How The Life Begin

Planck epoch Times shorter than 10 −43  seconds ( Planck time ) Main article:  Planck epoch The  Planck epoch  is an era in traditional (non-inflationary)  Big Bang cosmology immediately after the event which began our known universe. During this epoch, the temperature and average energies within the universe were so high that everyday subatomic particles could not form, and even the four fundamental forces that shape our universe— electromagnetism ,  gravitation ,  weak nuclear interaction , and  strong nuclear interaction —were combined and formed one fundamental force. Little is understood about physics at this temperature; different hypotheses propose different scenarios. Traditional big bang cosmology predicts a  gravitational singularity  before this time, but this theory relies on the theory of  general relativity , which is thought to break down for this epoch due to  quantum effects . In inflatio...

Further information:  Timeline of cosmological epochs ,  Timeline of natural history ,  Geologic time scale ,  Timeline of the evolutionary history of life , and  Timeline of the far future Further information:  Graphical timeline of the universe ,  Graphical timeline of the Big Bang ,  Graphical timeline from Big Bang to Heat Death , and  Graphical timeline of the Stelliferous Era Earliest stages of chronology shown below (before neutrino decoupling) are an active area of research and based on ideas which are still speculative and subject to modification as scientific knowledge improves. "Time" column is based on extrapolation of observed  metric expansion of space back in the past. For the earliest stages of chronology this extrapolation may be invalid. To give one example,  eternal inflation  theories propose that inflation lasts forever throughout most of the universe, making the notion of "N seconds since Big Bang" ill...

The universe as it appears today. From 1 billion years, and for about 12.8 billions of years, the universe has looked much as it does today. It will continue to appear very similar for many billions of years into the future. The  thin disk  of  our galaxy  began to form at about 5 billion years (8.8 bn years ago),and the  solar system  formed at about 9.2 billion years (4.6 bn years ago), with the earliest traces of  life  on Earth emerging by about 10.3 billion years (3.5 bn years ago). From about 9.8 billion years of cosmic time,the slowing expansion of space gradually begins to accelerate under the influence of  dark energy , which may be a  scalar field  throughout our universe. The present-day universe is understood quite well, but beyond about 100 billion years of cosmic time (about 86 billion years in the future), uncertainties in current knowledge mean that we are less sure which path our universe will take.

Dark Ages and large-scale  structure emergence , from 377,000 years until about 1 billion years. After  recombination  and  decoupling , the universe was transparent but the clouds of  hydrogen  only collapsed very slowly to form  stars  and  galaxies , so there were no new sources of light. The only photons (electromagnetic radiation, or "light") in the universe were those released during decoupling (visible today as the  cosmic microwave background ) and  21 cm radio emissions occasionally emitted by hydrogen atoms. The decoupled photons would have filled the universe with a brilliant pale orange glow at first, gradually  redshifting  to non-visible  wavelengths after about 3 million years, leaving it without visible light. This period is known as the  Dark Ages . Between about 10 and 17 million years the universe's average temperature was suitable for liquid water (273 – 373K) and there has been specula...

The  early universe , lasting around 377,000 years. Initially, various kinds of  subatomic particles  are formed in stages. These particles include almost equal amounts of  matter  and  antimatter , so most of it quickly annihilates, leaving a small excess of matter in the universe. At about one second,  neutrinos decouple ; these neutrinos form the  cosmic neutrino background . If  primordial black holes  exist, they are also formed at about one second of cosmic time.  Composite   subatomic particles  emerge – including  protons and  neutrons  – and from about 3 minutes, conditions are suitable for  nucleosynthesis : around 25% of the protons and all the neutrons  fuse   into heavier elements , mainly  helium-4 . By 20 minutes, the universe is no longer hot enough for fusion, but far too hot for neutral  atoms  to exist or  photons  to travel far. It is ...

Outline For the purposes of this summary, it is convenient to divide the chronology of the universe since it  originated , into five parts. It is generally considered meaningless or unclear whether  time existed before this chronology: The  very early universe  – the first  picosecond  (10 −12 ) of cosmic time. It includes the  Planck epoch , during which currently understood  laws of physics may not apply; the emergence in stages of the four known  fundamental interactions  or  forces  – first  gravity , and later the  strong ,  weak  and  electromagnetic  interactions; and the  expansion of space  and  supercooling  of the still immensely hot universe due to  cosmic inflation , which is believed to have been triggered by the separation of the  strong  and  electroweak interaction . Tiny ripples in the universe at this stage are believed...

The chronology of the universedescribes the history and  future of the universe  according to  Big Bang cosmology. The earliest stages of the universe's existence are estimated as taking place 13.8  billion years  ago, with an  uncertainty  of around 21 million years at the 68% confidence level.