ca. 0 seconds: Planck Epoch begins: earliest meaningful time. The Big Bang occurs in which ordinary space and time develop out of a primeval state (possibly a virtual particle or false vacuum) described by a quantum theory of gravity or "Theory of Everything". All matter and energy of the entire visible Universe is contained in an unimaginably hot, dense point (Gravitational singularity), a billionth the size of a nuclear particle. This state has been described as a particle desert. Other than a few scant details conjecture dominates discussion about the earliest moments of the universe's history since no effective means of testing this far back in space-time is presently available.
ca. 0 seconds: Infant Universe experiences cooling as it begins expanding outward - almost completely smooth, quantum variations begin causing slight variations in density
Grand Unification Epoch
ca. 10–43 seconds: Grand unification epoch begins: While still at an infinitesimal size, Universe cools down to 1032 kelvins.
ca.10–43 seconds: Gravity separates and begins operating on the Universe - remaining fundamental forces stabilize into electronuclear force, also known as the Grand Unified Force or Grand Unified Theory (GUT). Hypothetical X and Y bosons appear however physical characteristics such as mass, charge, flavour and colour charge are meaningless.
ca. 10–33 seconds: Space is subjected to a superfast inflation, influenced by a replusive energy field, expanding from the size of an atom to that of a grapefruit in a tiny fraction of a second. The inflation also generates two types of waves (gravitational and density) along which the previous quantum fluctuations inflate becoming structures that will influence future galaxy clustering
ca. 10–12 seconds: As fundamental interactions begin acting on the Universe, it remains too hot for quarks to bind together into larger forms of matter - domination of radiation over matter with quarks and gluons experiencing degrees of freedom. The universe cools to 1015 kelvins.
ca. 10–11 seconds: Baryogenesis may have taken place with matter gaining the upper hand over anti-matter as baryon to antibaryon constituencies are established. A second potential type of dark matter (neutrinos) may have been synthesized.
ca. 10–6 seconds): Hadron epoch begins: As the universe cools to about 1010 kelvins, a quark-hadron transition takes place in which quarks bind to form more complex particles - hadrons. This quark confinement includes the formation of protons and neutrons (nucleons), the building blocks of atomic nuclei.
ca. 1 second: Lepton epoch begins: The universe cools to 109 kelvins. At this temperature, the hadrons and antihadrons annihilate each other, leaving behind leptons and antileptons - possible disappearance of antiquarks.
ca. 1 second: Gravity governs the expansion of the universe: neutrinos decouple from matter creating a cosmic neutrino background.
ca. 13,790 Ma (ca. 10 seconds): Photon epoch begins: Most of the leptons and antileptons annihilate each other. As electrons and positrons annihilate, a small number of unmatched electrons are left over - disappearance of the positrons.
ca. 13,790 Ma (ca. 10 seconds): Universe dominated by photons of radiation - ordinary matter particles are coupled to light and radiation while dark matter particles start building non-linear structures. Because charged electrons and protons hinder the emission of light, the universe becomes a super-hot glowing fog.
ca. 13,790 Ma (ca. 377,000 yrs): Dark Ages (cosmology) begin - Recombination: electrons combine with nuclei to form atoms mostly hydrogen and helium. The glow from our infant Universe is unveiled. Distributions of hydrogen and helium at this time remains constant as the electron-baryon plasma thins. The temperature falls to 3000 degrees Kelvin. Ordinary matter particles decouple from radiation. The photons fly free releasing a Cosmic Microwave Background. The universe becomes neutral and transparent. the Afterglow light pattern source taken by later satellites is the farthest back our instruments can see. The Cosmic Microwave Background is also the only light source: with no stars there is no other source of light. The Universe empty except for the neutral clouds of hydrogen and helium.
ca. 13,790 Ma (ca. 400,000 yrs): Density waves begin imprinting characteristic polarization (waves) signals.
ca. 13,700 Ma: Gravitational collapse: ordinary matter particles fall into the structures created by dark matter. Reionization begins: smaller (stars) and larger non-linear structures (quasars) begin to take shape - their ultraviolet light ionizes remaining neutral gas
13,600–13,500 Ma: First stars begin to shine: Because many are Population III stars (some Population II stars are accounted for at this time) they are much bigger and hotter and their life-cycle is fairly short. Unlike later generations of stars, these stars are metal free.
13,600-13,500 Ma: As reionization intensifies, photons of light scatter off free protons and electrons - Universe becomes opaque again
ca. 13,600 Ma: HD 140283, the "Methuselah" Star, formed, the unconfirmed oldest star observed in the Universe. Because it is a Population II star, some suggestions have been raised that second generation star formation may have begun very early on.
ca. 13,500 Ma: First large-scale astronomical objects, protogalaxies and quasars may have begun forming.
ca. 13,500 Ma: As Population III stars continue to burn, stellar nucleosynthesis operates - stars burn mainly by fusing hydrogen to produce more helium in what is referred to as the Main Sequence. Over time these stars are forced to fuse helium to produce carbon, oxygen, silicon and other heavy elements up to iron on the periodic table. These elements, when seeded into neighbouring gas clouds by supernova, will lead to the formation of more Population II stars (metal poor) and gas giants.
13,370 Ma (380 million yrs): UDFj-39546284, current record holder for oldest known quasar.
13,330 Ma (ca. 420 million yrs): The quasar MACS0647-JD, forms
13,000 Ma: LAE J095950.99+021219.1, the Bogwiggit Galaxy, one of the most remote Lyman alpha emitter galaxies, forms. Lyman alpha emitters are considered to be the progenitors of spiral galaxies like the Milky Way.
12,970 Ma: Galaxy or possible proto-galaxy A1689-zD1 forms.
12,900 Ma: Quasar ULAS J1120+0641, one of the most distant, forms. One of the earliest galaxies to feature a supermassive black hole suggesting that such large objects existed quite soon after the Big Bang. The large fraction of neutral hydrogen in its spectrum suggests it may also have just formed or is in the process of star formation.
12.880 Ma: Galaxy IOK-1 a Lyman alpha emitter galaxy, forms.
12.800 Ma: Galaxy HCM-6A, the most distant normal galaxy observed, forms
12,800 MA: HE1327-2326, population II star, speculated to have formed from remnants of earlier Population III stars.
12.799 Ma (ca. 1 billion yrs): Reionization complete - the Universe becomes transparent again. Galaxy evolution continues as more modern looking galaxies form and develop. Because the Universe is still small in size, galaxy interactions become common place with larger and larger galaxies forming out of the galaxy merger process.
12,799 Ma (ca. 1 billion yrs): Galaxies may have begun clustering creating the largest structures in the Universe so far - the first galaxy clusters and galaxy superclusters appear.
11,520 Ma: Omega Centauri, largest globular cluster in the Milky Way forms
11 Ma: Formation of Gliese 581 planetary system: Gliese 581 c, the first observed ocean planet and Gliese 581 d, a super-earth planet, possibly the first observed habitable planets, form. Gliese 581 d has more potential for forming life since it is the first exoplanet of terrestrial mass proposed that orbits within the habitable zone of its parent star.
9,900 Ma: 16 Cygni Bb, the first gas giant observed in a single star orbit in a trinary star system, forms - orbiting moons considered to have habitable properties or at the least capable of supporting water
9,500 Ma: Fierce star formation in Andromeda making it into a luminous infra-red galaxy
8,000 Ma: Acceleration: dark energy begins dominating Universe - after being slowed for billions of years by gravity abundant dark matter takes hold and the cosmic expansion begins to speed up. As the cosmic expansion accelerates, the rate of galaxy interactions decreases - although near misses continue to distort some while collisions increase the size of others, distance makes the galaxy merger process less likely. Many galaxies like NGC 4565 become relatively stable - ellipticals result from collisions of spirals with some like IC 1101 being extremely massive.
8,000 - present Ma: The Universe continues to organize into larger wider structures. The great walls, sheets and filaments consisting of galaxy clusters and superclusters and voids crystallize. How this crystallization takes place is still conjecture. Certainly, it is possible the formation of super-structures like the Hercules-Corona Borealis Great Wall may have happened much earlier, perhaps around the same time galaxies first started appearing. Either way the observable universe becomes more modern looking.
5,800 Ma: Tau Ceti, nearby yellow star forms: five planets eventually evolve from its planetary nebula, orbiting the star - Tau Ceti e considered planet to have potential life since it orbits the hot inner edge of the star's habitable zone
5,500 Ma: GRB 101225A, the "Christmas Burst", considered the longest at 28 minutes, recorded
In the earliest solar system history, the Sun, the planetesimals and the jovian planets were formed. The inner solar system aggregated more slowly than the outer, so the terrestrial planets were not yet formed, including Earth and Moon.
4,533 Ma: Hadean Eon, Precambrian Supereon and unofficial Cryptic era start as the Earth–Moon system forms, possibly as a result of a glancing collision between proto–Earth and the hypothetical protoplanetTheia. (The Earth was considerably smaller than now, before this impact.) This impact vaporized a large amount of the crust, and sent material into orbit around Earth, which lingered as rings, similar to those of Saturn, for a few million years, until they coalesced to become the Moon. The Moon geology pre-Nectarian period starts. Earth was covered by a magmatic ocean 200 kilometres (120 mi) deep resulting from the impact energy from this and other planetesimals during the early bombardment phase, and energy released by the planetary core forming. Outgassing from crustal rocks gives Earth a reducing atmosphere of methane, nitrogen, hydrogen, ammonia, and water vapour, with lesser amounts of hydrogen sulfide, carbon monoxide, then carbon dioxide. With further full outgassing over 1000–1500 K, nitrogen and ammonia become lesser constituents, and comparable amounts of methane, carbon monoxide, carbon dioxide, water vapour, and hydrogen are released.
4,450 Ma: 100 million years after the Moon formed, the first lunar crust, formed of lunar anorthosite, differentiates from lower magmas. The earliest Earth crust probably forms similarly out of similar material. On Earth the pluvial period starts, in which the Earth's crust cools enough to let oceans form.
4,400 Ma: Fomalhaut b, first directly imaged planet, forms
2,700 Ma: Biomarkers of cyanobacteria discovered, together with steranes (sterols of cholesterol), associated with films of eukaryotes, in shales located beneath banded iron formation hematite beds, in Hamersley Range, Western Australia Skewed sulfur isotope ratios found in pyrites shows a small rise in oxygen concentration in the atmosphere
2,600 Ma: Oldest known giant carbonate platform
1,200 Ma: Stenian Period starts. Red algaBangiomorpha pubescens, earliest fossil evidence for sexually reproducing organism. Meiosis and sexual reproduction are present in single-celled eukaryotes, and possibly in the common ancestor of all eukaryotes. Supercontinent Rodinia comes together.
^Amelin,Yuri, Alexander N. Krot, Ian D. Hutcheon, & Alexander A. Ulyanov (Sept 2002), "Lead Isotopic Ages of Chondrules and Calcium-Aluminum-Rich Inclusions" (Science, 6 September 2002: Vol. 297. no. 5587, pp. 1678 - 1683)
^Taylor, G. Jeffrey (2006), "Wandering Gas Giants and Lunar Bombardment: Outward migration of Saturn might have triggered a dramatic increase in the bombardment rate on the Moon 3.9 billion years ago, an idea testable with lunar samples" 
^Mojzis, S, et al. (1996), Evidence for Life on Earth before 3800 million years ago", (Nature, 384)
^Butterfield, NJ. (2000). "Bangiomorpha pubescens n. gen., n. sp.: implications for the evolution of sex, multicellularity and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes". Paleobiology26 (3): 386–404. doi:10.1666/0094-8373(2000)026<0386:BPNGNS>2.0.CO;2.