In Hindu cosmology, the universe is cyclically created and destroyed. The cosmology divides time into four epochs or Yuga.
The texts of Hindu vedic cosmology says there is no absolute start to time, as it is considered infinite and cyclic. Similarly, the space and universe has neither start nor end, rather it is cyclical. The current universe is just the start of a present cycle preceded by an infinite number of universes and to be followed by another infinite number of universes.
There are multiple universes, each takes birth from chaos, grows, decays and dies into chaos, to be reborn again. Further, there are different and parallel realities.
One complete cycle of the four (Kṛta or Satya, Treta, Dvapara and Kali) Yugas is one Mahā-Yuga (4.32 million solar years) and is confirmed by the Gītā Śloka 8.17 (statement) “sahasra-yuga-paryantam ahar yad brahmaṇo viduḥ rātriṁ yuga-sahasrāntāṁ te ‘ho-rātra-vido janāḥ”, meaning, a day of brahma is of 1000 Mahā-Yuga. Thus a day of Brahma, Kalpa, is of duration: 4.32 billion solar years. Two Kalpas constitute 24 hours (day and Night) of Brahma. A Manvantara, which consists of 71 Mahā-Yuga (306,720,000 solar years) is ruled by a Manu. After each Manvantara follows one Sandhi Kāla, of the same duration as a Kṛta Yuga (1,728,000 Solar Years). It is said that during a Sandhi Kāla, the entire earth is submerged in water. According to Hindu scriptures, the world would be destroyed at the end of the Kali Yuga.
According to Henry White Wallis, the Rigveda and other Vedic texts are full of alternative cosmological theories and curiosity questions. For example, the hymn 1.24 of the Rigveda asks, “these stars, which are set on high, and appear at night, whither do they go in the daytime?” and hymn 10.88 wonders, “how many fires are there, how many suns, how many dawns, how many waters? I am not posing an awkward question for you fathers; I ask you, poets, only to find out?”. To its numerous open-ended questions, the Vedic texts present a diversity of thought, in verses imbued with symbols and allegory, where in some cases forces and agencies are clothed with a distinct personality, while in other cases as nature with or without anthropomorphic activity such as forms of mythical sacrifices.
The Rigveda contains the Nasadiya sukta hymn which does not offer a cosmological theory, but asks cosmological questions about the nature of universe and how it began.
Darkness there was at first, by darkness hidden;
Without distinctive marks, this all was water;
That which, becoming, by the void was covered;
That One by force of heat came into being;
Who really knows? Who will here proclaim it?
Whence was it produced? Whence is this creation?
Gods came afterwards, with the creation of this universe.
Who then knows whence it has arisen?
Whether God’s will created it, or whether He was mute;
Perhaps it formed itself, or perhaps it did not;
Only He who is its overseer in highest heaven knows,
Only He knows, or perhaps He does not know.
— Rigveda 10:129-6