Flat Universe
(a) A Universe in which there is no curvature to the spacetime continuum. This means that the kinetic energy of the expansion is exactly balanced by the potential gravitational energy of the matter.
Flat Universe
A model of the universe in which space-time is not curved.
Flatness Problem ...
Flat Universe
A geometric model of the universe in which the laws of geometry are like those that would apply on a flat surface such as a table top.
Grand Unified Theory (GUT) ...
A flat Universe is one in which the amount of matter present is just sufficient to halt its expansion, but insufficient to re-collapse it. This would represent a very fine balancing act indeed! ...
A flat Universe determines one distance; a curved universe determine another. If instruments measuring the cosmic microwave background don't see a peak temperature fluctuation at one degree, then inflation is wrong.
flat universe a universe that stop expanding only after an infinite amount of time (a special case of an open universe). flux the amount of energy passing through a given area (e.g., one square centimeter) in a second.
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149. Flat Universe
A model of the universe in which space-time is not curved.
Dark energy and flat Universe exposed by simple method BBC - November 25, 2010
Researchers have developed a simple technique that adds evidence to the theory that the Universe is flat.
Absent dark energy, a flat universe expands forever but at a continually decelerating rate, the rate of expansion asymptotically approaching zero.
Consider the evolution of a "top hat" fluctuation, a spherical region of space with an excess density embedded in a flat Universe (one with exactly the critical density).
What is meant by a flat Universe?
The Universe appears to be homogeneous and isotropic, and there are only three possible geometries that are homogeneous and isotropic as shown in Part 3.
In fact, to arrive at the flat universe that we live in, its energy density needs to be extremely fine-tuned: 1 part in 10^120, at least.
It is called the flat universe because of its overall geometry. Closed universes have the geometry of a sphere, as we discussed for the Einstein universe. As Einstein found, spherical universes, left to their own devices, will recollapse.
A two-dimensional flat Universe. Creatures in this Universe only know of two dimensions and things here would be similar to what you find on a flat sheet of paper.
The difference between the Open and Flat Universe is subtle. In the Flat Universe there is exactly enough matter to bring the expansion to an end when time has reached infinity.
Recent evidence indicates that dark matter contributes about 25% of the critical density for a flat universe, with the remainder, except ~5% ordinary matter, as dark energy.
Write a paper on the philosophical differences between living in an open, closed, or flat universe. Are there aspects of any of these three possibilities that are hard to accept?
The result confirms previous findings that the nature of dark energy likely corresponds to a flat Universe, which suggest that the expansion of the Universe will continue to accelerate and the Universe will expand forever.
Hence, we may be living in a flat universe (Case B in the figure). Those studies also suggest that the expansion of the universe is accelerating.
Thus, the universe has no bounds and will also expand forever, but with the rate of expansion gradually approaching zero after an infinite amount of time. This is termed a flat universe or a Euclidian universe (because the usual geometry of ...
it also requires adding up all the matter we can't see: the dark matter whose presence is revealed only by the forces it exerts on visible matter. Right now the observations seem to indicate an open universe, while theory prefers a flat universe.
The luminosity distance is that which makes the inverse-square law work as it does in a flat universe: luminosity/flux = 4 p DL².
 See also: Universe, Density, Time, Model, Energy
  
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