Definition of black hole -
A black hole is a region of space from which gravity prevents anything from escaping .
Event horizon -
The boundary of region from which no escape is possibe is called event horizon .
Although crossing the event horizon has enormous effect on the fate of
the object crossing it, it appears to have no locally detectable
features. In many ways a black hole acts like an ideal black body, as it reflects no light.Moreover, 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 on the order of billionths of a Kelvin for black holes of stellar mass, making it all but impossible to observe.
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.
, 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
0 comments:
Post a Comment