The concept of multiple universes arose in India long before the west caught up. There are many types of Multiverses, but I’ll only be discussing parallel universes today.
The parallel universe theory may be one of the most famous types of Multiverses. It says that there are infinite universes that are strikingly similar to ours, bearing a copy of you and me. In the Puranas, it is mentioned that they all have a Brahma, Vishnu, and Shiva of their own. A tale from the Bhagavata Purana bears testament to this.
Once, or infinite times in different universes, Lord Krishna was playing with his cowherd friends. Lord Brahma didn’t like the incarnation of Lord Vishnu mingling with mortals, so he abducted the boys and kept them in his realm.
Lord Krishna knew that Brahma had done that, so he made exact copies of those boys appear. They lived in the original boys’ houses under the care of their parents. Maybe that act meant that he brought the parallel universe versions of his friends to our earth.
A year passed on earth, and the cowherd boys’ families lived happily with the copies of their children. Lord Brahma returned and was shocked to see the boys playing with Krishna! He saw two versions of the same boys, one set asleep in his custody, the other living with Krishna. Shocked, Lord Brahma knelt before Krishna, accepting his defeat.
The cowherd boys created by Krishna were replaced by many Vishnus, each from a different universe. They disappeared too, and Krishna conjured a thousand parallel universe copies of Brahma. Our Brahma was speechless. Lord Krishna had broken his hubris, showing him that he was a fraction in perspective of the Multiverse.
It is not just the Bhagavata Purana that has the knowledge of parallel universes. The Yoga Vasishta written by Maharishi Valmiki has various information about parallel universes.
I saw countless creations, though they did not know of one another’s existence. Some were coming into being, others were perishing; all of them had different shielding atmospheres (from five to thirty-six atmospheres). There were different elements in each; they were inhabited by different types of beings, in different stages of evolution, with different natures and cultures; some had other universes within them; in some there were creatures you would not believe possible to exist; in some there was apparent natural order, and in others there was utter disorder; in some there was no light and hence no time-sense.Yoga Vashishta, Section VI-2, Chapter 58-59
These words by Sage Vasishta are proof that the ancients knew about parallel universes. Deeper research of the ancient texts may reveal more shocking facts. The question is: how many people are willing to explore?