RE Puranic & modern dating:
I should clarify that the authors write, “As discussed in Chapter 7, Purānic dates must be multiplied by two in order to be converted into modern radiometric dates.” They propose that the radiometric dates are correct & that there’s an error of a factor of two found in the Puranas. They propose “that it is due to an inadvertent substitution of a factor of two arising from the inherent nature of Purānic timekeeping, wherein a factor of two is repeatedly used: two fortnights is said to equal one month, two months is said to equal one season, two “Ayanas” (periods of the Sun’s trajectory north or south of the ecliptic) equals one year, and two “Parārdhas” (half-lifetimes) equals one lifetime of Brahmā…. The fact that all the Purānas have the same chronology (in terms of yugas, manvantaras, and kalpas) indicates that, at an early stage of their development, they were all in the hands of a single person. This indicates that, if there was a mistake, it must have been introduced at an early stage (thousands of years ago) when the Purānas were transmitted orally from spiritual master to disciple.” Thus the authors choose to say that Kali-yuga lasts 864,000 yrs., a divya-yuga 8.64 M yrs., Brahmā’s 12 hrs. 8.64 B yrs., etc.