A 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 a multiverse are sometimes called parallel
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
Multiverses have been hypothesized in cosmology, physics, astronomy,
philosophy, theology, and fiction, particularly in science fiction
and fantasy. The specific term "multiverse," which was coined by
William James, was popularized by science fiction author
In these contexts, parallel universes are also called,
The possibility of many universes raises various scientific and
Multiverse hypotheses in physics
Laura Mersini-Houghton claims that the WMAP cold spot may provide
testable empirical evidence for a parallel universe within the
According to Max Tegmark, 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
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
"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
universe" to refer to a model of the whole of a single connected
space-time in the sense of chaotic inflation models
The levels according to Tegmark's classification and using Ellis,
Koechner and Stoeger's terminology are briefly described below.
(Ellis, Koechner 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.)
Multiverses (Ellis, Koechner and Stoeger sense)
- Level III (Hugh Everett III's many-worlds interpretation)
interpretation of quantum mechanics that proposes the existence of
multiple universes, all of which are "identical", but exist in
possibly different states. It is widely believed that Everett's
interpretation (considered as a formal theory) is a conservative
extension of standard quantum mechanics – that is, as far as results
expressible in the language of ordinary quantum mechanics are
concerned, it leads to no new results.
This, according to Tegmark,
"is ironic given that this level has historically been the most
controversial". In September 2007 David Deutsch presented what is
considered a proof of the many-worlds interpretation. 
Ultimate ensemble -
Level IV (The ultimate "Ensemble theory" of Tegmark)
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. The question is open whether or not scientists
will subdivide Level IV in the future.
"Bubble universes", every disk is a bubble universe (Universe 1 to
Universe 6 are different bubbles, they have physical constants that
are different from our universe), our universe is just one of the
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.)
Counter-intuitively, these universes
are farther away than even the farthest universe in our open 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
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.
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  through quantum interference.
The state of the
entire multiverse is related to the states of the constituent
universes by quantum superposition, and is described by a single
Related are Richard Feynman's multiple
histories interpretation and H. Dieter Zeh's many-minds
Many worlds interpretation cannot explain the apparently Fine-tuned
universe. The physical constants of all the "many worlds" are the
same. Many worlds interpretation can, however explain the apparent
improbability of a planet like Earth existing.
If the Many worlds interpretation is true there are so
many copies of our universe that the existence of at least one
planet like Earth is not surprising.
A multiverse of a somewhat different kind has been envisaged within
the 11-dimensional extension of string theory known as
M-theory our universe and others are created by collisions between
membranes in an 11-dimensional space.
Unlike the universes in the
"quantum multiverse", these universes can have different laws of
The string landscape theory asserts that a different universe exists
for each of the very large ensemble of solutions generated when ten
dimensional string theory is reduced to the four-dimensional
low-energy world we see.
Criticisms of multiverse theories
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
Some have argued that the job of a scientist is
to provide fundamental explanations for observed phenomena, without
making reference to observers. Resorting to anthropic principles
constitutes a "lazy way out" of accounting for features such as the
apparent fine-tuning of parameters in relation to the existence of
Leonard Susskind claims, however, that some form of multiverse is
unavoidable, given the current state of physics, and that observer
effects are inevitable and have to be taken into account in other
To postulate an infinity of unseen and unseeable universes just to
explain the one we do see seems superficially contrary to
"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." 
Thus, according to Tegmark, paradoxically the
multiverse scenario is more parsimonious than that of a single
David Lewis, however, draws a distinction between qualitative and
quantitative excess. Postulating extra universes just like our own
does not increase the number of kinds of things there are, and thus
there is only qualitative invariance.
One unique universe
It is sometimes argued that the observed universe is the unique
possible universe, so that talk of "other" universes is ipso facto
meaningless. Einstein raised this possibility when he wondered
whether the universe could have been otherwise, or non-existent
This possibility is also expressed in
theories such as determinism and chaos theory.
The hope is sometimes
expressed that once a grand unified theory of everything is
achieved, it will turn out to have a unique "solution" corresponding
to the observed universe.
The entire range of
multiverse hypotheses, with specific emphasis on
Hugh Everett's many-worlds interpretation, have been criticized by
proponents of intelligent design.
William Dembski in particular,
derides it as inflating explanatory resources without evidence or
warrant, and terms such concepts "inflatons".
The concept of other universes has been proposed to explain why our
universe seems to be fine-tuned for conscious life as we experience
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.
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 multiverses, this scarcity of life-supporting universes does not
imply intelligent design as the only explanation of our existence.
Critics of this argument (Steven Jay Gould, Richard Dawkins and many
others) point out that the cause and the effect
have been reversed by those who claim that the universe seems to be
fine-tuned for our benefit.
Dr. Gould compared it to claiming that
sausages were originally made long and narrow so that they would fit
modern hotdog buns, or that humans evolved fingernails so that
fingernail polish would be invented.
Critics cite the vast store of
evolutionary evidence which shows that life is perfectly and
naturally tuned to the universe it arose in. Fossil, genetic and
other biological evidence abundantly supports the observation that
life adapts to physics, not the other way around.
Caroline Miller writes:
"The Anthropic Principle
is based on the underlying belief that the universe was created for
our benefit. Unfortunately for its adherents, all of the
reality-based evidence at our disposal contradicts this belief.
non-anthropocentric universe, there is no need for multiple
universes or supernatural entities to explain life as we know
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).
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
According to the counterpart theory of David Lewis, the
objects should be regarded as similar rather than identical.
Virtual realities as a multiverse
Some scientists entertain the possibility of creating artificial
conscious machines, and some artificial intelligence advocates even
claim we are not far from producing conscious computers. It is then but a small step to the point where the
engineered conscious beings inhabit a simulated reality.
beings, their "fake" universe will appear indistinguishable from
Multiverse hypotheses in religions around the globe
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
The concept of the multiverse figures prominently in many
fiction and fantasy novels'.
For some it serves primarily as a plot
device, a means to put characters into an unfamiliar situation, or a
framework that usually lies in the background for continuity
For others it is a major theme and focus of the work. It
is sometimes used as the basis for exploring "what if" scenarios,
such as in alternate history stories. The TV show Sliders from the
1990's first popularized the concept through the TV entertainment
The film The One (2002) starring Jet Li carried the same
idea to the action film medium. The popular MYST computer game
franchise uses concepts of describing a world and then linking to
that world, which is part of a multiverse of infinite possible and
concurrently existing universes, matching the descriptions.
the computer game Legacy of Kain: Soul Reaver and its sequels
feature two distinct parallel universes.
The protagonist, Raziel, is
capable of existing in both the Material Realm, or normal reality,
and the Spectral Realm, a dark and distorted version of the former
with its own physics and properties.
The Michael Crichton novel
Timeline featured a method for what appeared to be time travel by
traveling to parallel universes that are identical except for the
moment of their birth, thus rendering off-set yet parallel time.
The DC Universe, famous home of Batman and Superman, uses the multiverse as the basis for their universe. This is in part to help
deal with their 67 year history, beginning in The Flash issue #123.
In the 1980s DC published the ever popular Crisis on Infinite Earths
which detailed a breakdown of the Multiverse at the hands of the
The television series Star Trek has many times gone
into parallel "Mirror" universes, and Stargate SG-1 has postulated
parallel universes. The Anime series Bokurano is based on a
multiverse. In the BBC television show Doctor Who, the Doctor
travels between parallel universes and is parted indefinitely from
his companion Rose Tyler when she becomes trapped within one.
fantasy trilogy His Dark Materials by Philip Pullman is set in
multiple parallel universes.
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."
Max (May 2003). "Parallel Universes".
Tegmark, Max (January 23 2003).
Parallel Universes. Retrieved on
George F.R.; U. Kirchner, W.R. Stoeger
and physical cosmology". Monthly
Notices of the Royal Astronomical
Society 347: 921-936. Retrieved on
Breitbart.com, Parallel universes exist
- study, Sept 23 2007
Zeeya (2007-09-21), "Parallel
universes make quantum sense",
New Scientist (no. 2622),
Retrieved on 20
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
David Deutsch's Many Worlds,
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
Carl Sagan, Placido P D'Souza
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
del Sitio Web
Multiverso es un término usado para describir a un hipotético grupo
de todos los universos y/o dimensiones posibles; generalmente usado
en la ciencia ficción, aunque también como consecuencia de algunas
teorías científicas, para describir a un grupo de universos que
están relacionados (universos paralelos).
La idea de que el universo
que se puede observar es solo una parte de la realidad física dio
luz a la definición del concepto "multiverso".
Historia y descripción
El término "multiverso" se inventó en
diciembre de 1960, por Andy Nimmo, aquel entonces vice-director de
la British Interplanetary Society de Escocia cuando dio un discurso
para dicha organización acerca de la interpretación "varios-mundos"
de la física cuántica que se había publicado en 1957.
original de "multiverso" era:
"un universo aparente, una
multiplicidad de que, se combina para ser el universo entero."
A partir de este discurso, la palabra se usó correcta e
incorrectamente por unos años en varias instancias en grupos
científicos y de ciencia ficción.
En los años 60, el autor de
ciencia ficción, Michael Moorcock, interpretó la palabra en una
novela. Gracias a nuevas interpretaciones populares basadas en esta
obra, la palabra se usa en varios contextos y, se podría decir, con
un "multiverso" de definiciones.
Las evidencias científicas que postulan su posible existencia son
hoy en día un argumento muy usado para desbaratar la hipótesis del
diseño inteligente, y una nueva historia dentro de la cosmogonía.
El Multiverso en la ciencia
Aunque el multiverso
principalmente muy usado en la ciencia ficción, actualmente la
propuesta de la posible existencia de un multiverso igualmente se ha
originado como una consecuencia de teorías físicas elaboradas, como
la teoría de las cuerdas; en la que se desea llegar a obtener una
teoría del todo que explique el universo.