Time (kala) and space (akasha) are two important concepts in Jainism. Kala (time) is infinite but it has cycles in it, each cycle having two eras of equal durations known as avasarpini and utsarpini. Avasarpini is the descending era where virtue gradually decreases and utsarpini is the ascending era where the reverse takes place. The present era is Avasarpini.
Akasha (space) is also infinite and is conceived as having two parts, one lokakasha where movement is possible and the other alokakasha where movement is not possible. In the lokakasha, dravyas (substances) exist and the latter is empty space. The term dravya is applied to the six entities mentioned above – the jiva and the ajiva with its five-fold division. The dravyas except kala are called astikayas, a term which means that they are asti (real) and occupy kaya (space). Time is not an astikaya because it has no such parts, though it is an eternal entity.