Pleochroic halos, which are microscopic discolorations found in minerals like mica, provide evidence that challenges traditional views on the age of the Earth. These halos are created by the emission of alpha particles from radioactive inclusions within the mineral. The author of "Cosmological Implications of Extinct Radioactivity from Pleochroic Halos" focuses specifically on halos formed by the decay of polonium isotopes. The presence of these polonium halos, particularly those from the short-lived isotope Po-218, suggests that the polonium isotopes were present in the mica without their parent nuclides from the uranium series. The author proposes that the mica crystallized around small inclusions containing the polonium, and for the halos to be visible, this crystallization must have happened extremely quickly after the formation of the polonium isotopes. The short half-lives of these isotopes, with Po-218 having a half-life of only 3 minutes, mean that any significant delay between the formation of the isotope and the crystallization of the mica would have resulted in the decay of the polonium and no halo formation. The author argues that these halos are better explained by a rapid, "instantaneous" creation event rather than the long timescales proposed by conventional cosmological models.