Bulk-to-Brane Projection, Dynamical Nonclosure, and Observable Residues in Randall–Sundrum Gravity
The physical witness: identical brane readouts, different futures, and linked observable residues in RS2
Authority role
Within RS2 gravity, Paper 7 proves that identical instantaneous brane readouts can evolve into different futures, derives the exact projected Einstein equation, and links cosmological and weak-field residues through a parameter-free relation.
Summary
Working inside the positive-tension Randall–Sundrum (RS2) braneworld, this paper delivers the framework's concrete physical witness: an explicit pair of five-dimensional gravitational states identical to a brane observer now that evolve to differ later, so the instantaneous brane state admits no deterministic evolution law over the full source domain. It derives the exact projected Einstein equation line by line, obtains the positive high-density rho-squared term and bulk-state dark-radiation term, and eliminates the common AdS radius to yield a parameter-free cross-regime relation linking cosmology to weak-field gravity. A pushforward theorem proves that every brane-only protocol is reproduced exactly by a four-dimensional theory of the brane record, establishing the full operational-equivalence result.
Notes
Reading notes
The physical-witness layer of the sequence adopts the positive-tension, two-sided, -symmetric Randall–Sundrum model (RS2): five-dimensional Einstein gravity with a negative bulk cosmological constant and matter confined to a brane. RS2 supplies the declared source dynamics in which the abstract witness specification becomes a concrete gravitational result.
Theorem: Same readout, different future (the witness)
There exist two gauge-inequivalent bulk configurations: the unperturbed brane and a configuration carrying a smooth, finite-energy transverse-traceless bulk wave packet initially supported away from the brane. Their instantaneous brane readouts are identical, but their brane readouts differ at a later time. Existence is proved by explicit Kaluza–Klein spectral construction. Hence no deterministic evolution law on the instantaneous brane Cauchy state reproduces every source trajectory over the full RS2 source domain.
The tensorial counterpart is derived line by line: the Israel junction condition and Gauss–Codazzi identity give the exact projected Einstein equation with response tensor , where the Bianchi identity fixes only the divergence of the Weyl term; its transverse-traceless content, the free bulk response, is undetermined by brane data. Evaluated exactly in the Friedmann sector this yields a positive correction and a dark-radiation term whose magnitude is a bulk-state parameter, not brane matter. In the weak-field sector the bulk is eliminated exactly at linear tree level, and the long-distance potentials follow for .
Eliminating the common AdS radius between the cosmological and weak-field regimes leaves no free brane parameter. Violation falsifies minimal RS2; agreement at a nonzero value favors it without falsifying an independently parameterized 4D theory.
The paper then proves operational equivalence. A pushforward lemma shows that for every brane-only protocol, including adaptive ones, the induced Tier-1 history law reproduces the RS2 record distribution exactly, and in RS2 this is realized concretely: the four-dimensional gravity-plus-CFT description reproduces the same residue. This establishes the exact discrimination result: brane histories determine the pushforward theory while leaving the two source representations operationally equivalent from the brane.
Cite this paper
Rodgers, Jeremy. (2026). Bulk-to-Brane Projection, Dynamical Nonclosure, and Observable Residues in Randall–Sundrum Gravity. https://doi.org/10.5281/zenodo.21371861