What is Time?: "When was the 'Start of Everything'?

* The commonest view of scientists is that the universe, and hence time, came into existence with a 'big bang' about 16 billion (16x10⁹) years ago. This theory is based primarily on observations of colour patterns of stars, of the background radiation between stars, and of the distribution of elements in the universe. It is possible, however, that the colour patterns are partly, or entirely, due to a loss of energy of light with time, not solely to physical movement. It is even possible that the universe will prove to have indistinguishable 'big bang', 'tired light' and 'dissipative' models, just as it has several indistinguishable models of quantum mechanics, and that time thus has no true beginning. It's best to keep an open mind on this subject for some time to come.
* Our biological time began about 4 billion years ago, with the appearance of permanent liquid water on earth.
* The earliest human calendars (one is dated to 30,000 B.C.) kept track of the days in the moon cycle. Later ones counted moons or years from the accession to power of the head of a cultural group.
* The early Egyptian year began with the first visible rising of Sirius above the horizon. It was probably in use by 4200 B.C..
* The Mayan calendar of Central America began 12 August 3113 B.C. Gregorian, possibly the religious date of foundation of the first Egyptian dynasty. It was brought to the Olmec of the Gulf of Mexico by a fleet of Egyptian-derived reed boats headed by a senior religious person, the 'Plumed Serpent', about 2200 years ago. It is no longer in use, but is truly carved in stone.
* One Bishop Ussher considered that, according to the Bible, God created the world on 23 October 4004 B.C. We have just entered his 7th millennium. (A hundred years ago, 23 October 1997 would have been considered by many to be a more important date than 1 January 2000.)
* A short-lived French revolutionary calendar, with 10 day weeks, began 22"