Quasar axes know about each other across distances that should forbid acquaintance. Optical polarization vectors of quasars show coherent alignment over regions approaching a gigaparsec, at probabilities below a tenth of a percent of arising by chance (Hutsemekers et al. 2005), and the effect graduated from curiosity to crisis when VLBI measurements found the three-dimensional jet axes of radio AGN aligned over 400 to 900 megaparsec separations at greater than 99.5 percent significance, jets being direct tracers of black hole spin (Tiwari and Jain 2015; Blinov et al. 2020). Radio source dipoles exceeding the kinematic expectation compound the directional evidence (Secrest et al. 2021).
The scales are the indictment. A quasar's jet direction is set by its central black hole's spin axis, and in ΛCDM that spin is built locally, by accretion and mergers whose tidal-torque correlations fade beyond 30 to 50 megaparsecs. Spin axes coherent over twenty to thirty times that distance have no standard mechanism at any amplitude: not weak alignment but any alignment is forbidden, because nothing in the model connects black hole spins across a gigaparsec. The defenses are therefore all systematic, polarization contamination, selection effects, sparse-sample statistics, and the VLBI jet measurement, geometric rather than polarimetric, was constructed to evade exactly those.
The standing is one of the cleanest scale violations in the anomaly census, awaiting the order-of-magnitude larger samples SKA polarimetry and VLBI surveys will deliver.