Literature

We construct an explicit boundary-action realization of superoscillatory initial states (SIS) for inflation, in which quantum interference within a band-limited initial wavefunctional generates a spectrally localized Bogoliubov excitation with a rapidly winding phase. Starting from a quadratic boundary term on the initial time surface, we derive the Bogoliubov coefficients and the resulting primordial curvature spectrum, obtaining a localized oscillatory feature fixed by the superoscillatory parameters rather than imposed phenomenologically. We compute the projection of this feature onto CMB angular power spectra and show that transfer-function smearing strongly suppresses the oscillatory component; full CAMB calculations confirm the qualitative effect and show that a simple Gaussian approximation overestimates the peak signal by about a factor of three. Using Planck 2018 TT data, we obtain an indicative matched-filter bound for a representative feature centered near the first acoustic peak, at . We further derive correlated predictions for polarization and the bispectrum, identify structural constraints that distinguish SIS from generic excited-state models, and show that galaxy clustering provides a qualitatively more powerful probe because it preserves the full oscillatory structure that CMB projection suppresses. This framework provides a concrete and testable realization of how initial-state quantum interference can imprint itself on cosmological observables.

We study a restricted disformal completion of string-frame string gas cosmology in which the light sector propagates on an effective metric with matter-cone opening . Requiring the gravitational coupling to transform multiplicatively under T-duality reduces the problem to an exponential Cauchy equation, whose unique continuous solution is . The coupling is therefore duality-selected, not assumed.

Its magnitude is UV-sensitive: a varying matter cone does not arise from the Weyl-invariant tree-level gauge action, but instead reflects higher-derivative and string-scale corrections. We then develop the structural consequences of this result. In the Einstein frame the dilaton remains healthy, with non-ghost kinetic coefficient for all .

T-duality also defines a duality-invariant light-cone variable , which provides a compact way to track the matter cone through duality-related branches and toward the self-dual point.

As a controlled application on the analytic Hagedorn background, the wider early-time matter cone enlarges the comoving causal horizon by finite factors and for and , respectively, when the controlled phase is initialized at ; for , the cumulative horizon becomes dominated by the earliest times and correspondingly sensitive to the initial cutoff. The enhancement is therefore self-limiting through string-gas backreaction.

Throughout, the construction is interpreted as an effective-metric statement in the controlled weak-coupling regime, not as a fundamental variation of the speed of light, with matching across the self-dual transition left as the main open problem.

In this paper, we present a statistical model of spacetime trajectories based on a finite collection of paths organized into a branched manifold. For each configuration of the branched manifold, we define a Shannon entropy. Given the variational nature of both the action in physics and the entropy in statistical mechanics, we explore the hypothesis that the classical action is proportional to this entropy.

Under this assumption, we derive a Wick-rotated version of the path integral that remains finite and exhibits both quantum interference at the microscopic level and classical determinism at the macroscopic scale. In effect, this version of the path integral differs from the standard one because it assigns weights of non-uniform magnitude to different paths. The model suggests that wave function collapse can be interpreted as a consequence of entropy maximization.

Although still idealized, this framework provides a possible route toward unifying quantum and classical descriptions within a common finite-entropy structure.

We analyze branch decoherence in inflationary quantum cosmology by computing reduced density matrices and branch-overlap factors for long-wavelength perturbations. The Hartle-Hawking no-boundary state is real in the semiclassical regime and contains both expanding and contracting WKB components, whereas the tunneling state is selected as an outgoing complex WKB branch; expanding-contracting decoherence is therefore central for the former and mainly diagnostic for the latter. Using the influence-functional formalism, we derive the noise kernel for a light spectator environment and evaluate decoherence under horizon-based and EFT-motivated coarse grainings. We then compute the single-mode branch overlap directly from the Bunch-Davies mode functions, obtaining in the massless limit and on superhorizon scales for massive fields, where is the dimensionless wavenumber with the conformal time. In the massless case, the accumulated geometric branch functional is evaluated in closed form, with a leading cutoff-sensitive phase-space term and a universal subleading contribution. The calculation provides an explicit quantitative bridge between quantum-cosmological boundary conditions, inflationary squeezing, and the emergence of effectively classical cosmological histories.

We develop a cosmological framework in which spacetime is treated as a four-dimensional manifold dynamically embedded in a higher-dimensional flat Minkowski background. Ultrarelativistic motion of the embedded manifold induces strong time-dilation effects between embedding time and proper time, generating a genuine phase of inflation with strict exponential expansion for comoving observers, without invoking an inflaton field or scalar potential.

The inflationary phase satisfies the defining kinematic criteria, including a shrinking comoving Hubble radius, and admits a natural graceful exit as time dilation weakens. At late times, large-scale embedding dynamics give rise to a geometric expansion attractor that yields sustained cosmic acceleration without a bare cosmological constant. More generally, the attractor can be quasi-stationary, allowing a slow weakening of the effective acceleration rate while remaining non-phantom.

Small deviations from uniform embedding motion excite long-wavelength co-dimensional modes that generate subdominant oscillatory corrections to the expansion rate. We derive the structure of linear perturbations arising from embedding fluctuations and show that they naturally produce nearly scale-invariant curvature perturbations with a suppressed tensor-to-scalar ratio.

This framework provides a unified geometric origin for inflation, primordial structure, and late-time acceleration, without new fields or fine tuning.

We use principles from the thermodynamics of spacetime to modify the path integral of quantum mechanics. Entropy of the vacuum is interpreted as microstates that correspond to the measure of the path integral. The result is a contribution to the action that is proportional to the Einstein-Hilbert action. Because the contribution is real, not imaginary, it is likely to result in convergence in many cases.

Paths that minimize the Einstein-Hilbert action make the largest contribution to the path integral, implying that the maximum likelihood paths are solutions of the Einstein equation.