Nature of The Absolute Horizon
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. This is both an advantage and a disadvantage. The advantage is that this notion of a horizon is very geometrical, and does not depend on the observer, unlike apparent horizons, for example. The disadvantage is that it requires the full history (all the way into the future) of the spacetime to be known. 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.
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Famous quotes containing the words nature, absolute and/or horizon:
“If not against us, nature is not for us.”
—Herman Melville (1819–1891)
“the absolute flight and rest
The universal blue
And local green suggest.”
—Robert Frost (1874–1963)
“The bird is lost,
Dead, with all the music:
While sunsets heard the brain’s music
Faded to last horizon notes.”
—Owen Dodson (b. 1914)