The multiverse (or meta-universe, metaverse) is the hypothetical set of multiple possible universes (including our universe) that together comprise everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. The term was coined in 1895 by the American philosopher and psychologist William James. The different universes within the multiverse are sometimes calledparallel universes.

The structure of the multiverse, the nature of each universe within it and the relationship between the various constituent universes, depend on the specific multiverse hypothesis considered. Multiverses have been hypothesized in cosmology, physics, astronomy, philosophy, transpersonal psychology and fiction, particularly in science fiction and fantasy. In these contexts, parallel universes are also called “alternative universes”, “quantum universes”, “interpenetrating dimensions”, “parallel worlds”, “alternative realities”, and “alternative timelines”, among others.

Professor Arthur Holmes (1895-1965) geologist, professor at the University of Durham. He writes regarding the age of the earth in his great book, The Age of Earth (1913) as follows:

“Long before it became a scientific aspiration to estimate the age of the earth, many elaborate systems of the world chronology had been devised by the sages of antiquity. The most remarkable of these occult time-scales is that of the ancient Hindus, whose astonishing concept of the Earth’s duration has been traced back to Manusmriti, a sacred book.”

Alan Watts, a professor, graduate school dean and research fellow of Harvard University, drew heavily on the insights of Vedanta. Watts became well known in the 1960s as a pioneer in bringing Eastern philosophy to the West. He wrote:

“To the philosophers of India, however, Relativity is no new discovery, just as the concept of light years is no matter for astonishment to people used to thinking of time in millions of kalpas, ( A kalpa is about 4,320,000 years). The fact that the wise men of India have not been concerned with technological applications of this knowledge arises from the circumstance that technology is but one of innumerable ways of applying it.”

When the Hindu calculation of the present age of the earth and the expanding universe could make Professor Holmes so astonished, the precision with which the Hindu calculation regarding the age of the entire Universe was made would make any man spellbound.

(Hinduism and Scientific Quest – By T. R. R. Iyengar p. 20-21).

Srila Prabhupada: “There are innumerable universes beyond the one in which we are put, and all these material universes cover only an insignificant portion of the spiritual sky, which is described above as sanātana Brahmaloka.” (Purport to 2:5:40-41) 

Hinduism’s understanding of time is as grandiose as time itself. While most cultures base their cosmologies on familiar units such as few hundreds or thousands of years, the Hindu concept of time embraces billions and trillions of years. The Puranas describe time units from the infinitesimal truti, lasting 1/1,000,0000 of a second to a mahamantavara of 311 trillion years. Hindu sages describe time as cyclic, an endless procession of creation, preservation and dissolution. Scientists such as Carl Sagan have expressed amazement at the accuracy of space and time descriptions given by the ancient rishis and saints, who fathomed the secrets of the universe through their mystically awakened senses.

(Hinduism Today April/May/June 2007 p. 14).

Twice-Told Tale for Hindus

What the Western scientists had discovered in the 19th century, and which our 21st-century eminent scientists like Stephen Hawkingand Dr Michio Kaku (the person in the video above) have now affirmed and corroborate, is a twice-told tale for the great majority of the Hindus. That there are multiple or innumerable universes is no news to the Hindu who is learned in the Hindu scriptures. Not just one but several Puranas, viz., Vishnu Purana, Srimad Bhagavatam, Padma Purana and Vayu Purana, and authoritative Hindu scriptures like Atharva Veda have spoken of the differentuniverses:

Srimad Bhagavatam (10:87:41):Because You are unlimited, neither the lords of heaven nor even You Yourself can ever reach the end of Your glories. The countless universes, each enveloped in its shell, are compelled by the wheel of time to wander within You, like particles of dust blowing about in the sky. The śrutis, following their method of eliminating everything separate from the Supreme, become successful by revealing You as their final conclusion.

My dear son Nārada, know from me that there are seven lower planetary systems out of the total  fourteen. The first planetary system, known as Atala, is situated on the waist; the second, Vitala, is situated on the thighs; the third, Sutala, on the knees; the fourth, Talātala, on the shanks; the fifth, Mahātala, on the ankles; the sixth, Rasātala, on the upper portion of the feet; and the seventh, Pātāla, on the soles of the feet. Thus the virāṭ form of the Lord is full of all planetary systems.(Srimad Bhagavatam 2:5:40-41)

Every universe is covered by seven layers — earth, water, fire, air, sky, the total energy and false ego — each ten times greater than the previous one. There are innumerable universesbesides this one, and although they are unlimitedly large, they move about like atoms in You. Therefore You are called unlimited (Srimad Bhagavatam 6.16.37) 

Lord Śiva said: “My dear son, I, Lord Brahmā and the other devas, who move within this universe under the misconception of our greatness, cannot exhibit any power to compete with the Supreme Personality of Godhead, for innumerable universes and their inhabitants come into existence and are annihilated by the simple direction of the Lord” (Srimad Bhagavatam 9.4.56) 

After separating the different universes, the gigantic universal form of the Lord, which came out of the causal ocean, the place of appearance for the first puruṣa-avatāra, entered into each of theseparate universes, desiring to lie on the created transcendental water (Srimad Bhagavatam 2.10.10)

The number of universes seems to be uncountable, immeasurable, or incalculable according: 

Even though over a period of time I might count all the atoms of the universe, I could not count all of My opulences which I manifest within innumerable universes (Srimad Bhagavatam 11.16.39)

Analogies to describe multiple universes: 

What am I, a small creature measuring seven spans of my own hand? I am enclosed in a potlike universe composed of material nature, the total material energy, false ego, ether, air, water and earth. And what is Your glory? Unlimited universes pass through the pores of Your body just as particles of dust pass through the openings of a screened window (Srimad Bhagavatam 10.14.11) 

Because You are unlimited, neither the lords of heaven nor even You Yourself can ever reach the end of Your glories. Thecountless universes, each enveloped in its shell, are compelled by the wheel of time to wander within You, like particles of dust blowing about in the sky. The śrutis, following their method of eliminating everything separate from the Supreme, become successful by revealing You as their final conclusion (Srimad Bhagavatam 10.87.41) 

The layers or elements covering the universes are each ten times thicker than the one before, and all the universes clustered together appear like atoms in a huge combination(Srimad Bhagavatam 3.11.41)

Theconcept of parallel universes appears in the Brahma Vaivarta Purana: 

And who will search through the wide infinities of space to count the universes side by side, each containing its Brahma, its Vishnu, its Shiva? Who can count the Indras in them all–those Indras side by side, who reign at once in all the innumerable worlds; those others who passed away before them; or even the Indras who succeed each other in any given line, ascending to godly kingship, one by one, and, one by one, passing away? (Brahma Vaivarta Purana)

Horizontal and Vertical Dimensions
Vedic cosmology has horizontal and vertical dimensions. By horizontal dimension it means the space that spreads sideways. Vertical dimension refers to the space above and below away from the earth’s centre, and when the distance of an object from the earth, it refers to the distance from this centre. In Vedic cosmology, “up” means “towards the celestial north, in a dorection perpendicular to the plane of Bhu-mandala, and “down” means the opposite direction.(pg., 83, Vedic Cosmography & Astronomy by Dr Ricahrd L.Thompson). 

Three Main Division and 14 Sub-Divisions
Along this vertical direction, the universe is divided into three and also into fourteen subdivisions. The three main divisions are called the three worlds: lower, middle and upper. these worlds are often referred to as “Bhuh”, “Bhuvah” and “Svah” or “Patala”, “Martya” and “Svarga” (Purport to Srimad Bhagavatam 3:11:28). Please note that these two sets of names are not synonymous. (pg., 83, Vedic Cosmography & Astronomy by Dr Ricahrd L.Thompson). The three divisions: Svarga (Heaven:seven upper regions), Prithvi (earth) and Patala(the underworld and netherworld) (pgs.762-763, Encyclopedic Dictionary of Puranas by Swami Parmeshwaranand). For this reason, therefore, the term “triloka” (=consisting of three lokas) can be seen in the Vedic scriptures, and God is called “trilokinatha” (=the Lord of the three lokas) [pg., 71,Vedic Physics, Scientific Origin of Hinduism by Dr Raja Ram Mohan Roy)

Let’s now talk about the fourteen lokas (not to be confused with planets): seven higher worlds (heavens) and seven lower ones (underworlds). (The earth is considered the lowest of the seven higher worlds.). The higher worlds are theseven vyahrtis: bhuu,bhuvas, svar, mahas,janas, tapas, and satyaabove) and seven lower ones (the “seven undreworlds” or paatalas:atala, vitala, sutala,rasaataala, talatala,mahaatala and paatala loka):

Seven Vyahrtis : Gods and mortals live in these worlds
1 Satya-loka: Brahma’s loka. Satya-loka planetary system is not eternal. Abode of Truth or of Brahma, where atman are released from the necessity of rebirth.

2 Tapa-loka: Abode of tapas or of other deities. Ayohnija devadas live here.

3 Jana-loka: Abode of the sons of God Brahma.

4 Mahar-loka: The abode of great sages and enlightened beings like Markendeya and other rishies.

5 Svar-loka: Region between the sun and polar star, the heaven of the god Indra. Indra, devatas, Rishies, Gandharvas and Apsaras live here: a heavenly paradise of pleasure, where all the 330 million Hindu gods (Deva) reside along with the king of gods, Indra.

6 Bhuvar-loka (aka Pitri Loka): Sun, planets, stars. Space between earth and the sun, inhabited by semi-divine beings. The a real region, the atmosphere, the life-force.

7 Bhur-loka: Man and animals live here. The Vishnu Purana says that the earth is merely one
of thousands of billions of inhabited worlds like itself to be found in the universe.

Different realms of Patala are ruled by different demons and Nagas; usually with the Nagas headed by Vasuki assigned to the lowest realm.Vayu Purana records each realm of Patala has cities in it.

Seven paatalas
8 Atala-loka: Atala is ruled by Bala – a son of Maya – who possesses mystical powers. By one yawn, Bala created three types of women – svairiṇīs (“self-willed”), who like to marry men from their own group; kāmiṇīs (“lustful”), who marry men from any group, and the puḿścalīs (“whorish”), who keep changing their partners. When a man enters Atala, these women enchant him and serve him an intoxicating cannabis drink that induces sexual energy in the man. Then, these women enjoy sexual play with the traveller, who feels to be stronger than ten thousand elephants and forgets impending death.

9 Vitala-loka: Vitala is ruled by the god Hara-Bhava – a form of Shiva, who dwells with attendantganas including ghosts and goblins as the master of gold mines. The residents of this realm are adorned with gold from this region.

10 Sutala-loka: Sutala is the kingdom of the pious demon king Bali.

11 Talatala-loka: Talātala is the realm of the demon-architect Maya, who is well-versed in sorcery. Shiva, as Tripurantaka, destroyed the three cities of Maya but was later pleased with Maya and gave him this realm and promised to protect him.

12 Mahatala-loka: Mahātala is the abode of many-hooded Nagas (serpents) – the sons of Kadru, headed by the Krodhavasha (Irascible) band of Kuhaka, Taksshaka, Kaliya and Sushena. They live here with their families in peace but always fear Garuda, the eagle-man.

13 Rasatala-loka: Rasātala is the home of the demons – Danavas and Daityas, who are mighty but cruel. They are the eternal foes of Devas (the gods). They live in holes like serpents.

14 Patala-loka: The lowest realm is called Patala or Nagaloka, the region of the Nagas, ruled by Vasuki. Here live several Nagas with many hoods. Each of their hood is decorated by a jewel, whose light illuminates this realm.

Note 1: Vishnu Purana tells of a visit by the divine wandering sage Narada to Patala region. Narada describes Patala as more beautiful than Svarga (heaven). Patala is described as filled with splendid jewels, beautiful groves and lakes and lovely demon maidens. Sweet fragrance is in the air and is fused with sweet music. The soil here is white, black, purple, sandy, yellow, stony and also of gold.

Srimad Bhagavatam describes this region as being more opulent than the upper regions of the universe, which include heaven. The life here is of pleasure, wealth and luxury, with no distress. The demon architect Maya has constructed palaces, temples, houses, yards and hotels for foreigners, with jewels. The natural beauty of Patala is said to surpass that of the upper realms. There is no sunlight in the lower realms, but the darkness is dissipated by the shining of the jewels that the residents of Patala wear. There is no old age, no sweat, no disease in Patala.

Note 2: According to Vishnu Puranas “Hell”, which in the Hindu scriptures called “naraka, is below Patala. (It is the realm of death where sinners are punished). It is not equivalent to the concept of Hell in Christianity and other religions, as Yama is also Dharmaraja or God of justice; it is a temporary purgatorium for sinners or papis.

All the worlds except the earth are used as temporary places of stay as follows: upon one’s death on earth, the god of death (officially called ‘Yama Dharma Raajaa’ – Yama, the lord of justice) tallies the person’s good/bad deeds while on earth and decides if the soul goes to a heaven and/or a hell, for how long, and in what capacity. Some versions of the theology state that good and bad deeds neutralize each other and the soul therefore is born in either a heaven or a hell, but not both, whereas according to another school of thought, the good and bad deeds don’t cancel out each other. In either case, the soul acquires a body as appropriate to the worlds it enters. At the end of the soul’s time in those worlds, it returns to the earth (is reborn as a life form on the earth). It is considered that only from the earth, and only after a human life, can the soul reach supreme salvation, the state free from the cycle of birth and death, a state of absolute and eternal bliss.

Note 3: According to Hinduism, the universe (or multiverse) never came to be at some particular point, but always has been, always will be, but is perpetually in flux. Space and time are of cyclical nature. This universe is simply the current one, which is in flux and constantly changing, when it finally ceases to manifest, a new one will arise. An interesting parallel to these ideas can be found in the ekpyrotic model of the universe. This concept is also accepted by Buddhist Dharma.

Parallel Universes in 200 Words
(http://www.lifeslittlemysteries.com/2394-parallel-universes-explained.html)