Night of Brahma

Hindu texts describe units of Kala measurements, from microseconds to Trillions of years. According to these texts, time is cyclic, which repeats itself forever.

Various fragments of time are used in Hindu Scriptures like Vedas, Bhagavata Purana, Vishnu Puran, Mahabharata, Suryasidhanta etc. A summary of the Hindu metrics of time (kāla vyavahāra) follows.

The Lifespan of the pitras is 100 years of pitras (3,000 Solar years).

The life span of any Hindu deva spans nearly (or more than) 4.5 million years. Statistically, we can also look it as:

The Viṣṇu Purāṇa Time measurement section of the Viṣṇu Purāṇa Book I Chapter III explains the above as follows:

(2 Kalpas constitute a day and night of Brahma, 8.64 billion human years)

One day of Brahma is divided into 1000 parts called charaṇas.

Yugas can be understood easily by the Set theory. Satya Yuga is the largest set & other yugas are its subsets. It also implies that Satya/Truth exists in all Yugas. The charaṇas are divided as follows:

The cycle repeats itself, so altogether there are 1,000 cycles of Mahā-Yuga in one day of Brahma.

Currently, 50 years of Brahma have elapsed. The last Kalpa at the end of the 50th year is called Padma Kalpa. We are currently in the first 'day' of the 51st year. This Brahma's day, Kalpa is named as Shveta-Varaha Kalpa. Within this Day, six Manvantaras have already elapsed and this is the seventh Manvantara, named as – Vaivasvatha Manvantara (or Sraddhadeva Manvantara). Within the Vaivasvatha Manvantara, 27 Mahayugas (4 Yugas together is a Mahayuga), and the Krita, Treta and Dwapara Yugas of the 28th Mahayuga have elapsed. This Kaliyuga is in the 28th Mahayuga. This Kaliyuga began in the year 3102 BCE in the proleptic Julian Calendar. Since 50 years of Brahma have already elapsed, this is the second Parardha, also called as Dvithiya Parardha.

432000 × 10 × 1000 × 2 = 8.64 billion years (2 Kalpa (day and night))

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Wikipedia