The DemystifySci Podcast Cosmology: The Good, Bad, & Ugly - Dr. C.S. Unnikrishnan, DemystiCon '25, DemystifySci #382
Nov 23, 2025
Dr. C.S. Unnikrishnan, a physics professor at the TATA Institute, critically examines the standard ΛCDM cosmological model. He discusses the robustness of observational facts like redshift and CMBR while highlighting challenges in validating cosmological theories. Unnikrishnan also critiques the assumptions of dark matter and dark energy, explores alternative models, and questions claims about cosmic expansion impacting only certain systems. He argues for a shift toward data-based refutation, suggesting that current models may need significant revision.
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Cosmology Changes With Better Data
- Cosmology evolves as observations improve, so current models must remain open to change.
- Sustained, expert criticism refines models but rarely fully overturns established paradigms.
Lambda CDM Relies On Extra Ingredients
- Lambda CDM needs ingredients beyond GR and the particle standard model to match observations.
- Dark matter and dark energy are invoked because known physics cannot explain flat geometry and cosmic acceleration.
Homogeneity Means Gravitational Potentials
- The relevant cosmological homogeneity is about gravitational potentials, not raw matter distribution.
- Local inhomogeneities contribute negligibly to the overall gravitational potential at cosmological scales.
