A causal fermion system is a mathematical framework that describes the fundamental constituents of the physical universe and their interactions. It combines concepts from quantum field theory, general relativity, and techniques from the theory of causality.
In this framework, fermions are the basic building blocks of matter, and their behavior is governed by the laws of quantum mechanics. Fermions are distinguished from other particles by their half-integer spin, which gives rise to their unique statistical properties. They include fundamental particles such as electrons, quarks, and neutrinos.
The term "causal" in causal fermion system refers to the idea that the interactions between fermions occur through causal influences. This means that any interaction can only be transmitted at a finite speed, limited by the speed of light. This causality constraint is an essential feature of the framework, ensuring that the predictions made by the theory are consistent with the principles of special relativity.
The causal fermion system framework provides a mathematical formalism to describe the behavior of fermions in spacetime, where the gravitational interaction is also considered. This allows for a unified description of both matter and gravity within a single framework.
The theory of causal fermion systems has developed over recent years and continues to be an active area of research. It holds promise for addressing fundamental questions in physics, such as the nature of dark matter, the origin of the universe, and the behavior of matter in extreme astrophysical environments.
