Universe

The universe consists of all matter, light, and other forms of radiation and energy that have been discovered by man. The universe also consists of everything that man believes to be present in space / time as a result of his theories. This includes the Earth, solar system, stars which includes our sun. Most people believe that the universe is expanding.

In the first half of the 20th century, the name Universe was used to mean the whole spacetime continuum in which we exist, together with all the energy and matter within it. 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 cosmologists; where the former (usually) abandon the hope of observing the whole spacetime continuum, the latter retain this hope, attempting to find the most reasonable speculations for modelling the whole of spacetime, despite the extreme difficulty in imagining any empirical constraints on these speculations and the risk of declining into 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, Age, and Big Bang

The most important result of cosmology, the understanding 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 from the time of the Big Bang, was estimated to be about 13.7 billion (13.7 - 109) years, with a margin of error of about 1 % (ą 200 million years), according to NASA's WMAP (Wilkinson Microwave Anisotropy Probe). 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 galaxies 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 early period of inflationary expansion following the Big Bang.

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 down and will eventually collapse back on itself in a "Big 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 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.

Theories on the Ultimate 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. 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 is understood only when related to string theory.

Other Terms

Different words have been used throughout history to denote "all of space", including the equivalents and variants in various languages of "heavens," "cosmos," and "world." Macrocosm has also been used to this effect, although it is more specifically defined as a system that reflects in large scale one, some, or all of its component systems or parts. (Similarly, a microcosm is a system that reflects in small scale a much larger system of which it is a part.)

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 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. in the German word "Weltall".

Observable Universe - Size Wikipedia

Shape of the Universe

Cosmic latte - Color of the universe

In the News ...

Cataclysmic explosion of a giant star early in the history of the Universe is most distant single object ever detected BBC - April 28, 2009

The Farthest Explosion Yet Measured - 13 billion light years away NASA - April 29, 2009

Most distant object in the universe spotted New Scientist - April 27, 2009
Hubble Survey Reveals Formation Of Universe's First Massive Galaxies Science Daily - April 28, 2009

Most Distant Detection Of Water In The Universe Science Daily - April 26, 2009
'Wet' Early Universe: Water Vapor Detected At Record Distance Science Daily - December 19, 2008

Galaxy map hints at fractal universe New Scientist - June 25, 2008

Youngest Supernova in Milky Way Found National Geographic - May 15, 2008

Cosmic 'treasure trove' revealed BBC - March 11, 2008
Nasa space probe measuring the oldest light in the Universe has found that cosmic neutrinos made up 10% of matter shortly after the Big Bang.

Mysterious Explosion Detected In The Distant Past, Halfway Back To Big Bang Science Daily - January 9, 2008

New Risk to Earth Found in Supernova Explosions Live Science - January 8, 2008

Our Solar System is asymetrical Live Science - December 10, 2007

Scientists find the dent in our solar system MSNBC - December 10, 2007

Unexplained Hole in the Universe

Huge Void Implicated in Distant Universe NASA - August 27, 2007
Gaping "Hole" in the Sky Found, Experts Say National Geographic - August 25, 2007
Great 'cosmic nothingness' found BBC - August 25, 2007
Huge Hole Found in the Universe Live Science - August 23, 2007

The hole is nearly a billion light-years across. It is not a black hole, which is a small sphere of densely packed matter. Rather, this one is mostly devoid of stars, gas and other normal matter, and it's also strangely empty of the mysterious "dark matter" that permeates the cosmos. Other space voids have been found before, but nothing on this scale. Astronomers don't know why the hole is there.

Ancient Star Is Nearly as Old as Universe National Geographic - May 12, 2007

A galactic fossil: Star is found to be 13.2 billion years old PhysOrg - May 11, 2007
Ancient star nearly as old as the universe MSNBC - May 12, 2007

The universe is a string-net liquid New Scientist - March 16, 2007

First Triple Quasar Found, May Shed Light on Early Universe National Geographic - January 9, 2007

Newfound blob is biggest thing in universe National Geographic - July 31, 2006

Structure is 200 million light-years wide, made up of galaxies and gas

Our Universe: A Quantum Loop PhysOrg - April 25, 2006
There are two classical branches of the universe connected by a quantum bridge.

The Universe trapped in its own web PhysOrg - April 4, 2006

Ingredients for Life Found in Early Universe Space.com - July 29, 2005

Superwind discovered spreading Star Dust across the Universe PhysOrg - July 13, 2005

Scientists Ponder Universe's Missing Antimatter National Geographic - July 6, 2005

Early Universe was 'liquid-like' BBC - April 2005
Physicists say they have created a new state of hot, dense matter by crashing together the nuclei of gold atoms.

Motion Of Primordial Universe Unveiled: Science Daily - October 2004

New Data Suggests That The Universe Expanded Rapidly In The First Instants After The Big Bang

Rubber Band Invoked to Explain Dark Energy - Increasing Universe Theory Space.com - July 2004

'Birth cry' of the cosmos heard BBC - June 2004
Over the first million years the music of the cosmos changed from a bright major chord to a sombre minor one.

Primal Scream: The Infant Universe Speaks Space.com - June 2004
An astronomer has turned observations of the early universe into a sound clip that represents a primal scream from the first million years after the Big Bang.

Universe Measured: We're 156 Billion Light-years Wide! Space.com - May 2004

Cosmos is a billion years older than thought BBC - May 2004
A readjustment gives the Universe an age of 14.7 instead of 13.7 billion years.

Universe peaked twice at it formed ABC - February 2004

Universe Has At Least 30 Billion Years Left Space.com - February 2004

Universe is Finite, "Soccer Ball"-Shaped National Geographic - October 2003

Cosmos is 'shaped like a soccerball' BBC - October 2003

We could be living in a small Universe where space is curved in on itself, rather like a soccerball. More precisely, we may inhabit a dodecahedral cosmos. Dodecahedrons, and similar shapes, have long fascinated mankind. Plato believed that the Universe was made up of them. Leonardo da Vinci also studied them, as did the great astronomer Kepler, who thought the structure of the Solar System was based on geometrical shapes.