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{\fontsize{32}{38}\selectfont\bfseries\scshape Bidirectional Causality}

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{\fontsize{18}{24}\selectfont\scshape and the Physics of}

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{\fontsize{32}{38}\selectfont\bfseries\scshape Superluminal Propagation}

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{\large\itshape\begin{minipage}[c]{0.75\textwidth}\centering
A reformulation of causality, electrodynamics, gravitation, and quantum theory under a preferred frame defined by the future boundary of the universe
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{\Large\scshape Andrew Duquette}

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{\large Working Draft\,---\,February 2026}

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\begin{abstract}
\noindent We abandon Lorentz invariance as a fundamental symmetry and replace it with a preferred frame defined by the future boundary condition of the universe. This single structural change permits stable superluminal propagation, resolves the vacuum instability of tachyonic fields, and produces a bidirectional causal structure in which effects propagate forward in preferred time by default and backward from specific spacetime events. The future boundary is an extended spacetime volume, not a surface; agents operating within this volume can send tachyonic signals into the interior history, selecting which self-consistent history--boundary pair is realised from a space of allowed solutions---including the initial conditions themselves. Interior agents are part of the determined solution and lack this causal leverage. We reformulate electrodynamics with symmetric field coupling at enhanced strength, derive a modified dispersion relation that decouples mass from velocity class, reconstruct the gravitational field equations, and examine the consequences for quantum field theory. The tachyonic particle emerges as a massive spin-1 excitation---structurally identical to the photon but with a higher speed limit---governed by the same Maxwell field architecture at enhanced coupling strength. The cosmological history partitions into four causal epochs: boundary seeding of initial conditions, forward-causal propagation, tachyonic enforcement when the selected attractor requires it, and the boundary volume itself. The framework makes specific observational predictions distinguishable from standard physics.
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% PART I: FOUNDATIONS
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\input{sec01_foundations}
\input{sec02_electrodynamics}
\input{sec03_gravitation}
\input{sec04_quantum}
\input{sec05_tachyon}
\input{sec06_causality}
\input{sec07_cosmology}
\input{sec08_algebraic}
\input{sec09_enforcement}
\input{sec10_model_theory}
\input{sec11_predictions}
\input{sec12_summary}

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