The earliest cosmological models of the universe were developed by ancient Greek and Indian philosophers and were geostationary at the center. Over the centuries, more accurate astronomical observations inspired Nicholas Copernicus to develop heliocentric models with the Sun at the center of the solar system. In developing the law of universal gravitation, Isaac Newton produced the work of Copernicus as well as Johannes Kepler's laws of planetary motion and observations by Tycho Brahe.
Further observational corrections led to the realization that the Sun is one of the billions of stars in the Milky Way, one of at least hundreds of billions of galaxies in the universe. Many stars in our galaxy have planets. On the largest scale, galaxies are evenly and uniformly distributed in all directions, meaning that the universe has neither an edge nor a center. At smaller scales, galaxies are distributed in clusters and superclusters that form immense fibers and deflections in space, forming a massive foam-like structure. Discoveries in the early 20th century have suggested that the universe was the beginning and the place has been expanding since then, and it is currently expanding at an increasing rate.
The Big Bang theory is the prevailing cosmic description of the evolution of the universe. Under this theory, space and time together 13. theory 6 ago.021 billion years ago emerged and the energy and matter initially present became less dense as the universe expanded. At about 10 seconds32 seconds after an initial accelerated expansion is called the Inflationary Age, and after the separation of the four known fundamental forces, the universe slowly cooled down and continued to expand, allowing the first sub-atomic particles and simple atoms. Got permission to make. Dark matter collects slowly, forming a foam-like structure of filaments and widows under the influence of gravity. Huge clouds of hydrogen and helium were slowly drawn to the places where the dark matter was most dense, in which galaxies, stars and everything else were seen first. It is possible to see objects that are now more than 13.799 billion light years away as space has expanded itself, and it is still expanding today. This means that objects that are now 46.5 billion light years away can still be seen in their farthest past, because in the past, when their light was emitted, they were very close to the Earth.
By studying the motion of galaxies, it has been discovered that the universe contains a lot of matter according to visible objects; Stars, Akash Ganges, Nebula and Interstellar Gas. This overlooked case is known as Dark Matter (Dark means that there is a lot of strong indirect evidence in it, but we have not yet come to know it directly). The OfCDM model is the most widely accepted model of our universe. This suggests that approximately 69.2 %% 1.2% of the mass and energy in the universe is a cosmological constant (or, in the expansion of MCDM, other forms of dark energy, such as scalar fields) responsible for current. . The expansion of space, and about 25.8% of space is 1.1% Dark Matter. Ordinary ('Byronic') matter is only 4.84 %% 0.1% of the physical universe. Stars, planets, and visible gas clouds make up only 6% of normal matter or about 0.29% of the entire universe. The prevailing model for the development of the Universe is the Big Bang theory. The Big Bang model states that the earliest state of the universe was an extremely hot and dense one, and that the universe later expanded and cooled. The model is based on general relativity and simplifies assumptions like space symmetry and isotopic. A version of the model with a cosmic constant (lambda) and cold dark matter, known as the lambda-CDM model, is the simplest model that provides a reasonably good account of various observations about the universe. The Big Bang model describes observations such as the relationship of distance and redistribution of galaxies, the ratio of the number of hydrogen in helium atoms and the microwave radiation background. The initial warm, dense state is called the Planck epoch, a brief period extending from zero to a Planck time unit from a time of about 10 seconds43 seconds. During the Planck era, all types of matter and all types of energy were concentrated in a dense state, and gravity - currently the weakest of the four known forces - is believed to be strong like other fundamental forces, and all forces are May have been integrated. Since the Planck era, space has been expanding at its current scale, with a very short but intense period of temporal inflation believed to have occurred within the first 10–32 seconds. It was a type of expansion, which we can see around us today. Objects did not physically move in space; Instead of the metric defining the space itself changed. Although objects in spacetime cannot move faster than the speed of light, this limitation does not apply to metric governing spacetime itself. This early period of inflation is believed to explain why space appears to be very flat, and much larger than light can travel since the beginning of the universe.
Within the first part of a second of the universe's existence, the four fundamental forces were separated. As the universe cooled from its precarious hot state, a variety of sub-atomic particles became able to move in a short period of time known as the quark era, hadron age, and lepton age. Together, these eras included less than 10 seconds after the Big Bang. These elementary particles, including stable protons and neutrons, sometimes fused into larger combinations, which then formed more complex atomic nuclei through nuclear fusion. This process, known as Big Bang nucleosynthesis, lasted only about 17 minutes and ended about 20 minutes after the Big Bang, so only the fastest and simplest reactions occurred. About 25% of the protons and all neutrons of the universe, by mass, were converted to helium, with traces of deuterium (a form of hydrogen) and lithium in small amounts. Any other element was produced only in very small quantities. The other 75% of the protons remained unaffected as hydrogen nuclei.
After nucleosynthesis ends, the universe is known as the photon era. During this period, the universe was still too hot for matter to form neutral atoms, so it contained a hot, dense, foggy plasma of negatively charged electrons, neutral neutrinos, and positive nuclei. After about 377,000 years, the universe had cooled down so much that electrons and nuclei could first form 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 released photons ("decodes") when these atoms are formed can still be seen today; They form the Cosmic Microwave Background (CMB).
As the universe expands, the energy density of electromagnetic radiation decreases more rapidly than that of matter because the energy of a photon decreases with its wavelength. In about 47,000 years, the energy density of matter became larger than that of photons and neutrinos, and began to dominate the large-scale behavior of the universe. This marked the end of the radiation-dominant era and the beginning of the substance-dominated era.
In the early stages of the universe, dark matter concentrations slowly began to form due to small fluctuations within the density of the universe. Ordinary materials, which are attracted to them by gravity, form large gas clouds and, eventually, stars and galaxies, where the dark matter was most dense, and where it was least dense. After about 100 - 300 million years, the first star was formed, known as Population III star. These were probably very large, shiny, non-metallic and ephemeral. They were responsible for the gradual recombination of the universe between about 200–500 million years and 1 billion years, and also for the planting of a universe with elements heavier than helium through stellar nucleosynthesis.
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