Once deemed impossible, physicists have discovered the existence of very unusual elementary particles.

All fundamental elementary particles in the Universe are categorized into two groups: fermions and bosons. An older theory suggested the existence of a third group — para-particles. Physicists have since dismissed this theory, concluding that such particles cannot exist. However, the authors of a new study published in the journal Nature have suggested that para-particles do exist, but they are yet to be discovered, as reported by New Scientist.

Fundamental Particles: Fermions vs. Bosons — What’s the Difference?

The theory proposing that there may be another group of particles in the Universe, in addition to bosons and fermions, known as para-particles, emerged in the mid-20th century. First, it is essential to understand that the distinction between fermions and bosons lies in how two particles within the same group can switch places. For instance, the exchange of bosons, such as photons, does not alter their quantum wave function. This wave function serves as a complete mathematical description of particle properties in quantum mechanics. In contrast, the exchange of fermions, such as electrons, alters their quantum wave function, making it negative. This indicates that an infinite number of bosons can occupy the same space, while fermions must always be separated in space.

Impossible Particles

A more complex model of particle exchange, proposed in the mid-20th century by physicist Herbert Green, called parastatistics, suggested that the quantum wave function could be modified in entirely different ways compared to fermions and bosons. Consequently, the scientist hypothesized the existence of para-particles in the forms of para-bosons and para-fermions.

According to the para-particle theory, only a specific number of particles can exist in the same quantum state, rather than just one or an infinite number. Later, physicists rigorously examined this theory and concluded that para-particles would not behave differently from fermions and bosons, indicating that their existence is impossible.

Para-Particles Exist, But There’s a Problem

The authors of the new study concluded that para-particles may indeed exist physically. Physicists assert that there is a third group of elementary particles in addition to fermions and bosons. They have devised a new mathematical description of para-particles, which includes more stringent rules than previous definitions. Following this, physicists demonstrated that certain quantum systems should give rise to para-particles in the form of oscillations, thus allowing their physical existence to be confirmed through observations.

This research faces several challenges. Physicists have only shown that para-particles can exist in one or two dimensions, but their existence in three dimensions cannot be ruled out. Another issue is that the para-particles discussed by scientists are technically quasiparticles. This means they are not fundamental particles like electrons or photons. Instead, these quasiparticles represent collective oscillations that behave as if they were particles.

At the same time, physicists believe that para-particles could exist as fundamental particles since mathematics does not exclude this possibility, though it remains unclear where or how they might manifest. Nevertheless, the authors of the study are optimistic that para-particles can be detected. However, it is still uncertain what practical applications these particles might have if they are discovered.