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.

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.

The Morison equation is a mathematical model used in engineering, particularly in the fields of civil and ocean engineering, to estimate the wave forces on structures such as offshore oil platforms, wind turbines, and coastal structures. It accounts for both the inertia and drag forces acting on a structure submerged in a fluid, such as water.

A vacuum pump is a device that removes gas molecules from a sealed volume in order to create a vacuum — a space with significantly lower pressure than the surrounding atmosphere. These pumps are essential in a variety of applications across different industries, including scientific research, manufacturing, and medical technology. ### Types of Vacuum Pumps 1. **Positive Displacement Pumps**: These work by trapping a volume of gas and then reducing it either by mechanical means or through an expanding gas volume.

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 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.

A brown dwarf is a type of celestial object that falls between the largest planets and the smallest stars in terms of mass. Specifically, brown dwarfs have masses ranging from about 13 times the mass of Jupiter (approximately 0.012 times the mass of the Sun) to around 80 times the mass of Jupiter (about 0.07 times the mass of the Sun). They are not massive enough to sustain hydrogen fusion in their cores, which is the defining characteristic of true stars.

GPM J1839−10 is a millisecond pulsar located in the direction of the constellation Scorpius. It was discovered as part of the Galactic Pulsar Monitor (GPM) project, which aims to monitor and catalog pulsars in our galaxy. Millisecond pulsars are highly magnetized, rotating neutron stars that emit beams of electromagnetic radiation out of their magnetic poles.

Intermediate polars, also known as "IP" stars, are a specific class of cataclysmic variables, which are binary star systems consisting of a white dwarf and a companion star (usually a red dwarf). In these systems, the white dwarf has a strong magnetic field, which influences the accretion of material from the companion star onto the white dwarf.

An X-ray transient is a type of astronomical object that emits X-rays in a variable and often short-lived manner. These sources are typically associated with binary star systems where a compact object, such as a black hole or neutron star, is accreting material from a companion star. X-ray transients can exhibit outbursts or flares that can last from days to months, during which their X-ray emission increases significantly, often by several orders of magnitude.

"Earthquake weather" is a term that has been used historically to describe certain weather conditions that are believed to be associated with increased earthquake activity. The concept suggests that specific types of weather—such as changes in humidity, temperature, or atmospheric pressure—can somehow trigger or correlate with earthquakes. However, scientifically, there is no evidence to support a direct link between weather patterns and the occurrence of earthquakes.

A "tropical night" is a term used in meteorology to describe a night during which the temperature does not drop below a certain threshold, typically 20 degrees Celsius (68 degrees Fahrenheit). This phenomenon usually occurs in tropical or subtropical climates, where the temperatures tend to remain warm throughout the night due to high humidity and cloud cover. Tropical nights can have various implications for agriculture, health, and energy consumption.

Spontaneous magnetization refers to the phenomenon where a material exhibits a net magnetization in the absence of an external magnetic field. This typically occurs in ferromagnetic or ferrimagnetic materials at low temperatures, specifically below their Curie temperature. In these materials, individual atomic magnetic moments (due to unpaired electron spins) tend to align in a uniform direction even without an external magnetic field.

Delbrück scattering is a quantum electrodynamic effect that involves the scattering of photons by the electromagnetic field of a nucleus. It is named after the physicist Max Delbrück, who contributed to the theoretical understanding of the phenomenon. In Delbrück scattering, a high-energy photon can interact with the electric field of a heavy nucleus, leading to an intermediate state where the photon temporarily produces virtual electron-positron pairs.

Electron scattering is a process in which electrons are directed towards a target material, and their trajectories are altered as a result of interactions with the target’s atoms, nuclei, or electrons. This phenomenon is fundamental in various fields of physics and has important applications in understanding atomic structure, particle physics, and materials science. **Key Concepts:** 1. **Types of Scattering:** - **Elastic Scattering:** The kinetic energy of the electrons is conserved, although their direction may change.

An inelastic collision is a type of collision in which the total kinetic energy of the system is not conserved, although the total momentum is conserved. Inelastic collisions occur when two objects collide and become deformed, stick together, or otherwise interact in a way that some of the kinetic energy is transformed into other forms of energy, such as heat, sound, or internal energy. In perfectly inelastic collisions, the colliding objects stick together after the collision and move as a single entity.

The Lippmann–Schwinger equation is a fundamental equation in quantum mechanics that describes the scattering of particles. It is derived from the principles of quantum mechanics and is particularly useful in dealing with interactions in quantum systems. The equation can be expressed in two forms: the "in" and "out" formulations, corresponding to the incoming and outgoing states of the particles involved in scattering.

The R (cross section ratio) is a term commonly used in particle physics to describe the ratio of two different cross sections, which are measurements of the probability of a particular interaction occurring between particles.

The Sherman function, often referred to in the context of mathematics, particularly in number theory, is associated with the concept of arithmetic functions. It is commonly defined in relation to number theory, combinatorics, and sometimes even in more abstract fields such as algebraic geometry.