universe

everything that exists anywhere

"they study the evolution of the universe"

"the biggest tree in existence" (statistics) the entire aggregation of items from which samples can be drawn

"it is an estimate of the mean of the population" everything stated or assumed in a given discussion

otheruses The universe is the entire spacetime continuum in which we exist, together with all the energy and matter within it. It is important to understand the fact that (regardless of whether or not our universe is all that exists) the term universe is not defined as all existence or all reality, but more specifically as all existence in one space-time continuum. Attempts to understand the universe in this sense, on the largest possible scales, are made in cosmology, a science that has grown from physics and astronomy. During the second half of the 20th century, the development of observational cosmology, also called physical cosmology, led to a split in the meaning of the word ''universe'', between observational cosmologists and theoretical cosmologytheoretical cosmologists; where the former abandon the hope of observing the whole spacetime continuum, the latter retain this hope, attempting to find the most reasonable speculations for modeling the whole of spacetime, despite the extreme difficulty in imagining any empirical constraints on these speculations and the possibility of crossing over to metaphysics.The terms known universe, observable universe, or visible universe are often used to describe the part of the universe that we can see or otherwise observe. Those who believe it is impossible to observe the whole continuum may use our universe, referring only to that knowable by human beings in particular.

Expansion and age, and the Big Bang theory - mainAge of the universe The most important result of cosmology, that the universe is expanding, is derived from redshift observations and quantified by Hubble's Law. Extrapolating this expansion back in time, one approaches a gravitational singularity, a rather abstract mathematical concept, which may or may not correspond to reality. This gives rise to the Big Bang theory, the dominant model in cosmology today. The age of the Universe was estimated to be about 13.7 1 E9billion (13.7 × 10⁹) years, with a margin of error of about 1 percent (± 200 million years), according to NASA's Wilkinson Microwave Anisotropy Probe (WMAP). However, this is based on the assumption that the underlying model used for data analysis is correct. Other methods of estimating the age of the universe give different ages.A fundamental aspect of the Big Bang can be seen today in the observation that the farther away from us galaxygalaxies are, the faster they move away from us. It can also be seen in the cosmic microwave background radiation which is the much-attenuated radiation that originated soon after the Big Bang. This background radiation is remarkably uniform in all directions, which cosmologists have attempted to explain by an initial period of rapid Cosmic inflationinflation following the Big Bang.

Size of universe and observable universe - There is disagreement over whether the universe is finite or infinityinfinite in spatial extent and volume. However, the observable universe, consisting of all locations that could have affected us since the Big Bang given the finite speed of light, is certainly finite. The edge of the cosmic light horizon is 13.7 billion light years (4.19 gigaparsecgpc) distant. The ''present distance'' (comoving distance) to the edge of the observable universe is larger, since the universe has been expanding; it is estimated to be about 78 billion light years(7.8 × 10¹⁰ light years, or 7.4 × 10²³ km).This would make the comoving volume, of the known universe, equal to 1.9 × 10³³ cubic light years (assuming this region is perfectly spherespherical). The observable universe contains about 7 × 10²² stars, organized in about 10 billion galaxygalaxies, which themselves form groups and clusters of galaxiesclusters and superclusters. The number of galaxies may be even larger, based on the Hubble Deep Field observed with the Hubble Space Telescope. The Hubble Space Telescope discovered galaxies such as Abell 1835 IR1916, which are over 13 billion light years from earth.Both popular and professional research articles in cosmology often use the term "Universe" when they really mean "observable universe". This is because unobservable physical phenomena are scientifically irrelevant; that is, they cannot affect any events that we can perceive, and therefore, it is argued, effectively do not exist. See also Causality (physics).We live in the centre of the universe that we observe, in apparent contradiction to the Copernican principle which says that the Universe is more or less uniform and it has no distinguished centre. This is simply because light does not travel infinitely fast, and we make observations of the past. As we look further and further away, we see things from epochs (times) closer and closer to the limit of time=zero of the Big bang model. And since light travels at the same speed in any direction towards us, we live at the centre of our observable universe.

Shape of the universe - mainShape of the universe mainLarge-scale structure of the cosmos An important open question of cosmology is the shape of the universe. Mathematically, which 3-manifold is the universe?Firstly, whether or not the universe is ''flat'', i.e. whether the rules of Euclidean geometry are valid on the largest scales, is unknown. Currently, most cosmologists believe that the observable universe is (nearly) flat, with local wrinkles where massive objects distort spacetime, just as a lake is (nearly) flat. This opinion was strengthened by the latest data from WMAP, looking at "acoustic oscillations" in the cosmic background radiation temperature variations.Secondly, whether or not the universe is multiply connected, is unknown. The universe has no spatial boundary according to the standard big bang model, but nevertheless may be spatially finite (compact spacecompact). This can be understood using a two-dimensional analogy: the surface of a sphere has no edge, but nonetheless has a finite area. It is a two-dimensional surface with constant curvature in a third dimension. The 3-sphere is a three-dimensional equivalent in which all three dimensions are constantly curved in a fourth.If the universe is indeed spatially finite, as described, then traveling in a "straight" line, in any given direction, would theoretically cause one to eventually arrive back at the starting point.Strictly speaking, we should call the stars and galaxies "views" of stars and galaxies, since it is possible that the universe is multiply-connected and sufficiently small (and of an appropriate, perhaps complex, shape) that we can see once or several times around it in various, and perhaps all, directions. (Think of a house of mirrors.) If so, the actual number of physically distinct stars and galaxies would be smaller than currently accounted. Although this possibility has not been ruled out, the results of the latest cosmic microwave background research make this appear very unlikely.

Fate of the universe - Depending on the average density of matter and energy in the universe, it will either keep on expanding forever or it will be gravitationally slowed and will eventually collapse back on itself in a "Big Crunchbig crunch". Currently the evidence suggests not only that there is insufficient mass/energy to cause a recollapse, but that the expansion of the universe seems to be accelerating and will accelerate for the whole of eternity (see accelerating universe).Other ideas of the fate of our universe include the Big Rip, the Big Freeze, and Heat death of the universe theory. For a more detailed discussion of other theories, see the ultimate fate of the universe.

Multiverse - There is some speculation that multiple universes exist in a higher-level multiverse (also known as a megaverse), our universe being one of those universes (lower case). For example, matter that falls into a black hole in our universe could emerge as a "Big Bang," starting another universe. However, all such ideas are currently untestable and cannot be regarded as anything more than speculation.The concept of parallel universes are understood only when related to string theory.

Other terms - Different words have been used throughout history to denote "all of space", including the equivalents in various languages of "heavens", "cosmos" and "world". Although words like world and its equivalents in other languages now almost always refer to the planet Earth, they previously referred to everything that exists—see Copernicus, for example—and still sometimes do (as in "the whole wide world"). Some languages use the word for "world" as part of the word for "outer space", e.g. German languageGerman "Weltall".

See also -

Cosmic latte - the color of the Universe

Cosmology

Cosmos

Parallel universe

References -

Albert Einstein (1952). ''Relativity: The Special and the General Theory (Fifteenth Edition)'', ISBN 0-517-88441-0

External links -

anzwers.org - Richard Powell: ''An Atlas of the Universe'' - a series of images at various scales, with explanations.

? shekpvar.net - Cosmos - an Illustrated Dimensional Journey from microcosmos to macrocosmos

universe-review.ca - A Review of the Universe - Structures, Evolutions, Observations, and Theories

space.com - Age of the Universe at Space.Com

slate.msn.com - My So-Called Universe by Jim Holt, on various arguments for and against an infinite Universe and parallel universes

hep.upenn.edu - Parallel Universes by Max Tegmark

movingplanets.com - eXplore the Universe by Moving Planets

hedweb.com - Why Does Anything Exist?

astro.princeton.edu - Logarithmic Maps of the Universe

!setiathome.ssl.berkeley.edu - Seti@Home - the Search for Extraterrestrial Intelligence

exploreuniverse.com - Universe - Space Information Centre by !Exploreuniverse.comCategory:Un iverse Category:Environmentsar: فضاء كوني !bg:Вселенаca:Universcs: Vesmírda:Universetde:Universu m? !(Astronomie)et:Universumes:Uni versoeo:Universofr:Universko:� ��주hr:Svemirio:Universoid:Al am? !semestait:Universohe:יקוםc sb:Swiatnicala:Universumlv:Vis umsms:Alam? !Semestanl:Heelalja:宇宙no:Un iversetpl:Wszechświatpt:Unive rsoro:Universru:Вселенн аяsimple:Universesl:Vesoljef i:Maailmankaikkeussv:Universum vi:Vũ? trụzh:宇宙

Font Garden - the home of handwriting fonts
Font Garden - the home of handwriting fonts thousands of fonts and dingbats for PC and Mac. Handwriting to font conversion. Welcome!
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CyberSky
CyberSky is an exciting, entertaining, and educational astronomy program that transforms your personal computer into your personal planetarium. CyberSky provides an excellent way to learn about astronomy and to explore the wonders of the sky visible in the distant past, the present, and the far-off future.
http://www.cybersky.com/

Chris's Science Page
Chris Butterworth's Science Page
http://www.chrisbutterworth.com/science/index.htm

New Theoretical Physics - James A. Putnam
This new physics theory achieves unity beginning at the fundamental level. Essays on physics, life and intelligence are included.
http://www.newphysicstheory.com/

Pierre Schwartz
danish musician, playde guitar since 1966, many bands in Denmark, played in 23 years with Jays, ongoing with 5aLive.dk. Ibanez freak
http://www.pierreschwartz.com

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Asteroids and comets contain life-sustaining organics, nutrient salts and water. Our experiments with meteorites showed that microorganisms, algae and plants grow well on these materials. The measured nutrients show that our Solar System can sustain trillions of humans, and the Galaxy much more, for many trillions of eons. If we expand life in space, our family of gene/protein organic life can have an immense future.
http://www.astroecology.com/

Universe Today
Space exploration and astronomy news brought to you from around the Internet, updated daily.
http://www.universetoday.com

Imagine The Universe!
Dedicated to a discussion about our Universe... This site from NASA is intended primarily for ages 14 and up. If you are interested in a lower level, more basic discussion about astronomy and space exploration, try StarChild site.
http://imagine.gsfc.nasa.gov/

CD Universe
Offers domestic and imported movies on VHS and region 1 DVDs; music CDs and video games.
http://www.cduniverse.com/

Unix Guru Universe
Largest UNIX System Administration Resource site, for beginners and gurus that are looking for UNIX sites on the internet.
http://www.ugu.com/