Black holes

Black holes are regions in space where the gravitational pull is so strong that nothing, not even light, can escape from them. They are formed when massive stars exhaust their nuclear fuel and collapse under their own gravity. The core of the star contracts, and if its mass is sufficient, it can create a black hole. There are a few key features and concepts associated with black holes: 1. **Event Horizon**: This is the boundary surrounding a black hole beyond which nothing can escape.

Fiction about black holes often explores themes of science, philosophical inquiry, and the unknown. Here are some common aspects and examples found in various forms of media: 1. **Science Fiction Novels and Stories**: - *Interstellar* (film) and the accompanying novelization by Kip Thorne, delve into the concept of black holes as wormholes for space travel and explore the relativity of time. - In Arthur C.

Intermediate-mass black holes (IMBHs) are a class of black holes that are thought to have masses ranging from about \(100\) to \(100,000\) times the mass of our Sun (or \(10^2\) to \(10^5\) solar masses).

Stellar black holes are a type of black hole that forms from the gravitational collapse of massive stars. When a star with sufficient mass (typically more than about three times the mass of the Sun) exhausts its nuclear fuel, it can no longer support itself against the force of gravity. Consequently, it collapses under its own weight, and if the residual core's mass is sufficient, it can form a black hole.

ASASSN-19bt is a notable celestial event cataloged by the All-Sky Automated Survey for Supernovae (ASAS-SN), which is a project focused on the detection of transient astronomical events such as supernovae. ASASSN-19bt is classified as a Type Ia supernova, which is a particular kind of supernova that occurs in binary systems where one star is a white dwarf.

AdS black holes refer to black holes that are solutions to Einstein's equations in a spacetime with anti-de Sitter (AdS) symmetry. Anti-de Sitter space is a five-dimensional (or higher) spacetime that has a constant negative curvature, which can be visualized as a hyperbolic geometry. This spacetime is a key feature of certain theories in theoretical physics, particularly in the context of string theory and holographic duality.

A binary black hole system consists of two black holes that are in orbit around each other. These systems are significant in the field of astrophysics for a number of reasons: 1. **Formation**: Binary black holes can form from the gravitational collapse of massive stars in a binary star system. When these stars exhaust their nuclear fuel, they undergo supernova explosions, potentially leaving behind black holes.

The Black Hole Initiative (BHI) is a research project based at Harvard University, aimed at comprehensively studying black holes across various disciplines. It brings together scientists from different fields, including astrophysics, theoretical physics, and astronomy, to explore the fundamental nature and properties of black holes. The initiative seeks to foster interdisciplinary collaboration and to address key questions about black holes, such as their formation, evolution, and their role in the universe.

A black brane is a theoretical object in the context of string theory and higher-dimensional gravity, particularly in the study of black holes and their generalizations. The term "brane" refers to higher-dimensional objects (short for "membranes") that can exist in various dimensions in string theory, while "black" indicates that the object has the properties of a black hole, such as having an event horizon and being related to the gravitational collapse of matter.

The term "black hole bomb" refers to a theoretical phenomenon in the context of black hole physics and quantum field theory, where specific conditions could lead to the amplification of energy near a black hole, particularly in relation to bosonic particles. The idea is intricately linked to the behavior of fields in the curved spacetime surrounding black holes.

Black hole cosmology is a theoretical framework that explores the relationship between black holes and the overall structure and evolution of the universe. This field of study investigates various aspects of cosmology—including the origin and fate of the universe—through the lens of black hole physics. Some of the key concepts and ideas in black hole cosmology include: 1. **Black Holes as Cosmic Structures**: Black holes can play a significant role in the formation of galaxies and large-scale structures in the universe.

The term "black hole electron" is not a standard or widely recognized term in physics. It seems to combine two distinct concepts: "black holes" and "electrons," each of which have their own well-defined meanings: 1. **Black Holes**: These are regions in space where the gravitational pull is so strong that nothing, not even light, can escape from them.

Black hole greybody factors are a concept in theoretical physics that describe how the radiation emitted by a black hole is modified due to the black hole's properties and the surrounding spacetime geometry. When a black hole emits radiation, such as Hawking radiation, the efficiency of this emission can vary depending on the wavelength of the emitted radiation and the specific characteristics of the black hole.

The black hole information paradox is a theoretical dilemma in physics that arises from the intersection of quantum mechanics and general relativity. It involves the question of whether information that falls into a black hole is lost forever or whether it can be recovered in some way.

The black hole stability conjecture is a theoretical idea in the field of general relativity and mathematical physics that pertains to the stability of black hole solutions to the equations of general relativity, particularly under small perturbations. In essence, the conjecture suggests that black holes, once they form and settle into equilibrium (typically after dynamic processes like a merger or collapse), are stable objects.

Black holes in fiction refer to the creative use of the concept of black holes in literature, films, television shows, video games, and other forms of storytelling. These fictional representations often take the scientific principles of black holes and enhance or distort them for dramatic, thematic, or narrative purposes.

In the context of semiclassical gravity, a "black star" refers to a theoretical object that combines features of black holes and more exotic matter configurations. Unlike traditional black holes, which are defined by their event horizons and singularities, black stars do not necessarily possess an event horizon, though they may still exhibit gravitational effects similar to those of black holes.

The Blandford–Znajek process is a theoretical mechanism that describes how rotating black holes can extract energy from their environment, particularly from a magnetic field. It was proposed by Robert Blandford and Roman Znajek in a seminal paper published in 1977. The process is significant in astrophysics, especially in explaining how some astrophysical jets are powered from the vicinity of black holes, such as those observed in active galactic nuclei and gamma-ray bursts.

"Blanet" does not refer to any widely recognized concept, organization, or term based on my training data up to October 2021. It could be a misspelling, a brand name, a term from a specific niche, or something that has emerged more recently.

As of my last knowledge update in October 2023, "Blitzar" does not refer to any widely recognized concept, product, or service across popular fields such as technology, entertainment, or other industries. It is possible that it may be a new technology, company, app, or cultural reference that emerged after my last update.

Boyer-Lindquist coordinates are a specific way of expressing the spacetime around a rotating black hole, particularly the Kerr black hole solution in general relativity. These coordinates are a modification of spherical coordinates that take into account the effects of rotation and are particularly useful for analyzing the properties of rotating black holes. In Boyer-Lindquist coordinates, the spacetime is described using four coordinates: 1. **Time (t)**: Represents the time coordinate for an observer at infinity.

CENBOL, or Central Bank of Liberia, is the central banking institution of Liberia, responsible for formulating and implementing monetary policy, issuing currency, and regulating the banking sector in the country. It aims to maintain price stability and contribute to the economic growth of Liberia.

The Carter constant, often denoted as \( C \), is a key parameter in the study of black hole physics, particularly in relation to the Kerr black hole solution of Einstein's field equations in general relativity. The Carter constant arises in the context of the geodesic motion of particles and tests the symmetry of the Kerr metric.

A charged black hole is a theoretical type of black hole that possesses an electric charge in addition to the mass and angular momentum typically considered in black hole physics. In general relativity, black holes are classified by three parameters: mass, charge, and angular momentum.

A "collapsar" is a theoretical astronomical object that often refers to a massive star that undergoes gravitational collapse, leading to the formation of a black hole. The term is commonly associated with the study of gamma-ray bursts (GRBs), which are extremely energetic explosions observed in distant galaxies. These bursts are believed to be linked to the collapse of massive stars (collapsars) that are at least 30 times more massive than the Sun.

The Cosmic Censorship Hypothesis is a conjecture in general relativity proposed by physicist Roger Penrose in the 1960s. It primarily deals with the nature of singularities that can form in spacetime due to gravitational collapse.

Cosmic wind refers to the streams of charged particles released from celestial bodies into space, particularly from stars, including our sun. The most notable example of cosmic wind is the solar wind, which consists of a flow of electrons, protons, and other ions emitted from the upper atmosphere of the sun. This solar wind interacts with planetary atmospheres, magnetic fields, and celestial objects, influencing space weather and the conditions in the solar system.

The Distorted Schwarzschild metric is a solution to the Einstein field equations of general relativity that describes the spacetime geometry around a gravitating mass, particularly in scenarios where the symmetry of the Schwarzschild solution, which describes a perfect spherical non-rotating mass, is disrupted by some additional factors. This could include the effects of matter distribution, rotation, or other gravitational influences that cause deviations from the standard Schwarzschild solution.

A dynamical horizon is a concept that arises in the context of general relativity and black hole physics. It refers to a type of boundary in spacetime that can change or evolve over time, differentiating it from a static or fixed horizon. In particular, it is often associated with the event horizons of black holes, especially in situations where the mass of the black hole can change, such as during the process of accretion or after mergers with other black holes.

An extremal black hole is a type of black hole that exists at the limit of certain physical parameters, particularly when considering its mass and charge or angular momentum. In the context of general relativity and modern theoretical physics, extremal black holes are characterized by having their mass equal to a specific value where they cannot radiate further or absorb additional charge or angular momentum without becoming non-extremal.

Extreme mass ratio inspiral (EMRI) refers to a specific type of gravitational wave event that occurs when a small compact object, such as a stellar-mass black hole or a neutron star, orbits around a much more massive black hole, typically a supermassive black hole with a mass millions to billions of times that of the sun. The mass ratio of the two objects in an EMRI is extreme, often greater than 1000:1.

Feryal Özel is a renowned astrophysicist known for her work in the fields of astrophysics and planetary science. She has made significant contributions to our understanding of black holes, neutron stars, and the behavior of matter under extreme conditions. Özel has also been involved in the study of gravitational waves and their implications for our understanding of the universe. She is a professor at the University of Arizona and has published numerous research papers, contributing to various scientific discussions and advancements in astronomy.

In the context of physics, the term "firewall" typically refers to a hypothetical boundary or surface associated with a black hole that is theorized to exist when considering the principles of quantum mechanics and general relativity. This concept arises from discussions around the information paradox proposed by Stephen Hawking, which grapples with the fate of information that falls into a black hole.

Fuzzball is a concept within string theory, specifically in the context of understanding black holes and the nature of their information content. The term "fuzzball" is typically associated with the work of various researchers, particularly Samir Mathur and collaborators, who proposed that black holes in string theory may not be the singular, compact objects that are often depicted in classical physics.

GW190412 is the name given to a gravitational wave event detected by the LIGO and Virgo observatories on April 12, 2019. This event is notable for being the first clear detection of a gravitational wave signal that originated from the merger of two black holes that had significantly different masses. The signal was identified as originating from the merger of a black hole approximately 30 times the mass of the Sun and another black hole about 8 times the mass of the Sun.

GW190814 is the designation given to a gravitational wave event detected by the LIGO and Virgo observatories on August 14, 2019. This event was noteworthy because it involved the merger of two compact objects, one of which was likely a black hole and the other a neutron star. The key features of GW190814 include: 1. **Masses**: The heavier object was determined to have a mass of about 22 solar masses, classifying it as a black hole.

The term "golden binary" does not have a widely recognized definition in the fields of computer science, data processing, or related disciplines. However, it could potentially refer to a couple of different concepts depending on the context: 1. **Golden File/Binary in Software Development**: In software development, a "golden binary" often refers to a known, stable version of a program or application that serves as a reference point.

A Gravastar, or "gravitational vacuum star," is a theoretical astrophysical object proposed as an alternative to black holes. The concept was introduced by physicist Pawel Mazur and Wojciech Zurek in the early 2000s. Gravastars are thought to be composed of a "vacuum" or "negative energy" state surrounded by a shell of exotic matter, which might be able to resist gravitational collapse.

The Hawking-Page phase transition is a concept from theoretical physics that describes a phase transition between different types of states in a gravitational system, particularly in the context of anti-de Sitter (AdS) space and black holes. In the specific setup considered by Stephen Hawking and Malcolm Page in their seminal work in the early 1990s, they examined a system of black holes and thermal radiation in asymptotically anti-de Sitter space.

The Immirzi parameter is a constant that arises in the context of loop quantum gravity, a theoretical framework aimed at unifying general relativity and quantum mechanics. It is named after the physicist Barbero-Immirzi, who introduced it in the context of loop quantum gravity to address issues related to black hole entropy. In loop quantum gravity, the geometry of space is quantized, and the Immirzi parameter plays a significant role in the definition of the quantum states of the gravitational field.

The innermost stable circular orbit (ISCO) is a concept from general relativity that pertains to the orbits of objects around compact astrophysical objects, such as black holes or neutron stars. The ISCO represents the smallest orbit in which a test particle (like a small mass moving under gravitational influence) can stably orbit a massive body without spiraling into it due to gravitational or tidal forces. Here are key points about the ISCO: 1. **Stable vs.

Intermediate-mass black holes (IMBHs) are a class of black holes that have masses ranging between those of stellar black holes and supermassive black holes. While stellar black holes typically form from the collapse of massive stars and usually have masses between about 5 and 100 solar masses, supermassive black holes found at the centers of galaxies can have masses ranging from millions to billions of solar masses.

In the context of general relativity and black hole physics, an **isolated horizon** is a concept used to describe the boundaries of black holes in a way that allows for a clearer understanding of their thermodynamic properties and their interactions with the surrounding spacetime. An isolated horizon can be defined as a null hypersurface that is invariant under the action of the gravitational field but is not influenced by any external matter fields or energy.

The Kerr metric is a solution to the Einstein field equations of general relativity that describes the geometry of spacetime around a rotating, uncharged black hole. It generalizes the earlier Schwarzschild solution, which describes a non-rotating black hole. The Kerr metric accounts for the effects of angular momentum and can describe the rotation of the black hole as well as the gravitational fields that result from it.

A "list of black holes" generally refers to a catalog or compilation of known black holes, categorized by factors such as their mass, type, location, and the methods used to discover them. Black holes are typically classified into several categories: 1. **Stellar Black Holes**: Formed from the gravitational collapse of massive stars. Examples include: - V616 Monocerotis (A0620-00) - Cygnus X-1 2.

Lists of black holes typically refer to catalogs or databases that document known black holes in the universe. These lists can vary in terms of the types of black holes included, such as: 1. **Stellar Black Holes**: Formed from the remnants of massive stars after they have undergone supernova explosions. Many known stellar black holes fall within our own Milky Way galaxy.

MAXI J1659-152 is a binary system identified as a microquasar located in the constellation of Scorpius. It was discovered in 2010 by the MAXI (Monitor of All-sky X-ray Image) experiment aboard the International Space Station. The system consists of a black hole and a companion star, which is likely a red giant or a main-sequence star, transferring material to the black hole.

A Magnetospheric Eternally Collapsing Object (MECO) is a theoretical concept in astrophysics proposed to explain certain astronomical phenomena, particularly in relation to black holes and neutron stars. The idea was put forward by physicists like Robert P. Kirshner and others, suggesting that a MECO could be a type of object that does not form a conventional event horizon like a black hole but instead possesses a strong magnetic field that influences its structure and behavior.

The membrane paradigm is a conceptual framework used in the study of black holes, particularly within the context of general relativity and theoretical physics. It provides a way to understand the properties and behaviors of black holes by modeling them as "membranes" with specific physical characteristics, rather than focusing solely on their complex gravitational fields.

A micro black hole is a theoretical type of black hole that has a very small mass, typically in the range of subatomic scales up to a few times the mass of a standard stellar black hole. These black holes are significant in various fields of theoretical physics and cosmology.

NGC 3818 is a spiral galaxy located in the constellation Centaurus. It was discovered by the astronomer John Herschel on April 3, 1835. NGC 3818 is notable for its bright central region and well-defined spiral arms, making it an interesting subject for astronomical study. The galaxy is classified as a type of spiral galaxy and is part of the larger Centaurus group of galaxies. It is situated at a distance of approximately 60 million light-years from Earth.

A naked singularity is a hypothetical gravitational singularity that is not hidden behind an event horizon. In general relativity, a singularity typically occurs when gravitational forces cause matter to collapse to an infinitely dense point, such as at the center of a black hole. In such cases, the event horizon forms around the singularity, creating a boundary beyond which information cannot escape.

A near-extremal black hole refers to a type of black hole that is close to the extremal limit of its charge or angular momentum. In general relativity, black holes can be characterized by their mass, electric charge, and angular momentum. An **extremal black hole** is one that reaches the maximum possible charge or angular momentum for its mass, which means that its properties are at the limits set by the laws of physics.

The term "near-horizon metric" is often related to the field of general relativity and theoretical physics, specifically in the context of black holes and spacetime geometries. In the study of such systems, the "near-horizon" region refers to the area close to the event horizon of a black hole, where the gravitational effects are extremely strong and the behavior of spacetime can be quite different from that far away from the black hole.

The No-Hair Theorem is a concept in general relativity and black hole physics that suggests that black holes can be completely characterized by only a few observable properties: mass, electric charge, and angular momentum (or spin). This means that, regardless of the material that formed a black hole or any information about the matter that collapsed to create the black hole, all external, observable features of the black hole can be reduced to these three properties.

The term "non-expanding horizon" typically refers to a concept in various fields such as economics, decision-making, and optimization, particularly in the context of time and strategic planning. Here’s a general overview of what it means: 1. **Definition**: In decision-making contexts, a non-expanding horizon is a situation where the timeframe for making decisions does not extend or increase as time progresses. In other words, when making decisions, the planner considers only a fixed time period.

Nonsingular black hole models are theoretical constructs in the field of general relativity and theoretical physics that attempt to describe black holes without the singularities that traditional models, such as the Schwarzschild or Kerr black holes, predict. In standard general relativity, singularities are points in spacetime where the gravitational field becomes infinite, and physical quantities cease to be well-defined. This situation arises at the center of a black hole, leading to what is known as a gravitational singularity.

As of my last knowledge update in October 2021, "Nuker Team" does not refer to any widely recognized entity, concept, organization, or product. It’s possible that it could refer to a team involved in gaming, software development, or cybersecurity but without additional context, it’s hard to provide a precise answer.

OGLE-2011-BLG-0462 is a gravitational microlensing event that was detected by the Optical Gravitational Lensing Experiment (OGLE), which is a long-term astronomical project aimed at monitoring the brightness of millions of stars in the Milky Way galaxy. Specifically, OGLE-2011-BLG-0462 refers to a particular event that illuminated details about the nature of exoplanets and dark matter.

The Ophiuchus Supercluster is a massive structure in the universe that consists of a large number of galaxies and galaxy clusters. It is located in the direction of the constellation Ophiuchus and is one of the many superclusters that make up the large-scale structure of the universe. Superclusters are among the largest known structures in the cosmos, and they can contain tens to thousands of galaxies grouped together by gravitational attraction.

The Oppenheimer–Snyder model is a solution to Einstein's general relativity that describes the gravitational collapse of a homogeneous dust sphere. It was first introduced by physicists J. Robert Oppenheimer and Hartland Snyder in a landmark paper published in 1939. This model is significant in theoretical physics as it lays the groundwork for understanding black holes and gravitational collapse.

An **optical black hole** is a concept in the field of optics and experimental physics that refers to a medium or structure that can mimic the behavior of a gravitational black hole using light. Just as a gravitational black hole affects nearby matter and light through its immense gravitational pull, an optical black hole manipulates light in such a way that it creates an "event horizon," beyond which light cannot escape.

Orbital decay refers to the process by which an object in orbit around a planet, moon, or star gradually loses altitude and eventually descends toward the body it is orbiting. This phenomenon occurs primarily due to several factors, including: 1. **Atmospheric Drag**: For objects in low Earth orbit (LEO), the presence of the Earth's atmosphere, even at high altitudes, leads to drag that slows the object down. As the object loses energy, it gradually loses altitude.

The Paczyński–Wiita potential is a mathematical formulation used in the study of general relativity, particularly in the context of modeling the gravitational field around a Schwarzschild black hole. It provides a way to simplify the analysis of particle motion in strong gravitational fields by introducing an effective potential.

The Penrose process is a theoretical mechanism in general relativity that describes how energy can be extracted from a rotating black hole. Named after the physicist Roger Penrose, who proposed it in 1969, the process exploits the unique features of a rotating black hole, specifically the phenomenon associated with its event horizon and ergosphere. Here's a simplified explanation of how it works: 1. **Rotating Black Hole**: A black hole that rotates is described by the Kerr solution to Einstein's equations.

A photon sphere is a theoretical area in the vicinity of a black hole or another massive object where gravity is strong enough that photons (light particles) can orbit the object in unstable circular paths. This occurs at a specific radius, known as the photon sphere radius, which is typically located at 1.5 times the Schwarzschild radius of a non-rotating black hole.

The term "photon surface" can refer to different concepts depending on the context in which it's used, particularly in physics and cosmology. Here are a couple of interpretations: 1. **Photon Sphere**: In the context of general relativity and black hole physics, the concept often referred to is the "photon sphere." This is a spherical region around a black hole where gravity is strong enough that photons (light particles) can orbit the black hole.

A Planck star is a theoretical concept in the realm of quantum gravity, particularly in the context of certain models that attempt to unify quantum mechanics and general relativity. The idea was proposed by physicist Carlo Rovelli and others as part of an effort to understand the behaviors of black holes and the nature of singularities. In simple terms, a Planck star is thought to be a hypothetical state of matter that represents the quantum gravitational state of a black hole.

A quasi-star is a theoretical type of astronomical object that is believed to have existed in the early universe. It is essentially a massive star that forms at the center of a massive accretion disk filled with gas and dust. Quasi-stars are thought to be capable of growing to enormous sizes, potentially hundreds of times the mass of our Sun, due to the intense gravitational pull exerted by their central black hole.

The Reissner–Nordström metric is a solution to the equations of general relativity that describes the spacetime geometry outside of a charged, non-rotating, spherically symmetric mass. It generalizes the Schwarzschild solution, which describes the gravitational field of a non-charged mass, by including the effects of electric charge.

A ring singularity is a type of singularity that arises in certain solutions to the equations of general relativity, particularly in the context of rotating black holes, such as the Kerr black hole. Unlike a point singularity, which is a singularity that is concentrated at a single point (as found in a non-rotating, spherical black hole), a ring singularity is shaped like a ring or a torus.

A rogue black hole is a type of black hole that does not reside within a stable gravitational environment, such as a galaxy or a star cluster. Instead, these black holes move freely through space and are not bound to any particular astronomical structure. They can be formed through various processes, including: 1. **Supernova Explosions**: When massive stars go supernova, they can leave behind a black hole.

A rotating black hole, also known as a Kerr black hole, is a type of black hole characterized by its rotation around an axis. The concept was first formulated by mathematician Roy P. Kerr in 1963. Unlike non-rotating (Schwarzschild) black holes, which are spherically symmetric, rotating black holes have an axial symmetry and are described by more complex mathematical structures.

The Schwarzschild metric is a solution to the Einstein field equations of general relativity that describes the gravitational field outside a spherical, non-rotating, and uncharged mass such as a planet or a non-rotating star. It is one of the simplest and most important solutions in general relativity, providing insights into the geometry of spacetime in the presence of a gravitational source.

The Schwarzschild radius is a characteristic radius associated with a non-rotating black hole, named after the German physicist Karl Schwarzschild, who derived the solution to Einstein's field equations of general relativity in 1916. The Schwarzschild radius (denoted as \( r_s \)) defines the size of the event horizon of a black hole, which is the boundary beyond which nothing can escape the gravitational pull of the black hole, not even light.

"Singularity" is a science fiction novel by Dutch author and architect, B.M. deSmedt. The story explores themes of artificial intelligence, consciousness, and the implications of advanced technology on society. Set in a near-future world, it follows characters as they navigate the challenges and moral dilemmas posed by rapidly advancing AI and its integration into human life.

A "sonic black hole," also known as a "sonic horizon," is a concept in theoretical physics that pertains to the behavior of sound waves in a medium moving at supersonic speeds. It is an analog to the event horizon of a gravitational black hole but involves the dynamics of fluid mechanics rather than gravity. In a sonic black hole, a fluid can flow faster than the speed of sound within that medium.

Spaghettification is a term used in astrophysics to describe the process by which objects are stretched and elongated due to extreme gravitational forces, particularly in the vicinity of a black hole. This phenomenon occurs because of the strong gravitational gradient present in such regions, meaning that the gravitational pull on an object (or a person) is significantly stronger at one end than at the other, especially as one gets closer to the black hole.

Spin-flip is a physical process in quantum mechanics and condensed matter physics where the spin state of a particle is reversed or flipped. Spin is an intrinsic form of angular momentum carried by elementary particles, composite particles (hadrons), and atomic nuclei. It is a key property that influences the magnetic and quantum characteristics of a particle.

A stellar black hole is a type of black hole that forms when a massive star exhausts its nuclear fuel and undergoes gravitational collapse at the end of its lifecycle. These black holes typically have a mass ranging from about three times to a few tens of times the mass of our Sun.

Surface gravity refers to the gravitational acceleration experienced at the surface of a celestial body, such as a planet, moon, or star. It is a measure of how strongly the body attracts objects toward its center due to gravity. Surface gravity can be calculated using the formula: \[ g = \frac{G \cdot M}{r^2} \] Where: - \( g \) is the surface gravity, - \( G \) is the gravitational constant (\(6.

The Tendex line, often referred to in the context of sports analytics, specifically basketball, is a statistical measure used to evaluate a player's overall impact on the game. The name "Tendex" originates from combining "Tennessee" (the University of Tennessee, where the metric was developed) and "index," signifying its analytical nature.

The Thorne–Hawking–Preskill bet was a famous wager made in 1997 between three prominent physicists: Kip Thorne, Stephen Hawking, and John Preskill. The bet revolved around the nature of black holes and the information paradox, which questions whether information that falls into a black hole is lost forever or can be recovered. In essence, the bet was about whether information that falls into a black hole is truly irretrievable.

The timeline of black hole physics spans several centuries, marked by significant theoretical developments, observational milestones, and the evolution of our understanding of black holes. Here’s a chronological overview highlighting key events in the field: ### 18th Century - **1783**: John Michell proposes the concept of "dark stars," suggesting that there could be stars so massive that their gravitational pull would prevent light from escaping.

The Tolman–Oppenheimer–Volkoff (TOV) limit is a theoretical maximum mass for a stable, cold neutron star. It arises from the principles of general relativity and describes how the structure of compact stars is affected by gravity and the properties of dense matter. The limit is named after physicists Richard Tolman, J. Robert Oppenheimer, and George Volkoff, who worked on this topic in the 1930s.

The Vaidya metric is a solution to the Einstein field equations in general relativity that describes the spacetime geometry around a radiating body. It is particularly useful for modeling scenarios where a star or another massive object is losing mass due to radiation, which can occur during supernovae, for example. The Vaidya solution is an extension of the Schwarzschild solution, which describes the gravitational field outside a non-radiating, spherically symmetric massive body.

A "virtual black hole" is not a standard term in astrophysics, but it can refer to a couple of different concepts depending on the context: 1. **Quantum Physics Context**: In the realm of quantum mechanics, virtual particles are temporary fluctuations that occur in a vacuum. Some theoretical frameworks suggest the existence of "virtual black holes" as a way to understand certain aspects of quantum gravity, where the properties of black holes may emerge from more fundamental quantum states.

Weyl metrics refer to a type of geometric structure in differential geometry, specifically in the study of Riemannian and pseudo-Riemannian manifolds. They are associated with Weyl's concept of conformal equivalence and are used in various areas of theoretical physics, especially in general relativity and string theory. ### Key Concepts: 1. **Conformal Geometry**: In conformal geometry, we study properties of shapes that are invariant under scaling.