Quantum physics likely suggest to us that particles are lack of basic properties such as the definite location. There is an idea that nature is inherently probabilistic. So, particles have hard properties and this idea becomes the standard equations of quantum mechanics. Surprisingly, there is a new set of experiments with fluids with the finding revived the old skepticism about the worldview. The results are like digging the forgotten version of quantum mechanics up.

## About The Experiments

So, scientists used oil droplets and the droplet then bounced along the surface of a liquid. What happened here was the droplet gently sloshed the liquid every bounce. Ripples from the past bounces then affected the course. This experiment created droplet’s interaction with its ripples and we called it as the pilot wave. The wave exhibited the elementary particles, such as behavior with no specific location until scientist measured it.

So, particles at the quantum scale could do something more than human-scale objects. They can tunnel through the barriers, appear or annihilate spontaneously, or occupy the discrete energy levels. From this new research, it reveals that oil droplets, when waves guide the droplets, they can exhibit the quantum-like features. Some scientists from these experiments suggest that quantum objects are the same as droplets. Pilot waves guided them and it is like fluid undulations in time and space. Of course, these arguments added a new life into a theory of the microscopic world that was proposed and rejected when quantum mechanics were born. The man behind these droplet experiments is John Bush, a professor of applied mathematics at the Massachusetts Institute of Technology.

## The Magical Measurements

There is an old view of quantum mechanics scientist called it as the “Copenhagen interpretation”. It was when Danish physicist Niels Bohr, one of the architects argues that particles are able to play out all possible realities at the same time. Each particle is a “probability wave”. So, when scientists measured the particle, the wave will collapse into a definite state. It is more about how the calculations work, not about how the properties of particles solidify at the moment of measurements.

## The Riding Waves

The pilot waves perhaps can exp0lain the peculiarities of particles related to quantum mechanics. Louis de Broglie, the French physicist presented the first version of the pilot-wave theory, back in 1927 at the Solvay Conference in Brussels. It was a popular gathering of the founders of the field. There, Broglie explained to Bohr, Erwin Schrodinger, Albert Einstein, Werner Heisenberg and others physicists about pilot-wave theory. He believed that the theory made all the same predictions of the probabilistic formulation of quantum mechanics that refer to “Copenhagen” interpretation in the 1950s, but without mysterious collapse.

Bohr then championed the probabilistic version that involves a single equation that represents the locations of particles as peak and a wave’s troughs. Also, Bohr interpreted that this equation is a complete definition of the particle. But, de Broglie urged them to use two equations: First to describe the real and physical wave while another is to tie the trajectory of an actual particle to the variables in that wave equation since the wave interacts and propels the particles. Nevertheless, the pilot-wave theory is deterministic. It means that the future evolves dynamically from the past. It means if the exact state of all particles in this universe were recognized at a given instant, we could calculate their states at all future times.

In 1932, Hungarian American mathematician, John Von Neumann claimed that he had the evidence about probabilistic wave equation in quantum mechanics have no hidden variables or missing components like the particles of de Broglie with its trajectory. He also argued that pilot-wave theory was so poor so most physicists believed in his proof. Up to 30 years, von Neumann’s proof was shown false. At the same time, David Bohm, a physicist revived pilot-wave theory in the modified form in 1952. Einstein was the man who supported, and he made clear that it did work, but never caught on. This theory is also popular as Bohmian mechanics or de Broglie-Bohm theory.

Next, the Northern Irish physicist John Stewart Bell believed in pilot-wave theory. He could tell the world about the flaws in the original proof provided by von Neumann. Then, he wrote that the pilot-wave theory was so natural and simple to resolve the wave-particle dilemma in a clear way. He wrote this in 1986.

Many decades that people ignored about this thing until Sheldon Goldstein, a professor of mathematics, physics, and philosophy at Rutgers University, and the supporter of pilot-wave theory, together with several others noted that researchers risk their careers when they are questioning about quantum orthodoxy.

## Quantum Drop

Finally, the pilot-wave theory did its minor comeback. Milewski said that he wished the people who were developing the pilot-wave theory had access to the experiments since the whole history of quantum mechanics could be different.

A decade ago, experiments started when Yves Couder and his colleagues at Paris Diderot University found that vibrating a silicon oil bath tup and down at the particular frequency will induce a droplet to bounce along the surface. They found the droplet’s path that was guided by the slated contours of the liquid surface. The liquid surface is generated from the droplet’s bounces. So, there is a mutual particle-wave interaction that is related to de Broglie’s pilot-wave theory.

Also, there is a groundbreaking experiment done by Paris researchers. They demonstrated the single-and double-slit interference by using the droplet setup. They found that when a droplet bounces toward a pair of openings in a dam-like barrier, it can pass through only one slit or the other. Meanwhile, the pilot wave passes through both. They did repeated trials and showed that the overlapping wavefronts of the pilot wave steer the droplets to certain places but not locations in between. This is a clear replication of the interference pattern in the quantum double-slit experiment.

How does the quantum statistic look apparent?

In one recent test, Couder and his friends placed a magnet at the center of their oil bath. They observed the magnetic ferrofluid droplet. They discovered that the bouncing droplet adopted a discrete set of stable orbits around the magnet with a set of energy level and angular momentum. It is like an electron occupying the fixed energy levels when it comes to the nucleus.

If we talk about the standard quantum mechanics, the effect is the instantaneous collapse of the particle’s joint probability wave. On the other hands, when it is about the pilot wave version of events, there will be an interaction between two particles in the superfluid universe sets them on the paths that stay correlated forever. It is because the interaction will affect the contours of the superfluid permanently.

## Subatomic Realities

In the end, quantum physicists tend to have less significant findings. The fluid research cannot provide the direct evidence that pilot waves propel particles at the quantum scale. Their analogy between electrons and oil droplets cannot provide new or better calculations as it is explained by Gerard‘t Hoof, a Nobel Prize-winning particle physicist at Utrecht University, Netherlands. He argued the quantum theory is incomplete but he cannot go with pilot-wave theory.

So far, the pilot-wave formulation of quantum mechanics just describes the simple interaction between matter and electromagnetic fields. This is an argument stated by David Wallace, a philosopher of physics from the University of Oxford, England. He added that they cannot capture the physics of the ordinary light bulb.

Pilot-wave theory is more cumbersome compared to standard quantum mechanics. According to some scientists, the theory has trouble with identical particles and becomes unwieldy to describe multiparticle interactions. Also, they claimed that it needs something more to combine with special relativity. On the other hands, other specialists in the quantum mechanics disagreed because the approach is under-researched. It could be about the matter of recasting the predictions of the quantum mechanics in the pilot-wave language.