Apr 12, 2025 07:49 PM
https://www.quantamagazine.org/paraparti...-20250411/
EXCERPTS: When the paper appeared, Markus Müller, a physicist at the Institute for Quantum Optics and Quantum Information in Vienna, was already contending with the notion of paraparticles for a different reason. According to quantum mechanics, an object or observer can be in multiple locations at once. Müller was thinking about how you can, on paper, switch between the perspectives of observers in these coexisting “branches” of reality. He realized that this came with new constraints on the possibility of paraparticles, and his team described their results in a preprint in February that’s now under review for publication in a journal.
The close timing of the two papers was a coincidence. But taken together, the work is reopening the case of a physics mystery that was believed to be solved decades ago. A basic question is being reevaluated: What kinds of particles does our world allow?
All known elementary particles fall into one of two categories, and the two behave almost as opposites. There are the particles that make up matter, called fermions, and the particles that impart the fundamental forces, called bosons.
The defining characteristic of fermions is that if you switch the positions of two fermions, their quantum state gains a minus sign. The presence of that measly minus sign has enormous ramifications. It means that no two fermions can be in the same place at the same time. When packed together, fermions cannot be compressed past a certain point. This feature prevents matter from collapsing in on itself — it’s why the electrons in every atom exist in “shells.” Without this minus sign, we couldn’t exist.
Bosons have no such restriction. Groups of bosons will happily all do exactly the same thing. Any number of particles of light, for instance, can be in the same place. This is what makes it possible to build lasers, which emit many identical light particles. This ability comes down to the fact that when two bosons swap places, their quantum state stays the same.
It’s not obvious that fermions and bosons should be the only two options.
[...] In theory, quantum particles can also have hidden internal states, mathematical structures not seen in direct measurements, which also go away when squared. A third, more general category of particle, known as a paraparticle, could arise from this internal state changing in a myriad of ways while the particles swap places.
While quantum theory seems to allow it, physicists have had difficulty finding a mathematical description of a paraparticle that works... (MORE - details)
EXCERPTS: When the paper appeared, Markus Müller, a physicist at the Institute for Quantum Optics and Quantum Information in Vienna, was already contending with the notion of paraparticles for a different reason. According to quantum mechanics, an object or observer can be in multiple locations at once. Müller was thinking about how you can, on paper, switch between the perspectives of observers in these coexisting “branches” of reality. He realized that this came with new constraints on the possibility of paraparticles, and his team described their results in a preprint in February that’s now under review for publication in a journal.
The close timing of the two papers was a coincidence. But taken together, the work is reopening the case of a physics mystery that was believed to be solved decades ago. A basic question is being reevaluated: What kinds of particles does our world allow?
All known elementary particles fall into one of two categories, and the two behave almost as opposites. There are the particles that make up matter, called fermions, and the particles that impart the fundamental forces, called bosons.
The defining characteristic of fermions is that if you switch the positions of two fermions, their quantum state gains a minus sign. The presence of that measly minus sign has enormous ramifications. It means that no two fermions can be in the same place at the same time. When packed together, fermions cannot be compressed past a certain point. This feature prevents matter from collapsing in on itself — it’s why the electrons in every atom exist in “shells.” Without this minus sign, we couldn’t exist.
Bosons have no such restriction. Groups of bosons will happily all do exactly the same thing. Any number of particles of light, for instance, can be in the same place. This is what makes it possible to build lasers, which emit many identical light particles. This ability comes down to the fact that when two bosons swap places, their quantum state stays the same.
It’s not obvious that fermions and bosons should be the only two options.
[...] In theory, quantum particles can also have hidden internal states, mathematical structures not seen in direct measurements, which also go away when squared. A third, more general category of particle, known as a paraparticle, could arise from this internal state changing in a myriad of ways while the particles swap places.
While quantum theory seems to allow it, physicists have had difficulty finding a mathematical description of a paraparticle that works... (MORE - details)