[25] Similarly, deuterium fuses extremely easily; any alternative explanation must also explain how conditions existed for deuterium to form, but also left some of that deuterium unfused and not immediately fused again into helium. [52], The October 2010 discovery of UDFy-38135539, the first observed galaxy to have existed during the following reionization epoch, gives us a window into these times. After cosmic inflation ends, the universe is filled with a hot quark–gluon plasma, the remains of reheating. Quasars provide some additional evidence of early structure formation. The FLRW metric very closely matches overwhelming other evidence, showing that the universe has expanded since the Big Bang. A few isotopes, such as lithium-7, were found to be present in amounts that differed from theory, but over time, these differences have been resolved by better observations.[25]. {\displaystyle a} At some time the Stelliferous Era will end as stars are no longer being born, and the expansion of the universe will mean that the observable universe becomes limited to local galaxies. The exact timings of the first stars, galaxies, supermassive black holes, and quasars, and the start and end timings and progression of the period known as reionization, are still being actively researched, with new findings published periodically. Theory predicts that about 1 neutron remained for every 6 protons. T Between about 2 and 20 minutes after the Big Bang, the temperature and pressure of the universe allowed nuclear fusion to occur, giving rise to nuclei of a few light elements beyond hydrogen ("Big Bang nucleosynthesis"). [26], However, Big Bang cosmology makes many predictions about the CνB, and there is very strong indirect evidence that the CνB exists, both from Big Bang nucleosynthesis predictions of the helium abundance, and from anisotropies in the cosmic microwave background (CMB). In several of the more prominent models, it is thought to have been triggered by the separation of the strong and electroweak interactions which ended the grand unification epoch. At around 47,000 years,[2] as the universe cools, its behaviour begins to be dominated by matter rather than radiation. As the universe continued to cool and expand, reionization gradually ended. [4][50] Loeb argues that carbon-based life might have evolved in a hypothetical pocket of the early universe that was dense enough both to generate at least one massive star that subsequently releases carbon in a supernova, and that was also dense enough to generate a planet. Forces and interactions arise due to these fields, so the universe can behave very differently above and below a phase transition. Structures may have begun to emerge from around 150 million years, and early galaxies emerged from around 380 to 700 million years. Beyond this, all objects in the universe will cool and (with the possible exception of protons) gradually decompose back to their constituent particles and then into subatomic particles and very low level photons and other fundamental particles, by a variety of possible processes. The spherical volume inside it is commonly referred to as the observable universe. Cosmology is the natural complement of the special sciences. (Such dense pockets, if they existed, would have been extremely rare.) (However the total matter in the universe is only 31.7%, much smaller than the 68.3% of dark energy.) In inflationary models of cosmology, times before the end of inflation (roughly 10−32 seconds after the Big Bang) do not follow the same timeline as in traditional big bang cosmology. The lepton epoch follows a similar path to the earlier hadron epoch. To explain the observed homogeneity of the universe, the duration in these models must be longer than 10−32 seconds. The ultimate fate of our universe hinges on dark energy. COSMOLOGY, THEORIES. If we can take anything from this invaluable knowledge, is that the march of scientific must continue…because the universe sure isn’t going to slow down and wait for us to catch up. The newly formed atoms—mainly hydrogen and helium with traces of lithium—quickly reach their lowest energy state (ground state) by releasing photons ("photon decoupling"), and these photons can still be detected today as the cosmic microwave background (CMB). (We do not have separate observations of very early individual stars; the earliest observed stars are discovered as participants in very early galaxies.) In the early universe, dark matter gradually gathers in huge filaments under the effects of gravity, collapsing faster than ordinary (baryonic) matter because its collapse is not slowed by radiation pressure. [28] Several mechanisms could produce dense regions meeting this criterion during the early universe, including reheating, cosmological phase transitions and (in so-called "hybrid inflation models") axion inflation. (Much later, hydrogen and helium hydride react to form molecular hydrogen, the fuel needed for the first stars.). [66] Only about 10 of these extremely early objects are currently known. The first generation of stars, known as Population III stars, formed within a few hundred million years after the Big Bang. At around 100,000 years, the universe has cooled enough for helium hydride, the first molecule, to form. As neutrinos rarely interact with matter, these neutrinos still exist today, analogous to the much later cosmic microwave background emitted during recombination, around 370,000 years after the Big Bang. Atomic nuclei will easily unbind (break apart) above a certain temperature, related to their binding energy. k Aristotle's cosmology belonged to the class of steady-state theories in so far … It will continue to look similar for many more billions of years into the future. There are several competing scenarios for the possible long-term evolution of the universe. {\displaystyle a^{-2}} Random fluctuations could lead to some regions becoming dense enough to undergo gravitational collapse, forming black holes. Not now considered likely. This heating effect led to the universe being repopulated with a dense, hot mixture of quarks, anti-quarks and gluons. This was the period in the evolution of the early universe immediately after electroweak symmetry breaking, when the fundamental interactions of gravitation, electromagnetism, the strong interaction and the weak interaction had taken their present forms, but the temperature of the universe was still too high to allow quarks to bind together to form hadrons. This occurs because the energy density of matter begins to exceed both the energy density of radiation and the vacuum energy density. δ Observations challenge cosmological theories. {\displaystyle a^{-1}} Even atomic nuclei will be torn apart. Lemaître used these findings to draw attention to his earlier paper, in which he explained the relationship between the distance of a galaxy and the recession velocity of that same galaxy. Someone is looking for the history of the big bang, creation of atoms, etc, only to find that he is looking at the history of the THEORIES about these matters. The most distant galaxy observed as of October 2016, GN-z11, has been reported to be 32 billion light-years away,[53][68] a vast distance made possible through spacetime expansion (z = 11.1;[53] comoving distance of 32 billion light-years;[68] lookback time of 13.4 billion years[68]). Cosmology is concerned with fundamental questions about the formation and evolution of the universe. Therefore, in inflationary cosmology, the earliest meaningful time "after the Big Bang" is the time of the end of inflation. It is widely believed that a correct theory of quantum gravity may allow a more correct description of that event, but no such theory has yet been developed. At about 370,000 years,[3] the universe finally becomes cool enough for neutral atoms to form ("recombination"), and as a result it also became transparent for the first time. Timeline. About 370,000 years after the Big Bang, two connected events occurred: recombination and photon decoupling. In doing so, they completely shift how they interact. Instead of slowing down and perhaps beginning to move inward under the influence of gravity, from about 9.8 billion years of cosmic time, the expansion of space starts to slowly accelerate outward at a gradually increasing rate. Going forward, this provides a model of the universe which matches all current physical observations extremely closely. If this is true, at 30 billion years all other galaxies are pulled from our view and all evidence of the big bang is lost forever (it may be possible that future astronomers could deduce its existence using a few methods…but hopefully we keep good records). After most leptons and antileptons are annihilated at the end of the lepton epoch, most of the mass-energy in the universe is left in the form of photons. To ionize neutral hydrogen, an energy larger than 13.6 eV is required, which corresponds to ultraviolet photons with a wavelength of 91.2 nm or shorter, implying that the sources must have produced significant amount of ultraviolet and higher energy. In the case of indefinitely continuing metric expansion of space, the energy density in the universe will decrease until, after an estimated time of 10, Expansion of space accelerates and at some point becomes so extreme that even subatomic particles and the fabric of, For any value of the dark energy content of the universe where the negative pressure ratio is less than -1, the expansion rate of the universe will continue to increase without limit. The Planck epoch is an era in traditional (non-inflationary) Big Bang cosmology immediately after the event which began the known universe. 0.1 c These phase transitions in the universe's fundamental forces are believed to be caused by a phenomenon of quantum fields called "symmetry breaking". It begins where they leave off, and its domain is quite distinct from theirs. 100 million years: the limit of current observations, that is, the highest red-shifted objects detectable (the oldest objects that we can see) are at a time of when the universe was 600 million years old. Around the same time as recombination, existing pressure waves within the electron-baryon plasma—known as baryon acoustic oscillations—became embedded in the distribution of matter as it condensed, giving rise to a very slight preference in distribution of large-scale objects. Although light and objects within spacetime cannot travel faster than the speed of light, in this case it was the metric governing the size and geometry of spacetime itself that changed in scale. 1929. The singularity from the FLRW metric is interpreted to mean that current theories are inadequate to describe what actually happened at the start of the Big Bang itself. . For a slightly different perspective, also see the section on Cosmological Theories Through History. At about one second, neutrinos decouple; these neutrinos form the cosmic neutrino background (CνB). By the end of recombination, most of the protons in the universe have formed neutral atoms. 3 Ordinary matter eventually gathers together faster than it would otherwise do, because of the presence of these concentrations of dark matter. Directly combining in a low energy state (ground state) is less efficient, so these hydrogen atoms generally form with the electrons still in a high energy state, and once combined, the electrons quickly release energy in the form of one or more photons as they transition to a low energy state. [25], At approximately 1 second after the Big Bang neutrinos decouple and begin travelling freely through space. Mid 1600s 1687 1687 1791 1848 1895 1905 1915 1922 1940s 1970s 1980s 1927 Big Bang Theory 1929 Discovery of Red Shift So how does this prove the Big Bang Theory? 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Read about Copernicus' heliocentric view, Descartes' vortices, Einstein's relativity revolution, the first big bang models and the startling new inflation and multiverse hypotheses. If the universe continues to grow at about the same pace, this will result in all the last stars burning out in about 100 trillion years (so we’ve got some time left anyway). [67] More recent observations have shown these ages to be shorter than previously indicated. Earliest galaxies: from about ¿300–400 Ma? And at 30 billion years, we could have what is known as a “Big crunch”. At this epoch, the collision rate is proportional to the third root of the number density, and thus to 1917: Albert Einstein Invents the Cosmological Constant Albert Einstein is widely celebrated as one of the most brilliant scientists who ever lived. And this was the birth of Big Bang cosmology. Note: While the concept of dark energy in modern cosmological theory also accelerates the expansion of the universe, the mechanisms involved appear to be very different from those involved in inflation theory. [64] (This age estimate is now believed to be slightly overstated).[65]. ℏ Just before recombination, the baryonic matter in the universe was at a temperature where it formed a hot ionized plasma. This amplifies the tiny inhomogeneities (irregularities) in the density of the universe which was left by cosmic inflation. The universe has existed for around 13.8 billion years, and we believe that we understand it well enough to predict its large-scale development for many billions of years into the future—perhaps as much as 100 billion years of cosmic time (about 86 billion years from now). Therefore dark matter collapses into huge but diffuse filaments and haloes, and not into stars or planets. 10 ^-35 seconds: cosmic inflation creates what is known as quark–gluon plasma. The matter in the universe is around 84.5% cold dark matter and 15.5% "ordinary" matter. In either case, these early generations of supernovae created most of the everyday elements we see around us today, and seeded the universe with them. After cosmic inflation ends, the universe is filled with a hot quark–gluon plasma, the remains of reheating. {\displaystyle (k_{B}T/\hbar c)^{3}} Subsequently, Leiden University's Rychard J. Bouwens and Garth D. Illingworth from UC Observatories/Lick Observatory found the galaxy UDFj-39546284 to be even older, at a time some 480 million years after the Big Bang or about halfway through the Dark Ages 13.2 billion years ago. 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. 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