The number of elementary particles is not a local hidden variable. In other words, the reality of an "elementary particle" does not exist before measurement.

Everything in our bodies and the objects around us is made of elementary particles such as electrons and quarks. In our daily sense, we tend to think that these elementary particles exist in specific locations, but this idea of "local realism" has been refuted by experimental verification of the violation of Bell's inequality in quantum mechanics. It is a shocking fact, but elementary particles are not things that "exist there."

If elementary particles were classical realities, they would have to be local realities that "exist there," and in that case, the elementary particles should be described by classical realistic parameters called "hidden variables." However, the violation of Bell's inequality in quantum entangled states has refuted the existence of such hidden variables. Today, it is more natural to view all things with diverse characteristics made from elementary particles not as realities, but as quantum information.

Whether an elementary particle exists or not is characterized by the number of such particles. If the number of elementary particles is zero, it means a vacuum state, which signifies "nothingness." If the number of elementary particles is one or two, it signifies "existence." Furthermore, in quantum mechanics, there exists a linear superposition state of the vacuum state and the particle state. In other words, a state that is neither "nothing" nor "something" actually exists. Using this quantum superposition of the number of elementary particles, it is possible to create quantum entanglement between a state with zero elementary particles and a state with a finite number of particles in a spatial region A and a distant spatial region B, but in that state, the Bell inequality required by the premise that "objects exist there" is violated. What this means is the surprising reality that the value of the number of elementary particles is not determined before measurement; furthermore, the value of the number of elementary particles itself did not exist before measurement. The phenomenon of whether an elementary particle is there or not emerges during the measurement process, and before measurement, the elementary particle does not exist there.

In the first place, elementary particles are excitations of what is called a "quantum field." This quantum field is a local physical degree of freedom associated with each point in space. For example, the excitation of a quantum electromagnetic field is an elementary particle called a photon.

This quantum field can be compared to a collection of elements that emit the three primary colors of light arranged at each location on a monitor. And an element that is lit up by an input electrical signal is considered an elementary particle at that location. For example, A and B lit up in Figure 1 indicate elementary particles that existed at those locations.

Changing the location of these lit elements represents the movement of elementary particles in space. At the same time as turning off the power to the original element, you turn on the power to one adjacent element. Then, it should look as if the elementary particle has moved to the next location. In reality, objects are not moving; the location of the blinking elements is simply being controlled by a program while preserving the number of lit elements. When this is applied to the "elementary particles" A and B in Figure 1, A and B indeed move as shown in Figures 2 through 4. This is the analogy of elementary particles in a quantum field.

If this quantum field itself were a reality, logically, the elementary particles that are its excitations would also have to be realities. However, the reality of those elementary particles has been refuted by the existence of quantum entanglement. Therefore, the reality of the original quantum field is also refuted. Using the analogy of elements lighting up on a monitor, the local reality of elementary particles like A and B was refuted first. If that is the case, it means that the original monitor elements themselves were not realities that existed there. If the elements were realities, A and B should also be realities, but since that has been refuted, the elements themselves are not realities either.

This fact of modern physics also applies to our bodies, which are collections of elementary particles. In other words, our bodies also did not exist there from before measurement.

Modern physics is not an interesting story about some distant world, but a story that is truly "about us," and it shakes our very existence. The fact that many people were unaware of this shocking truth, which the violation of Bell's inequality implies, was one of the reasons I wrote "What is Nothingness" (Masahiro Hotta, SB Shinsho).