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==Multiverse hypotheses in religions around the globe== |
==Multiverse hypotheses in religions around the globe== |
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===Hindu universes=== |
===Hindu universes=== |
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No Hindu Universe Exists |
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The earliest known records describing the concept of a multiverse are found in ancient [[Hindu cosmology]], in texts such as the [[Puranas]]. They expressed the idea of an infinite number of universes, each with its own gods, inhabitants and planets, and an infinite cycle of births, deaths, and rebirths of a universe, with each cycle lasting 8.4 billion years. The belief is too that the number of universes is infinite.<ref>[[Carl Sagan]], Placido P D'Souza (1980s). [http://www.rediff.com/news/jan/29sagan.htm Hindu cosmology's time-scale for the universe is in consonance with modern science.]; Dick Teresi (2002). ''Lost Discoveries : The Ancient Roots of Modern Science – from the Babylonians to the Maya''.</ref> |
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==See also== |
==See also== |
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Revision as of 09:10, 9 October 2008
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The multiverse (or meta-universe) is the hypothetical set of multiple possible universes (including our universe) that together comprise all of reality. The different universes within the multiverse are sometimes called parallel 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. The specific term "multiverse," which was coined in 1895 by psychologist William James,[1] was popularized by science fiction author Michael Moorcock. In these contexts, parallel universes are also called "alternative universes," "quantum universes," "parallel worlds," "alternate realities," "alternative timelines," etc.
Multiverse hypotheses in physics
Laura Mersini-Houghton claims that the WMAP cold spot may provide testable empirical evidence for a parallel universe within the multiverse. According to Max Tegmark,[2] the existence of other universes is a direct implication of cosmological observations. Tegmark describes the set of related concepts which share the notion that there are universes beyond the familiar observable one, and goes on to provide a taxonomy of parallel universes organized by levels.[3]
Classification
In order to clarify terminology, George Ellis, U. Kirchner and W. R. Stoeger recommend using the term "the Universe" for the theoretical model of the whole of the causally connected spacetime in which we live, universe domain for the observable universe or a similar part of the same space-time, "universe" for a general space-time, either our own "Universe" or another one disconnected from our own, multiverse for a set of disconnected space-times, and multi-domain universe to refer to a model of the whole of a single connected space-time in the sense of chaotic inflation models.[4]
The levels according to Tegmark's classification and using Ellis, Kirchner and Stoeger's terminology are briefly described below.
Multi-domain universes (Ellis, Kirchner and Stoeger sense):
Level I: (Open multiverse) A generic prediction of cosmic inflation is an infinite ergodic universe, which, being infinite, must contain Hubble volumes realizing all initial conditions.
Universes with different physical constants
Level II: (Andrei Linde's bubble theory) In chaotic inflation, other thermalized regions may have different effective physical constants, dimensionality and particle content. (Surprisingly, this level includes Wheeler's oscillating universe theory as well.)
Ultimate ensemble
Level IV: (The Ultimate ensemble theory of Tegmark) Other mathematical structures give different fundamental equations of physics. This level considers "real" any hypothetical universe based on one of these structures. Since this subsumes all other possible ensembles, it brings closure to the hierarchy of multiverses: there cannot be a Level V.
Jürgen Schmidhuber, however, says the "set of mathematical structures" is not even well-defined, and admits only universe representations describable by constructive mathematics, that is, computer programs. He explicitly includes universe representations describable by non-halting programs whose output bits converge after finite time, although the convergence time itself may not be predictable by a halting program, due to Kurt Gödel's limitations.[5][6][7] He also explicitly discusses the more restricted ensemble of quickly computable universes.[8]
Bubble theory
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Bubble theory posits an infinite number of open multiverses, each with different physical constants. (The set of bubble universes is thus a Level II multiverse.)
The formation of our universe from a "bubble" of a multiverse was proposed by Andre Linde. This Bubble universe theory fits well with the widely accepted theory of cosmic inflation. The bubble universe concept involves creation of universes from the quantum foam of a "parent universe." On very small scales, the foam is frothing due to energy fluctuations. These fluctuations may create tiny bubbles and wormholes. If the energy fluctuation is not very large, a tiny bubble universe may form, experience some expansion like an inflating balloon, and then contract and disappear from existence. However, if the energy fluctuation is greater than a particular critical value, a tiny bubble universe forms from the parent universe, experiences long-term expansion, and allows matter and large-scale galactic structures to form.
Many worlds interpretation of quantum physics
Hugh Everett's many-worlds interpretation (MWI) is one of several mainstream interpretations of quantum mechanics. Other interpretations include the Copenhagen and the consistent histories interpretations. The multiverse proposed by MWI has a shared time parameter. In most formulations, all the constituent universes are structurally identical to each other and though they have the same physical laws and values for the fundamental constants, they may exist in different states. The constituent universes are furthermore non-communicating, in the sense that no information can pass between them, although in Everett's formulation they may potentially affect each other[9] through quantum interference.[10] The state of the entire multiverse is related to the states of the constituent universes by quantum superposition, and is described by a single universal wavefunction. Related are Richard Feynman's multiple histories interpretation and H. Dieter Zeh's many-minds interpretation.
Many worlds interpretation cannot explain the apparently Fine-tuned universe since the physical constants of all the "many worlds" are the same. The many worlds interpretation can, however, explain the apparent improbability of a planet like Earth existing. See Rare Earth hypothesis. If the many worlds interpretation is true there are so many possibilities that are realised, that the existence of at least one planet like Earth is not surprising.
M-theory
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A multiverse of a somewhat different kind has been envisaged within the 11-dimensional extension of string theory known as M-theory. In M-theory our universe and others are created by collisions between membranes in an 11-dimensional space. This is unlike the universes in the "quantum multiverse".
Criticisms of multiverse theories
Non-scientific claims
Critics claim that these theories lack empirical correlation and testability, and without hard physical evidence are unfalsifiable; outside the methodology of scientific investigation to confirm or disprove.
Occam's Razor
To postulate an infinity of unseen and unseeable universes just to explain the one we do see seems superficially contrary to Occam's Razor.
Tegmark answers: "A common feature of all four multiverse levels is that the simplest and arguably most elegant theory involves parallel universes by default. To deny the existence of those universes, one needs to complicate the theory by adding experimentally unsupported processes and ad hoc postulates: finite space, wave function collapse and ontological asymmetry. Our judgment therefore comes down to which we find more wasteful and inelegant: many worlds or many words."[11] Thus, according to Tegmark, paradoxically the multiverse scenario is more parsimonious than that of a single universe. This reflects an old insight from algorithmic information theory: the information conveyed by a set may be far less than the information conveyed by its individual elements. According to Jürgen Schmidhuber, the appropriate mathematical theory of Occam's razor already exists, namely, Ray Solomonoff's theory of optimal inductive inference [12] and its extensions [13].
Other objections
The entire range of multiverse hypotheses, with specific emphasis on Hugh Everett's many-worlds interpretation, have been criticised by proponents of intelligent design. William Dembski in particular, derides it as inflating explanatory resources without evidence or warrant, and terms such concepts "inflatons".[14]
Anthropic principle
The concept of other universes has been proposed to explain why our universe seems to be fine-tuned for conscious life as we experience it. If there were a large number (possibly infinite) of different physical laws (or fundamental constants) in as many universes, some of these would have laws that were suitable for stars, planets and life to exist. The anthropic principle could then be applied to conclude that we would only consciously exist in those universes which were finely-tuned for our conscious existence. Thus, while the probability might be extremely small that there is life in most of the universes, this scarcity of life-supporting universes does not imply intelligent design as the only explanation of our existence.
Modal realism
Additionally, possible worlds are a way of explaining probability, hypothetical statements and the like, and some philosophers such as David Lewis believe that all possible worlds exist, and are just as real as the actual world (a position known as modal realism).[15]
Trans-world identity
A metaphysical issue that crops up in multiverse schema that posit infinite identical copies of any given universe is that of the notion that there can be identical objects in different possible worlds. According to the counterpart theory of David Lewis, the objects should be regarded as similar rather than identical.[16][17]
Multiverse hypotheses in religions around the globe
Hindu universes
No Hindu Universe Exists
See also
- The Fabric of Reality
- Fictional universe
- Multiple histories
- Parallel universes in fiction
- Philosophy of physics
- Philosophy of space and time
- Planescape
- Quantum gravity
- Reductionism
- Simulated reality
- String theory landscape
- Counterpart theory
Notes
- ^ James, William, The Will to Believe, 1895; and earlier in 1895, as cited in OED's new 2003 entry for "multiverse": "1895 W. JAMES in Internat. Jrnl. Ethics 6 10 Visible nature is all plasticity and indifference, a multiverse, as one might call it, and not a universe."
- ^ Tegmark, Max (2003). "Parallel Universes". Scientific American.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Tegmark, Max (2003). Parallel Universes (PDF). Retrieved 2006-02-07.
{{cite book}}: Unknown parameter|month=ignored (help) (PDF). - ^ Ellis, George F.R. (2004). "Multiverses and physical cosmology". Monthly Notices of the Royal Astronomical Society. 347: 921–936. Retrieved 2007-01-09.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ J. Schmidhuber (1997): A Computer Scientist's View of Life, the Universe, and Everything. Lecture Notes in Computer Science, pp. 201-208, Springer: http://www.idsia.ch/~juergen/everything/
- ^ J. Schmidhuber (2000): Algorithmic Theories of Everything http://arxiv.org/abs/quant-ph/0011122
- ^ J. Schmidhuber (2002): Hierarchies of generalized Kolmogorov complexities and nonenumerable universal measures computable in the limit. International Journal of Foundations of Computer Science 13(4):587-612 http://www.idsia.ch/~juergen/kolmogorov.html
- ^ J. Schmidhuber (2002): The Speed Prior: A New Simplicity Measure Yielding Near-Optimal Computable Predictions. Proc. 15th Annual Conference on Computational Learning Theory (COLT 2002), Sydney, Australia, Lecture Notes in Artificial Intelligence, pp. 216-228. Springer: http://www.idsia.ch/~juergen/speedprior.html
- ^ Tegmark, Max, The Interpretation of Quantum Mechanics: Many Worlds or Many Words?, 1998. To quote: "What Everett does NOT postulate: "At certain magic instances, the world undergoes some sort of metaphysical 'split' into two branches that subsequently never interact." This is not only a misrepresentation of the MWI, but also inconsistent with the Everett postulate, since the subsequent time evolution could in principle make the two terms...interfere. According to the MWI, there is, was and always will be only one wavefunction, and only decoherence calculations, not postulates, can tell us when it is a good approximation to treat two terms as non-interacting."
- ^ Deutsch, David, David Deutsch's Many Worlds, Frontiers, 1998.
- ^ http://www.elfis.net/phorum/read.php?f=3&i=22&t=22
- ^ Ray Solomonoff (1964): A formal theory of inductive inference. Part I. Information and Control, 7:1-22, 1964
- ^ J. Schmidhuber (2006) The New AI: General & Sound & Relevant for Physics. In B. Goertzel and C. Pennachin, eds.: Artificial General Intelligence, p. 177-200 http://arxiv.org/abs/cs.AI/0302012
- ^ http://www.iscid.org/papers/Dembski_ChanceGaps_012002.pdf
- ^ Lewis, David (1986). On the Plurality of Worlds. Basil Blackwell.
- ^ Deutsch, Harry, "Relative Identity", The Stanford Encyclopedia of Philosophy (Summer '02), Edward N. Zalta (ed.)
- ^ Paul B. Kantor "The Interpretation of Cultures and Possible Worlds", 1 October 2002
References
- Deutsch, David (1985). Splash (ed.). Quantum theory, the Church-Turing principle and the universal quantum computer (Proceedings of the Royal Society of London A 400 ed.). mos craciun. pp. 97–117.
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External links
- Physics in the Multiverse, published by Aurélien Barrau in the CERN Courier
- Preprint of David Deutsch's paper The Structure of the Multiverse
- BBC Horizon -Parallel Universes
- Michael Price's Everett FAQ
- Mulitverse Cosmological Models by P.C.W. Davies
- The ensemble of universes describable by constructive mathematics by Jürgen Schmidhuber
- Interview with Tufts cosmologist Alex Vilenkin on his new book, "Many Worlds in One: The Search for Other Universes" on the podcast and public radio interview program ThoughtCast.
- Joseph Pine II about Multiverse, Presentation at Mobile Monday Amsterdam, 2008
- Multiple Universes ?, in French by A. Barrau