How does one determine the length of a day without the sun?
(a question...by the way...that was already being asked in ancient times)
Yep exactly. If “1” day was say 1000 years- those “years” would be based on what? A number of 24 hour days. Since day and night didn’t exist yet, the “first day” must have been 24 hours, not 1000 years, or whatever someone wishes to state, because no actual “days existed yet” with which to measure by.