The expression parama vyoman refers to the “highest firmament of heaven in space”. The term vyoman: vi-yoman vi-yu – Heaven or div is commonly termed vyoman, the luminous space. The third ridge in the luminous space or heaven is mentioned (Rig Veda 9.86.27).
The three heavens are often called the three luminous spaces: the highest (uttama), the middle and the lowest (Rig Veda 5.60.6). The highest heaven is also termed uttara or parya (Rig Veda 4.26.6; 6.40.5). The highest space is spoken of as uttama (Rigveda. 9.22.5), parama (Rigveda 3.30.2) or tritiya (Rigveda 9.74.6; 10.45.3), where the waters and Soma are. In the third or highest heave, Fathers and Soma dwell. The dead person meets with the Fathers where they dwell along with Yama (Rigveda 10.14.8; 10.15.4-5; Atharva Veda 4.34.3). Agni takes the corpse to the other world, also the Fathers and the gods (Rigveda 10.16.1-4). Shiva granted Yama the favor of dwelling in the world of the Fathers (Matsya Purana 11.18).
The third space belongs to Vishnu (Rigveda 7.99.1). Vishnu’s highest place is on the surface of the firmament (Mahanarayana Upanishad 176); Katha Upanishad 3.6.9). The firmament of (Rg Veda 10.90.16) is regarded as Vishnu’s highest place. The abode where the Fathers and Yama dwell is situated in the midst of the sky (Rgveda 10.15.14), in the highest heaven (Rgveda 10.14.8); (Atharvaveda 11.4.11), in the third heaven, where the eternal light is (Rigveda 9.113.7-9). In Atharvaveda (19.53.3), praise of Time is made wherein Time exists in the highest firmament. That space, the highest space (vyoman) is free from impurity (Ahirbudhnya Samhita 6.22).
The concept of the highest heaven is very vital in the Vedic and post-Vedic mythology.