Realm of Boundless Empty Space ［空無辺処］ ( Ākāshānantyāyatana;  Kūmuhen-jo): Also, Ākāshānantya Realm, or Heaven of Boundless Empty Space. The first and the lowest of the four realms of the world of formlessness. Meditation leading to rebirth in this heaven is termed meditation on the Realm of Boundless Empty Space. In this meditation, one becomes free from all thought of matter, meditating on the limitless space where no matter exists. The life span of beings in the Realm of Boundless Empty Space is said to be twenty thousand kalpas. See also world of formlessness.