All together it was a huge achievement. What matters is that your theory predict what occurs in experiments. It has survived all tests and there is no reason to believe there is any flaw in it. After it was realized that light could act as either a wave or a particle french physicist De Broglie proposed that matter could also act as either a particle or a wave. There is one simplification at least.
Lets review some important wave properties.
Waves can interfere with each other. In constructive interference, the two waves reinforce each other to produce a larger-amplitude wave. However, in destructive interference, the two waves exactly cancel out. In the 1920's experiments show that you can shoot a beam of atoms at a double slit apparatus and it will also produce an interference pattern. Even if you only let one atom go at a time the interference pattern will slowly emerge.