Temporal cosmology
Buddhist temporal cosmology describes how the universe comes into being and is dissolved.
Like other Indian cosmologies, it assumes an infinite span of time and is cyclical.
This does not mean that the same events occur in identical form with each cycle, but merely that, as with the cycles of day and night or summer and winter, certain natural events occur over and over to give some structure to time.
The basic unit of time measurement is the
mahākalpa or "
Great Eon".
The exact length of this time in human years is never defined exactly, but it is meant to be very long, to be measured in billions of years if not longer.
A
mahākalpa is divided into
four kalpas or "eons", each distinguished from the others by the stage of evolution of the universe during that kalpa.
The four kalpas are:
- Vivartakalpa "Eon of evolution" – during this kalpa the universe comes into existence.
- Vivartasthāyikalpa "Eon of evolution-duration" – during this kalpa the universe remains in existence in a steady state.
- Saṃvartakalpa "Eon of dissolution" – during this kalpa the universe dissolves.
- Saṃvartasthāyikalpa "Eon of dissolution-duration" – during this kalpa the universe remains in a state of emptiness.
Each one of these
kalpas is divided into
20 antarakalpas (Pāli antarakappa, "inside eons") each of about the same length.
For the Saṃvartasthāyikalpa this division
is merely nominal, as nothing changes from one antarakalpa to the next;
but for the other three kalpas it marks an interior cycle within the kalpa.