# Big-Bang Nucleosynthesis And The Baryon Density Of The Universe

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Current models of the universe suggest the first galaxies began forming about 100 million years after the Big Bang, marking the beginning of the end of the dark ages.

This process of star and galaxy formation gradually continued until virtually all the hydrogen and helium that make up most of the universe was once again ionized, this time by starlight, about 500 million years after the Big Bang.

It is known that the weak force has a CP asymmetry that could contribute to a larger number of particles over antiparticles.

To match the otherwise expected equality, roughly, of baryons and photons, it would have to account for the roughly 1 billion to 1 preference for particles over antiparticles.

Deuterium is observed as a Lyman-$\alpha$ feature in the absorption spectra of high-redshift quasars.

A recent analysis gives $\Omega(^2$H$)h^2 = 0.020 \pm 0.001 \quad (1 \sigma \;$CL$)$ more precisely than any other determination.Even cold hydrogen gives off light in the form of radio waves with a specific wavelength of 21 centimeters. An easy to read article on Galaxy Cosmos Redshift 7 is Science Magazine's "Astronomers spot first-generation stars, made from big bang", by Daniel Clery (Jun. The baryon to photon ratio is estimated and measured. The photon density is calculated in various ways, but one way is from the CMB temperature of 2.73K.The baryon to photon ratio is estimated in a more complex way, and is related to the ratio of baryon density to the critical density (for a flat universe), and the Hubble constant.Studies of Big Bang Nucleosynthesis - the formation of atomic nuclei like those of helium, deuterium or lithium in the early universe - have led to some of the most impressive predictions of the big bang models.A brief overview can be found in the spotlight text Big Bang Nucleosynthesis: Cooking up the first light elements - here, we take a closer look at the physics behind the predictions.Is this ratio derived from first principles -if so, how- or, if it results from a small favoritism for matter over antimatter in the early universe, then from what observations is the baryon/photon ratio calculated -and how?Though the early universe is assumed to be dominated by radiation, how do we know this?The He and other baryons produced in Big Bang nucleosynthesis (BBN) is also covered in that reference, and others.The abundance of $^4H_e$ is not too sensitive to $\eta$ but the other light elements up to $L_i$ are.By definition, in thermodynamic equilibrium the energy is distributed evenly among all components of a system.For a simple gas, this would mean that, on average, all of the myriads of particles flying around have the same kinetic energy.

## Comments Big-Bang Nucleosynthesis And The Baryon Density Of The Universe

• ###### Big Bang nucleosynthesis - Alchetron, the free social

The baryon–photon ratio, η, is the key parameter determining the abundance of light elements present in the early universe. During the 1970s, there was a major puzzle in that the density of baryons as calculated by Big Bang nucleosynthesis was much less than the observed mass of the universe.…

• ###### Big Bang nucleosynthesis

Big Bang nucleosynthesis begins about one minute after the Big Bang, when the universe has cooled enough to form stable protons and neutronsThis fraction is in favour of protons, because the higher mass of the neutron results in a spontaneous decay of neutrons to protons with a half-life of.…

• ###### Big Bang Nucleosynthesis

The Big Bang Nucleosynthesis theory predicts that roughly 25% of the mass of the Universe consists of Helium. Further support comes from the consistency of the other light element abundances for one particular baryon density. It seems like we really understand the physical.…

• ###### The Big Bang, Nucleosynthesis, and the Formation of

Roughly three minutes after Big Bang, temperature of Universe rapidly cooled from its phenomenal 1032 Kelvin to approximately 109 Kelvin, allowing nucleosynthesis, or the productionone value of baryon density in the early Universe can explain all the observed abundances at once -- theory works!…

• ###### Big Bang Nucleosynthesis - an overview ScienceDirect

The theory of big-bang nucleosynthesis BBN predicts rather successfully the primordialHowever we know that even in the least dense regions of the universe there are hydrogen gas cloudsIn the early days of big bang cosmology, the baryon asymmetry was considered to be an initial condition.…

• ###### Big Bang nucleosynthesis Baryon–photon ratioedit

Big Bang nucleosynthesis began roughly 10 seconds after the big bang, when the universe had cooled sufficiently to allow deuterium nuclei toA version of the periodic table indicating the origins – including big bang nucleosynthesis – of the elements All elements above 103 lawrencium are also.…

• ###### Big Bang Nucleosynthesis Research Papers - Academia.edu

Big Bang Nucleosynthesis. 10 Followers. Papers. People. A range of baryonic density between 0.01 and 0.2 is obtained when recent studies of the influence of the quark-hadron should carry unique signatures from the earliest epochs in the evolution of the Universe, inaccessible to.…

• ###### Big Bang nucleosynthesis" in Wikipedia 2.2 Baryon

The baryon-photon ratio Eta, is a strong indicator of the abundance of light elements present in the early universe. During the 1970s, there was a major puzzle in that the density of baryons as calculated by Big Bang nucleosynthesis was much less than the observed mass of the universe.…

• ###### Big-bang nucleosynthesis and the baryon density of the

For almost 30 years, the predictions of big-bang nucleosynthesis have been used to test the big-bang model to within a fraction of a second of the bang. The agreement between the predicted and observed.…

• ###### Big Bang nucleosynthesis - WikiVisually Early universe

Big Bang nucleosynthesis began roughly 10 seconds after the big bang, when the universe had cooled sufficiently to allow deuterium nuclei toAs the universe expands, it cools. Free neutrons are less stable than helium nuclei, and the protons and neutrons have a strong tendency to form helium-4.…