Time = 10^-43s Temp = 10^32K

T= 0 the big big bang occurs. The evidence: comparable ages yielded by studies in stellar evolution, radioactivity and Hubble's Red shifting Galaxies. In addition the discovery of inhomogeneities in the Cosmic Microwave Background radiation is one of the two great cosmological discoveries of our time (Hubble's Red shifting galaxies being the other).

We do not know anything from T=0 to T=10^-43s (Planck time) after the Big bang since a quantum theory of gravity is needed at such high temperatures and density and we do not have one. General relativity posits a gravitational singularity but the GR equations break down under such conditions. Superstring theorists are attempting to change this. Our entire universe was extremely small at this time and very hot. Particle physicists believe that the four fundamental forces were unified into a single force during this time (gravity, strong, weak and electromagnetic) and that distinctions between the elementary particles and their force transmitters did not exist until it became cool enough for the Higg's field to condense into a particular non-zero number. The Higg's Field or "ocean" is what some researchers feel is responsible for inertia and its resistance to acceleration and also the distinctions between particles and their different masses. The gravitational force is thought to be the first to condense out which leads us to the Grand Unified era.

Just realize what a huge temperature that actually is:

100,000,000,000,000,000,000,000,000,000,000 kelvin or celsius (the +/-273 is irrelevant at this point)

Gut stands for Grand Unified Theory and it involves the merging of the strong, weak and electromagnetic forces into a single force. There were two fundamental forces during this time period: gravity and the grand unified one. Distinctions between quarks and leptons do not exist at this time.

Towards the end of the GUT era is when some cosmologists believe the inflationary expansion of our universe began. The inflation is said to only last for a a tiny fraction of a blink of an eye (10^-35s) but the universe may have increased in size by a factor of 10^30,10^50, 10^100 or even more. These numbers are staggering. Brian Green says that for the conservative 10^30 its would be like "scaling up a molecule of DNA to roughly the size of the Milky Way galaxy, and in a time interval that's much shorter than a billionth of a billionth of a billionth of a link of an eye."

Gravity is dependent not only on masses (Newton) but on temperature, energy and pressure (Einstein). A false pressure vacuum or negative pressure led to gravity being repulsive for a short time, yes gravity an be repulsive! Inflation, first proposed by particle physicist Alan Guth and modified by others helps solve several difficulties with the big bang model (flatness, magnetic monopole, etc).

Once the strong force condenses out leaving only the electroweak unification free quarks can exist. Some theorists think the condensing of the strong force from the electroweak was the phenomenon causing the false pressure vacuum and inflationary expansion of the universe. Leptons are also thought to exist at this time. Free quarks do not exist today. They appear too tightly bound.

Once quarks started condensing into particles such as neutrons and protons, quark confinement or the hadron era begins. The hadron era is though to extend to about 10^-4s after the big bang but I put this marker in because it is at this time frame that most of the hadrons disappear.

At Ti=10^-6s,Te=10^13k and KE = 1Ge. When KE > 1GeV protons, neutrons and their antiparticles are continually created in collisions with photons and other particles. Just as quickly as they are created they annihilate one another. Originally their numbers were high, roughly equal to lepton numbers but as universe expanded, cooled and KE decreased to < 1GeV no new hadrons were created. They could still be destroyed however! Thus they annihilated one and without a source of replenishment their numbers dwindled but not to zero! Since matter is dominant over antimatter today we must suppose that early after the big there were more quarks than antiquarks. These excess nucleons that formed from the quarks is what we are made of today. Photons and nucleons were roughly equal early in the hadron era but by the end there was one 1 nucleon per 10^9 photons. As these heavier particles died off the lighter ones dominated leading us to the Lepton Era.

The Lepton Era tends to go to about 10 second after the big bang but at the critical juncture listed on the left a similar process that happened in the Hadron era occurs. The temperature cooled enough due to the expansion of the universe and the critical KE was reached whereby Lepton production ceases and they end up annihilating one another just as the hadrons did before them.

The universe's first second was arguably the busiest one in cosmic history! Inflation, quark confinement, 10 billion degree cooling, the condensing out of forces, etc.

Ten seconds after the big bang the universe entered the radiation era (photons, neutrinos) where more energy was in radiation than matter. This era lasted until about T=380,000 years when decoupling occurred. To understand decoupling we will look at the CMBR.

In 1964 Penzias and Wilson experienced difficulties with their radio telescope. They thought is was static or background noise. They measured its wavelength at 7.35 cm (in the microwave). Its intensity did not vary by day or night or time of year nor depend on direction varied by 1 pp thousand. Eventually they realized it was real and coming from outside our Galaxy. THis was considered to be background radiation leftover from the big bang and it was spread evenly throughout the universe.

Theorists felt there must be small inhomogeneities in the Cosmic Microwave Background radiation to act as seeds for planetary, stellar and galactic formations. In 1992 COBE found them at T = 2.7k. This was one of the two great cosmological discoveries of our era, Hubble's being the other. Why is there CMBR spread evenly through out space?

By definition the Big bang occurred everywhere and tremendous releases of energy and extremely high temperature were evident in the beginning. Atoms were not possible but atoms radiation(photons!) and elementary particles did exist. The universe would have been opaque as emitted photons would be trapped, aka scattered or absorbed by electrons immediately. CMB is strong evidence that matter and energy were once at equilibrium. As universe expanded its volume increased, energy spread out decreasing temps. Once T = 3000k (300,000years later) could atoms exist. As free electrons combined with nuclei to make atoms all the trapped photons would be released or “decoupled”. This provides the background for the CMB observed in all directions at 2.7K today.

Atoms were actually possible (nucleosynthesis) between T=10^2 and 10^3s but the universe actually is said to have cooled too fast! Protons (hydrogen ions) and neutrons begin to combine into atomic nuclei in the process of nuclear fusion. However, nucleosynthesis only lasts for about seventeen minutes, after which time the temperature and density of the universe has fallen to the point where nuclear fusion cannot continue. At this time, there is about three times more hydrogen than helium-4 (by mass) and only trace quantities of other nuclei. The production of atoms resumes when Te=3000k and decoupling occurs. The CMB radiation is actually stronger than all the other radiation sources that exist today (e.g. stars) and radiation once dominated the universe until decoupling; now matter dominates.

It is at this stage that our solar system is thought to have begun forming. A giant nebula, or cloud of gas, stardust and space junk was disrupted, probably by a nearby supernova and this accelerated gravitational contraction. As material pulled together under attractive gravitational forces friction from collisions began to heat things up and eventually a net random motion (circulation) occurred. due to all the impacts.

Eventually a proto-sun formed and as more and more objected were attracted to it it kept heating up until it became so hot nuclear fusion could occur. This is what happens in our sun: 4H convert into 1He with a small mass loss in the process. This mass is converted into pure energy (E=mc^2 where c = speed of light in vacuum) and our sun exists as an ordinary main sequence star balancing the inward gravitational pressure with outward thermo-nuclear pressure--until the hydrogen fuel runs out at least.

The abundance of heavier elements in our solar systems tells us that our sun is not a first generation star. THe planets themselves formed out of the same nebula and this is roughly the age of the earth which formed 4.6bya or at T = 9.1by after the bang. This view of the solar system's formation is consistent with the following data:

All planets orbit the Sun in the same direction (CCW). Most planets' orbits lie in nearly the same plane. Most planetary moons orbit their planets in the same direction (CCW) The planets' orbits are nearly circular. There is a progression of planetary properties; the planets farther from the Sun tend to be less dense and richer in VOLATILE materials (e.g., ice, hydrogen gas). All solid-surfaced bodies have been CRATERED. The Sun contains 99% of the mass of the solar system. Mercury appears to be the most heavily cratered (stuff coming into sun). Superposition seems to show that the size of the cratering decreased over time. Against these observations are the following:

Venus's rotation is retrograde (E to W). Uranus's equator is tilted 98° to its orbital plane. Neptune's largest moon Triton is in a nearly circular but retrograde (CW) orbit. Comets have very large and very elliptical (hairpin) orbits, both directional (CCW) and retrograde (CW). Many of Jupiter's and Saturn's outer moons are in retrograde (CW) orbits. Many of these exceptions may prove the rule. Giant collisions were likely early in the condensation nebula theory so motion changing collisions are expected.

Phanerozoic EON
(544 mya to present)

"The age of visible life"

Cenozoic Era
(65 mya to today)

Quaternary (1.8 mya to today)

Radiation of more modern animals: most modern bird forms have appeared; most modern mammals have appeared.

Cretaceous (146 to 65 mya)

Late // Early

Major extinction includes dinosaurs and ammonites (K-T)
Appearances include: flowering plants (angiosperms); lizards; placental animals (early mammals); snakes; social insects; marsupial and primitive placental animals
Modern insect forms radiate

Paleozoic Era
(544 to 245 mya)

Major extinction of invertebrates (P-T). Trilobites fade away forever. All but articulate crinoids dissapear
Seedplants producing large trees

Precambrian Time
(4,500 to 544 mya)

"deep time on earth"

Cold climate with glaciation in late Proterozoic

Extinction at end of Vendian Appearance of Tommotian fauna at 560-570 MA - the small shelly animals Macroscopic, soft-bodied organisms radiating. Oldest metazoans (multicellular animals) - Ediacaran Fauna.

Rodinia supercontinent splits (.75 ba) forming Panthalassic Ocean

Macroscopic fossils of soft-bodied organisms. Chloroblasts arise from cyanobacteria through endosymbiosis. Stromatolites diminishing.

Rodinia supercontinent forms (1.1 ba)

Sexual reproduction appears (about 1 billion years ago) First land fungi

Archaean
(3800 to 2500 mya)

Toxic atmosphere of ammonia methane and other gases
Formation of stromatolites

Primitive Eukarya appear Photosynthesis appears Oldest fossils - Apex Chert of Australia (3.55 BYA) Prokaryotes dominate (Eubacteria and Archaea); simple cell forms form extensive stromatolites systems First life appears - Chemotrophic, anerobic, Asexual Oldest sedimentary rocks (3.8 BYA)

4600mya The planet Earth forms from the accretion disc revolving around the young Sun.

4533mya the planet Earth and the planet Theia collide, sending countless moonlets into orbit around the young Earth. These moonlets eventually coalesce to form the Moon. The gravitational pull of the new Moon stabilises the Earth's fluctuating axis of rotation and sets up the conditions for the formation of life.

4100mya as the Earth undergoes differentiates (heavier stuff sinks to core) the surface cools enough for the crust to solidify. The atmosphere and the oceans form.PAH infall, and Iron-Sulfide synthesis along deep ocean platelet boundaries, may have led to the RNA world of competing metabolising organic compounds

3900 mya lunar catyclysm occurs or late heavy bombardment: peak rate of impact events upon the inner planets by meteors. This constant disturbance probably obliterated any life that had already evolved, as the oceans boiled away completely; conversely, life may have been transported to Earth by a meteor Earth is continually bombarded by left over planetesimals at a decreasing rate throughout its history.

3800 mya its environment is extremely hostile to life as we know it.The oldest rocks form at about this time.