"A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it."
A phenomenon that occurs when a massive object collapses under its own gravity, creating a region of space-time from which nothing, including light, can escape.
Theory of General Relativity: General relativity is the theoretical framework within which black holes were first predicted. Understanding the basic principles of general relativity are essential to understand black holes.
Schwarzschild Solution: The Schwarzschild solution is a mathematical solution to the equations of general relativity that describes the space-time outside a non-rotating spherically symmetric massive object, such as a black hole. It was first derived by Karl Schwarzschild in 1916.
Event Horizon: The event horizon is a boundary around a black hole beyond which all matter and radiation are expected to fall in and never escape. The event horizon plays a crucial role in the definition and behavior of a black hole.
Singularity: Singularity is a point in space-time where the curvature of space-time becomes infinitely high. Singularity is predicted to exist at the center of a black hole and is considered to be a region where all physical laws of our current understanding break down.
Black Hole Formation: Black holes are formed when massive stars run out of fuel and collapse under their own gravity. Understanding the process of black hole formation is essential to understand their properties and behavior.
Types of black holes: There are several types of black holes, including stellar black holes, intermediate black holes, and supermassive black holes. Understanding the types of black holes and their properties is an important aspect of studying black holes.
Accretion Disks: Accretion disks are dense disks of gas and dust that form around black holes and other massive objects. The accretion disk is the primary source of energy for many black holes and plays a crucial role in the behavior of the black hole.
Gravitational Waves: Gravitational waves are ripples in space-time that are caused by the acceleration of massive objects. Black holes are one of the primary sources of gravitational waves, and studying gravitational waves is an important aspect of black hole research.
Hawking Radiation: Hawking radiation is a theoretical concept proposed by Stephen Hawking in 1974 that suggests black holes emit radiation due to quantum effects near the event horizon. Hawking radiation plays a crucial role in understanding the behavior and properties of black holes.
The Information Paradox: The information paradox is a theoretical problem that arises when one tries to account for the loss of information that occurs when matter falls into a black hole. The resolution of the information paradox is still an active area of research and an important aspect of studying black holes.
Stellar black holes: These are formed from the core collapse of massive stars that have used up all of their nuclear fuel. They have a mass between 5 and 100 times the mass of the sun and are relatively small in size.
Intermediate black holes: These are hypothetical black holes with a mass between 100 and 100,000 times the mass of the sun. There is some evidence to suggest that these types of black holes exist, but they have not been directly observed yet.
Supermassive black holes: These are the largest type of black holes, with a mass that can range from millions to billions of times the mass of the sun. They are found at the center of most galaxies, including our own Milky Way.
Primordial black holes: These are hypothetical black holes that could have formed in the early universe shortly after the Big Bang. They would be much smaller in size than stellar black holes and could have a mass ranging from a few grams to several solar masses.
Micro black holes: These are also hypothetical black holes that could be formed in high-energy particle collisions (such as those that occur in the Large Hadron Collider). They would be incredibly small, with a mass less than that of an asteroid.
Naked black holes: These are black holes that have no event horizon, meaning that they are visible from the outside. It is not yet clear whether such black holes can actually exist in the universe.
"The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole."
"The boundary of no escape is called the event horizon."
"It has no locally detectable features according to general relativity."
"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 Michell and Pierre-Simon Laplace."
"Karl Schwarzschild found the first modern solution of general relativity that would characterize a black hole."
"David Finkelstein, in 1958, first published the interpretation of 'black hole' as a region of space from which nothing can escape."
"The discovery of neutron stars by Jocelyn Bell Burnell in 1967 sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality."
"The first black hole known was Cygnus X-1, identified by several researchers independently in 1971."
"Black holes of stellar mass form when massive stars collapse at the end of their life cycle."
"Supermassive black holes of millions of solar masses may form by absorbing other stars and merging with other black holes."
"There is consensus that supermassive black holes exist in the centres of most galaxies."
"The presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light."
"Any matter that falls onto a black hole can form an external accretion disk heated by friction, forming quasars, some of the brightest objects in the universe."
"If other stars are orbiting a black hole, their orbits can be used to determine the black hole's mass and location."
"Such observations can be used to exclude possible alternatives such as neutron stars. In this way, astronomers have identified numerous stellar black hole candidates in binary systems."
"The radio source known as Sagittarius A*, at the core of the Milky Way galaxy, contains a supermassive black hole of about 4.3 million solar masses."