Hindu Cosmology upholds the idea that creation is timeless, having no beginning in time. Each creation is preceded by dissolution and each dissolution is followed by creation. The whole cosmos exists in two states – the unmanifested or undifferentiated state and the manifested or differentiated state. This has been going on eternally. There are many universes – all follow the same rhythm, creation and dissolution (the systole and diastole of the cosmic heart). According to the Bhagavad Gita this srishti (creation) and pralaya (dissolution) recur at a period of 1,000 mahayuga or 4.32 billion years or 4,320 million years:
For a thousand ages lasts One day of Brahma, And for a thousand ages one such night;
This knowing, men will know (what is meant by) day and night.
At the day’s dawning all things manifest; Spring forth from the Unmanifest;
And then at nightfall they dissolve again, In (that same mystery) surnamed “Unmanifest.”
Long regarded as non-astronomical by historians of science, Hindu cosmological time cycles are shown here to be the most accurate solar calendar known, the progenitor of the sexagesimal number system and the 360 + 5 day calendars of antiquity, and one of the greatest achievements of humanity.
Hindu cosmological time cycles, as well as common units of measuring time and angles, are generated from the concept that the Sun has three distinct mean motions which work together like the hour, minute and second hands of a clock. The exact sidereal solar year of 365.2563795 mean solar days, constant of precession of 50″.4 and week of precessional years of 180,000 sidereal solar years used in the construction of the cycles may be inferred from their infrastructure. With the astronomical quantities known, the kaliyuga epoch of February 18, 3102 B.C. of the Julian calendar establishes the summer solstice as the initial tropical point of the cycles, 147108 B.C. as the beginning of the current week of precessional years and closely approximates the fixed initial point of the sidereal sphere given in the SuryaSiddhanta commentary.
Not only does the astronomical basis of the cycles conclusively prove the non-Greek origin and ancient age of Indian astronomical science, but the extremely high level of astronomical knowledge used and method of construction of the cycles cannot be placed in any known historical frame of reference. The implications of these findings for mankind are, therefore, very far-reaching.