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Raphael Bousso
Raphael Bousso () (born 1971) is a theoretical physicist and cosmologist. He is a professor at the Berkeley Center for Theoretical Physics in the Department of Physics, UC Berkeley. He is known for the Bousso bound on the information content of the universe. With Joseph Polchinski, Bousso proposed the string theory landscape as a solution to the cosmological constant problem. Life and career Bousso was born in Haifa, Israel, the son of late scientisDino Bousso He grew up near Augsburg, Germany, where he studied physics from 1990 until 1993. Bousso earned his Ph.D. at Cambridge University in 1997; his doctoral advisor was Stephen Hawking. Bousso did postdoctoral research at Stanford University until 2000, and at the Kavli Institute for Theoretical Physics in Santa Barbara until 2002. In 2002/03, Bousso was a fellow at the Harvard University physics department and the Radcliffe Institute for Advanced Study. Since 2002, he has been a professor in the physics department at the Uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physicist
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena. The advancement of science generally depends on the interplay between experimental studies and theory. In some cases, theoretical physics adheres to standards of mathematical rigour while giving little weight to experiments and observations.There is some debate as to whether or not theoretical physics uses mathematics to build intuition and illustrativeness to extract physical insight (especially when normal experience fails), rather than as a tool in formalizing theories. This links to the question of it using mathematics in a less formally rigorous, and more intuitive or heuristic way than, say, mathematical physics. For example, while developing special relativity, Albert Einstein was concerned with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Gravity
Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics; it deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the vicinity of black holes or similar compact astrophysical objects, such as neutron stars. Three of the four fundamental forces of physics are described within the framework of quantum mechanics and quantum field theory. The current understanding of the fourth force, gravity, is based on Albert Einstein's general theory of relativity, which is formulated within the entirely different framework of classical physics. However, that description is incomplete: describing the gravitational field of a black hole in the general theory of relativity leads physical quantities, such as the spacetime curvature, to diverge at the center of the black hole. This signals the breakdown of the general theory of relativity and the need for a theory that goes b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1971 Births
* The year 1971 had three partial solar eclipses ( February 25, July 22 and August 20) and two total lunar eclipses (February 10, and August 6). The world population increased by 2.1% this year, the highest increase in history. Events January * January 2 – 66 people are killed and over 200 injured during a crush in Glasgow, Scotland. * January 5 – The first ever One Day International cricket match is played between Australia and England at the Melbourne Cricket Ground. * January 8 – Tupamaros kidnap Geoffrey Jackson, British ambassador to Uruguay, in Montevideo, keeping him captive until September. * January 9 – Uruguayan president Jorge Pacheco Areco demands emergency powers for 90 days due to kidnappings, and receives them the next day. * January 12 – The landmark United States television sitcom ''All in the Family'', starring Carroll O'Connor as Archie Bunker, debuts on CBS. * January 14 – Seventy Brazilian political prisoners ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Theorists
This is a list of string theory topics. String theory * Strings * Nambu–Goto action * Polyakov action * Bosonic string theory * Superstring theory ** Type I string ** Type II string *** Type IIA string theory *** Type IIB string theory ** Heterotic string * N=2 superstring * M-theory ** Matrix theory ** Introduction to M-theory * F-theory * String field theory * Matrix string theory * Nonlinear sigma model * Tachyon condensation * RNS formalism * String theory landscape * History of string theory ** First superstring revolution ** Second superstring revolution String duality * T-duality * S-duality * U-duality * Montonen–Olive duality * Mysterious duality Particles and fields * Graviton * Dilaton * Tachyon * Ramond–Ramond field * Kalb–Ramond field * Magnetic monopole Branes * D-brane * S-brane * Black brane * Black holes * Black string * Brane cosmology * Quiver diagram * Hanany–Witten transition Supersymmetry * Supergravity * Superspace * Lie sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmologists
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate.For an overview, see Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood. Physical cosmology, as it is now understood, began with the development in 1915 of Albert Einstein's general theory of relativity, followed by major observational discoveries in the 1920s: first, Edwin Hubble discovered that the universe contains a huge number of external galaxies beyond the Milky Way; then, work by Vesto Slipher and others showed that the universe is expanding. These advances made it possible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physicists
The following is a partial list of notable theoretical physicists. Arranged by century of birth, then century of death, then year of birth, then year of death, then alphabetically by surname. For explanation of symbols, see Notes at end of this article. Ancient times * Thales (c. 624 – c. 546 BCE) * Pythagoras^* (c. 570 – c. 495 BCE) * Democritus° (c. 460 – c. 370 BCE) * Aristotle‡ (384–322 BCE) * Archimedesº* (c. 287 – c. 212 BCE) * Hypatia^ªº (c. 350–370; died 415 AD) Middle Ages * Al Farabi (c. 872 – c. 950) * Ibn al-Haytham (c. 965 – c. 1040) * Al Beruni (c. 973 – c. 1048) * Omar Khayyám (c. 1048 – c. 1131) * Nasir al-Din Tusi (1201–1274) * Jean Buridan (1301 – c. 1359/62) * Nicole Oresme (c. 1320 – 1325 –1382) * Sigismondo Polcastro (1384–1473) 15th–16th century * Nicolaus Copernicusº (1473–1543) 16th century and 16th–17th centuries * Gerolamo Cardano (1501–1576) * Tycho Brahe (1546–1601) * Giordano Bruno (1548– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Living People
Related categories * :Year of birth missing (living people) / :Year of birth unknown * :Date of birth missing (living people) / :Date of birth unknown * :Place of birth missing (living people) / :Place of birth unknown * :Year of death missing / :Year of death unknown * :Date of death missing / :Date of death unknown * :Place of death missing / :Place of death unknown * :Missing middle or first names See also * :Dead people * :Template:L, which generates this category or death years, and birth year and sort keys. : {{DEFAULTSORT:Living people 21st-century people People by status ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Energy
Vacuum energy is an underlying background energy that exists in space throughout the entire Universe. The vacuum energy is a special case of zero-point energy that relates to the quantum vacuum. The effects of vacuum energy can be experimentally observed in various phenomena such as spontaneous emission, the Casimir effect and the Lamb shift, and are thought to influence the behavior of the Universe on cosmological scales. Using the upper limit of the cosmological constant, the vacuum energy of free space has been estimated to be 10−9 joules (10−2 ergs), or ~5 GeV per cubic meter. However, in quantum electrodynamics, consistency with the principle of Lorentz covariance and with the magnitude of the Planck constant suggests a much larger value of 10113 joules per cubic meter. This huge discrepancy is known as the cosmological constant problem or, colloquially, the "vacuum catastrophe." Origin Quantum field theory states that all fundamental fields, such as the electromagnet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmological Constant
In cosmology, the cosmological constant (usually denoted by the Greek capital letter lambda: ), alternatively called Einstein's cosmological constant, is the constant coefficient of a term that Albert Einstein temporarily added to his field equations of general relativity. He later removed it. Much later it was revived and reinterpreted as the energy density of space, or vacuum energy, that arises in quantum mechanics. It is closely associated with the concept of dark energy. Einstein originally introduced the constant in 1917 to counterbalance the effect of gravity and achieve a static universe, a notion that was the accepted view at the time. Einstein's cosmological constant was abandoned after Edwin Hubble's confirmation that the universe was expanding. From the 1930s until the late 1990s, most physicists agreed with Einstein's choice of setting the cosmological constant to zero. That changed with the discovery in 1998 that the expansion of the universe is accelerating, im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Solution
In general relativity, a vacuum solution is a Lorentzian manifold whose Einstein tensor vanishes identically. According to the Einstein field equation, this means that the stress–energy tensor also vanishes identically, so that no matter or non-gravitational fields are present. These are distinct from the electrovacuum solutions, which take into account the electromagnetic field in addition to the gravitational field. Vacuum solutions are also distinct from the lambdavacuum solutions, where the only term in the stress–energy tensor is the cosmological constant term (and thus, the lambdavacuums can be taken as cosmological models). More generally, a vacuum region in a Lorentzian manifold is a region in which the Einstein tensor vanishes. Vacuum solutions are a special case of the more general exact solutions in general relativity. Equivalent conditions It is a mathematical fact that the Einstein tensor vanishes if and only if the Ricci tensor vanishes. This follows from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Theory
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries the gravitational force. Thus, string theory is a theory of quantum gravity. String theory is a broad and varied subject that attempts to address a number of deep questions of fundamental physics. String theory has contributed a number of advances to mathematical physics, which have been applied to a variety of problems in black hole physics, early universe cosmology, nuclear physics, and conde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Hole Information Paradox
The black hole information paradox is a puzzle that appears when the predictions of quantum mechanics and general relativity are combined. The theory of general relativity predicts the existence of black holes that are regions of spacetime from which nothing — not even light — can escape. In the 1970s, Stephen Hawking applied the rules of quantum mechanics to such systems and found that an isolated black hole would emit a form of radiation called Hawking radiation. Hawking also argued that the detailed form of the radiation would be independent of the initial state of the black hole and would depend only on its mass, electric charge and angular momentum. The information paradox appears when one considers a process in which a black hole is formed through a physical process and then evaporates away entirely through Hawking radiation. Hawking's calculation suggests that the final state of radiation would retain information only about the total mass, electric charge and angular m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
