Abhidharma thought also analyzes material units. For example, a paramāṇzu or particle is the smallest unit of matter, and a kṣaṇa, said to be 1/65th the length of a finger snap, is the smallest unit of time. A kalpa or eon is the longest unit of time. It is said to be half a day for Brahman and 4.32 billion years in the human world.