@article {1809.09092, archivePrefix = {arXiv}, eprint = {1809.09092}, primaryClass = {hep-th}, author = {Delilah Gates and Daniel Kapec and Alexandru Lupsasca and Yichen Shi and Andrew Strominger}, title = {Polarization Whorls from M87 at the Event Horizon Telescope}, year = {2018}, url = {http://arxiv.org/abs/1809.09092} }