Introduction
The advent of science fiction in the late 19th century saw many experimental concepts written about in literature, some of which even entered into scientific talk. Many of these concepts are now standard tropes of science fiction such as traveling into space, creatures from other planets, and a thousand other ideas. Like many of these concepts, the idea behind multiverses and time travel are parts of fairy tales and myths adapted to the materialistic philosophy behind science fiction (time travel), or used as a reaction against materialistic science (multiverse).
This series seeks to provide an overview of the concepts behind multiverses and time travel, examine where they came from and the lore behind them, look at the ways that they have been used in fiction, and finish with some personal recommendations about how to use them consistently.
Multiverses
First, how can one define a multiverse? Well, there are two primary ways. From a point of view of substance, any systems that are fundamentally unconnected from one another can be considered as separate universes. The second way that one can define a universe is the incarnation point of one part of a substance. Thus, if a substance or metabeing incarnates as separate avatars in multiple worlds, each unaware of the current existence of the other, such would also qualify as a multiverse.
To begin talking about how this fits in with the primary world philosophies, let us begin with a discussion about how the universe is conceived in Monist and Dualistic philosophies.
Suppose that there is an original substance of the universe, whether known as God, Soul, Eternity, or Chaos. From the perception point of this substance, everything is a part of its mind and form. It knows everything, is sees everything, and everything moves within it, whether consciously or unconsciously. Existence flows from whatever impulse is present within that being, and, in turn, existence realizes itself as a part of that being. This idea is known as Monism.
Here are some examples from Hinduism about Brahman, the supreme being:
“The body is called a field, Arjuna; the one who knows it is called the Knower of the field. This is the knowledge of those who know. I am the Knower of the field in everyone, Arjuna. Knowledge of the field and its Knower is true knowledge. Listen and I will explain the nature of the field and how change takes place within it. I will also describe the Knower of the field and his power.”
Bhagavad Gita Chapter 13 (1-3)
“I will tell you of the wisdom that leads to immortality: the beginningless Brahman, which can be called neither being nor non-being. It dwells in all, in every hand and foot and head, in every mouth and eye and ear in the universe. Without senses itself, it shines through the functioning of the senses. Completely independent, it supports all things. Beyond the gunas*, it enjoys their play. It is both near and far, both within and without every creature; it moves and is unmoving. In its subtlety it is beyond comprehension. It is indivisible, yet appears divided in separate creatures. Know it to be the creator, the preserver, and the destroyer. Dwelling in every heart, it is beyond darkness. It is called the light of light, the object and goal of knowledge, and knowledge itself.”
Bhagavad Gita Chapter 13 (12-23)
* The Gunas are the attributes of primordial matter, Tamas (primordial darkness, potential, and destruction), Raja (the energy of change), and Sattva (the energy of light and purity).
The contrasting idea of dualism is presented by Christianity, Islam, and Judaism (although note that some versions of esoteric Judaism tend towards monism). In those religions, there are essentially two eternal coexisting substances. One is God, the other is the universe, a non-aware substance that God creates in which is apart from him. In Genesis, this chaotic substance is the primordial waters that the spirit hovers over (note that water is historically regarded as the fundamental matter of the universe in the Middle East).
“In the beginning God created the heavens and the earth. The earth was formless and void, and darkness was over the surface of the deep, and the Spirit of God was moving over the surface of the waters. Then God said, “Let there be light”; and there was light. God saw that the light was good; and God separated the light from the darkness. God called the light day, and the darkness He called night. And there was evening and there was morning, one day. Then God said, “Let there be an expanse in the midst of the waters, and let it separate the waters from the waters. God made the expanse, and separated the waters which were below the expanse from the waters which were above the expanse; and it was so. God called the expanse heaven.”
Genesis 1: 1-8
Judaism typically presents this concept as follows: The substance of the universe is the result of God withdrawing himself from a space to create. This results in a space of darkness (whether perceived by God as such or only by created beings as such) that is surrounded by the substance of God. God’s light is left in this substance like a thread surrounded by shadows:
“At the head of the King’s authority He carved out of the supernal luminescence a Lamp of Darkness. And there emerged out of the Hidden of Hidden the Mystery of the Infinite, an unformed line, embedded in a ring, measured with a thread.”
Zohar 1:15
Thus is is said:
“Rabbi Nehuniah ben HaKana said, ‘One verse states, ‘And now they do not see light, it is brilliant in the skies.’
Another verse, however, states, ‘He made darkness His hiding place.’ It is also written, ‘Cloud and gloom surround him.’ This is an apparent contradiction.
A third verse comes and reconciles the two. It is written, ‘Even darkness is not dark to You. Night shines like day – light and darkness are the same.’
Rabbi Berachiah said, ‘It is written, ‘The earth was Chaos and Desolation.’ What is the meaning of the word “was” in this verse? This indicates that the Chaos existed previously. What is Chaos? Something that confounds people. What is Desolation? It is something that has substance. This is the reason that it is called Bohu, that is, “it is in it.”’ “
The Bahir 1-2
“Rabbi Levatas ben Tavrus said, ‘All agree, even Rabbi Yochanan, that the water already existed on the first day. But it was on the second day that, “He raftered His upper chambers with water.” At that time He created the one who “makes the clouds his chariot,” and the one who “walks on the wings of the wind.” But His messengers were not created until the fifth day.”
The Bahir 21
In Monism existence flows from the thoughts of the original substance, divided into true thoughts and errors, that which is to be preserved and that which is to be destroyed, that which is dreamed and the dreamer. By contrast, in Dualism God must intentionally act upon the universe to manifest a thought, leaving his own mind alien, or separate, to the beings of that universe.
In Christianity, Jesus the Son is the way in which the thoughts of God interact with the universe and create. As this entity joins with the universe, he brings together the two separate parts, becoming the bridge in between. This is known to God who sent him, and a revelation to the part of the universe apart from God (the darkness).
“In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things came into being through him, and apart from Him not even one thing came into being that has come into being. In Him was life, and the life was the Light of mankind. And the Light shines in the darkness, and the darkness did not comprehend it.”
John 1: 1-5
In contrast to this view of the Son, Gnostic thought suggests a Monist viewpoint that the Son is the bridge between knowledge and ignorance.
“All have sought for the one from whom they have come forth. All have been within him, the illimitable, the inconceivable, who is beyond all thought. But ignorance of the Father brought terror and fear, and terror grew dense like a fog, so that no one could see. Thus Error grew powerful. She worked on her material substance in vain. Since she did not know the truth, she assumed a fashioned figure and prepared, with power and in beauty, a substitute for truth.
This was not humiliating for the illimitable, inconceivable one. For this terror and forgetfulness and this deceptive figure were as nothing, whereas established truth is unchanging, unperturbed, and beyond beauty. For this reason, despise Error.
Error has no root; she was in a fog regarding the Father. She was there preparing works and deeds of forgetfulness and fear in order, by them, to attract those of the middle and take them captive.
…
“He (Jesus) has brought many back from Error. He went before them to the places from which they had turned when they followed Error, because of the depth of him who surrounds every place, though nothing surrounds him. Indeed, it is amazing that they were in the Father without knowing him and that they could leave on their own, since they were not able to contemplate or know the one in whom they were.
…
“For where there is enmity and strife there is deficiency, but where there is unity there is completeness. Since deficiency came about because the Father was not known, from the moment when the Father is known, deficiency will cease to be. As one’s ignorance about another vanishes when one gains knowledge, and as darkness departs when light comes, so also deficiency disappears in completeness. From then on the world of appearance will no longer be evident, but rather it will disappear in the harmony of unity.
Now the works of all lie scattered. In time unity will make the heavenly places complete, and in unity all individually will come to themselves. By means of knowledge they will purify themselves from multiplicity into unity, devouring matter within themselves like fire, darkness by light, death by life.
…
Such are those who possess something of this immeasurable majesty from above, as they await that unique and perfect One who is a Mother to them. And they do not go down to the underworld, nor do they have envy or groaning, nor is death with them. They rest in one who rests, and they are not weary or confused about truth.”
The Gospel of Truth
Compare to the monism of Sethian Gnosticism (which also notably incorporates the Ennead of Egypt, with the supreme God (the Son, or the Prince) being Seth.
“The One is the Invisible Spirit. We should not think of it as a god or like a god, for it is greater than a god, because it has nothing over it and no lord above it. It does not exist within anything inferior to it, since everything exists within itself. It is eternal, since it does not need anything. For it is absolutely complete. It has never lacked anything in order to be completed by it. Rather, it is always absolutely complete in light.
…
This Father is the one who beholds himself in the light surrounding him, which is the spring of living water and provides all the realms. He reflects on his image everywhere, sees it in the spring of the Spirit, and becomes enamoured of his luminous water, for his image is in the spring of pure luminous water surrounding him.
His thought became a reality, and she who appeared in his presence in shining light came forth. She is the first power who preceded everything and came forth from his mind as the Forethought of the All. Her light shines like the Father of light; she, the perfect power, is the image of the Perfect and Invisible Virgin Spirit.
She, the first power, the glory of Barbelo, the perfect glory among the aeons, the glory of revelation, she glorified and praised the Virgin Spirit, for because of the Spirit she had come forth.
She is the first Thought, the image of the Spirit. She became the universal womb, for she precedes everything.”
The Secret Book of John
The fall of Sophia in Gnosticism has an element of multiversal creation to it as well.
“Let’s call together an assembly. Let’s examine this creation of his and send someone, just as he also examined thoughts in the regions below.
I said this to all the members of the whole vast assembly of the Majesty, so that they rejoiced, and the entire household of the Father of truth rejoiced. Since I am of them, I reminded them of the thoughts that had come from the undefiled Spirit and had descended to the water – that is, to the regions below. A single thought was in all of them, since it came from a single source. They expressed their decision to me, and I concurred and went forth to reveal glory to my kin, my friends in spirit.
Those in the world had been prepared by the will of our sister Sophia, whose indiscretion was without guile. She was not sent out, nor did she request anything from the realm of the All, the Majesty of the assembly, and the Fullness when she first came to prepare homes and habitations for the child of light. From the elements below she derived collaborators to construct bodily dwellings for them, but in their vainglory they fell into ruin. Yet it was in these dwellings that those in the world came to live. And since they were prepared by Sophia, they are ready to receive the saving word of the ineffable One and the Majesty the assembly of all those who still are in waiting and those who already are in me.
I approached a bodily dwelling and evicted the previous occupant, and I went in. The whole multitude of archons was upset, and all the material stuff of the rulers and the powers born of earth began to tremble at the sight of the figure with a composite image. I was in it, and I did not look like the previous occupant. He was a worldly person, but I, I am from above the heavens. I did not defy them, and I became an anointed one, but neither did I reveal myself to them in the love coming from me. Rather, I revealed that I am a stranger to the regions below.”
The Second Discourse of Great Seth
Application to the Multiverse
Having stated the differences between Monism and Dualism, how are multiverses applied in each theory? From the perspective of the primal substance a truly separate multiverse can only exist if dualism is true. In Monism, since the thing and the thinker are one and the same, separation cannot be thought of in physical terms.
Yet, that is from the perception point of the primal substance. Eastern monist thought often uses the concept of multiverses while western dualistic thought is focused upon a single universe.
The following demonstrate the concept of the multiverse as it exists in Hinduism:
Consider the following from The Devi Bhagavatam*.
“Narayana said, “O Devarsi! The egg that was floating in the water for a period equal to the life of Brahma now, in the fullness of time, separated into two parts. Within that egg, there was a powerful Child, lustrous like a billion suns. This child could not suck its mother’s milk, as it was forsaken by her. So, being tired of hunger, the child cried for a moment. The child that will become the Lord of countless Brahmandas**, now an orphan with neither father nor mother, began to look upwards from the waters… Yet, this boy is the Sole Stay of all this universe, and he was named Maha-Visnu. In his every pore, countless universes exist, so much so that even S’ri Krisna could not count them. If it were possible to count the number of dust particles, it would still be impossible to count the number of universes. So there are endless Brahmas, Visnus, and Mahes’varas. In every Brahmanda there is a Brahma, Visnu, and Mahes’a.
…
When this Brahmanda dissolves, everything dissolves and is destroyed. Everything is temporary, like bubbles of water. Only Goloka and Vaikuntha are eternal. In every pore of Maha Virat, a Brahmanda exists. What can one say to others when even Krisna cannot could the number of these Brahmandas? In every Brahmanda there is Brahma, Visnu, and Mahes’a. O Child Narada! In every Brahmanda the number of the gods is thirty million. Some of them are the regents of quarters, some are the rulers of quarters, some are asterisms, and some planets.”
Devi Bhagavatam (Book 9: Chapter 3)
* In many Hindu sects, Devi is considered the supreme goddess.
** Brahmanda – universe
Similarly, here is a description of the spiritual sky and the planets of the gods which rule over the universes. This leads into a story where Krishna summons millions of incarnations of the same god from across the universes, each of which rules over a mighty universe where evil has been cast out. This is to impress upon the god of our own universe (Brahma) his own smallness, and to give him a taste of the great potential his own being possesses.
“Sri Caitanya Mahaprabhu continued, “All the transcendental forms of the Lord are situated in the spiritual sky. They preside over spiritual planets in that abode, but there is no counting those Vaikuntha planets. The breadth of each Vaikuntha planet is described as eight miles multiplied by one hundred, by one thousand, by ten thousand and by ten million. In other words, each Vaikuntha planet is expanded beyond our ability to measure. Each Vaikuntha planet is very large, and each is made of spiritual bliss. The inhabitants are all associates of the Supreme Lord, and they have full opulence like the Lord himself. This is how the Vaikuntha planets are all situated. Since all the Vaikuntha planets are located in a certain corner of the spiritual sky, who can measure the spiritual sky? The shape of the spiritual sky is comparable to a lotus flower. The topmost region of that flower is called the whorl, and within that whorl is Krishna’s abode. The petals of the spiritual lotus flower consist of many Vaikuntha planets. Each Vaikuntha planet is full of spiritual bliss, complete opulence and space, and each is inhabited by incarnations. If Lord Brahma and Lord Siva cannot estimate the length and breadth of the spiritual sky and the Vaikuntha planets, how can ordinary living entities begin to imagine them?”
Sri Caitanya Caritamrta Madhya-lila (21:1-8)
“At Vrindavana, the Lord immediately created all material and spiritual planets in one moment. Indeed, all of them were created with their predominating deities. We do not heart of such wonderful things anywhere else. Simply by one’s hearing of those incidents, one’s consciousness is agitated and cleansed. According to Sukadeva Gosvami, Krishna had unlimited calves and cowherd boys with Him. No one could count their actual number. Each of the cowherd boys was tending calves to the extent of a koti, arbuda, sankha and padma. That is the way of counting. All the cowherd boys had unlimited calves. Similarly, their canes, flutes, lotus flowers, horns, garments and ornaments were all unlimited. They cannot be limited by writing about them. The cowherd boys then became four-handed Narayanas, predominating Deities of Vaikuntha planets. All the separate Brahmas from different universes began to offer their prayers unto the Lords. All these transcendental bodies emanated from the body of Krishna, and, within a second, they entered again into His body.
When the Lord Brahma from this universe saw this pastime, he was astonished and struck with wonder. After offering his prayers, he gave the following conclusion. Lord Brahma said, ‘If someone says that he knows everything about Krishna’s opulence, let him think that way. Yet, as far as I am concerned, with my body and mind I consider it in this way. My Lord, your opulence is like an unlimited ocean of nectar, and it is verbally and mentally impossible for me to realize even a drop of that ocean. There are people who say, ‘I know everything about Krishna.’ Let them think that way. As far as I am concerned, I do not wish to speak very much about this matter. O my Lord, let me say this much. As far as your opulences are concerned, they are all beyond the reach of my mind, body and words.’
Let the glories of Lord Krishna be! Who could be aware of all of them? His abode, Vrindavana, has many wonderful opulences. Just try to see them all. According to the revelations of revealed scripture, Vrindavana extends only thirty-two miles. Nonetheless, all the Vaikuntha planets and innumerable universes are located in one corner of this tract.”
Sri Caitanya Caritamrta Madhya-lila (21: 17-29)
“Once, when Krishna was ruling Dvaraka, Lord Brahma came to see Him, and the doorman immediately informed Lord Krishna of Brahma’s arrival. When Krishna was so informed, He immediately asked the doorman, ‘Which Brahma? What is his name?’ The doorman therefore returned and questioned Lord Brahma. When the doorman asked, ‘Which Brahma?’ Lord Brahma was surprised. He told the doorman, ‘Please go inform Lord Krishna that I am the four-headed Brahma who is the father of the four Humaras.’ The doorman then informed Lord Krishna of Lord Brahma’s description, and Lord Krishna gave him permission to enter. The doorman escorted Lord Brahma in, and as soon as Brahma saw Lord Krishna, he offered obeisances at his lotus feet.
After being worshipped by Lord Brahma, Lord Krishna also honored him with suitable words. Then Lord Krishna asked him, ‘Why have you come here?’ Being questioned, Lord Brahma immediately replied, ‘Later I shall tell You why I have come. First of all there is a doubt in my mind which I wish You would kindly dissipate. Why did you inquire which Brahma had come to see You? What is the purpose of such an inquiry? Is there any Brahma besides me within this universe?’
Upon hearing this, Sri Krishna smiled and immediately meditated. Unlimited Brahmas arrived instantly. These Brahmas had different numbers of heads. Some had ten heads, some twenty, some a hundred, some a thousand, some ten thousand, some a hundred thousand, some ten million and others a hundred million. No one can count the number of faces they had. There also arrived many Lord Sivas with various heads numbering one hundred thousand and ten million. Many Indras also arrived, and they had hundreds of thousands of eyes all over their bodies. When the four-headed Brahma of this universe saw all these opulences of Krishna, he became very much bewildered and considered himself a rabbit among many elephants.
All the Brahmas who came to see Krishna offered their respects at His lotus feet, and when they did this, their helmets touched His lotus feet. No one can estimate the inconceivable potency of Krishna. All the Brahmas who were there were resting in the one body of Krishna. When all the helmets struck together at Krishna’s lotus feet, there was a tumultuous sound. It appeared that the helmets themselves were offering prayers unto Krishna’s lotus feet. With folded hands, all the Brahmas and Sivas began to offer prayers unto Lord Krishna, saying, ‘O Lord, You have shown me a great favor. I have been able to see Your lotus feet.’ All of them then said, ‘It is my great fortunate, Lord, that You have called me, thinking of me as Your servant. Now let me know what Your order is so that I may carry it on my heads.’ Lord Krishna replied, ‘Since I wanted to see all of you together, I have called all of you here. All of you should be happy. Is there any fear from the Asuras?’ They replied, ‘By Your mercy, we are victorious everywhere. Whatever burden was upon the earth You have taken away by descending to that planet.’ This is the proof of Dvaraka’s opulence, all of the Brahmas thought, Krishna is now staying in my jurisdiction.
Thus, the opulence of Dvaraka was perceived by each and every one of them. Although they were assembled together, no one could see anyone but himself. Lord Krishna then bade farewell to all the Brahmas there, and after offering their obeisances, they all returned to their respective homes. After observing all these opulences, the four-headed Brahma of this universe was astonished. He again came before the lotus feet of Krishna and offered him obeisances.
Brahma then said, ‘Whatever I formerly decided about my knowledge I have now just had personally verified. There are people who say, “I know everything about Krishna.” Let them think in that way. As far as I am concerned, I do not wish to speak very much about this matter. O my Lord, let me say this much. As far as Your opulences are concerned, they are all beyond the reach of my mind, body and words.’
Krishna said, ‘Your particular universe has a diameter of four billion miles; therefore it is the smallest of all the universes. Consequently you have only four heads. Some of the universes are one billion Yojanas in diameter, some one trillion, some ten trillion, and some one hundred trillion yojanas. Thus, there are almost unlimited in area. According to the size of the universe, there are so many heads on the body of Brahmas. In this way I maintain innumerable universes.”
Sri Caitanya Caritamrta Madhya-lila (21: 59-89)
Thus, in this form of thought there are many universes into which metaforces incarnate as distinctive personalities. All Brahmandas (universes) are considered to be connected within the body of God, coming into existence at the same time, then dissolving together.
Western dualism and western monism (as represented in scientific materialism) do not have a concept of a multiverse. The monotheistic religions typically hold to a layered reality with different realms such as heaven, the underworld, and earth, some of which have multiple layers, however even then there is some debate about the nature of these places (for example, whether heaven and hell are different places, or simply the same place that is perceived differently). Importantly, there is only a single manifestation of a being at a time. Scientific materialism takes this a step further and supposes that there is only a single universe and one realm. Sometimes this is altered to incorporate multi dimensional or string theory, which proposes different realms, albeit these seem more philosophical in nature than practical.
Pop Culture Multiverse
Having shown where the concept of the multiverse comes from, we can now talk about its adaptation in pop culture. Amongst the pop culture world it can be generally said that there were two primary schools of thought that emerged towards the end of the 19th century. The first was the system thinkers who were heavily invested in promoting the bright scientific future that they saw around them, heavily materialistic in nature. The second can be known as the critics, men who typically sought solace in occultism and eastern mysticism, which they preferred over scientific materialism. The 20th century was very harsh on the school of scientific materialism, where the dreams of progress seemed to result, not in the promulgation of luxury and advancement, but in ever greater means of destruction and oppression. Artistic thinkers, on the left and right alike, turned on scientific materialism and one of the reactions against the Big Bang Theory, and the singular existence said to flow from it, was the multiverse.
In the same way that some sects of Hinduism believe that metabeings manifest in many universes at the same time, the pop culture multiverse does the same thing with archetypal characters. Amongst the general public, the multiverse was popularized in the public imagination by comic books and the mirror universe of Star Trek. DC comics has historically had a branching multiverse that is essentially infinite in scale. For every action and choice that is made, one or more universes split off from the main universe, resulting in a near countless number of universes. Marvel comics also used the concept of multiverses, which was recently popularized in the MCU. While the artistic reasons for multiverses have long since turned to commercial dross (courtesy of endless reboots), this still resulted in some interesting concepts and a general expansion of artistic freedom.
The Mental Multiverse
With all this talk of multiverses, metabeings that incarnate in many worlds, and universal perspectives, we must ask, how does any of this really effect the individual? Well, the truth is that the individual only experiences a single universe (or perhaps at most two, depending on how philosophical one wishes to be). Yet, one part of us is a type of multiverse, our minds. We can imagine alternative choices, different versions of beings, different realities, different rules for the world, all within ours minds. This is the mental multiverse.
Whenever we create a work of art, a multitude of potential paths unfold. Every piece of music has slight variations during each and every performance. Every painting is made of many brushstrokes and colors, each of which represents a multitude of choices. Every story has many ways that it could be told and described. The vast majority of potential paths will forever remain unexplored (that which never comes into being), while others are explored in detail (that which is being). Thus, from our point of view, the multiverse is mental.
Use
Having described the history and theory behind multiverses, we can now move onto worthwhile use cases.
Multiple Authors/Large Franchises
One of the largest problems in any pop culture property is consistency. Because franchises like DC, Marvel, Star Wars, Star Trek, and others have decades of source material written by large numbers of writers, inconsistencies in characterization and story lines inevitably emerge. This can even lead to examples where the original creators of characters disown said characters because a successor writer has messed up. Even if a writer has good intentions, they still inherit the work of everyone who has come before, the good, the mediocre, the bad, and the catastrophic. Then there are the editorial mandates. Editors are necessary in large projects to keep everything consistent and in line, however they can also mandate bad ideas, greenlight bad ideas, or egotistically stamp out creativity. This is especially true if the editor is narcissistic.
Thus, a multiverse can help in larger properties by isolating the work of artists from one another. This is even better if the different universes have limited or no interaction with one another, therefore the fans of one universe can effectively ignore what goes on in another. However, as soon as two universes interact together, what happened in one must be regarded as canon in the other. And this tendency to merge universes in popular franchises can often lead to disaster.
This use of a multiverse is not without its flaws. Constantly using established characters in different settings with different characterizations can still damage the image of that character or their associated franchise. Essentially, the popular perception of a character is typically controlled by their most popular incarnation (Usually descending from Movies to TV shows to Games to Comics/Books). Each alternative variation on a character has a potential to diminish what made them special to begin with. There is also the cynical element of branding over artistic merit where, though there is little reason to use an established character in a story, a character is shoehorned into a work because they will sell an alternative setting. One merely need think about the seemingly endless stream of cynical reboots and “creative reimaginings” that barrage us in popular media.
Does the Alt Setting Really Matter?
So you’ve just established a multiversal setting. How do you get readers to care about it? Most readers are interested in reading other stories about characters or settings that they love because they want them to be expanded on. In the case of a multiverse, the ties between the original characters they loved and the new characters strained. If the new characters are variants of the old characters, you are asking the audience to disregard the previous stories that they cared about, all to replace them with yet unproven characterization. If you are using entirely new characters, then you have the uphill battle of making readers care about the setting on the power of branding/name recognition alone.
Multiversal works also suffer from dubious canonicity. Many modern day games, movies, and tv shows offer tie in works like comics and novelizations. However, everyone knows that the first thing writers in the more prominent works of movies, television, and games ignore are the tie in works. This means that it is hard for fans to get invested in these alternatives. In more extreme examples, this can lead to fans who reject the mainstream works (like movies or tv show continuity) in favor of the novels and comics. Thus, this effectively results in a literary multiverse, whether the franchise acknowledges it or not.
No franchises embody this more than Star Trek and Star Wars. Star Trek has historically treated its novels and comics are essentially non-canonical, though they do not market them as such. You thus have the case where people invested in the novels are at least partially divided from those invested in the television shows/movies. This only got worse with the introduction of new timelines in the most recent works.
The Star Wars EU was in a similar position prior to the Disney purchase of the franchise. It is debatable whether the novels and comics were considered officially canon, with prominence being given to the movies, games, and tv shows, even to the point of overwriting previous works. Thus, like many other franchises, the tie in works formed a soft canon. After the Disney takeover, all works, except the Movies and one tv show, were removed from canon to make way for the new movie canon. This resulted in a split between fans who accepted this move and those who rejected it in favor of old canon.
Editorial laziness
This brings us to another bad reason for multiverses, editorial laziness. Writing a work in an established decades old canon is difficult. As the series expands and grows, characterization, previous interactions with other characters, and the timeline of the setting all has to be kept in mind. Reboots often do away with previous canon because the project leaders cannot be bothered to work their story into the established setting. In this case, multiverses are used as a deflection tactic to assure original fans that the previous works still matter, even while effectively disregarding them.
Conclusion
If you do not want to use the same characters in radically different settings, and do not want to discuss issues of greater cosmology or primordial substances, then there is no need to use multiverses in your works. Properly using a multiverse is more difficult than using realms or dimensions.
On the other hand, if you want characters to be embodied in different worlds with different life stories, or if you want to explore the concept of primordial substances and linked universes, then you may want to use a multiverse. Note that if you only want to use the same character in different historical periods, it is probably easier to just use the concept of reincarnation or time travel.
Time Travel
Time travel has been a stock trope of science fiction ever since it was popularized by H.G. Wells in The Time Machine, a book which features both backwards and forwards time travel. Since then, the trope has appeared frequently in science fiction works, pulp fiction, and comics. As with many other modernized science fiction concepts, time travel has a lengthy history in myth.
Both eastern religions and western fairy tales have stories that involve missing or altered time. It is said that when a human travels into the otherworld of fairy tales or the realm of the gods, time often passes faster than they perceive. Thus, a day in another realm might be years on earth. The tale of Rip van Winkle is typical of this where an encounter with a fey-like man results in years passing by for the titular character as he is caught in an enchanted sleep. The more unusual form of backwards time travel can be seen in works like Mark Twain’s book A Connecticut Yankee in King Arthur’s Court.
An example can be cited from The Hunter and the Thunder Spirits, a tale from Algonquin folklore. In this story, a hunter explores a cave system when he hears noises coming from behind the rock walls. He is astonished when a beautiful girl appears and speaks to him telepathically. She asks him to join her, which he does. They then fly away on a rock slab until they come to a large cavern where the girl’s family, rock giants and lightning spirits, appear. The hunter stays the day with them, then returns home. The following occurs:
“Now when the day was done the hunter returned to his home, and when there, found he had been gone seven years.”
The Algonquin Legends of New England, Charles G. Leland, 1884
Types of Time Travel
Future Time Travel
Future time travel takes a character from their present, then transports them to the future. While the character is in transit from one time to another, they have no effect on the world and time flows normally without alteration. Because the universe is not altered or interrupted, this can be considered a logically consistent form of time travel.
Future travel can be used to bring characters or objects from the past to the present, or to transport characters from the present into the future. For example, an ancient army can be brought into the present to offer a challenge. All this can occur without any logical problems.
Backwards Time Travel
Backwards time travel takes a character from the present or future, and transports them back in time. In most stories with backwards travel, the character is able to physically interact with the past, altering it. This presents the logical problem known as the Grandfather Paradox. In short, the Grandfather Paradox conjures up a situation where a man goes back in time and impregnates his grandmother, becoming his own grandfather. Logically, the man could never have come to be if he hadn’t gone back in time, therefore there is the question of how he could exist in the first place if time hadn’t been altered in the past.
In a setting with a single universe and timeline, the past must always occur sequentially. Therefore, any action that alters the past is an impossibility, and therefore cannot have an effect. However, in a setting with multiple universes and timelines, a split occurs when time travel is used, resulting in the original universe continuing along its destined path, while a separate universe and timeline splits off to account for the alteration.
The most logically consistent form of backwards time travel occurs in a multiverse where the character stays in the past. Choosing this form of time travel should have severe consequences to it, and be done with an understanding that the universe that the character will experience is not their own. The ability to rewrite the past is far too powerful for casual use, and can easily become a cheap deus ex machina that ruins the stakes of a story should proper precautions not be taken. Should a fictional work take place in a less serious world, like one designed for children, such logical considerations can be waved.
I leave one final caution concerning backwards time travel. Going back in time requires every single part of the universe to be rewound to a point in time, which means that the exact relationships of every force and particle in the universe must also be rewound. That includes every atom, every electron, everything. This requires a cosmology with a high control mechanism, such as a God or divine machine that can remember every single moment of history in its entirety. Even if such an entity exists, it is unlikely that a human could convince them to allow such a thing, nor does it seem possible for a machine to exist which could enable such travel.
Checkpoint Time Travel
Those familiar with video games will know about the concept of checkpoints. At certain intervals in a map, the player’s progress will be saved, which allows them to return to that point in the event of a failure. How the player gets to the checkpoint will vary with every playthrough, but they must get to the checkpoint nevertheless.
A variant of altering the past is the assumption that the force controlling the universe has fixed “checkpoints” in its story that must always happen. For example, there is the meme trope of assassinating Hitler where all assassination attempts fail because World War 2 must happen. The same could be applied for almost all events of historical significance. Thus, while minor events might be changed and altered in moving to the next checkpoint, the checkpoint must always occur.
Observer Time Travel
An alternative to physically altering the past is to project the character into the past or future in a way that does not alter it. Such a form of time travel can be seen in A Christmas Carol where Scrooge is transported into the past as an observer, then into a potential future.
Because nothing about the past is physically altered, this is a logically consistent version of past time travel that can provide knowledge about the past. All knowledge in the past is either known or exists as a potential, which means that there is no paradox involved in gathering previously unknown knowledge from the past. Observing the future is more complex, since a version of the grandfather paradox occurs. If the character looks into the future to see what will happen, gathering information from that observation, there is the question of whether that future occurred only because of their actions. For example, if a character looks into the future and finds the blueprints for a certain technological device, then they are the reason why that technological device came to be. In an even more dramatic version of events, say that a certain person is observed as a dictator in the future. If they are eliminated in the present, that means the observed future could never come to pass. Note that it is possible to solve this reverse paradox by using split timelines.
One possibility is that the future is deterministic, meaning that no matter what is done, what is observed will always come to be. Thus, if one tries to assassinate the future dictator, that might well be the catalyst that sets them on the path to becoming a future dictator. Note however that this has the philosophical implication that there is essentially no free will in the setting, nor any way to truly alter events.
Cyclical History
One of the more exotic ways of doing past time travel is cyclical history. Cyclical history assumes that the world functions like a wheel, moving in cycles which repeat the same story and history with minor differences. Thus, in the next cycle, one will see the same or very similar events taking place until they are altered. There will always be a roman empire, the rise of the major religions, etc. When one travels to the past, they actually travel into the future during the next cycle. When they alter that past, they are altering the future of that cycle, but not their own past. This is a potential way to do an alternative history, though it can be rather deterministic.
Conclusion
Time travel can be an interesting way to bring elements from the past, present, and future into contact. However, it is important to be logically consistent with how time travel is applied. Consider carefully how you intend to integrate time travel and make sure that it works with your cosmology.
Kotharian Lightning 