Coherence measurements of polaritons in thermal equilibrium reveal a power law for two-dimensional condensates. H. Alnatah, Q. Yao, J. Beaumariage, S. Mukherjee, M. C. Tam, Z. Wasilewski, K. West, K. Baldwin, L. N. Pfeiffer and D. W. Snoke in Science Advances 10: (2024).