As of 2025, the polarization signal from primordial gravitational waves has not been detected by BICEP or the Keck Array.
Notes on verification
Multiple independent, high-quality sources (arXiv preprint, peer-reviewed IOPscience article, CERN Courier) consistently confirm that BICEP/Keck has only produced upper limits on the tensor-to-scalar ratio r, not a detection, as of the mid-2020s. Tentative statistical hints in 2025 papers are explicitly sub-threshold and not framed as detections. [tier=gold indep_score=0.867 clusters=3 claim_tier=notable]
Sources
- BICEP and Keck Array (wikipedia)
- https://arxiv.org/abs/2203.16556 (corroboration)
- https://iopscience.iop.org/article/10.3847/1538-4357/ac9ea3 (corroboration)
- https://cerncourier.com/a/bicep-crunches-primordial-gravitational-waves/ (corroboration)