Black Hole | Dark Matter | Anti Matter

Black Hole Definition:
An area of space-time with a gravitational field so intense that its escape velocity is equal to or exceeds the speed of light.


Cosmic body with gravity (see gravitation) so intense that nothing, not even light, can escape. It is suspected to form in the death and collapse of a star that has retained at least three times the Sun's mass.


ack holes cannot be observed directly because they are small and emit no light. However, their enormous gravitational fields affect nearby matter, which is drawn in and emits X rays as it collides at high speed outside the event horizon. 


When a star with a mass greater than about four times that of the sun collapses even the neutrons cannot stop the force of gravity. There is nothing to stop the contraction, and the star collapses forever. The material is so dense that nothing-not even light-can escape. The American physicist John Wheeler gave this phenomenon the name "black hole" in 1967. Since no light escapes from a black hole, it cannot be observed directly. However, if a black hole existed near another star, it would draw matter from the other star into itself and, in effect, produce X-rays. In the constellation of Cygnus, there is a strong X-ray source named Cygnus X-1. 

There are four other possible black holes: a Schwarzschild black hole has no charge and no angular momentum; a Reissner-Nordstrom black hole has charge but no angular momentum; a Kerr black hole has angular momentum but no charge; and a Kerr-Newman black hole has charge and angular momentum.

Dark Matter Definition : 

In astronomy and cosmology, dark matter is a theoretical form of matter that is undetectable by its emitted radiation, but whose presence can be inferred from gravitational effects on visible matter.

dark matter, material that is believed to make up (along with dark energy) more than 90% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, such as light or radio signals. Its existence would explain gravitational anomalies seen in the motion and distribution of galaxies. Dark matter can be detected only indirectly, e.g., through the bending of light rays from distant stars by its gravity.

The first person to provide evidence and infer the presence of dark matter was Swiss astrophysicist Fritz Zwicky, of the California Institute of Technology in 1933.[5] He applied the virial theorem to the Coma cluster of galaxies and obtained evidence of unseen mass. Zwicky estimated the cluster's total mass based on the motions of galaxies near its edge and compared that estimate to one based on the number of galaxies and total brightness of the cluster. He found that there was about 400 times more estimated mass than was visually observable. The gravity of the visible galaxies in the cluster would be far too small for such fast orbits, so something extra was required. This is known as the "missing mass problem". Based on these conclusions, Zwicky inferred that there must be some non-visible form of matter which would provide enough of the mass and gravity to hold the cluster together.

Anti Matter: 

Substance composed of elementary particles having the mass and electric charge of ordinary matter (such as electrons and protons) but for which the charge and related magnetic properties are opposite in sign. The existence of antimatter was posited by the electron theory of P.A.M. Dirac. In 1932 the positron (antielectron) was detected in cosmic rays, followed by the antiproton and the antineutron detected through the use of particle accelerators. Positrons, antiprotons, and antineutrons, collectively called antiparticles, are the antiparticles of electrons, protons, and neutrons, respectively. When matter and antimatter are in close proximity, annihilation occurs within a fraction of a second, releasing large amounts of energy.

Matter which is made up of antiparticles. At the most fundamental level every type of elementary particle has its anti-counterpart, its antiparticle. The existence of antiparticles was implied by the relativistic wave equation derived in 1928 by P. A. M. Dirac in his successful attempt to reconcile quantum mechanics and special relativity.