Info Flow & Matter Creation in Cosmology

• Information Flow and Matter Creation are fundamental concepts connecting entropy dynamics to the emergence of matter via gravitational and quantum mechanisms.
• They integrate cosmological models, nonequilibrium statistical mechanics, and quantum field theory to explain cosmic acceleration and structure formation.
• Recent advances reveal that entanglement entropy and phase-space divergence drive observable matter creation in both macroscopic and microscopic systems.

Information flow and matter creation are deeply intertwined concepts that manifest across cosmology, nonequilibrium statistical mechanics, kinetic theory, and quantum field theory. Information flow (including entropy and its variations) mediates, quantifies, and often operationalizes the transformation of gravitational or energetic degrees of freedom into matter, while matter creation processes, in turn, generate observable changes in the entropy content and phase space of the universe. Recent advances have clarified how information-theoretical principles can govern macroscopic processes such as cosmic acceleration, structure formation, and even the microscopic initiation of particles. This article provides a comprehensive overview of theoretical foundations, modeling frameworks, thermodynamic and observational implications, and the operational mechanisms connecting information dynamics to matter creation in contemporary research.

1. Theoretical Foundations: Information, Entropy, and Dynamical Systems

The emergence of information flow within dynamical systems is most fundamentally linked to the divergence properties of phase-space trajectories. As established by rigorous derivations (Kumar, 2023), the local divergence of the dynamical vector field, ∇·F, determines the evolution of the system’s entropy and the flow of information between coupled components. In systems with ∇·F ≠ 0 (dissipative or driven systems), the probability density function's structure evolves beyond a mere advection of initial conditions, generating genuine informational dependencies across variables. Mathematically, the entropy rate involves an explicit divergence term:

$$\frac{dH_Z}{dt} = \mathbb{E}[\psi(Z, t)\, \nabla\cdot F]$$

where ψ(Z, t) = $\log(1/p(Z, t))$. This term is responsible for emergent information flow, which determines how changes in the configuration space (e.g., volume contraction or expansion, as in cosmological models) generate or dissipate information content.

In linear stochastic systems, the causality and directionality of information flow can be quantified exactly: the rigorous formula shows that causation implies correlation, but the converse is not true, thereby resolving the correlation–causation debate in time-continuous and stochastic models (Liang, 2015).

2. Matter Creation in Cosmological Frameworks

2.1. Gravitational and Thermodynamic Origin of Matter Creation

Modern cosmological scenarios routinely invoke matter creation via gravitational or thermodynamically motivated open-system extensions. The canonical macroscopic description is based on the balance equation for particle number density:

$\dot{n} + 3H n = n \Gamma$

where H is the Hubble parameter and Γ is the particle creation rate.

In adiabatic models, a "creation pressure" emerges:

$p_c = -\frac{\rho + p}{3H} \Gamma$

with ρ and p the energy density and pressure, respectively. This negative pressure effect is responsible for cosmic acceleration in models that replace dark energy with matter creation (Jesus et al., 2011, Bhattacharjee et al., 21 Jul 2025, Trevisani et al., 2023). For example, choosing

$$\Gamma = 3\alpha H \left( \frac{\rho_{c0}}{\rho_{dm}} \right)$$

yields a density evolution that incorporates a cosmological constant–like term, driving late-time acceleration without explicit dark energy.

2.2. Horizon Thermodynamics and the Holographic Principle

Irreversible matter creation, grounded in the non-conservation of the energy–momentum tensor in various modified gravity or open-system cosmologies (Harko, 2014, Lobo et al., 2015), connects with the generalized second law of thermodynamics:

$dS = dS_e + dS_i \geq 0$

where $dS_e$ is the entropy change associated with the cosmic horizon (e.g., $S_H = \pi/H^2$) and $dS_i$ is the internal entropy production from matter creation. This formulation, especially relevant in scenarios with explicit geometry–matter coupling or nonminimal curvature–matter interactions, imposes strong constraints: the entropy growth is intimately tied to matter creation rates, often uniquely determining Γ under adiabatic and equilibrium conditions (Cárdenas et al., 24 Jan 2025, Valentim et al., 2019).

The holographic perspective identifies the observable horizon as the physical substrate on which information is encoded (the "holographic bound"), and constrains the expansion history and equilibrium attainability of the universe.

3. Operational Mechanisms: Information Flow as a Driver of Particle Creation

Recent quantum field theoretical approaches have made explicit the operational mechanism by which variations in information content (measured by entanglement entropy) induce matter creation (Good et al., 23 Aug 2025). In systems with a time-dependent entanglement entropy S(t), the particle number spectrum, total particle number, and radiated energy are directly expressible as functionals of the Fourier components of S(t):

$$N = \frac{24}{\pi} \int_0^\infty \omega |S_\omega|^2 d\omega, \quad E = \frac{12}{\pi} \int_0^\infty \omega^2 |S_\omega|^2 d\omega$$

This realizes the "it-from-bit" program by demonstrating that changes in quantum informational structure (e.g., from a moving mirror, black hole evaporation, or nonstationary boundary conditions) generate real, observable particles.

The low-entropy (nonrelativistic) limit yields precise agreement with semiclassical results (such as Larmor radiation), while pronounced periodic entropy modulation (e.g., harmonic cycles) can produce large-scale matter creation, with average particle energy scaling directly with the characteristic frequency of entropy variation.

4. Thermodynamic and Kinetic Modeling: Bulk Viscosity, Dissipation, and Feedback

Dissipative cosmological fluids that combine matter creation with bulk viscosity (Cárdenas et al., 2020) encapsulate the effects of irreversible entropy generation on expansion dynamics. For instance, in the adiabatic case ($\dot{S} = 0$), the thermodynamic relations give:

$\Pi = -\rho(1 + \omega) \frac{\Gamma}{3H}$

$$\omega_{eff} = \omega - (1 + \omega) \frac{\Gamma}{3H}$$

Models based on the noncausal Eckart formalism can exhibit big rip singularities and unbounded matter creation, while causal (Israel–Stewart) treatments yield bounded, quintessence-like solutions, consistent with current constraints on the effective equation of state parameter ($\omega_{eff} \simeq -0.82$ for optimal η values).

In nonequilibrium statistical mechanics, feedback and information flow are formalized through fluctuation theorems (Rosinberg et al., 2016), where entropy production, heat, and information current are interrelated, and information can, in principle, be traded for work or energy, suggesting mechanisms by which information flow—especially in coupled adaptive systems—can catalyze matter creation.

5. Observational Constraints and Cosmological Implications

Matter creation models are strongly constrained by observational data—Type Ia supernovae, baryon acoustic oscillations, CMB distance priors, and cosmic chronometers—often via Bayesian or MCMC analyses (Bhattacharjee et al., 21 Jul 2025, Chander et al., 13 Apr 2025). For parameterizations where the creation rate is proportional to the Hubble parameter (Γ = 3αH...), the resulting cosmological expansion is statistically indistinguishable from the ΛCDM scenario, but with robust evidence for nonzero creation at high statistical significance for certain datasets (notably those including DESI BAO DR2). Information criteria (AIC/BIC) show that such models compete directly with standard cosmology, and may resolve or ameliorate existing tensions (e.g., H₀, S₈) by slightly modifying the thermal and dynamical history (Trevisani et al., 2023). Incorporating photon creation or entropy-driven rates presents new predictions for the CMB temperature–redshift relation and the Sunyaev–Zeldovich effect, offering a pathway to empirical discrimination.

6. Broader Theoretical and Quantum Information Perspectives

Nonminimal geometry–matter coupling (Lobo et al., 2015), the explicit violation of the standard conservation law in open cosmological systems, and the formulation of creation pressure as arising from information or entropy production, reinforce the centrality of information flow in cosmic evolution. The intimate connection between phase-space divergence, entropy production, and matter creation, as illustrated in both classical and quantum theoretical constructs, suggests a universal framework where informational dynamics dictate physical outcomes.

Contemporary work has operationalized this at the level of quantum field theory via explicit formulas linking entanglement entropy’s temporal modulation to observable matter creation (Good et al., 23 Aug 2025). In classical many-body physics and even in simple coupled systems, the maximum rate of information flow is set by the ratio of energy transfer to initial energy content—an analogue of signal-to-noise—and unique observability conditions further elucidate when the state of one subsystem (e.g., the environment) completely determines the emergent physical content in another (Miller-Dickson et al., 30 Jan 2025).

Conclusion

The synthesis of information flow and matter creation, realized in cosmological, statistical, thermodynamic, and quantum frameworks, offers a robust alternative to traditional dark energy, provides a mechanism for cosmic acceleration, and deepens our understanding of cosmic evolution. The modern perspective, integrating horizon thermodynamics and information theory, indicates that the processes governing structure formation and universal dynamics may be fundamentally informational in character, with profound implications for both fundamental physics and observational cosmology.