Viscous Cosmology and Dark Energy Models
Summary
Viscous cosmology explores the influence of internal frictional effects in the cosmic fluid on the large-scale dynamics of the universe. In this framework, bulk and shear viscosity act as dissipative processes that can mimic or augment the effects of dark energy, potentially driving the observed accelerated expansion without invoking a separate exotic component. By extending the standard Friedmann framework to include viscous pressures, researchers can address tensions in key parameters such as the Hubble constant and the amplitude of matter fluctuations, while providing a unified description of the dark sector. Causal theories of viscosity, notably the Israel–Stewart formalism, ensure that dissipative processes respect relativistic causality and stability conditions. Observational constraints from supernovae, cosmic microwave background measurements and large-scale structure surveys place bounds on the magnitude and evolution of viscosity coefficients, informing models of cosmic acceleration and the ultimate fate of the universe. The interplay between viscous effects and conventional dark energy parametrisations enriches our understanding of cosmic history, from inflationary regimes through to late-time acceleration and potential future singularities.
Research from Nature Portfolio
No recent Nature Portfolio content available.
Viscous Cosmology and Dark Energy Models publication trend
The graph below shows the total number of articles in viscous cosmology and dark energy models across all publications each year (not limited to Nature Index journals).
Technical terms
Bulk viscosity: Resistance of a fluid to uniform expansion or contraction, acting as an effective pressure term in cosmology.
Shear viscosity: Resistance of a fluid to differential motion or shear, affecting the evolution of perturbations.
Equation of state: Relation between pressure and energy density of a cosmic component, often written as p=wρ.
Hubble parameter: Time-dependent rate of cosmic expansion, H(t)=ā/a.
Israel–Stewart theory: A causal, relativistic framework for describing dissipative processes in fluids, ensuring stability and finite propagation speeds.
References
- Dark Matter Cosmology with Varying Viscosity: A Possible Resolution to the S 8 Tension. The Astrophysical Journal (2023).
- Symmetry-based study and dynamics of casual bulk viscous matter-dominated universe. European Physical Journal C (2024).
- Testing a Nonlinear Solution of the Israel–Stewart Theory. Galaxies (2024).
About these summaries
This Nature Research Intelligence Topic summary is created with the cited references and a large language model. We take care to ground generated text with facts, and have systems in place to gain human feedback on the overall quality of the process in line with our AI principles. We strive to create accurate and useful summaries for people unfamiliar with the research topic and that supports this goal. These pages are a beta release and will be updated as we learn how best to help people gain value from a research topic summary.
Turn complex research questions into confident strategic decisions
When you're under pressure to set direction, justify investment, or understand your competitive position, you need more than raw data — you need trusted insights you can act on.
Benchmark your performance against global peers using robust, methodologically sound analysis.
Combine quantitative metrics with qualitative expert insight to uncover strengths, gaps and emerging opportunities.
Gain tailored, decision-ready recommendations aligned to your strategic priorities.
Talk to us to learn more about our data dashboards and bespoke strategy reports.
Grow research skills, confidence and careers with training built for every stage of the research lifecycle.
Developed with Nature Portfolio journal Editors and internationally renowned experts. Discover three ways to learn:
Self-paced, online courses in convenient bite-sized units, covering key skills across scientific writing, publishing, grant writing, data analysis, and more.
Expert trainer-led workshops with hands-on exercises and real-time feedback across core research skills, delivered via interactive group sessions.
Editor-led workshops combining core principles in writing and publishing, personalised 1:1 feedback from Nature Portfolio Editors and hands-on exercises.
Explore course catalogues and workshop agendas, enquire about the options or request institutional pricing.