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Luboš Motl
Luboš Motl (; born 5 December 1973) is a Czech physicist and blogger. He was an assistant professor in physics at Harvard University from 2004 to 2007. His scientific publications were focused on string theory. Life and career Motl was born in Plzeň, present-day Czech Republic. He won a Bronze Medal at the 1992 International Mathematical Olympiad. He received his master's degree from the Charles University in Prague, and his Doctor of Philosophy degree from Rutgers University (2001) and has been a Harvard Junior Fellow (2001–2004) and assistant professor (2004–2007) at Harvard University. In 2007, he left Harvard and returned to the Czech Republic. Although an undergraduate at a Czech university where none of the faculty specialized in string theory, Motl came to the attention of string theorist Thomas Banks in 1996, when Banks read an arXiv posting by Motl on matrix string theory. "I was at first a little annoyed by otl'spaper, because it scooped me," said Banks. "This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plzeň
Plzeň (; German and English: Pilsen, in German ) is a city in the Czech Republic. About west of Prague in western Bohemia, it is the Statutory city (Czech Republic), fourth most populous city in the Czech Republic with about 169,000 inhabitants. The city is known worldwide for Pilsner beer, created by Bavarian brewer Josef Groll in the city in 1842. Administrative division Plzeň is divided into ten boroughs, which are further divided into 25 administrative parts (in brackets): *Plzeň 1-Bolevec (Bolevec and Severní Předměstí) *Plzeň 2-Slovany (Božkov, Černice (partly), Doudlevce (partly), Hradiště, Koterov, Lobzy (partly) and Východní Předměstí (partly)) *Plzeň 3-Bory (Doudlevce (partly), Jižní Předměstí, Litice (partly), Nová Hospoda, Radobyčice, Skvrňany, Valcha, Vnitřní Město and Východní Předměstí (partly)) *Plzeň 4-Doubravka (Bukovec, Červený Hrádek, Doubravka, Lobzy (partly), Újezd and Východní Předměstí (partly)) *Plzeň 5-K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prague
Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 million people. The city has a temperate oceanic climate, with relatively warm summers and chilly winters. Prague is a political, cultural, and economic hub of central Europe, with a rich history and Romanesque, Gothic, Renaissance and Baroque architectures. It was the capital of the Kingdom of Bohemia and residence of several Holy Roman Emperors, most notably Charles IV (r. 1346–1378). It was an important city to the Habsburg monarchy and Austro-Hungarian Empire. The city played major roles in the Bohemian and the Protestant Reformations, the Thirty Years' War and in 20th-century history as the capital of Czechoslovakia between the World Wars and the post-war Communist era. Prague is home to a number of well-known cultural attractions, many of which survived the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Quantum Gravity
Loop quantum gravity (LQG) is a theory of quantum gravity, which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. It is an attempt to develop a quantum theory of gravity based directly on Einstein's geometric formulation rather than the treatment of gravity as a force. As a theory LQG postulates that the structure of Spacetime, space and time is composed of finite loops woven into an extremely fine fabric or network. These networks of loops are called spin networks. The evolution of a spin network, or spin foam, has a scale above the order of a Planck length, approximately 10−35 meters, and smaller scales are meaningless. Consequently, not just matter, but space itself, prefers an atomic hypothesis, atomic structure. The areas of research, which involves about 30 research groups worldwide, share the basic physical assumptions and the mathematical description of q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasinormal Mode
Quasinormal modes (QNM) are the modes of energy dissipation of a perturbed object or field, ''i.e.'' they describe perturbations of a field that decay in time. Example A familiar example is the perturbation (gentle tap) of a wine glass with a knife: the glass begins to ring, it rings with a set, or superposition, of its natural frequencies — its modes of sonic energy dissipation. One could call these modes ''normal'' if the glass went on ringing forever. Here the amplitude of oscillation decays in time, so we call its modes ''quasi-normal''. To a high degree of accuracy, quasinormal ringing can be approximated by :\psi(t) \approx e^\cos\omega^t where \psi\left(t\right) is the amplitude of oscillation, \omega^ is the frequency, and \omega^ is the decay rate. The quasinormal frequency is described by two numbers, :\omega = \left(\omega^ , \omega^\right) or, more compactly :\psi\left(t\right) \approx \operatorname(e^) :\omega =\omega^ + i\omega^ Here, \mathbf is what is comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Hole
A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary (topology), boundary of no escape is called the event horizon. Although it has a great effect on the fate and circumstances of an object crossing it, it has no locally detectable features according to general relativity. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with thermal radiation, the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly. Obje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersymmetry
In a supersymmetric theory the equations for force and the equations for matter are identical. In theoretical and mathematical physics, any theory with this property has the principle of supersymmetry (SUSY). Dozens of supersymmetric theories exist. Supersymmetry is a spacetime symmetry between two basic classes of particles: bosons, which have an integer-valued spin and follow Bose–Einstein statistics, and fermions, which have a half-integer-valued spin and follow Fermi–Dirac statistics. In supersymmetry, each particle from one class would have an associated particle in the other, known as its superpartner, the spin of which differs by a half-integer. For example, if the electron exists in a supersymmetric theory, then there would be a particle called a ''"selectron"'' (superpartner electron), a bosonic partner of the electron. In the simplest supersymmetry theories, with perfectly " unbroken" supersymmetry, each pair of superpartners would share the same mass and intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gauge Theory
In physics, a gauge theory is a type of field theory in which the Lagrangian (and hence the dynamics of the system itself) does not change (is invariant) under local transformations according to certain smooth families of operations (Lie groups). The term ''gauge'' refers to any specific mathematical formalism to regulate redundant degrees of freedom in the Lagrangian of a physical system. The transformations between possible gauges, called ''gauge transformations'', form a Lie group—referred to as the ''symmetry group'' or the ''gauge group'' of the theory. Associated with any Lie group is the Lie algebra of group generators. For each group generator there necessarily arises a corresponding field (usually a vector field) called the ''gauge field''. Gauge fields are included in the Lagrangian to ensure its invariance under the local group transformations (called ''gauge invariance''). When such a theory is quantized, the quanta of the gauge fields are called '' gauge bosons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twistor Theory
In theoretical physics, twistor theory was proposed by Roger Penrose in 1967 as a possible path to quantum gravity and has evolved into a branch of theoretical and mathematical physics. Penrose proposed that twistor space should be the basic arena for physics from which space-time itself should emerge. It leads to a powerful set of mathematical tools that have applications to differential and integral geometry, nonlinear differential equations and representation theory and in physics to general relativity and quantum field theory, in particular to scattering amplitudes. Development seems to be indirectly influenced by Einstein–Cartan–Sciama–Kibble theory. Overview Mathematically, projective twistor space \mathbb is a 3-dimensional complex manifold, complex projective 3-space \mathbb^3. It has the physical interpretation of the space of massless particles with spin. It is the projectivisation of a 4-dimensional complex vector space, non-projective twistor space \mathbb w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AdS/CFT
In theoretical physics, the anti-de Sitter/conformal field theory correspondence, sometimes called Maldacena duality or gauge/gravity duality, is a conjectured relationship between two kinds of physical theories. On one side are anti-de Sitter spaces (AdS) which are used in theories of quantum gravity, formulated in terms of string theory or M-theory. On the other side of the correspondence are conformal field theories (CFT) which are quantum field theories, including theories similar to the Yang–Mills theories that describe elementary particles. The duality represents a major advance in the understanding of string theory and quantum gravity.de Haro et al. 2013, p. 2 This is because it provides a non-perturbative formulation of string theory with certain boundary conditions and because it is the most successful realization of the holographic principle, an idea in quantum gravity originally proposed by Gerard 't Hooft and promoted by Leonard Susskind. It also provides a pow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid digital media, digital subscribers. It also is a producer of popular podcasts such as ''The Daily (podcast), The Daily''. Founded in 1851 by Henry Jarvis Raymond and George Jones (publisher), George Jones, it was initially published by Raymond, Jones & Company. The ''Times'' has won List of Pulitzer Prizes awarded to The New York Times, 132 Pulitzer Prizes, the most of any newspaper, and has long been regarded as a national "newspaper of record". For print it is ranked List of newspapers by circulation, 18th in the world by circulation and List of newspapers in the United States, 3rd in the U.S. The paper is owned by the New York Times Company, which is Public company, publicly traded. It has been governed by the Sulzberger family since 189 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Glanz
James Glanz is an American journalist who was appointed as Baghdad bureau chief of ''The New York Times'' in 2007. Glanz joined the ''Times'' in 1999. Articles he wrote with Eric Lipton and others on the World Trade Center were chosen as a finalist for a Pulitzer Prize in explanatory journalism in 2002. Articles Lipton and Glanz wrote were also a part of the Nation Challenged package that won a Pulitzer for Public Service in 2002. He received three Gerald Loeb Awards – the 2020 Breaking News award for "Crash in Ethiopia," and two consecutive Visual Storytelling awards, first in 2021 for "Visualizing the Pandemic Economy" and again in 2022 for "Why the Mexico City Metro Collapsed". Glanz has a Ph.D. in astrophysical sciences from Princeton University Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matrix String Theory
In physics, matrix string theory is a set of equations that describe superstring theory in a non-perturbative framework. Type IIA string theory can be shown to be equivalent to a maximally supersymmetric two-dimensional gauge theory, the gauge group of which is U(''N'') for a large value of ''N''. This matrix string theory was first proposed by Luboš Motl in 1997 and later independently in a more complete paper by Robbert Dijkgraaf, Erik Verlinde, and Herman Verlinde. Another matrix string theory equivalent to Type IIB string theory was constructed in 1996 by Ishibashi, Kawai, Kitazawa and Tsuchiya. See also * Matrix theory (physics) In theoretical physics, the BFSS matrix model or matrix theory is a quantum mechanical model proposed by Tom Banks, Willy Fischler, Stephen Shenker, and Leonard Susskind in 1997. Overview This theory describes the behavior of a set of nine large ... References String theory {{String theory topics , state=collapsed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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