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Causal Fermion Systems—An Overview

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The Continuum Limit of Causal Fermion Systems

Part of the book series: Fundamental Theories of Physics ((FTPH,volume 186))

Abstract

Causal fermion systems were introduced in [FGS] as a reformulation and generalization of the setting used in the fermionic projector approach [F7]. In the meantime, the theory of causal fermion systems has evolved to an approach to fundamental physics. It gives quantum mechanics, general relativity and quantum field theory as limiting cases and is therefore a candidate for a unified physical theory. In this chapter, we introduce the mathematical framework and give an overview of the different limiting cases.

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Notes

  1. 1.

    The support of a measure is defined as the complement of the largest open set of measure zero, i.e.

    It is by definition a closed set. This definition is illustrated in Exercise 1.5.

  2. 2.

    For clarity, we point out that our notion of causality does allow for nonlocal correlations and entanglement between regions with space-like separation. This will become clear in Sects. 1.1.4 and 1.5.3.

  3. 3.

    For example, one may choose  as the set of all vectors  satisfying the conditions

  4. 4.

    It is a general property of the closed chain that if \(\lambda \) is an eigenvalue, then so is \(\overline{\lambda }\); see Exercise 1.15.

  5. 5.

    In order to avoid confusion, we note that the operators \(\hat{\Psi }(x)^\dagger \) which appear in the usual equal-time canonical commutation relations \(\{ \hat{\Psi }^\alpha (t,\vec {x}), \hat{\Psi }^\beta (t,\vec {y})^\dagger \} = \delta ^\alpha _\beta \, \delta ^3(\vec {x}-\vec {y})\) are related to the above operators by \(\hat{\Psi }^\alpha (x)^\dagger = 2 \pi \sum _{\beta =1}^4 \hat{\Psi }^\beta (x)^* \,(\gamma ^0)^\beta _\alpha \).

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Correspondence to Felix Finster .

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© 2016 Springer International Publishing Switzerland

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Finster, F. (2016). Causal Fermion Systems—An Overview. In: The Continuum Limit of Causal Fermion Systems. Fundamental Theories of Physics, vol 186. Springer, Cham. https://doi.org/10.1007/978-3-319-42067-7_1

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