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The multiverse (or meta-universe, metaverse) is the hypothetical set of multiple possible universes (including the historical universe we consistently experience) that together comprise everything that exists and can exist: the entirety of space, time, matter, and energy as well as the physical laws and constants that describe them. The term was coined in 1895 by the American philosopher and psychologist William James.^[1] The various 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, religion, philosophy, transpersonal psychology and fiction, particularly in science fiction and fantasy. In these contexts, parallel universes are also called "alternative universes", "quantum universes", "interpenetrating dimensions", "parallel dimensions", "parallel worlds", "alternative realities", "alternative timelines", and "dimensional planes," among others.

Multiverse hypotheses in physics[link]

Artistic impression of a level 2 multiverse

Tegmark's classification[link]

Cosmologist Max Tegmark has provided a taxonomy of universes beyond the familiar observable universe. The levels according to Tegmark's classification are arranged such that subsequent levels can be understood to encompass and expand upon previous levels, and they are briefly described below.^[2][3]

Level I: Beyond our cosmological horizon[link]

A generic prediction of chaotic inflation is an infinite ergodic universe, which, being infinite, must contain Hubble volumes realizing all initial conditions.

Accordingly, an infinite universe will contain an infinite number of Hubble volumes, all having the same physical laws and physical constants. In regard to configurations such as the distribution of matter, almost all will differ from our Hubble volume. However, because there are infinitely many, far beyond the cosmological horizon, there will eventually be Hubble volumes with similar, and even identical, configurations. Tegmark estimates that an identical volume to ours should be about 10¹⁰¹¹⁵ meters away from us.^[4][5] This estimate implies use of the cosmological principle, wherein one assumes our Hubble volume is not special or unique. By extension of the same reasoning, there would, in fact, be an infinite number of Hubble volumes identical to ours in the universe.

Level II: Universes with different physical constants[link]

"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 bubbles.

In the chaotic inflation theory, a variant of the cosmic inflation theory, the multiverse as a whole is stretching and will continue doing so forever, but some regions of space stop stretching and form distinct bubbles, like gas pockets in a loaf of rising bread. Such bubbles are embryonic level I multiverses. Linde and Vanchurin calculated the number of these universes to be on the scale of 10^1010,000,000.^[6]

Different bubbles may experience different spontaneous symmetry breaking resulting in different properties such as different physical constants.^[4]

This level also includes John Archibald Wheeler's oscillatory universe theory and Lee Smolin's fecund universes theory.

Level III: Many-worlds interpretation of quantum mechanics[link]

Hugh Everett's many-worlds interpretation (MWI) is one of several mainstream interpretations of quantum mechanics. In brief, one aspect of quantum mechanics is that certain observations cannot be predicted absolutely. Instead, there is a range of possible observations, each with a different probability. According to the MWI, each of these possible observations corresponds to a different universe. Suppose a die is thrown that contains six sides and that the numeric result of the throw corresponds to a quantum mechanics observable. All six possible ways the die can fall correspond to six different universes. (More correctly, in MWI there is only a single universe but after the "split" into "many worlds" these cannot in general interact.)^[7] Tegmark argues that a level III multiverse does not contain more possibilities in the Hubble volume than a level I-II multiverse. In effect, all the different "worlds" created by "splits" in a level III multiverse with the same physical constants can be found in some Hubble volume in a level I multiverse. Tegmark writes that "The only difference between Level I and Level III is where your doppelgängers reside. In Level I they live elsewhere in good old three-dimensional space. In Level III they live on another quantum branch in infinite-dimensional Hilbert space." Similarly, all level II bubble universes with different physical constants can in effect be found as "worlds" created by "splits" at the moment of spontaneous symmetry breaking in a level III multiverse.^[4]

Related to the many-worlds idea are Richard Feynman's multiple histories interpretation and H. Dieter Zeh's many-minds interpretation.

Level IV: Ultimate Ensemble[link]

The Ultimate Ensemble is the hypothesis of Tegmark himself. This level considers equally real all universes that can be described by different mathematical structures. Tegmark writes that "abstract mathematics is so general that any Theory Of Everything (TOE) that is definable in purely formal terms (independent of vague human terminology) is also a mathematical structure. For instance, a TOE involving a set of different types of entities (denoted by words, say) and relations between them (denoted by additional words) is nothing but what mathematicians call a set-theoretical model, and one can generally find a formal system that it is a model of." He argues this "implies that any conceivable parallel universe theory can be described at Level IV" and "subsumes all other ensembles, therefore brings closure to the hierarchy of multiverses, and there cannot be say a Level V."^[8]

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.^[9][10][11] He also explicitly discusses the more restricted ensemble of quickly computable universes.^[12]

Cyclic theories[link]

In several theories there is a series of infinite, self-sustaining cycles (for example: an eternity of Big Bang-Big crunches).

M-theory[link]

A multiverse of a somewhat different kind has been envisaged within the multi-dimensional extension of string theory known as M-theory, also known as Membrane Theory.^[13] In M-theory our universe and others are created by collisions between p-branes in a space with 11 and 26 dimensions (the number of dimensions depends on the chirality of the observer);^[14][15] each universe takes the form of a D-brane.^[14][15] Objects in each universe are essentially confined to the D-brane of their universe, but may be able to interact with other universes via gravity, a force which is not restricted to D-branes.^[16] This is unlike the universes in the "quantum multiverse", but both concepts can operate at the same time.

Anthropic principle[link]

The concept of other universes has been proposed to explain how our Universe appears to be fine-tuned for conscious life as we experience it. If there were a large (possibly infinite) number of universes, each with possibly different physical laws (or different fundamental physical constants), some of these universes, even if very few, would have the combination of laws and fundamental parameters that are suitable for the development of matter, astronomical structures, elemental diversity, stars, and planets that can exist long enough for life to emerge and evolve. The weak anthropic principle could then be applied to conclude that we (as conscious beings) would only exist in one those few universes that happened to be finely tuned, permitting the existence of life with developed consciousness. Thus, while the probability might be extremely small that any particular universe would have the requisite conditions for life (as we understand life) to emerge and evolve, this does not require intelligent design per the teleological argument as the only explanation for the conditions in the Universe that promote our existence in it.

Criticism[link]

Non-scientific claims[link]

In his book, A Brief History of the Multiverse, author and cosmologist, Paul Davies, offers a variety of arguments that multiverse theories are non-scientific :^[17]

For a start, how is the existence of the other universes to be tested? To be sure, all cosmologists accept that there are some regions of the universe that lie beyond the reach of our telescopes, but somewhere on the slippery slope between that and the idea that there are an infinite number of universes, credibility reaches a limit. As one slips down that slope, more and more must be accepted on faith, and less and less is open to scientific verification. Extreme multiverse explanations are therefore reminiscent of theological discussions. Indeed, invoking an infinity of unseen universes to explain the unusual features of the one we do see is just as ad hoc as invoking an unseen Creator. The multiverse theory may be dressed up in scientific language, but in essence it requires the same leap of faith.

— Paul Davies, A Brief History of the Multiverse

Taking cosmic inflation as a popular case in point, George Ellis provides a balanced criticism of not only the science, but as he suggests, the scientific philosophy, by which multiverse theories are generally substantiated. He, like most cosmologists, accepts Tegmark's level I “domains”, even though they lie far beyond the cosmological horizon. Likewise, the multiverse of cosmic inflation is said to exist very far away. It would be so far away, however, that it's very unlikely any evidence of an early interaction will be found. He argues that for many theorists, the lack of empirical testability or falsifiability is not a major concern. “Many physicists who talk about the multiverse, especially advocates of the string landscape, do not care much about parallel universes per se. For them, objections to the multiverse as a concept are unimportant. Their theories live or die based on internal consistency and, one hopes, eventual laboratory testing.” Although he believes there's little hope that will ever be possible, he grants that the theories on which the speculation is based, are not without scientific merit. He concludes that multiverse theory is a “productive research program”:^[18]

As skeptical as I am, I think the contemplation of the multiverse is an excellent opportunity to reflect on the nature of science and on the ultimate nature of existence: why we are here… In looking at this concept, we need an open mind, though not too open. It is a delicate path to tread. Parallel universes may or may not exist; the case is unproved. We are going to have to live with that uncertainty. Nothing is wrong with scientifically based philosophical speculation, which is what multiverse proposals are. But we should name it for what it is.

— George Ellis, Scientific American, Does the Multiverse Really Exist?

Occam's razor[link]

Critics^[who?] argue that to postulate a practically infinite number of unobservable universes just to explain our own seems contrary to Occam's razor.^[19]

Max Tegmark answers:

"A skeptic worries about all the information necessary to specify all those unseen worlds. But an entire ensemble is often much simpler than one of its members. This principle can be stated more formally using the notion of algorithmic information content. The algorithmic information content in a number is, roughly speaking, the length of the shortest computer program that will produce that number as output. For example, consider the set of all integers. Which is simpler, the whole set or just one number? Naively, you might think that a single number is simpler, but the entire set can be generated by quite a trivial computer program, whereas a single number can be hugely long. Therefore, the whole set is actually simpler. Similarly, the set of all solutions to Einstein's field equations is simpler than a specific solution. The former is described by a few equations, whereas the latter requires the specification of vast amounts of initial data on some hypersurface. The lesson is that complexity increases when we restrict our attention to one particular element in an ensemble, thereby losing the symmetry and simplicity that were inherent in the totality of all the elements taken together. In this sense, the higher-level multiverses are simpler. Going from our universe to the Level I multiverse eliminates the need to specify initial conditions, upgrading to Level II eliminates the need to specify physical constants, and the Level IV multiverse eliminates the need to specify anything at all."

He continues:

"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. Perhaps we will gradually get used to the weird ways of our cosmos and find its strangeness to be part of its charm."^[4]

Multiverse hypotheses in philosophy and logic[link]

Modal realism[link]

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).^[20]

Trans-world identity[link]

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.^[21][22]

Fictional realism[link]

The view that because fictions exist, fictional characters exist as well. There are fictional entities, in the same sense in which, setting aside philosophical disputes, there are people, Mondays, numbers and planets.^[23][24]

See also[link]

Physics portal

• Multiverse (religion)
• Impossible world
• Modal realism
• Omniverse
• Roger Penrose
• Parallel universe (fiction)
• Philosophy of physics
• Philosophy of space and time
• Reductionism
• Simulated reality
• The Fabric of Reality
• As contrary concepts
  • Determinism
  • Fatalism
  • Predestination

References[link]

Notes[link]

Bibliography[link]

External links[link]

• Aurélien Barrau, "Physics in the Multiverse."
• --------, "Multiple Universes?" (in French). Review of Carr (2007).
• Davies, Paul (2004). "Multiverse Cosmological Models". Mod.Phys.Lett. A 19: 727–744. arXiv:astro-ph/0403047. Bibcode 2003MPLA...18.2895M. DOI:10.1142/S0217732303012325. 
• Max Tegmark (2003) "Parallel Universes. Not just a staple of science fiction, other universes are a direct implication of cosmological observations."
• David Deutsch (2001) "The Structure of the Multiverse."
• BBC Horizon -Parallel Universes.
• Michael Price's Everett FAQ.
• Jürgen Schmidhuber, "The ensemble of universes describable by constructive mathematics."
• 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
• Multiverse - Radio-discussion on BBC Four with Melvyn Bragg
• Multiverse theory suggested by microwave background, BBC news website, 2011/08/03

Brian Greene
At the launch of the World Science Festival, April 2008
Born	(1963-02-09) February 9, 1963 (age 49) New York City, U.S.
Residence	United States
Nationality	USA
Fields	Physics
Institutions	Cornell University Columbia University
Alma mater	Stuyvesant High School Harvard University Oxford University
Doctoral advisor	Graham G. Ross (Oxford University) James Binney
Known for	String theory The Elegant Universe The Fabric of the Cosmos

Brian Greene (born February 9, 1963) is an American theoretical physicist and string theorist. He has been a professor at Columbia University since 1996. Greene has worked on mirror symmetry, relating two different Calabi-Yau manifolds (concretely, relating the conifold to one of its orbifolds). He also described the flop transition, a mild form of topology change, showing that topology in string theory can change at the conifold point. He has become known to a wider audience through his books for the general public, The Elegant Universe, Icarus at the Edge of Time, The Fabric of the Cosmos, The Hidden Reality, and a related PBS television special. Greene also appeared on The Big Bang Theory episode "The Herb Garden Germination."

Early life[link]

Greene was born in New York City. His father, Alan Greene, was a one-time vaudeville performer and high school dropout who later worked as a voice coach and composer. After attending Stuyvesant High School,^[1] Greene entered Harvard in 1980 to concentrate in physics. After completing his bachelor's degree, Greene earned his doctorate from Oxford University as a Rhodes Scholar, graduating in 1987. While at Oxford, Greene also studied piano with the concert pianist Jack Gibbons.

Career[link]

Greene joined the physics faculty of Cornell University in 1990, and was appointed to a full professorship in 1995. The following year, he joined the staff of Columbia University as a full professor. At Columbia, Greene is co-director of the university's Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), and is leading a research program applying superstring theory to cosmological questions. He is also one of the FQXi large grant awardees, his project title being "Arrow of Time in the Quantum Universe". His co-investigators are David Albert and Maulik Parikh.

Research[link]

Greene's area of research is string theory, a candidate for a theory of quantum gravity. String theory attempts to explain the different particle species of the standard model of particle physics as different aspects of a single type of one-dimensional, vibrating string. One peculiarity of string theory is that it postulates the existence of extra dimensions of space – instead of the usual four dimensions, there must be ten spatial dimensions and one dimension of time to allow for a consistently defined string theory. The theory has several explanations to offer for why we do not perceive these extra dimensions, one being that they are "curled up" (compactified, to use the technical term) and are hence too small to be readily noticeable.

In the field, Greene is best known for his contribution to the understanding of the different shapes the curled-up dimensions of string theory take on. The most important of these shapes are so-called Calabi-Yau manifolds; when the extra dimensions take on those particular form, physics in three dimensions exhibits an abstract symmetry known as supersymmetry.

Greene has worked on a particular class of symmetry relating two different Calabi-Yau manifolds, known as mirror symmetry (concretely, relating the conifold to one of its orbifolds). He is also known for his research on the flop transition, a mild form of topology change, showing that topology in string theory can change at the conifold point.

Currently, Greene studies string cosmology, especially the imprints of trans Planckian physics on the cosmic microwave background, and brane-gas cosmologies that could explain why the space around us has three large dimensions, expanding on the suggestion of a black hole electron, namely that the electron may be a black hole.

Communicating science[link]

Brian Greene on Bookbits radio.

Greene is well known to a wider audience for his work on popularizing theoretical physics, in particular string theory and the search for a unified theory of physics. His first book, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory, published in 1999, is a popularization of superstring theory and M-theory. It was a finalist for the Pulitzer Prize in nonfiction, and winner of The Aventis Prizes for Science Books in 2000.^[2] The Elegant Universe was later made into a PBS television special of the same name, hosted and narrated by Greene, which won a 2003 Peabody Award.

Greene's second book, The Fabric of the Cosmos: Space, Time, and the Texture of Reality (2004), is about space, time, and the nature of the universe. Aspects covered in this book include non-local particle entanglement as it relates to special relativity and basic explanations of string theory. It is an examination of the very nature of matter and reality, covering such topics as spacetime and cosmology, origins and unification, and including an exploration into reality and the imagination.

Greene's third book, The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos, published in January 2011, deals in greater depth with multiple universes, or, as they are sometimes referred to collectively, the multiverse.

A book for a younger audience, Icarus at the Edge of Time ISBN 978-0-307-26888-4, which is a futuristic re-telling of the Icarus myth, was published September 2, 2008.^[3] In addition to authoring popular-science books, Greene is an occasional Op-Ed Contributor for The New York Times, writing on his work and other scientific topics.

The popularity of his books and his natural on-camera demeanor have resulted in many media appearances, including Charlie Rose, The Colbert Report, The NewsHour with Jim Lehrer, The Century with Peter Jennings, CNN, TIME, Nightline in Primetime, Late Night with Conan O'Brien, and The Late Show with David Letterman. It has also led to Greene helping John Lithgow with scientific dialogue for the television series 3rd Rock from the Sun, and becoming a technical consultant for the film Frequency, in which he also had a cameo role. Recently, he was a consultant in the time-travel movie Déjà Vu. He also had a cameo appearance as an Intel scientist in 2007's The Last Mimzy. Greene was also mentioned in the 2002 Angel episode "Supersymmetry" and in the 2008 Stargate Atlantis episode "Trio". Through his film credits, combined with his research publications in mathematical physics, Greene is one of the few people to have a defined Erdős–Bacon number. In April 2011 he appeared on The Big Bang Theory in the episode "The Herb Garden Germination" as himself, speaking to a small crowd about the contents of his most recent book.

Greene often lectures outside of the collegiate setting, at both a general and a technical level, in more than twenty-five countries. One of his latest projects is to organize an annual science festival held in New York City, the World Science Festival. The first such festival took place in May/June 2008.^[4][5]

Personal life[link]

Greene is married to former ABC producer Tracy Day.^[4] He became vegan in 1997^[6] after touring Farm Sanctuary in Watkins Glen, New York.^[7][8]

Bibliography[link]

Technical articles[link]

For a full list of technical articles, consult the publication list in the SPIRES database

• Easther, Richard; Greene, Brian R.; Jackson, Mark G.; Kabat, Daniel (2005). "String windings in the early universe". Journal of Cosmology and Astroparticle Physics. arXiv:hep-th/0409121v1. DOI:10.1088/1475-7516/2005/02/009. 
• Easther, Richard; Greene, Brian R.; Kinney, William H.; Shiu, Gary (2002). "A generic estimate of trans-Planckian modifications to the primordial power spectrum in inflation". Physical Review D 66 (2). arXiv:hep-th/0204129v1. DOI:10.1103/PhysRevD.66.023518. 
• R. Easther, B. Greene, W. Kinney, G. Shiu, "Inflation as a Probe of Short Distance Physics". Phys. Rev. D64 (2001) 103502.
• Brian R. Greene, "D-Brane Topology Changing Transitions". Nucl. Phys. B525 (1998) 284-296.
• Michael R. Douglas, Brian R. Greene, David R. Morrison, "Orbifold Resolution by D-Branes". Nucl.Phys. B506 (1997) 84-106.
• Brian R. Greene, David R. Morrison, Andrew Strominger, "Black Hole Condensation and the Unification of String Vacua". Nucl.Phys. B451 (1995) 109-120.
• P.S. Aspinwall, B.R. Greene, D.R. Morrison, "Calabi-Yau Moduli Space, Mirror Manifolds and Spacetime Topology Change in String Theory". Nucl.Phys. B416 (1994) 414-480.
• B.R.Greene and M.R.Plesser, "Duality in Calabi-Yau Moduli Space". Nucl. Phys. B338 (1990) 15.

Books for general readers[link]

• 1999. The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory.
• 2005. The Fabric of the Cosmos: Space, Time, and the Texture of Reality.
• 2008. Icarus at the Edge of Time.
• 2011. The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos.

See also[link]

• List of physicists
• List of theoretical physicists
• Theory of everything
• Unified Field Theory

References[link]

External links[link]

Wikiquote has a collection of quotations related to: Brian Greene

• Brian Greene faculty homepage
• Brian Greene at the Internet Movie Database

This article contains Japanese text. Without proper rendering support, you may see question marks, boxes, or other symbols instead of kanji and kana.

Michio Kaku (加来 道雄, Kaku Michio^?, born January 24, 1947) is an American theoretical physicist, the Henry Semat Professor of Theoretical Physics in the City College of New York of City University of New York, a co-founder of string field theory,^[1] a futurist, and a "communicator" and "popularizer" of science. He has written several books about physics and related topics; he has made frequent appearances on radio, television, and film; and he writes extensive online blogs and articles. He has written two New York Times best sellers, Physics of the Impossible (2008) and Physics of the Future (2011). He has hosted several TV specials for BBC-TV, the Discovery Channel, and the Science Channel.

Early life and education[link]

Kaku was born in San Jose, California to Japanese immigrant parents. His grandfather came to the United States to take part in the clean-up operation after the 1906 San Francisco Earthquake^{[citation needed]}. His father was born in California but was educated in Japan and spoke little English. Both his parents were put in the Tule Lake War Relocation Center, where they met and where his two brothers were born.

At Cubberley High School in Palo Alto, Kaku assembled an atom smasher in his parents' garage for a science fair project.^[2] At the National Science Fair in Albuquerque, New Mexico, he attracted the attention of physicist Edward Teller, who took Kaku as a protégé, awarding him the Hertz Engineering Scholarship. Kaku graduated summa cum laude from Harvard University in 1968 and was first in his physics class. He attended the Berkeley Radiation Laboratory at the University of California, Berkeley and received a Ph.D. in 1972, and in 1972 he held a lectureship at Princeton University.

During the Vietnam War, Kaku completed his U.S. Army basic training at Fort Benning, Georgia and his advanced individual training at Fort Lewis, Washington.^[3] However, the Vietnam War ended before he was deployed as an infantryman.

Academic career[link]

Kaku became a visiting professor at the Institute for Advanced Study in Princeton,^[4] and New York University.^[5] He currently holds the Henry Semat Chair and Professorship in theoretical physics at the City College of New York.^[6]

Kaku has had over 70 articles published in physics journals such as Physical Review, covering topics such as superstring theory, supergravity, supersymmetry, and hadronic physics.^[7] In 1974, along with Prof. Keiji Kikkawa of Osaka University, he authored the first papers describing string theory in a field form.^[8][9]

Kaku is the author of several textbooks on string theory and quantum field theory.

Popular science[link]

Kaku is most widely known as a popularizer of science.^[10] He has written books and appeared on many television programs as well as film. He also hosts a weekly radio program.

Books[link]

Kaku is the author of various popular science books.

• Hyperspace (1994)
• Beyond Einstein (with Jennifer Thompson) (1995)
• Visions: How Science Will Revolutionize the 21st Century^[11] (1998)
• Einstein's Cosmos (2004)
• Parallel Worlds (2004)
• Physics of the Impossible (2008)
• Physics of the Future (2011)

Hyperspace was a best-seller and was voted one of the best science books of the year by both The New York Times^[10] and The Washington Post. Parallel Worlds was a finalist for the Samuel Johnson Prize for non-fiction in the UK.^[12]

Radio[link]

Kaku is the host of the weekly, one-hour radio program Explorations, produced by the Pacifica Foundation's WBAI in New York. "Explorations" is syndicated to community and independent radio stations and makes previous broadcasts available on the program's website. Kaku defines the show as dealing with the general topics of science, war, peace, and the environment.

In April 2006, Kaku began broadcasting Science Fantastic on 90 commercial radio stations, the only nationally syndicated science program on commercial radio in the United States. It is syndicated by Talk Radio Network and now reaches 130 radio stations and America's Talk on XM. The program is formatted as a live listener call-in show, focusing on "futurology," which he defines as the future of science.^{[citation needed]} Featured guests include Nobel laureates and top researchers on the topics of string theory, time travel, black holes, gene therapy, aging, space travel, artificial intelligence, and SETI. When Kaku is busy filming for television, Science Fantastic goes on hiatus, sometimes for several months. Kaku is also a frequent guest on many programs, where he is outspoken in all areas and issues he considers of importance, such as the program Coast to Coast AM, where on 30 November 2007, he reaffirmed his belief that there is a 100% probability of extraterrestrial life in the universe.^[13]

Kaku has appeared on The Opie and Anthony Show a number of times, discussing popular fiction such as Back to The Future, Lost, and the theories behind time-travel that these and other fictional entertainment focus on.

Television and film[link]

Kaku has appeared in many forms of media and on many programs and networks, including Good Morning America, The Screen Savers, Larry King Live, 60 Minutes, Nightline, 20/20, Naked Science, CNN, ABC News, CBS News, NBC News, Al Jazeera English, Fox News Channel, The History Channel, Conan, The Science Channel, The Discovery Channel, TLC, Countdown with Keith Olbermann, The Colbert Report, The Art Bell Show and its successor, Coast To Coast AM, BBC World News America, The Opie & Anthony Show, The Covino & Rich Show, Head Rush, The Late Show with David Letterman, and Real Time with Bill Maher.

In 1999, Kaku was one of the scientists profiled in the feature-length film Me and Isaac Newton, directed by Michael Apted. It played theatrically in the United States, was later broadcast on national TV, and won several film awards.^{[citation needed]}

In 2005, Kaku appeared in the short documentary Obsessed & Scientific. The film is about the possibility of time travel and the people who dream about it. It screened at the Montreal World Film Festival and a feature film expansion is in development talks. Kaku also appeared in the ABC documentary UFOs: Seeing Is Believing, in which he suggested that while he believes it is extremely unlikely that extraterrestrials have ever actually visited Earth, we must keep our minds open to the possible existence of civilizations a million years ahead of us in technology, where entirely new avenues of physics open up. He also discussed the future of interstellar exploration and alien life in the Discovery Channel special Alien Planet as one of the multiple speakers who co-hosted the show, and Einstein's Theory of Relativity on The History Channel.

In February 2006, Kaku appeared as presenter in the BBC-TV four-part documentary Time which seeks to explore the mysterious nature of time. Part one of the series concerns personal time, and how we perceive and measure the passing of time. The second in the series deals with cheating time, exploring possibilities of extending the lifespan of organisms. The geological time covered in part three explores the ages of the earth and the sun. Part four covers the topics of cosmological time, the beginning of time and the events that occurred at the instant of the big bang.

On January 28, 2007, Kaku hosted the Discovery Channel series 2057. This three-hour program discussed how medicine, the city, and energy could change over the next 50 years.

In 2008, Kaku hosted the three-hour BBC-TV documentary Visions of the Future, on the future of computers, medicine, and quantum physics, and he appeared in several episodes of the History Channel's Universe series.

On December 1, 2009, he began hosting a 12-episode weekly TV series for the Science Channel at 10 pm, called Sci Fi Science: Physics of the Impossible, based on his best-selling book. Each 30-minute episode discusses the scientific basis behind imaginative schemes, such as time travel, parallel universes, warp drive, star ships, light sabers, force fields, teleportation, invisibility, death stars, and even superpowers and flying saucers. Each episode includes interviews with the world's top scientists working on prototypes of these technologies, interviews with science fiction fans, clips from science fiction movies, and special effects and computer graphics. Although these inventions are impossible today, the series discusses when these technologies might become feasible in the future.^[14]

In 2010, he began to appear in a series on the website Gametrailers.com called Science of Games, discussing the scientific aspects of various popular video games such as Mass Effect 2 and Star Wars: The Force Unleashed.

Kaku is popular in mainstream media because of his knowledge and his accessible approach to presenting complex subjects in science. While his technical writings are confined to theoretical physics, his public speaking and media appearances cover a broad range of topics, from the Kardashev scale to more esoteric subjects such as wormholes and time travel. In January 2007, Kaku visited Oman. While there, he talked at length to select members of that country's decision makers. In an interview with local media, Dr Kaku elaborated on his vision of mankind's future. Kaku considers climate change and terrorism as serious threats in man's evolution from a Type 0 civilization to Type 1.^[15]

He is pictured in Symphony of Science's newest song (as of September 6, 2011), 'The Quantum World.'

On October 11, 2010, Michio Kaku appeared in the BBC program "What Happened Before the Big Bang" (along with Laura Mersini-Houghton, Andrei Linde, Roger Penrose, Lee Smolin, Neil Turok, and other notable cosmologists and physicists), where he propounded his theory of the universe created out of nothing.^[16]

Social policy advocacy[link]

Kaku has publicly stated his concerns over matters including the anthropogenic cause of global warming, nuclear armament, nuclear power and the general misuse of science.^[17] He was critical of the Cassini–Huygens space probe because of the 72 pounds (33 kg) of plutonium contained in the craft for use by its radioisotope thermoelectric generator. Conscious of the possibility of casualties if the probe's fuel were dispersed into the environment during a malfunction and crash as the probe was making a 'sling-shot' maneuver around earth, Kaku publicly criticized NASA's risk assessment.^[18] He has also spoken on the dangers of space junk and called for more and better monitoring. Kaku is generally a vigorous supporter of the exploration of outer space, believing that the ultimate destiny of the human race may lie in extrasolar planets; but he is critical of some of the cost-ineffective missions and methods of NASA.

Kaku credits his anti-nuclear war position to programs he heard on the Pacifica Radio network, during his student years in California. It was during this period that he made the decision to turn away from a career developing the next generation of nuclear weapons in association with Edward Teller and focused on research, teaching, writing and media.^{[citation needed]} Kaku joined with others such as Helen Caldicott, Jonathan Schell, Peace Action and was instrumental in building a global anti-nuclear weapons movement that arose in the 1980s, during the administration of U.S. President Ronald Reagan.

Kaku was a board member of Peace Action and on the board of radio station WBAI-FM in New York City where he originated his long running program, Explorations, that focused on the issues of science, war, peace and the environment.

His remark from an interview in support of SETI, "We could be in the middle of an intergalactic conversation...and we wouldn't even know.", is used in the third Symphony of Science installment "Our Place in the Cosmos".

Personal life[link]

Kaku is married to Shizue Kaku and has two daughters.^[19]

Bibliography[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Michio Kaku

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• Official website
• Michio Kaku on Twitter
• Getting Physical: Dr. Michio Kaku Explains Einstein's Genius
• Russia Takes Aim at Asteroids, op-ed on asteroid defense, Wall St. Journal, Jan. 5, 2010
• The Skeptics' Guide To The Universe interview
• Michio Kaku at the Internet Movie Database
• Michio Kaku on National Public Radio
• About Michio Kaku
• Video: Michio Kaku discusses Physics of the Future on March 23, 2011, on Forum Network.
• In Depth interview with Kaku, October 3, 2010

This article relies on references to primary sources or sources affiliated with the subject, rather than references from independent authors and third-party publications. Please add citations from reliable sources. (January 2012)

Max Tegmark
Born	(1967-05-05) May 5, 1967 (age 45) Sweden
Nationality	Swedish-American
Fields	Cosmology
Institutions	MIT
Alma mater	Royal Institute of Technology Berkeley

Max Tegmark (born 5 May 1967) is a Swedish-American cosmologist. Tegmark is a professor at the Massachusetts Institute of Technology and belongs to the scientific directorate of the Foundational Questions Institute.

Biography[link]

Early life[link]

Tegmark was born as Max Shapiro in Sweden, son of Karin Tegmark and Harold S. Shapiro, studied at the Royal Institute of Technology in Stockholm, and later received his Ph.D. from the University of California, Berkeley. After having worked at the University of Pennsylvania, he is now at the Massachusetts Institute of Technology. While still in high-school, Max wrote, and sold commercially, together with school buddy Magnus Bodin a word processor written in pure machine code ^[1] for the Swedish 8-bit computer ABC80.

Career[link]

His research has focused on cosmology, combining theoretical work with new measurements to place constraints on cosmological models and their free parameters, often in collaboration with experimentalists. He has over 200 publications, of which 9 have been cited over 500 times.^[2] He has developed data analysis tools based on information theory and applied them to Cosmic Microwave Background experiments such as COBE, QMAP, and WMAP, and to galaxy redshift surveys such as the Las Campanas Redshift Survey, the 2dF Survey and the Sloan Digital Sky Survey.

With Daniel Eisenstein and Wayne Hu, he introduced the idea of using Baryon Acoustic Oscillations as a Standard Ruler.^{[3][non-primary source needed]}

With Angelica de Oliveira-Costa and Andrew Hamilton, he discovered the anomalous multipole alignment in the WMAP data sometimes referred to as the "axis of evil".^{[4][non-primary source needed]}

Tegmark has also formulated the "Ultimate ensemble theory of everything", whose only postulate is that "all structures that exist mathematically exist also physically". This simple theory, with no free parameters at all, suggests that in those structures complex enough to contain self-aware substructures (SASs), these SASs will subjectively perceive themselves as existing in a physically "real" world. This idea is formalized as the "Mathematical universe hypothesis" ^[5]

Personal life[link]

He was married to astrophysicist Angelica de Oliveira-Costa in 1997, and divorced in 2009. They have two sons, Philip and Alexander.^[6]

In the media[link]

• In 2006, Tegmark was one of fifty scientists interviewed by New Scientist about their predictions for the future. His prediction: "In 50 years, you may be able to buy T-shirts on which are printed equations describing the unified laws of our universes."^[7]
• Tegmark appears in the documentary Parallel Worlds, Parallel Lives in which he is interviewed by Mark Oliver Everett, son of the founder of the many-worlds interpretation of quantum mechanics, Hugh Everett.
• Tegmark also appears in "Who's afraid of a big black hole?","What time is it?", "To Infinity and Beyond", "Is Everything We Know About The Universe Wrong?" and "What is Reality?", all part of the BBC's Horizon scientific series of programmes.

Notes[link]

External links[link]

Wikiquote has a collection of quotations related to: Max Tegmark

• Max Tegmark's website