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Kugelblitz (astrophysics)
A kugelblitz () is a theoretical astrophysical object predicted by general relativity. It is a concentration of heat, light or radiation so intense that its energy forms an event horizon and becomes self-trapped. In other words, if enough radiation is aimed into a region of space, the concentration of energy can warp spacetime so much that it creates a black hole. This would be a black hole the original mass–energy of which was in the form of radiant energy rather than matter; however, there is currently no uniformly accepted method of distinguishing black holes by origin. (See the no-hair theorem.) John Archibald Wheeler's 1955 '' Physical Review'' paper entitled " Geons" refers to the kugelblitz phenomenon and explores the idea of creating such particles (or toy models of particles) from spacetime curvature. A study published in ''Physical Review Letters'' in 2024 argues that the formation of a kugelblitz is impossible due to dissipative quantum effects like vacuum pola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physics
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict List of natural phenomena, 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 E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geon (physics)
In general relativity, a geon is a nonsingular electromagnetic or gravitational wave which is held together in a confined region by the gravitational attraction of its own field energy. They were first investigated theoretically in 1955 by J. A. Wheeler, who coined the term as a contraction of "gravitational electromagnetic entity". Overview Since general relativity is a classical field theory, Wheeler's concept of a geon does not treat them as quantum-mechanical entities, and this generally remains true today. Nonetheless, Wheeler speculated that there might be a relationship between geons and elementary particles. This idea continues to attract some attention among physicists, but in the absence of a viable theory of quantum gravity, the accuracy of this speculative idea cannot be tested. Wheeler did not present explicit geon solutions to the vacuum Einstein field equation, a gap which was partially filled by Dieter R. Brill and James Hartle in 1964 by the Brill–Hartle ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Holes
A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. The boundary of no escape is called the event horizon. A black hole has a great effect on the fate and circumstances of an object crossing it, but 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. Quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with 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. Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micro Black Hole
Micro black holes, also known as mini black holes and quantum mechanical black holes, are hypothetical tiny (<1 ) , for which effects play an important role. The concept that black holes may exist that are smaller than was introduced in 1971 by . It is possible that such black holes were creat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bekenstein Bound
In physics, the Bekenstein bound (named after Jacob Bekenstein) is an upper limit on the thermodynamic entropy ''S'', or Shannon entropy ''H'', that can be contained within a given finite region of space which has a finite amount of energy—or conversely, the maximum amount of information that is required to perfectly describe a given physical system down to the quantum level. It implies that the information of a physical system, or the information necessary to perfectly describe that system, must be finite if the region of space and the energy are finite. Equations The universal form of the bound was originally found by Jacob Bekenstein in 1981 as the inequality S \leq \frac, where ''S'' is the entropy, ''k'' is the Boltzmann constant, ''R'' is the radius of a sphere that can enclose the given system, ''E'' is the total mass–energy including any rest masses, ''ħ'' is the reduced Planck constant, and ''c'' is the speed of light. Note that while gravity plays a significant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frederik Pohl
Frederik George Pohl Jr. (; November 26, 1919 – September 2, 2013) was an American list of science fiction authors, science-fiction writer, editor, and science fiction fandom, fan, with a career spanning nearly 75 years—from his first published work, the 1937 poem "Elegy to a Dead Satellite: Luna", to the 2011 novel ''All the Lives He Led''. From about 1959 until 1969, Pohl edited ''Galaxy Science Fiction, Galaxy'' and its sister magazine ''If (magazine), If''; the latter won three successive annual Hugo Awards as the year's best professional magazine. His 1977 novel ''Gateway (novel), Gateway'' won four "year's best novel" awards: the Hugo voted by convention participants, the Locus voted by magazine subscribers, the Nebula voted by American science-fiction writers, and the juried academic John W. Campbell Memorial Award for Best Science Fiction Novel, John W. Campbell Memorial Award. He won the Campbell Memorial Award again for the 1984 collection of novellas ''The Ye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heechee Saga
The Heechee Saga, also known as the Gateway series, is a series of science fiction novels and short stories by Frederik Pohl. The Heechee are an advanced alien race that visited the Solar System hundreds of millennia ago and then mysteriously disappeared. They left behind bases containing artifacts, including working starships, which are discovered and exploited by humanity. Plot overview A prospector on Venus finds an abandoned Heechee spaceship and launches it, with himself aboard. The ship automatically returns to a hollowed out asteroid within the Solar System, later named Gateway. Before he dies from lack of food and water, he manages to signal the rest of humanity his location. On Gateway is a priceless treasure: nearly a thousand small starships, many of them still functional. They come in three sizes, barely capable of carrying one, three or five passengers along with supplies. The Gateway Corporation takes control of the asteroid on behalf of the United States of Ameri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Umbrella Academy (TV Series)
''The Umbrella Academy'' is an American superhero comedy-drama television series based on the comic book series of the same name written by Gerard Way, illustrated by Gabriel Bá, and published by Dark Horse Comics. Created for Netflix by Steve Blackman and developed by Jeremy Slater, it revolves around a dysfunctional family of adopted sibling superheroes who reunite for their father's funeral and the threat of an imminent apocalypse. The series is produced by Borderline Entertainment (season 1–2), Irish Cowboy (season 3), Dark Horse Entertainment, and Universal Content Productions. Netflix gave seasons 1 and 2 a TV-14 rating, while seasons 3 and 4 received a TV-MA rating. The cast features Elliot Page, Tom Hopper, David Castañeda, Emmy Raver-Lampman, Robert Sheehan, Aidan Gallagher, Cameron Britton, Mary J. Blige, John Magaro, Adam Godley, Colm Feore, Justin H. Min, Ritu Arya, Yusuf Gatewood, Marin Ireland, Kate Walsh, Genesis Rodriguez, and Britne Oldford. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of The British Interplanetary Society
The ''Journal of the British Interplanetary Society'' (''JBIS'') is a monthly peer-reviewed scientific journal that was established in 1934. The journal covers research on astronautics and space science and technology, including spacecraft design, nozzle theory, launch vehicle design, mission architecture, space stations, lunar exploration, spacecraft propulsion, robotic and crewed exploration of the Solar System, interstellar travel, interstellar communications, extraterrestrial intelligence, philosophy, and cosmology. It is published monthly by the British Interplanetary Society. History The journal was established in 1934 when the British Interplanetary Society was founded. The inaugural editorial stated: The first issue was only a six-page pamphlet, but has the distinction of being the world's oldest surviving astronautical publication. Notable papers Notable papers published in the journal include: * The B.I.S Space-Ship, H.E.Ross, ''JBIS'', 5, pp. 4–9, 1939 * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Hole Starship
In astronautics, a black hole starship is the theoretical concept of a starship capable of interstellar travel using a black hole as an energy source for spacecraft propulsion. The concept was first discussed in science fiction, notably in the book '' Imperial Earth'' by Arthur C. Clarke, and in the work of Charles Sheffield, in which energy extracted from a Kerr–Newman black hole is described as powering the rocket engines in the story "Killing Vector" (1978). In a more detailed analysis, a proposal to create an artificial black hole and using a parabolic reflector to reflect its Hawking radiation was discussed in 2009 by Louis Crane and Shawn Westmoreland.Louis Crane and Shawn Westmoreland,Are Black Hole Starships Possible (ArXiv preprint 12 Aug 2009). Retrieved 7 April 2017. Their conclusion was that it was on the edge of possibility, but that quantum gravity effects that are presently unknown will either make it easier, or make it impossible. Similar concepts were also sket ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Polarization
In quantum field theory, and specifically quantum electrodynamics, vacuum polarization describes a process in which a background electromagnetic field produces virtual electron–positron pairs that change the distribution of charges and currents that generated the original electromagnetic field. It is also sometimes referred to as the self-energy of the gauge boson (photon). It is analogous to the electric polarization of dielectric materials, but in vacuum without the need of a medium. The effects of vacuum polarization have been routinely observed experimentally since then as very well-understood background effects. Vacuum polarization, referred to below as the one loop contribution, occurs with leptons (electron–positron pairs) or quarks. History Vacuum polarization was first discussed in papers by Paul Dirac and Werner Heisenberg in 1934. After developments in radar equipment for World War II resulted in higher accuracy for measuring the energy levels of the h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Review Letters
''Physical Review Letters'' (''PRL''), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. The journal is considered one of the most prestigious in the field of physics. Over a quarter of Physics Nobel Prize-winning papers between 1995 and 2017 were published in it. ''PRL'' is published both online and as a print journal. Its focus is on short articles ("letters") intended for quick publication. The Lead Editor is Hugues Chaté. The Managing Editor is Robert Garisto. History The journal was created in 1958. Samuel Goudsmit, who was then the editor of '' Physical Review'', the American Physical Society's flagship journal, organized and published ''Letters to the Editor of Physical Review'' into a new standalone journal'','' which became ''Physical Review Letters''. It was the first journal intended for the rapid publication of short articles, a format that eventually became popular in many other fiel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
