See: The Inflation Debate : Scientific American Mar. 2011

♦ Lepton Epoch, from 1 second to 3 minutes:

Within the last part of the first second the universe is a hot, relativistic plasma of particles dominated by radiation; quarks, leptons (such as electrons) and neutrinos are formed.
It was opaque due to the constant interchange of energy between matter and radiation.
Source: The Physics of the Universe - Timeline of the Big Bang

♦ 3 minutes - 240,000 years (Nucleosynthesis,): The Universe then cooled to a temperature of ∼ 4,000 K through its expansion. At this stage, the matter does not have sufficient energy to remain ionised.

♦ 240,000 - 380,000 years The electrons combine with the protons to form atoms. Hydrogen, Helium and Lithium at first.
The universe becomes a transparent fog of about 75% hydrogen and 25% helium.

♦ 380,000 to 150 million years - Dark Age (or Dark Era)
The period after the formation of hydrogen and before the first stars is dominated by mysterious "dark matter"

The cosmic microwave background (CMB) radiation is created about 380,000 years after the big bang. In 2003 NASA lauhched the Wilkinson Microwave Anisotropy Probe (WMAP) to study the afterglow of the big bang, called the cosmic microwave background.
They produce a map of CMB from 380,000 years after the big bang.
In January, 2010 the WMAP team has reported the first direct detection of pre-stellar helium.
See youtube video

♦ 150 million to 1 billion years: The first quasars form from gravitational collapse. The intense radiation they emit reionizes the surrounding universe.

♦ 300 - 500 million years:
Early active galaxies, and population III stars.

♦ 500 million years: Cold Dark Matter cosmology - As the universe cooled clumps of dark matter began to condense, and within them gas began to condense. The primordial fluctuations gravitationally attracted gas and dark matter to the denser areas, and thus the seeds that would later become galaxies were formed.

On July 11, 2007, using the 10 metre Keck II telescope on Mauna Kea, Richard Ellis of the California Institute of Technology at Pasadena and his team found six star forming galaxies about 13.2 billion light years away and therefore created when the universe was only 500 million years old.

♦ 500 million years to present - Creation of other Chemical Elements:
Atoms of heavier elements could not be manufactured until there was a significant amount of helium. However fusing helium into heavier elements requires higher temperatures and pressures than fusing hydrogen into helium.
When massive stars run out of hydrogen they begin burning helium and then successively heavier elements until they have an iron core.

These stars then explode as a type II supernova. The supernova simultaneously manufactures the heaviest elements, and blasts material containing all the elements that the star has made in its lifetime back into the interstellar medium.

Fusion stops at iron, the boundary between fusion and fission. Fusing elements heavier than iron requires rather than releases energy.

The Flatness Problem :
Our universe is apparently flat. That is, it appears to have just the "right" density--or nearly so--to continue its slow expansion forever. Too much matter, and the universe eventually collapses in on itself under the influence of its own gravitational pull. Called the "Big Crunch". Too little matter, and gravity will never be able to halt the expansion of the universe. The universe eventually be populated only by gas, dust and the relics of stars, growing increasingly cold with its infinite expansion. This bleak scenario is called the Big Chill.
See The Flatness Problem at NCSA - U. Ill.

Expansion Speeds up:
It was assumed that the gravitational force of dark matter would slow down the expansion of the universe. However, a 1998 discovery showed that expansion is speeding up. This has been attributed to "Dark Energy" which is not well understood.

It is speculated that this shift from slowing expansion to accelerated expansion occurred about 5 billion years ago. See The Expanding Universe: From Slowdown to Speed Up: Scientific American.

Current estimates are that Dark Energy makes up 73% of the universe, Dark Matter makes up 23% of the universe. The visible matter that we are familiar with, only makes up 4% of the universe.
See: A Quintessential Introduction to Dark Energy from Paul Steinhardt at Princeton.

A 2008 study using WMAP data found that distant galaxy clusters appear to be zooming through space at phenomenal speeds that surpass 1 million mph. The clusters were tracked to 2.5 billion light-years away - twice as far as earlier measurements, along a path roughly centered on the southern constellations Centaurus and Hydra .
Dark flow is the name given to this.
The dark flow is controversial because the distribution of matter in the observed universe cannot account for it. Its existence suggests that some structure beyond the visible universe -- outside our "horizon" -- is pulling on matter in our vicinity.

At a 2002 NASA press release the Hubble team announced they had computed the age of white dwarfs in globular cluster M4 in the Milky Way to be 12-13 billion years old. These extremely old, dim stars provide a completely independent reading of the universe's age without relying on measurements of the universe's expansion, which came up with estimates of 14 Billion years. Because the first stars formed less than 1 billion years after the universe's birth in the big bang these findings are consistent.

Astronomers say that in around 100 trillion years (10¹⁴) all stars will decay into white dwarfs or explode in supernovas leaving behind a neutron star or black hole. So the universe will be very dim. Most of the radiation a neutron star is X-rays with little in the visible spectrum.
The white dwarfs will eventually decay into brown dwarfs (originally called black dwarfs) which are too low in mass to sustain hydrogen fusion.

About 3,000 stars are visable from earth with the naked eye. The andromeda gallexy can be seen with the naked eye in ideal conditions (low light and clear skies).

    Mostly H with some He
   -> Hyper Novi
   Creats 
1 Billion Yrs
Stars (Initially H fused to create He)
   As a star starts to use up He it starts to shrink and gets hotter
   so it can burn He.
   3 He -> C
   Creates more elements up to Fe (Iron) 
   Creats super Nova which creates heavier elements

Terms - Glossary:

CMB - Cosmic microwave background  
ESA - European Space Agency
GUT - Grand unification Theory  
Hypernova - Supernova of a hypergiant star.
Nebula - Interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases.
Quasar - A compact region in the center of a massive galaxy surrounding
         its central supermassive black hole. They are sources of electromagnetic energy,
         including radio waves and visible light, that were point-like, similar to stars.
Supernova - A stellar explosion of a dying massive star.
WMAP - Wilkinson Microwave Anisotropy Probe 

(1) Until the mid-1990s the data on the rate cosmic expansion were so uncertain that the best estimates of the age the universe stood at between 10 and 20 billion years. New calculations have zeroed in on 13.7 B years.

In 2004 Astronomers announced that "The Universe is is at least 156 Billion light years across."
The cosmos is 13.7 Billion years old but the stretching of space with its expansion after the Big Bang means that simple distance measurements do not apply. Astronomers realise the Universe is more complex. It has been expanding ever since the Big Bang when energy, space and time itself began. To get the picture try to imagine the Universe a million years after the Big Bang. Light travels for a year, covering one light-year. But at that time, the Universe was about a thousand times smaller than it is today meaning that one light-year has now become stretched to about a thousand light-years.
See The Size of the Universe: A Hard Question

History > Universe

See Also:
Big Bang:
Big Bang Theory - Crystalinks
The Physics of the Universe - Timeline of the Big Bang
The Description, Origin, and Development of the Universe at nasa.gov
Foundations of Big Bang Cosmology at nasa.gov
Cosmic Evolution: An Interdisciplinar Approach at Tufts.
TimeLine at HistoryOfTheUniverse.com

Other:
Frequently Asked Questions in Cosmology at UCLA
The Hubble Deep Field
Hubble Ultra Deep Field in 3D
http://www.space.com/
DeepAstronomy.com
European Space Agency (ESA)
Solar System