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.
Sources
- BICEP and Keck Array (en.wikipedia.org)
- https://arxiv.org/abs/2203.16556 (arxiv.org)
- https://iopscience.iop.org/article/10.3847/1538-4357/ac9ea3 (iopscience.iop.org)
- https://cerncourier.com/a/bicep-crunches-primordial-gravitational-waves/ (cerncourier.com)