The droplet experiments provide an intriguing analogue or “toy model” for de Broglie’s pilot waves, but there is still no direct evidence of pilot waves at the quantum scale. “Time will tell whether the quantum-like behavior of the walking dropets is mere coincidence,” Bush told me via email. Also, the theory is currently limited to describing the simplest interactions between particles and electromagnetic fields. “It is not by itself capable of representing very much physics,” Oxford University physics philosopher David Wallace told Quanta earlier this year. “In my own view, this is the most severe problem for the theory, though, to be fair, it remains an active research area.”

Nobody is claiming that quantum mechanics is wrong; there is too much experimental evidence that the equations do make accurate predictions about how things work at the subatomic scale. But the implications of the standard interpretations remain troubling. The pioneers of quantum mechanics came up with the most plausible theory they could, given the resources they had, and they transformed modern physics in the process. Contemplating the possibility of pilot wave theory might lead to a fresh interpretation of quantum weirdness, one that prompts physicists to rethink their longstanding assumptions about the true nature of the quantum world. Another transformation could be lurking in the wings.

Go Deeper
Author’s picks for further reading

Cocktail Party Physics, Scientific American: The Photon Has Two Faces
Jennifer Ouellette on quantum interference, the wave-particle duality, and that “cheeky over-achieving upstart” Thomas Young.

Quanta: Fluid Tests Hint at Concrete Quantum Reality
Natalie Wolchover on macroscale analogs for pilot wave physics.

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