavior of subatomic particles. They knew that these particles could behave like waves, but they couldn’t figure out how. Then, in 1905, Albert Einstein proposed his theory of special relativity. This theory showed that matter could be both a wave and a particle.

In 1923, French physicist Louis de Broglie proposed that all matter, not just subatomic particles, could be a wave. This idea was revolutionary, and it helped physicists to finally understand the strange behavior of subatomic particles. Together, Einstein and de Broglie laid the foundation for the field of quantum mechanics.

## Other related questions:

### Q: Who is Louis de Broglie How did he contribute to quantum theory?

A: Louis de Broglie was a French physicist who made several important contributions to quantum theory. In particular, he proposed that particles of matter have wave-like properties, and he developed the theory of wave-particle duality.

### Q: What did Albert Einstein contribute to quantum mechanics?

A: Albert Einstein was one of the founding fathers of quantum mechanics. He developed the theory of special relativity, which led to the development of the theory of general relativity. He also made important contributions to the understanding of the photoelectric effect, which is the basis of quantum mechanics.

### Q: What did Planck and Einstein contribute to quantum mechanics?

A: Planck and Einstein were two of the key figures in the development of quantum mechanics. Planck’s work on black-body radiation laid the foundation for the quantum theory, while Einstein’s work on the photoelectric effect showed that light could be quantized. Together, their work helped to create the framework of quantum mechanics.

### Q: What did Einstein think of quantum mechanics?

A: “Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us closer to the secret of the ‘old one.’ I, at any rate, am convinced that He does not throw dice.”