Learning Physics/
black hole တြင္းနက္ နိဒါဏ္း
This behavior is so puzzling that it has been called the black hole information loss paradox.[36][37]
https://en.wikipedia.org/wiki/Black_hole_information_paradox
updated 28 feb. 2016
A black hole is defined as a region of spacetime from which gravity prevents anything, including light, from escaping.[1]
The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole.[2]
Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return.
The hole is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.[3][4] Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature.
This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater.
black hole တြင္းနက္ နိဒါဏ္း
This behavior is so puzzling that it has been called the black hole information loss paradox.[36][37]
https://en.wikipedia.org/wiki/Black_hole_information_paradox
updated 28 feb. 2016
A black hole is defined as a region of spacetime from which gravity prevents anything, including light, from escaping.[1]
The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole.[2]
Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return.
The hole is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.[3][4] Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature.
This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater.
Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace.
The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958.
Long considered a mathematical curiosity, it was during the 1960s that theoretical work showed black holes were a generic prediction of general relativity.
The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.
The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958.
Long considered a mathematical curiosity, it was during the 1960s that theoretical work showed black holes were a generic prediction of general relativity.
The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.
Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle.
After a black hole has formed it can continue to grow by absorbing mass from its surroundings.
By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form
. There is general consensus that supermassive black holes exist in the centers of most galaxies.
After a black hole has formed it can continue to grow by absorbing mass from its surroundings.
By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form
. There is general consensus that supermassive black holes exist in the centers of most galaxies.
Despite its invisible interior, the presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as light.
Matter falling onto a black hole can form an accretion disk heated by friction, forming some of the brightest objects in the universe.
If there are other stars orbiting a black hole, their orbit can be used to determine its mass and location.
Such observations can be used to exclude possible alternatives (such as neutron stars).
Matter falling onto a black hole can form an accretion disk heated by friction, forming some of the brightest objects in the universe.
If there are other stars orbiting a black hole, their orbit can be used to determine its 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, and established that the core of the Milky Way contains a supermassive black hole of about 4.3 million solar masses.
Far away from the black hole, a particle can move in any direction, as illustrated by the set of arrows.
It is only restricted by the speed of light.Closer to the black hole, spacetime starts to deform.
There are more paths going towards the black hole than paths moving away.[Note 1]
Inside of the event horizon, all paths bring the particle closer to the center of the black hole. It is no longer possible for the particle to escape.
Far away from the black hole, a particle can move in any direction, as illustrated by the set of arrows.
It is only restricted by the speed of light.Closer to the black hole, spacetime starts to deform.
There are more paths going towards the black hole than paths moving away.[Note 1]
Inside of the event horizon, all paths bring the particle closer to the center of the black hole. It is no longer possible for the particle to escape.
15 may 2014
Properties and structure
The no-hair theorem states that, once it achieves a stable condition after formation, a black hole has only three independent physical properties: mass, charge, and angular momentum.[28]
Any two black holes that share the same values for these properties, or parameters, are indistinguishable according to classical (i.e. non-quantum) mechanics.
Any two black holes that share the same values for these properties, or parameters, are indistinguishable according to classical (i.e. non-quantum) mechanics.
These properties are special because they are visible from outside a black hole.
For example, a charged black hole repels other like charges just like any other charged object.
Similarly, the total mass inside a sphere containing a black hole can be found by using the gravitational analog of Gauss's law, the ADM mass, far away from the black hole.[34]
Likewise, the angular momentum can be measured from far away using frame dragging by the gravitomagnetic field.
When an object falls into a black hole, any information about the shape of the object or distribution of charge on it is evenly distributed along the horizon of the black hole, and is lost to outside observers. For example, a charged black hole repels other like charges just like any other charged object.
Similarly, the total mass inside a sphere containing a black hole can be found by using the gravitational analog of Gauss's law, the ADM mass, far away from the black hole.[34]
Likewise, the angular momentum can be measured from far away using frame dragging by the gravitomagnetic field.
The behavior of the horizon in this situation is a dissipative system that is closely analogous to that of a conductive stretchy membrane with friction and electrical resistance—the membrane paradigm.[35] This is different from other field theories like electromagnetism, which do not have any friction or resistivity at the microscopic level, because they are time-reversible.
Because a black hole eventually achieves a stable state with only three parameters, there is no way to avoid losing information about the initial conditions: the gravitational and electric fields of a black hole give very little information about what went in.
The information that is lost includes every quantity that cannot be measured far away from the black hole horizon, including approximately conserved quantum numbers such as the total baryon number and lepton number.
This behavior is so puzzling that it has been called the black hole information loss paradox.[36][37]
17 NOV. 2016.
