Summary
Astronomers have developed diagnostic tests for a central assumption of modern cosmology—that the universe is homogeneous and isotropic on large scales (FLRW cosmology). Applying these tests to observational data, they found mild deviations (2–4 sigma) that may indicate new physics beyond the standard model, though results are preliminary.
Key Details
- Researchers developed consistency tests based on the Clarkson-Bassett-Lu method, generalized for non-FLRW universes, and used symbolic regression to reconstruct cosmic expansion history from data.
- Data sources: Pantheon+ supernova catalog, Dark Energy Spectroscopic Instrument (DESI), and baryon acoustic oscillation surveys.
- Two possible effects considered: Dyer-Roeder effect (light traveling through voids) and cosmological backreaction (large-scale structure altering expansion).
- Deviations from FLRW predictions were observed at statistical significance of 2–4 sigma, below the 5-sigma threshold for a discovery.
Statements
Study co-author Asta Heinesen: "We saw a surprising violation of an FLRW curvature consistency test, hinting at new physics beyond the standard model."
Heinesen added: "The main finding is that you can directly measure Dyer-Roeder and backreaction effects from available cosmological data... This was previously not possible in such a direct way."
Context
- FLRW cosmology underlies the standard model of cosmology (ΛCDM).
- The real universe contains cosmic web structures, which FLRW may not perfectly describe.
- Future surveys with more precise data are needed to confirm whether deviations are genuine.