Building Archimedean Space

TL;DR

This paper explores how physical theories over finite fields, like p-adic numbers, can be used to construct or decompose conventional theories over the real numbers, with applications to quantum mechanics, gravity, and string theory.

Contribution

It introduces a novel framework linking finite place theories to real theories, including explicit examples and geometric structures like Bruhat-Tits trees and buildings.

Findings

Finite place theories can reproduce real quantum mechanics and gravity.

Decomposition of theories applies to various physical models including string theory.

Finite structures like Bruhat-Tits trees mirror spacetime symmetries.

Abstract

I propose that physical theories defined over finite places (including $p$-adic fields) can be used to construct conventional theories over the reals, or conversely, that certain theories over the reals "decompose" over the finite places, and that this decomposition applies to quantum mechanics, field theory, gravity, and string theory, in both Euclidean and Lorentzian signatures. I present two examples of the decomposition: quantum mechanics of a free particle, and Euclidean two-dimensional Einstein gravity. For the free particle, the finite place theory is the usual free particle $p$-adic quantum mechanics, with the Hamiltonian obtained from the real one by replacing the usual derivatives with Vladimirov derivatives, and numerical coefficients with $p$-adic norms. For Euclidean two-dimensional gravity, the finite place objects mimicking the role of the spacetime are $\mathrm{SL}(\mathbb{Q}_p)$ Bruhat-Tits trees. I furthermore propose quadratic extension Bruhat-Tits trees as the finite place objects into which Lorentzian $\mathrm{AdS}_2$ decomposes, and Bruhat-Tits buildings as a natural generalization to higher dimensions, with the same symmetry group on the finite and real sides for the manifolds and buildings corresponding to the vacuum state.