Evidence for the Big Bang - TalkOrigins Archive: …
Big Bang - Wikipedia
Periodic Table Database | Chemogenesis
A star gains heavier elements by combining its lighter nuclei, , , , , and , which were found in the initial composition of the interstellar medium and hence the star. Interstellar gas therefore contains declining abundances of these light elements, which are present only by virtue of their nucleosynthesis during the Big Bang. Larger quantities of these lighter elements in the present universe are therefore thought to have been restored through billions of years of (mostly high-energy proton) mediated breakup of heavier elements in interstellar gas and dust. The fragments of these cosmic-ray collisions include the light elements Li, Be and B.
occurred within the first three minutes of the beginning of theuniverse and is responsible for much of the abundance ratios of1H (), 2H (), 3He(), and4He (),in the universe .Although 4He continues to be produced by othermechanisms (such as stellar fusion and alpha decay) and traceamounts of 1H continue to be produced by and certaintypes of radioactive decay ( and ), most of the mass of these isotopes in the universe,and all but the insignificant traces of the 3He anddeuterium in the universe produced by rare processes such as , arethought to have been produced in the . The nuclei of these elements, alongwith some 7Li, and 7Be are believed to havebeen formed when the universe was between 100 and 300 seconds old,after the primordial - plasma froze out to form and . Because of the very short period inwhich Big Bang nucleosynthesis occurred before being stopped byexpansion and cooling, no elements heavier than could be formed. (Elements formedduring this time were in the plasma state, and did not cool to thestate of neutral atoms until much later).
Theo Gray's Photographic Periodic Table
It is thought that the primordial nucleons themselves were formed from the during the as it cooled below two trillion degrees. A few minutes afterward, starting with only and , nuclei up to and (both with mass number 7) were formed, but the abundances of other elements dropped sharply with growing atomic mass. Some may have been formed at this time, but the process stopped before significant could be formed, as this element requires a far higher product of helium density and time than were present in the short nucleosynthesis period of the Big Bang. That fusion process essentially shut down at about 20 minutes, due to drops in temperature and density as the universe continued to expand. This first process, , was the first type of nucleogenesis to occur in the universe.
The abundance of the light elements can be predicted using just one quantity — the density of baryons at the time of nucleosynthesis. Baryons are particles made with three quarks, such as protons and neutrons. Using the baryon density predicted by big bang nucleosynthesis, the total mass of the universe would have been 25% helium, 0.01% deuterium and even less than that would have been lithium. These primordial abundances can be tested, and, of course, have been. Nowhere in the universe is helium seen with an abundance less than 23%. This is a major piece of evidence for the big bang.
The INTERNET Database of Periodic Tables - Periodic …
producessome of the lightest elements present in the universe (though notsignificant ).Most notably spallation is believed to be responsible for thegeneration of almost all of 3He and the elements , and (some lithium-7 and beryllium-7 are thoughtto have been produced in the Big Bang). The spallation processresults from the impact of (mostlyfast protons) against the . These impactsfragment carbon, nitrogen and oxygen nuclei present in the cosmicrays, and also these elements being struck by protons in cosmicrays. The process results in these light elements (Be, B, and Li)being present in cosmic rays at much higher proportion than theyare represented in solar atmospheres, whereas H and He nuclei arerepresented in cosmic rays with approximately primordial abundancewith regard to each other.
ABSTRACT With the advent of the new extragalactic deuterium observations, Big Bang nucleosynthesis (BBN) is on the verge of undergoing a transformation. In the past, the emphasis has been on demonstrating the concordance of the BBN model with the abundances of the light isotopes extrapolated back to their primordial values by using stellar and galactic evolution theories. As a direct measure of primordial deuterium is converged upon, the nature of the field will shift to using the much more precise primordial D/H to constrain the more flexible stellar and galactic evolution models (although the question of potential systematic error in 4He abundance determinations remains open). The remarkable success of the theory to date in establishing the concordance has led to the very robust conclusion of BBN regarding the baryon density. This robustness remains even through major model variations such as an assumed first-order quarkhadron phase transition. The BBN constraints on the cosmological baryon density are reviewed and demonstrate that the bulk of the baryons are dark and also that the bulk of the matter in the universe is nonbaryonic. Comparison of baryonic density arguments from Lyman-α clouds, x-ray gas in clusters, and the microwave anisotropy are made.
Introduction Why yet another review of big bang nucleosynthesis (BBN)
Title: Big-Bang nucleosynthesis (PDG mini-review)
Primordial nucleosynthesis - Revolvy
the primordial abundances at the end of the big-bang.
a) Purpose of this FAQ; b) General outline; c) Further sources for information; 1) What is the Big Bang theory
These primordial abundances can be tested, ..
Big Bang nucleosynthesis occurred within the first three minutes of the beginning of the universe and is responsible for much of the abundance of 1H (), 2H (D, ), 3He (), and 4He (). Although 4He continues to be produced by stellar fusion and and trace amounts of 1H continue to be produced by and certain types of radioactive decay, most of the mass of the isotopes in the universe are thought to have been produced in the . The nuclei of these elements, along with some 7Li and 7Be are considered to have been formed between 100 and 300 seconds after the Big Bang when the primordial froze out to form and . Because of the very short period in which nucleosynthesis occurred before it was stopped by expansion and cooling (about 20 minutes), no elements heavier than (or possibly ) could be formed. Elements formed during this time were in the plasma state, and did not cool to the state of neutral atoms until much later.
bbn - 20 Big-Bang nucleosynthesis 1 20 BIG ..
The Big Bang itself had been proposed in 1931, long before this period, by , a Belgian physicist, who suggested that the evident expansion of the Universe in time required that the Universe, if contracted backwards in time, would continue to do so until it could contract no further. This would bring all the mass of the Universe to a single point, a "primeval atom", to a state before which time and space did not exist. Hoyle later gave Lemaître's model the derisive term of Big Bang, not realizing that Lemaître's model was needed to explain the existence of deuterium and nuclides between helium and carbon, as well as the fundamentally high amount of helium present, not only in stars but also in interstellar space. As it happened, both Lemaître and Hoyle's models of nucleosynthesis would be needed to explain the elemental abundances in the universe.
Sarkar BBN | Dark Matter | Big Bang - Scribd
The paper was published in Physical Review on April 1st 1948. Titled “The Origin of Chemical Elements”, it described a process by which all of the known elements in the universe could have come into existence shortly after the big bang. It built on previous work by Gamow that suggested the elements originated “as a consequence of a continuous building-up process arrested by a rapid expansion and cooling of the primordial matter” — in other words, different atoms were made by adding one nucleon at a time to the nucleus, before the process was stopped when the universe became too cool.
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