I heard that at the end of Kali Yuga, the world will be destroyed.
- What does this mean?
- Will the Earth be destroyed or the entire universe be destroyed?
- Can someone throw light on this?
No, the world won't actually get destroyed at the end of the Kali Yuga. Rather, what's going to occur is that when the evil and decadence of the Kali Yuga reaches its zenith, Vishnu will have an incarnation (avatara) as Kalki the horse rider, to kill all the evil people and restore Dharma on earth, commencing a new Satya Yuga. Here is how the Srimad Bhagavatam describes it:
So even if some people are killed, the world will still go on after the end of the Kali Yuga. The Satya Yuga, Treta Yuga, Dwapara Yuga, and Kali Yuga keep repeating in a cycle. Now one cycle of all four Yugas is called a Mahayuga or Chatur Yuga, and 1000 Mahayugas make up one Kalpa. A Kalpa constitutes just one day for Brahma the creator god. After the day is over, Brahma goes to sleep, and then the Pralaya, or night of Brahma, commences. The Pralaya, of equal length to a Kalpa, is the time period when the entire three worlds (the physical universe along with Devaloka and Asuraloka) are destroyed by fire emanating from the mouth of Vishnu's serpent Adiseshan. Here is how it's described in the Srimad Bhagavatam:
And by the way, all this annihilation is overseen by Shiva the god of destruction, who engages in his cosmic Tandava dance in order to direct all this destruction.
After the Pralaya is over, Brahma wakes up and commences the creation of the three worlds again, and thus a new Kalpa begins. Now a Kalpa is already an incredibly long period of time, but it's just one day in the life of Brahma. Now imagine how long a hundred years is in the life of Brahma! That is how long Brahma lives for, and it's called Mahakalpa. And after the Mahakalpa is over, Brahma dies, and then there is a period of even greater destruction, the Mahapralaya, which lasts as long as Mahakalpa. And then Brahma is reborn, marking the start of a new Mahakalpa. And the cycle begins again!
The Yuga Time Period
All the four yugas combined together is called Maha Yuga. One Maha Yuga comprises of 43,20,000 years. 1000 maha yugas are equivalent to the day time of the Brahma. Brahma’s night is also of the same time.
So Brahma’s one full day is equivalent to 864,00,00,000 human years. Brahma’s one second is equivalent to 1,00,000 human years on earth. Brahma lives like this for 100 years (in human years 864,00,00,00 x 365 days x 100 years), and the entire life time of brahma is equivalent to one breath of Sri Maha Vishnu.
It is said that when Sri Maha Vishnu exhilirates, the entire world is created, and when he annihilates the entire world is destroyed. The timespan between his exhiliration and annihilation is equivalent to 100 years for Brahma.
The Vishnu Purana states that at the end of the daytime period of Brahma, a dreadful drought will occur that will last 100 years, and all the waters will dry up. The Sun will change into seven Suns, and the three worlds (Bhurloka or Earth, Bhuvarloka or the lowest heaven, and Svargloka or the next higher heaven) and the underworlds will be burned bare of life. The inhabitants of Bhuvarloka and Svargloka flee to the next higher heaven, Mahaloka, to escape the heat; and then to the next higher heaven, Janaloka.
Then mighty clouds will form and the three worlds will be completely flooded with water. Lord Vishnu reposes on the waters in meditative rest for another whole kalpa (4.32 billion years) before renewing the creation.
The destruction that takes place at the end of a daytime of Brahma is referred to as 'naimittika', which is incidental or occasional. The characteristic of this destruction is that the three worlds continue to exist but are made uninhabitable. The souls of individuals also continue to exist to be reincarnated in the next daytime of Brahma.