For over three decades, Felix Finster has been developing a unique and ambitious reformulation of physics known as Causal Fermion Systems (CFS). Physicists usually describe the world in terms of fields defined on a spacetime manifold. Within this familiar framework, abstract quantities such as correlations between matter fields at different points in spacetime can be computed. In mathematical language, these correlations are captured by operators acting on a Hilbert space.

What Felix realized is that this process can be reversed. If you start with a suitable collection of operators on a Hilbert space, satisfying certain mathematical properties, you can in principle reconstruct the underlying spacetime and fields that would give rise to those operators as operators of correlations.

In this sense, Causal Fermion Systems offers a dual description of reality. On the one hand, reality can be described in terms of symmetries, fields, and manifolds - the usual language of physics. On the other hand, CFS proposes that reality can just as well be described using abstract structures: Hilbert spaces, operators, and measures on sets of operators. Spacetime, matter, and everything we observe then emerges from these underlying mathematical quantities.

The beauty of reformulating physics this way is that it opens up an entirely new framework in which to explore some of the deepest open questions in physics: What is spacetime like at the smallest scales? Why do we see precisely the particles we do in experiments? The hope is that within the CFS framework, answers to such questions might become more natural or even inevitable.

Of course, we can’t cover a 30-year research program in full detail in a single conversation. The goal here is to get a sense of the flavor of Felix’s approach to physics. For the full details, you can explore Felix's books
(e.g. https://www.cambridge.org/core/books/causal-fermion-systems/CCA6DE1E1F4DA3AC0EF6729664A5D5B9 ).

►Watch on YouTube:
https://youtu.be/qQl51qifus0

►Find out more about Felix's work here:
https://www.uni-regensburg.de/mathematik/mathematik-1/startseite/index.html
https://causal-fermion-system.com/