The Bullet Cluster, often considered proof of dark matter, can also be explained by quantized inertia (QI) instead.
The cluster exhibits a symmetrical bullet shape, with the blue areas coinciding with the spin axis of the cluster.
Quantized inertia predicts that under low mutual acceleration, particles, including photons, should bend more under gravity, mimicking the effect of dark matter.
The low acceleration in the blue areas of the Bullet Cluster supports the importance of QI, rather than dark matter, in explaining the observed phenomenon.