We present complex-time (CT) theory, a framework in which the fundamental structures of quantum mechanics are derived from three physical postulates concerning the internal structure of time. The postulates are: (P1) physical time possesses two orthogonal components — past-fixed (pf), representing actualized, irreversible records, and future-pending (fp), representing physically real but undetermined possibilities; (P2) pf and fp are orthogonal (pf fp); and (P3) the total temporal magnitude is conserved (pf + fp = 1). From these three postulates alone, we show that: (i) the state space is the unit circle and the dynamical group is , so that the imaginary unit arises as the unique generator of temporal evolution — not as a mathematical convenience but as a consequence of temporal geometry; (ii) the Schrödinger equation follows from the identification of energy with the rate of phase rotation in the pf–fp plane, with the Planck constant playing the role of a natural constant intrinsic to the pf/fp structure; (iii) the de Broglie–Einstein relation holds universally — for massive and massless particles alike — because the wave structure belongs to time itself, not to any particular particle; (iv) the uncertainty principle is a geometric consequence of the impossibility of fully eliminating fp while preserving ; (v) the complex structure of Hilbert space, the inner product, and the Born rule all follow from the geometry of fp pf projection; and (vi) energy quantization emerges from a “real-axis sampling” rule without imposing discreteness on the underlying dynamics. We further show that the CT framework provides unified descriptions of double-slit interference, quantum tunneling, unstable-state decay widths, and the structural origin of the arrow of time. Preliminary experimental predictions for quantum-circuit observables are stated, and applications to cosmological dark-energy phenomenology, galaxy rotation curves, and Lorentzian path-integral contour selection are outlined with references to dedicated companion papers. The central thesis is that quantum mechanics is not a theory of particles with mysterious wave-like properties, but a consequence of the internal structure of time — time whose wave-like phase (fp) is projected, irreversibly and discretely, onto the real axis (pf) in every act of measurement. Keywords: complex time; temporal structure; imaginary unit; quantum mechanics derivation; past-fixed / future-pending decomposition; Born rule; energy quantization; measurement; irreversibility; arrow of time
This paper derives the Dirac equation as the logically forced relativistic completion of the de Broglie wave dynamics established in prior work of this series. Starting from the logical foundation that yields Lorentz/Poincaré invariance, we promote the non-relativistic framework (continuous spacetime, Fourier duality, local plane-wave structures, and probability conservation via statistical energy flux) to the relativistic regime. We show that the requirements of exact local relativistic plane-wave structures (with phase gradients satisfying the mass-shell condition
pμpμ=m2c2), first-order time evolution (needed for clean probability conservation), and full Lorentz covariance together force the introduction of a specific non-commuting algebraic structure and a multi-component wave function. The Dirac equation emerges as the unique linear differential operator of order at most one in the spacetime derivatives that consistently glues these local structures across smooth backgrounds while preserving a conserved four-current with positive-definite time component. This multi-component structure arises naturally as the minimal algebraic consequence of the constraints, without any separate postulate for intrinsic angular momentum. In exact analogy with the emergence of the finite invariant causal speed in special relativity, the Dirac dynamics is revealed not as an ad-hoc linearization of the Klein--Gordon equation, but as the mathematically inevitable description of indivisible particles in continuous relativistic spacetime. The derivation thereby completes the single-particle sector of the series, demonstrating that core structures of relativistic quantum mechanics flow deductively from a small number of deep, nearly tautological commitments.
Abstract We introduce a complex-time framework in which the imaginary unit i is interpreted not as a formal algebraic device but as the generator of a physically meaningful temporal transformation. In this formulation, time is represented as a complex quantity T = pf + i·fp with |T| = 1, where pf (past-fixed) denotes the real component representing actualized, recorded history, and fp (future-pending) denotes the imaginary component representing undetermined possibilities. The constraint |T| = 1 expresses conservation of total temporal magnitude: as possibilities are determined (fp decreases), actualized history accumulates (pf increases). Temporal evolution is described by continuous rotation in the complex-time plane, governed by dT/dθ = iT, while a non-Hermitian extension dT/dθ = iT − γT (γ > 0) describes dissipative processes and the emergence of the arrow of time. Within this framework, quantum measurement is identified with a discrete, irreversible real-axis projection—the conversion of fp into pf—that constitutes a single step of time’s advance from the imaginary to the real axis. This identification yields three concrete predictions for quantum circuits: (i) measurement-induced effects depend on measurement count M rather than free-evolution time T (T-independence); (ii) irreversibility accumulates linearly with M in time-reversal protocols; and (iii) the elementary duration δ of one real-axis projection is implementation-dependent. The framework provides a unified structural basis for the continuity of motion, quantum uncertainty, and macroscopic irreversibility, suggesting that these phenomena arise from a single generative process: the continuous, irreversible conversion of future-pending structure into past-fixed record. Keywords: complex time; past-fixed / future-pending decomposition; quantum measurement; irreversibility; arrow of time; uncertainty principle
Abstract We propose a two-component structure of physical time based on a distinction between Past-fixed (pf) and future-pending (fp) contributions. pf time encodes events that have already been realized and recorded, while fp time encodes those possibilities that have not yet become facts but may do so. This structure is represented by a complex-time variable and a normalized complex amplitude with , where pf and fp denote, respectively, the pf and fpcomponents. In this framework the imaginary unit is interpreted as a generator of rotations between pf and fp, rather than as a purely formal algebraic device. We show that unitary quantum dynamics can be understood as the conservation of the combined pf – fp weight, and that the Schrödinger equation describes rotations of the complex-time amplitude with angular velocity . Measurement processes are described as projections from fp to pf, and we argue that the Born rule arises from natural symmetry and additivity requirements on the frequencies of such future-to-past conversions. For two-level systems, equal fp alternatives lead to equal pf frequencies; for rational amplitude ratios, fp can be decomposed into equal “future packets” whose uniform projection into pf yields probabilities proportional to the squared amplitudes. In higher dimensions, Gleason’s theorem implies that these conditions uniquely single out the usual Born rule. We further show that discrete energy spectra can be viewed as a consequence of sampling the complex-time rotation only at those instants where lies on the real axis, , at which fp vanishes and the corresponding mode is fully pf. This leads to a quantization condition that reproduces Planck-type discrete energies for simple systems. Finally, we interpret tunnelling and evanescent domains as manifestations of fp structure: from the pf perspective an infinite barrier still enforces , but from the fp perspective a particle that has not yet appeared in that pf spacetime may exhibit fp amplitudes that transiently extend into the barrier region. Taken together, these results suggest that the imaginary unit can be interpreted as a “future factor” in quantum theory, and that a complex-time geometry provides a coherent route to connect quantum dynamics, probability, and discrete spectra with the temporal status of physical reality. Running Title: What is Time? Complex-Time Geometry Key words: complex time; past-fixed and future-pending; time in quantum mechanics; Born rule; unitary dynamics; quantum tunnelling; quantum foundations
This paper extends the stochastic electrodynamic framework of Papers 1, 2, and 3 [1–3] to relativistic quantum mechanics, deriving the Dirac equation from the relativistic Coulomb field. The non-relativistic Brownian motion of Paper 1 is generalised to a four-dimensional stochastic process in Minkowski spacetime, parameterised by proper time τ . The relativistic diffusion coefficient isD4D = ℏ/m—exactly twice the non-relativistic value ℏ/2m—arising from the additional contribution of the temporal component of the four-dimensional Wiener process. The covariant zero-point field spectral tensor Sμν(ω) = (ℏω^3/6π^2ϵ0c^3)gμν is derived from the relativistic Coulomb field through the Lorentz-covariant Einstein–Hopf detailed balance and the ergodic theorem, whose applicability to the SED electron-vacuum system is proved in Paper 3 [3]. Relativistic stochastic optimal control gives the Hamilton–Jacobi–Bellman (HJB) equation in four-dimensional configuration space, which yields the Klein–Gordon equation for spin-0 particles through the relativistic Itô correction (ℏ/2m)□. Linearisation of the relativistic Lagrangian −mc√uμuμ via Dirac matrices γμ satisfying {γμ, γν} = 2gμν converts the second-order HJB equation into a first-order equation—the Dirac equation: (iℏγμ∂μ−eγμAμ/c−mc)ψ = 0. The central new result is that spin- 1/2 is not introduced by the linearisation: it is already present in the geometry of the four-dimensional stochastic path. The mass-shell constraint uμuμ = −c^2 forces the relativistic Brownian path to be helical, with radius ℏ/mc and angular frequency 2mc^2/ℏ (Zitterbewegung). The angular momentum of this helix is ℏ/2 (spin- 1/2 ) and the magnetic moment gives g = 2—both following from the Coulomb field without additional assumptions. The linearisation then finds the unique first-order wave equation consistent with this pre-existing helical spin structure. The four-component Dirac spinor encodes four degrees of freedom already determined by the stochastic path: two spin states (helix handedness) and two time directions (particle/antiparticle).
The Schrödinger equation need not be postulated. This paper demonstrates that the imaginary unit
i in quantum mechanics and the Schrödinger equation itself are both derived consequences of the Dirac equation when formulated in the real Clifford algebra
Cl(1,3) - the Spacetime Algebra introduced by Hestenes (1966). No new physics is proposed; the result collects and organises existing mathematical results into a single self-contained derivation chain:
Cl(1,3)→Hestenes-Dirac→γ0-split→Pauli→Schroedinger The role of
i is played by the spin-plane bivector
γ21=γ2γ1, a real geometric object satisfying
γ212=−1 as a consequence of the Minkowski metric. Complex-valued wavefunctions are thus projection artifacts: the residue of real four-dimensional geometry viewed from a three-dimensional observer frame. Key Results - The imaginary unit
i in the Schrödinger equation is identified as the spin-plane bivector
γ21 - a directed plane in spacetime, not an abstract algebraic postulate.- The Schrödinger equation is derived as the non-relativistic limit of the Hestenes--Dirac equation via the
γ0-split (observer frame choice), with
i inherited from the spacetime bivector structure.- Two of the five standard axioms of quantum mechanics (complex Hilbert space and the Schrödinger equation) are demoted from postulates to derived theorems. The measurement postulate and tensor product rule are retained.- Full compatibility with the Renou et al. (2021) no-go theorem and the Chen et al. (2022) experimental confirmation: the formulation is isomorphic to complex quantum mechanics, not a real restriction of it.
Cl(1,3) contains the required complex structure via
γ21.- Convergence with Penrose's twistor programme: both approaches conclude that complex structure in quantum mechanics and Lorentzian spacetime geometry have a common origin. Document Contents - complex_wavefunctions.pdf - Main paper (13 pages). Self-contained derivation from
Cl(1,3) to Schrödinger, with compatibility analysis (Renou/Chen/Penrose), axiom restructuring, and pedagogical appendix.- complex_wavefunctions.tex - LaTeX source. Standalone, no external dependencies. Scope and Originality This paper presents no new mathematical results. The identification
i↔γ21 is due to Hestenes (1967); the non-relativistic reduction in geometric algebra is given in Doran & Lasenby (2003). The contribution is expository: collecting the derivation chain into a single path with the geometric identity of
i tracked at each step, and situating the result in the context of the Renou et al. no-go theorem and its experimental confirmation.