Perhaps even more damning to pilot-wave theory is the fact that it doesn't account for the theory of relativity. The most recent and famous being John Stewart Bell's theorem, which concludes that, 'No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics.' This does not necessarily mean that pilot-wave theory is incorrect, but it requires that any hidden variables exist across the wave function rather than applying only to the particle. This is a controversial idea, although it was famously supported by Einstein, who once declared, 'I am convinced God does not play dice.'īut despite Einstein's reservations, multiple mathematical theorems have all but proven that hidden variables cannot explain away all of the bizarre behaviors seen in quantum mechanics. This is counter to the general idea of quantum mechanics, which states that the course of the individual particle is fundamentally random, or probabilistic.įor one, pilot-wave theory requires that 'hidden variables' exist to describe the properties of the particles-variables that we cannot, or haven't yet determined that would explain the probabilistic results of quantum experiments according to the rules of classical physics, removing the randomness. If we could only know all the properties of the particle-its velocity, direction, location, etc.-then we could accurately predict where it is going to ultimately land. Pilot-wave theory, alternatively, says that physical waves exist in addition to the particles and create kind-of tracks for the particles to follow. But when you shoot a single photon particle through the double slits, it still creates the interference pattern even though there is nothing to interfere with it, leading most physicists to conclude that the particle simultaneously exists as a non-physical wave function. When light is shone through two parallel slits, the light waves run into each other on the far side and create a pattern-called an interference pattern-on the surface it hits. Take the double-slit experiment for example. Pilot-wave theory argues that particles don't also exist as probabilistic waves, but that there are both real particles-which always have definable properties-and real waves influencing how the particles move. Until the particle is measured, causing the wave function to 'collapse,' that matter really does exist with all possible properties.īut there is one theory that does not require you to accept these wacky ideas about matter: The De Broglie–Bohm pilot-wave theory, which is the subject of a great new episode of PBS's Space Time.

The wave function is a representation of all the possible quantum states of a particle. These various properties of atomic particles are called quantum states, and the theory of quantum superposition says that particles can exist in multiple quantum states at once. They model this mathematically by using wave functions-equations that have multiple values that make them true.

To put it simply, physicists generally grapple with this odd behavior of particles by accepting that matter can in fact exist with multiple properties at once. Particles can exist in two different places at once, and particle-like interferences in space are thought to leap in and out of existence. On the atomic and subatomic scale, matter seems to behave in ways that we, in the macro world, would generally think of as impossible.

Louis de broglie atomic theory