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.”