Parallel world

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The term parallel world , also parallel universe, describes a hypothetical universe outside the known. The totality of all parallel worlds is called a multiverse. The assumption of parallel worlds (multi-world theory) has been discussed in philosophy since ancient times . A distinction must be made between the discussion about theoretically possible worlds from a formal point of view and the hypotheses in which such worlds are ascribed a real existence. The possibility of the real existence of parallel worlds is also discussed in physical cosmology . The idea is known to a broader public primarily from science fiction .

In a figurative sense, the term is also used in psychology, social sciences and colloquial. There, “parallel world” means an area that is delimited to the outside in which the life of certain people or groups takes place independently of the “outside world”.

physics

The Many Worlds Interpretation of Quantum Mechanics

The Many Worlds Interpretation is an interpretation of quantum mechanics first proposed by Hugh Everett in 1957 . It is intended to explain why the probability of each measured value in a quantum mechanical system can be calculated precisely, but in general the result of a single measurement cannot be foreseen. According to this interpretation, several new parallel worlds each with different measurement results arise from a measurement from an original world.

In connection with this interpretation of quantum mechanics, Andy Nimmo introduced the term multiverse in a lecture on Everett's ideas in December 1960 and February 1961 . According to his use of the word, a multiverse is "an apparent universe, a multiplicity of which go to make up the whole universe", "a [our observation] manifest universe, of which a large number make up the entire universe". In the context of interpretations of quantum mechanics, the term multiverse used e.g. B. David Deutsch , however in the meaning of the infinite totality of all physically possible divisions of reality into local physical systems. Here the term “multiverse” roughly denotes what Nimmo calls “the entire universe”. Deutsch suggested explaining the structure of the “multiverse” by means of quantum information , in analogy to the infinite possibilities within general relativity to relate space-time to hypersurfaces . Deutsch regards both approaches as borderline cases of a theory that has yet to be developed, which would have to describe the structure of the multiverse under conditions of quantum gravity .

Big Bang models

The model of the formation of the known universe from a “bubble” of a multiverse was devised by Andrei Dmitrijewitsch Linde . It fits well with the widely accepted theory of the big bang and inflation in the early stages of the universe. An initially small region of space can, after finite expansion, complete its “phase transition” and, for example, encompass our entire universe observable today, while in the rest of space the inflation continues forever. According to the hypothesis of “ chaotic inflation ” developed by Andrei Linde, small “germs ” form at various other points in the room with a quantum physical chance, in which the “phase transition” comes to an end at some point. In each “germ”, a hot “big bang” creates its own universe. Even Alexander Vilenkin represents such a model.

The theory of a multiverse should allow an explanation of the precise fine-tuning of the natural constants . Every single universe has certain values ​​for its natural constants (e.g. fine structure constant , gravitational constant ). Only in a relatively few universes do values ​​permit life. The observable universe belongs to the subset of those universes in which intelligent life is possible. If the number of parallel universes is infinite, the supposedly random existence of the universe observable by humans is necessary. The various versions of the anthropic principle deal with the relationship between the observer and the observable universe .

philosophy

Antiquity

The hypothesis of the existence of parallel worlds has already been discussed in ancient philosophy . One of its first representatives was Petron von Himera , a Greek of Sicilian origin who probably lived in the 5th or early 4th century BC. Lived. He was convinced that the number of worlds must be finite, and speculated about their spatial arrangement. According to his hypothesis, there are 183 worlds ( kósmoi ) that are strung together and touching one another; they form an equilateral triangle, with 60 worlds forming the three sides and the other three being the corners. Many details and in particular the reason are unknown, since Petron's model has only been passed down through the representation by Plutarch . Petron probably imagined the worlds to be spherical.

Also the pre-Socratic Anaximander , who in the 6th century BC A many-worlds model is ascribed. Theophrast reports that Anaximander assumed “a certain other, unlimited nature from which all heavens and the worlds in them arise”. According to the current state of research, however, it can be assumed that Theophrastus offers a falsifying representation of Anaximander's cosmology, which was shaped by later developments in the history of philosophy.

What is certain is that the atomists Leukippus and Democritus developed a many-worlds model. According to their view, the reasons which, out of mechanical necessity, led to the creation of this world must also have and continue to cause the creation of an infinite number of other worlds. According to the atomistic theory, the worlds can exist simultaneously as well as one after the other. They arise and pass away; while some are in the making, others are already dissolving. Metrodorus von Chios , who is said to have been a student of Democritus, illustrated the atomists' considerations with a comparison that perhaps originated from Democritus himself: It is just as unlikely that only a single cosmos will arise in infinite space as that only one single cosmos will arise in a large field Grain stalks grow. In the atomistic model there are innumerable atoms and unlimited space. The atoms are constantly in motion, and clusters of them form, which lead to the creation of eddies or eddies from which the worlds are then formed. A membrane or shell of atoms forms around every world, which delimits it. The worlds are of different dimensions, between them there is empty space. The distribution of the worlds in space is uneven. The number and size of the stars in the different worlds also differ, as the respective course of the world formation process is influenced by random factors. In some worlds there is no life.

Plato rejected the hypothesis of several worlds and in particular the assumption that there are infinitely many. In his dialogue Timaeus , he had the main character Timaeus of Lokroi present the conviction that the Creator, who always wants the best, has created the best possible world based on his own nature. There can only be one best possible world. The Creator is only one and his creation corresponds to him also with regard to the singular. If there were several worlds, they would not be modeled directly on the Creator, but on the multiverse that encompasses them. Then they would be subordinate to the multiverse as its parts; they would only be images of a created pattern and therefore not perfect in every respect. But the world is so beautiful that it must be created directly on the model of the perfect Creator. At a later point in his remarks, Plato's Timaeus returns to the question and now expresses himself more cautiously. He contemplates the possibility that there are five worlds corresponding to the five platonic solids . Although he decides again for the uniqueness of the world, since this is the most plausible theory, he now leaves open the possibility that another hypothesis is true. However, an infinite number of worlds is excluded.

Aristotle thought it impossible for there to be “multiple heavens”. He said that several worlds could not exist one after the other or side by side. No body can be outside the known limited universe. With several arguments he tried to refute the multi-world theory. One of his considerations was that several worlds, if they existed, would have to be composed of the same elements and that these would have to have the same natural directions of movement everywhere. Everything heavy must naturally strive towards the same point, everything light strive away from it. This point can only be the center of a single cosmos. As a result, a multiverse in which each world has its own center was excluded for Aristotle.

The Platonist Plutarch discussed the multi-world theory in detail in his work De defectu oraculorum . There arguments for and against the existence of a multiverse are discussed in a literary dialogue. An attempt is made to refute Aristotle's argument. The hypothesis of the number five considered in Plato's Timaeus is also examined in detail. The question remains open. Unlike Plato, the investigation does not end with a preference for the one-world theory; rather, the conclusion is that the multi-world theory is not inferior to the opposite view in plausibility.

The late antique Neo-Platonist Proclus dealt with the question in his commentary on Plato's Timaeus . He made a strong case for the one-world theory.

middle Ages

In the Middle Ages , the one-world theory generally dominated. It was disputed whether the uniqueness of the world and the nature of creation are a necessity or whether God could also create other worlds if he wanted. The authority of the ancient philosophical tradition, both Platonic and Aristotelian, weighed in favor of necessity. Theologians, however, turned against the necessity hypothesis, who saw it as an inadmissible restriction of God's omnipotence and freedom of choice. They said that God chose the existing shape of the cosmos from a number of possibilities. This view was u. a. the influential Islamic theologian al-Ghazali and the Jewish thinker Maimonides . Among the Christian scholars in particular Petrus Johannes Olivi and Richard von Mediavilla developed the doctrine that God could create several worlds. But they assumed that he actually only created one. The Aristotelian view, according to which the existence of more than one world is in principle impossible, was condemned by the church in 1277 .

Early modern age

In the 16th century, Giordano Bruno turned against Aristotelian cosmology. He assumed an infinite universe containing an infinite number of finite worlds (mondi) . However, the worlds are not parallel universes closed off from one another by barriers, because for Bruno there is only one universe and this forms a unit. The universe is a continuum, defined as the infinite physical substance in infinite space. It is undivided, of a uniform nature and uniformly organized; all of its components are interrelated. There is nothing outside of the universe.

Descartes assumed that matter must be the same everywhere and that all possible worlds must therefore consist of one and the same matter. Against the assumption of parallel worlds he advanced the argument that the nature of matter consists only in being an extended substance, and this must fill every space, including all possible spaces that other worlds could occupy. So there can only be one world.

Leibniz assumed that the existing world was the best of the infinitely many possible worlds. In his model there is only one real world, since God, who wants the best, has necessarily only realized the best of all theoretical possibilities.

Kant believed that it was "true in the very metaphysical sense" that more than one world could exist. By this he meant worlds sealed off from one another, the substances of which are only linked to other substances within their own world and are not related to anything in any other world. God could have created many millions of such worlds. Whether they actually exist cannot be decided. However, Kant considered an assessment of the probability of parallel universes to be sensible. He argues that it is unlikely that God created several worlds that spatially correspond to the known world and therefore could be connected to it. Against this assumption speaks that creation shows an imperfection when such worlds coexist without being connected. Connectedness creates harmony and is an aspect of perfection. Therefore, the hypothesis of parallel worlds is only plausible if it is about spatially different, non-three-dimensional universes that in principle cannot be connected with the three-dimensional world. Such universes are likely to exist, since all of God's works are of the maximum possible size and variety.

Modern

Possible world models play an important role in modal logic . It is about the semantic evaluation of the modal statements “It is possible that A” and “It is necessary that A”. The statement A is then necessarily true if it is true in all possible worlds - i.e. in all conceivable alternatives to the given world in which the statement “It is necessary that A” is interpreted. What is essential is the relation that determines which worlds are alternatives to the given world. The investigation of modal logics and the classes of possible world models assigned to them is independent of assumptions about the ontological status of the possible worlds.

In the recent debate about ontological status, there are mainly two opposing positions: actualism and possibilism, possibilistic realism or modal realism . From an actualistic point of view, concrete objects only exist in the given world (actual world) , while all other worlds only exist abstractly. As a result, the given world is distinguished as actual (actually) above all other worlds. The opposing position, whose most well-known representative is David Lewis , rejects such an award for a certain world. According to this view, statements about factuality are not statements about the world to which they refer, but only statements about the position of the speaker, like "here" and "now" only statements about the spatial or temporal position of the speaker and not about places in space and time. Accordingly, all possible worlds that are non-actual from the speaker's point of view have an existence that is just as real as the world given to the speaker. The word "exist" is used in the same sense for both. Lewis imagines the parallel worlds as spatiotemporally and causally isolated. He argues against duplication of parallel worlds and against the adoption of Trans-World-Individuals : Although it to every individual in the world to him more or less similar counterparts (counterparts) are in other worlds, it is not to an individual who at the same time different worlds listened to. In dealing with criticism of his theory, Lewis also turns against (apparently) mediating positions such as that of Robert Stalnaker , which are in reality actualistic. He calls such positions ersatz modal realism or ersatzism (“substituteism”). He believes that the “substitutes” cannot keep their promise that their models will do the same thing as real modal realism without having to accept its ontological consequences.

In the dispute between theists and atheists , the multi-world theory is brought forward from the atheist side. The atheist Richard Dawkins uses them to make his view plausible that it is not necessary to assume a creative and directing intelligent authority to explain the origin and nature of the world and mankind. Theist's argument that the statistical improbability of the spontaneous development of a world of this nature speaks in favor of a Creator can be refuted if one regards the given world as part of a multiverse of innumerable worlds. Then it is not surprising that such a multiverse also includes worlds in which the complicated conditions are given that are necessary to make human life possible.

The theologian and theoretical physicist John Polkinghorne counters this by saying that the multi-world theory is not a physical, but a metaphysical theory because of the logical impossibility of empirically grasping possible other worlds. This puts her on a par with her belief in a creator god who is “more elegant and economical” in comparison with her.

The astronomer and Nobel Prize winner Arno Penzias also considered the multi-world theory to be implausible. He expressed the view that opponents of the idea of ​​a systematically created universe needed a theory that made planning (such as the fine-tuning of the natural constants) superfluous, and instead resorted to what was undetectable.

psychology

In psychology , the term parallel world is sometimes used to denote modes of escape from reality . With the help of their imagination, people can imaginatively live out unfulfilled longings, wishes or needs or suppress unbearable situations by creating parallel worlds or “substitute realities” for themselves. In the parallel world, the person who fantasizes thinks about one or more virtual , desired roles, communicates with the people living in them and creates an environment in which the real obstacles to his longings are no longer present.

This is normal to a certain extent and as a counterbalance to stressful experiences it is even helpful for psychological regeneration and relaxation - just as the dream, which humans cannot do without, can be viewed as a parallel world. In the course of personality disorders , however, fantasy worlds can also take on problematic proportions, especially when these worlds become more important than actual reality, as is the case with escapism . Media offers such as television, computer games and the Internet can also play a role here.

Arts and entertainment

The concept of an alternate world is often implemented in films. This is done by showing alternative storylines (“What if ...?”). Examples of this are works like Butterfly Effect , Run Lola , Isn't Life Beautiful? , " Time Cop " and Back to the Future . A direct reference to the multiverse theory can be found at the end of the movie Men in Black , where the universe shrinks to a marble among many others.

The television series Sliders - The Gate into a Foreign Dimension deals with parallel worlds in detail. Parallel universes also play a major role in the Superman comics, the Justice League and their films. B. Justice League: Crisis on Two Earths and Justice League: The Flashpoint Paradox .

In some series of the Star Trek franchise, an alternative reality appears under the term mirror universe , sometimes over several episodes ( Star Trek: Deep Space Nine ). There is a parallel universe in which the main characters are sometimes completely reversed, have fascist traits and the political situation is different and therefore often requires different character developments. In Starship Enterprise: The Next Century , different timelines appear in some episodes; Episodes begin in changed realities, with the changes sometimes noticeable, sometimes subtle. The series Star Trek: Enterprise and Star Trek: Discovery also have several episodes in which parallel universes are built into the storylines.

Further examples:

  • Fringe , television series broadcast since 2008, especially from the 2nd season.
  • His Dark Materials book trilogy , best known in German-speaking countries through the film Der Goldene Kompass : Here the action takes place in parallel worlds, especially from the 2nd book (The Magic Knife) . Likewise, Stephen King's Dark Tower cycle creates the idea of ​​a multiverse in which the main protagonist, the gunslinger Roland Deschain, first has to walk through several times and parallel worlds in order to finally get to the dark tower.
  • Independent film production Coherence from 2013: The consequences of the coherence of temporarily overlapping parallel worlds are shown.
  • Computer game BioShock Infinite : Interacting parallel worlds as an explanation for the powers of the character Elizabeth and as an essential part of the plot.
  • Fairy tale film Little Red Riding Hood in the film version from 2005.
  • The idea behind many films or individual episodes was Isn't life beautiful? . In Shrek Forever After , the title hero learns what the world would look like if he had never existed.
  • The entire Rick and Morty series is based on the concept of a multiverse.
  • The film The One is set in a multiverse.
  • In the novel or audio book by Frank Schätzings The Tyranny of the Butterfly , parallel universes are taken up and are an important part of the plot.
  • In the novel Der Zeitenläufer ( Dark Matter ), a scientist develops a method with which one can move into parallel worlds, and in one of them he takes the place of his alternative self
  • Long Earth , a series of novels by Stephen Baxter and Terry Pratchett , which plays with the idea of ​​traveling and settling parallel worlds with a device.
  • In the film Yesterday from 2019, a musician lives after a power failure in a seamlessly connected and almost identical world, in whose history at least the Beatles , Coca-Cola , cigarettes and Harry Potter were never invented.
  • The series The Man in the High Castle deals with parallel worlds in which World War II took a different course.

Delimitation of the parallel universe and the other world

In some fairy tales and stories, the main character comes into contact with an “other world”, but this corresponds more to a different kind of “other world”, a fairy tale world or dream world, than a parallel universe.

In many cases, a parallel universe is understood to be a cosmos in which actual or fictional events took a different course (Hitler won the World War, Jesus Christ was not crucified, Superman married, etc.), which has far-reaching consequences. An Otherworld, on the other hand, is in many cases a fairytale, otherworldly, often better world. Well-known representations of such other worlds are The Neverending Story of Michael Ende, the fairy tale Hans and the Beanstalk and the films Cursed and The Wizard of Oz .

literature

General

  • Johann E. Hafner , Joachim Valentin (ed.): Parallel worlds. Christian religion and the multiplication of reality . Kohlhammer, Stuttgart 2009, ISBN 978-3-17-020565-9 (collection of essays on parallel worlds in philosophy, theology and cultural studies)

physics

  • Bernard Carr (Ed.): Universe or Multiverse? Cambridge University Press, Cambridge 2007, ISBN 978-0-521-84841-1
  • Fred Adams: Life in the Universe . Deutsche Verlags-Anstalt, Munich 2004, ISBN 3-421-05748-6
  • Fred Adams, Greg Laughlin: The Five Ages of the Universe . Deutsche Verlags-Anstalt, Stuttgart / Munich 2000, ISBN 3-421-05345-6
  • John D. Barrow : The Origin of the Universe. How space, time and matter came about. Bertelsmann, Munich 1998, ISBN 3-570-12001-5
  • David Deutsch: The physics of world knowledge . Deutscher Taschenbuchverlag, Munich 2000, ISBN 3-423-33051-1
  • Timothy Ferris: Chaos and Necessity. Report on the state of the universe . Droemer, Munich 2000, ISBN 3-426-27078-1
  • Alan Guth : The birth of the cosmos from nothing. The theory of the inflationary universe . Droemer, Munich 1999, ISBN 3-426-26618-0
  • Tobias Hürter, Max Rauner: The crazy world of the parallel universes . Piper, Munich / Zurich 2011, ISBN 978-3-492-26407-5
  • Michio Kaku : In the parallel universe: A cosmological journey from the Big Bang to the 11th dimension . 4th edition, Rowohlt, Reinbek 2011, ISBN 978-3-499-61948-9
  • Lisa Randall : Hidden Universes. A journey into extra-dimensional space . 3rd edition, Fischer, Frankfurt 2006, ISBN 978-3-10-062805-3
  • Rüdiger Vaas : Inflation of the Universes . In: Bild der Wissenschaft 2005, No. 11
  • Rüdiger Vaas: Tunnel through space and time . 6th, extended edition, Franckh-Kosmos, Stuttgart 2013, ISBN 978-3-440-14098-7
  • Steven Weinberg : Living in the Multiverse , opening lecture at the Symposium Expectations of a Final Theory , Trinity College, Cambridge, September 2, 2005, hep-th / 0511037
  • Fred Alan Wolf: Parallel Universes. The search for other worlds . Insel, Frankfurt am Main / Leipzig 1993, ISBN 3-458-16568-1

philosophy

  • Ernst Behler : One World Theory / Multi World Theory . In: Historical Dictionary of Philosophy . Volume 2. Schwabe, Basel 1972, Col. 423-425
  • Ulrich Dirks: Possible worlds . In: Hans Jörg Sandkühler (Ed.): Encyclopedia Philosophy . Volume 2. Meiner, Hamburg 2010, ISBN 978-3-7873-1999-2 , pp. 1639-1642
  • Schleiff, Matthias: Creation, Coincidence or Many Universes? A teleological argument from fine-tuning the natural constants, Mohr Siebeck, Tübingen 2020, ISBN 978-3-16-156418-5 (discussion of the multiverse theory and other explanations of fine-tuning)
  • Wolfgang Schwarz: David Lewis: Metaphysics and Analysis . Mentis, Paderborn 2009, ISBN 978-3-89785-617-2 , p. 16 f., 41–75, 237–241 (presentation and criticism of Lewis' multi-world theory)
  • John Divers: Possible Worlds . Routledge, London 2002, ISBN 0-415-15555-X (thorough presentation of the controversy over modal realism from the perspective of a proponent)

Fiction

  • Ingo Sundmacher: About quanta and immortal soldiers . Tübingen 2002 (Multiversum as a stylistic basis in the work of the contemporary Danish author Ib Michael ) (PDF; 1.4 MB)

Web links

Wiktionary: Multiverse  - explanations of meanings, word origins, synonyms, translations
Wiktionary: Parallel world  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ David Deutsch: The Structure of the Multiverse . 2001, arxiv : quant-ph / 0104033 .
  2. Lawrence M. Krauss : Waves of the Big Bang - The plausible multiverse . Spectrum of Science Compact 04.17. | Big Bang, p. 52.
  3. On Petron and its multiverse, see the detailed description in Constantinos Macris: Pétrôn d'Himère . In: Richard Goulet (ed.): Dictionnaire des philosophes antiques , Volume 5, Part 1, Paris 2012, pp. 246–263.
  4. Anaximander, fragment DK 12 A 9; see. DK 12 A 10 and DK 12 A 11.
  5. Niels Christian Dührsen: Anaximander . In: Hellmut Flashar u. a. (Ed.): Early Greek Philosophy (= Outline of the History of Philosophy . The Philosophy of Antiquity , Volume 1), Half Volume 1, Basel 2013, pp. 263-320, here: pp. 284 f.
  6. See on the many worlds theory of the atomists Georg Rechenauer : Leukipp und Demokrit . In: Hellmut Flashar u. a. (Ed.): Early Greek Philosophy (= Outline of the History of Philosophy. The Philosophy of Antiquity , Volume 1), Half Volume 2, Basel 2013, pp. 833–946, here: 875f .; Geoffrey S. Kirk, John E. Raven, Malcolm Schofield: Die vorsokratischen Philosophen , Stuttgart 1994, pp. 454-459.
  7. ^ Plato, Timaeus 31a – b.
  8. Plato, Timaios 55c-d.
  9. Aristotle, Across the Sky 276a18–279b3.
  10. Plutarch, De defectu oraculorum 21-38.
  11. Proklos, In Platonis Timaeum I 436.4–458.11. See Constantinos Macris: Pétrôn d'Himère . In: Richard Goulet (Ed.): Dictionnaire des philosophes antiques , Volume 5, Part 1. Paris 2012, pp. 246–263, here: 249f.
  12. See Ernst Behler: Einwelttheorie / Mehrweltentheorie . In: Historical Dictionary of Philosophy , Volume 2, Basel 1972, Sp. 423-425, here: 423 f.
  13. ^ See on Bruno's concept Anne Eusterschulte: Giordano Bruno for introduction , Hamburg 1997, pp. 97–115; Beate Hentschel: Giordano Bruno's philosophy - chaos or cosmos? , Frankfurt am Main 1988, pp. 113-119.
  14. René Descartes: Principia philosophiae II § 22.
  15. Immanuel Kant: Thoughts on the true appraisal of living forces § 8 and 11.
  16. Lewis' position is set out in his study On the Plurality of Worlds , Oxford 1986. For the debate, see the review by Scott A. Shalkowski: Modality, Philosophy and Metaphysics of . In: Donald M. Borchert (Ed.): Encyclopedia of Philosophy . 2nd Edition. Volume 6. Detroit 2006, pp. 280-289, here: 284-288.
  17. ^ Richard Dawkins: The God Delusion , Boston 2006, pp. 145-147.
  18. ^ John Polkinghorne: One World , London 1986, p. 80.
  19. Denis Brian: The Voice of Genius. Conversations with Nobel Scientists and Other Luminaries , Cambridge (Massachusetts) 1995, pp. 165-166 ( online ).
  20. Henrik Hansemann: The philosophy at Star Trek. With Kirk, Spock and Picard on a journey through endless expanses , Weinheim 2013 ( online ).