In the case of numerical relativity, where a spacetime is simply being evolved into the future, only a finite portion of the spacetime can be known.Absolute poverty The condition of having too little income to buy the necessities- food, shelter, clothing, health care.Īchieved status A social position (status) obtained through an individual's own talents and efforts.Īffirmative action The requirement that employers make special efforts to recruits hire and promote qualified members of previously excluded groups including women and minorities.Īggregate A collection of unrelated people who do not know one another but who may occupy a common space-for example, a crowd of people crossing a city street.Īgrarian societies Societies in which large scale cultivation using plows and draft animals is the primary means of subsistence.Īlienation The separation or estrangement of individuals from themselves and from others.Īmalgamation The biological as well as cultural assimilation (merging) of racial or ethnic groups.Īnomalies In science observations or problems that cannot be explained or solved in terms of a prevailing paradigm.Īnomie A breakdown or confusion in the norms, values, and culture of a group or a society.
ABSOLUTE NOTION DEFINITION FULL
The disadvantage is that it requires the full history (all the way into the future) of the spacetime to be known. The advantage is that this notion of a horizon is very geometrical, and does not depend on the observer, unlike apparent horizons, for example. This is both an advantage and a disadvantage. The definition of an absolute horizon is sometimes referred to as teleological, meaning that it cannot be known where the absolute horizon is without knowing the entire evolution of the universe, including the future. An absolute horizon is defined as the past null cone of future null infinity. These points are only defined in an asymptotically flat universe. This is the technical meaning of "external universe". This is the set of points which are approached asymptotically by null rays ( light rays, for example) which can escape to infinity. The particular feature of asymptotic flatness which is needed is a notion of " future null infinity".
Nonetheless, we can think of an isolated object in an FRW universe as being nearly an isolated object in an asymptotically flat universe. The FRW universe – which is believed to be a good model for our universe – is generally not asymptotically flat.
Examples of asymptotically flat spacetimes include Schwarzschild and Kerr black holes. An absolute horizon is only defined in an asymptotically flat spacetime – a spacetime which approaches flat space as one moves far away from any massive bodies.
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