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Human timeline and Life timeline The prevailing model for the evolution of the Universe is the Big Bang theory. The model is based on general relativity and on simplifying assumptions such as homogeneity and isotropy of space. A version of the model with a cosmological constant Lambda and cold dark matterknown as the Lambda-CDM modelis the simplest model that provides a reasonably good account of various observations about the Universe.
The Big Bang model accounts for observations such as the correlation of distance and redshift of galaxies, the ratio of the number of hydrogen to helium atoms, and the microwave radiation background.
In this diagram, time passes from left to right, so at any given time, the Universe is represented by a disk-shaped "slice" of the diagram.
During the Planck epoch, all types of matter and all types of energy were concentrated into a dense state, and gravity - currently the weakest by far of the four known forces - is believed to have been as strong as the other fundamental forces, and all the forces may have been unified.
Although objects in spacetime cannot move faster than the speed of lightthis limitation does not apply to the metric governing spacetime itself. This initial period of inflation is believed to explain why space appears to be very flat, and much larger than light could travel since the start of the universe.
As the universe continued to cool down from its inconceivably hot state, various types of subatomic particles were able to form, in short periods of time known as the quarkhadronand lepton epochs.
Together, these epochs encompassed less than 10 seconds of time following the Big Bang. These elementary particles associated stably into ever larger combinations, including stable protons and neutronswhich then formed more complex atomic nuclei through nuclear fusion. This process, known as Big Bang nucleosynthesisonly lasted for about 17 minutes and ended about 20 minutes after the Big Bang, so only the fastest and simplest reactions occurred.
Any other element was only formed in very tiny quantities.
After nucleosynthesis ended, the universe entered a period known as the photon epoch. During this period, the Universe was still far too hot for matter to form neutral atomsso it contained a hot, dense, foggy plasma of negatively charged electronsneutral neutrinos and positive nuclei.
After aboutyears, the universe had cooled enough that electrons and nuclei could form the first stable atoms. This is known as recombination for historical reasons; in fact electrons and nuclei were combining for the first time.
Unlike plasma, neutral atoms are transparent to many wavelengths of light, so for the first time the universe also became transparent. The photons released " decoupled " when these atoms formed can still be seen today; they form the cosmic microwave background CMB.
In this section, we're going to take a brief excursion through the various theories that science has put forth to explain the origin of the universe. By far the most popular theory in science today is the big bang theory, the idea that the universe came into existence at a certain point in time roughly 15 to 20 billion years ago. The Origin of the Universe This lecture is the intellectual property of Professor plombier-nemours.comg. You may not reproduce, edit, translate, distribute, publish or host this document in any way with out the permission of Professor Hawking. From the inside, the result would look like a tremendous explosion. Even more intriguing, the theoretical characteristics of that explosion closely matched the observed properties of the Big Bang—including the cosmic microwave background, the afterglow of the universe’s fiercely hot early days.
As the Universe expands, the energy density of electromagnetic radiation decreases more quickly than does that of matter because the energy of a photon decreases with its wavelength.
At around 47, years, the energy density of matter became larger than that of photons and neutrinosand began to dominate the large scale behavior of the universe. This marked the end of the radiation-dominated era and the start of the matter-dominated era. Ordinary matter, attracted to these by gravityformed large gas clouds and eventually, stars and galaxies, where the dark matter was most dense, and voids where it was least dense.From the inside, the result would look like a tremendous explosion.
Even more intriguing, the theoretical characteristics of that explosion closely matched the observed properties of the Big Bang—including the cosmic microwave background, the afterglow of the universe’s fiercely hot early days. According to physics, the universe sprang into existence from a singularity — a term physicists use to describe regions of space that defy the laws of physics.
They know very little about singularities, but it's known that such regions exist in the cores of black holes. A look at the most dangerous objects known in space: all-consuming black holes, A look back in time billions and billions of years to the origin of the Big Bang.
A look at how the universe could end with various theories explored such as a "random quantum fluctuation" where everything is obliterated in the blink of an eye; where all. The Origin of the Universe This lecture is the intellectual property of Professor plombier-nemours.comg.
You may not reproduce, edit, translate, distribute, publish or host this document in any way with out the permission of Professor Hawking. What are the various theories that aim to explain the origin of the universe?
Update Cancel. What are the other theories aside from big bang and steady state theory explaining the origin of the universe? What are the theories of punishment? Ask New Question. Still have a question? Ask your own! Creationist Views of the Origin of the Universe, Earth, and Life Many religious persons, including many scientists, hold that God created the universe and the various processes driving physical and biological evolution and that these processes then resulted in the creation of galaxies, our solar system, and life on Earth.