Talk:Big Bang nucleosynthesis

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Contents 1 Falicious Times for Early Universe Events are Obtained with Non-Relativistic Models 2 p + p → d + π 3 Question 4 Citation needed 5 Request for comments: cited articles/article for general audience

[edit] Falicious Times for Early Universe Events are Obtained with Non-Relativistic Models

I suspect that the universe started with roughly 10¹¹ dead galaxies falling in with a total mass of approximately 2x10²² solar masses that were composed largely of white dwarf material that slammed together a bit like the pieces of a uranium bomb. The infalling material was primarily cooled white dwarf remanant material with a small admixture of neutron stars, and when it slammed together the radiation-dominated era began immediately. Calculations show that the initial fireball was radially unstable, such that the energy required to compress it against radiation pressure for a meter was just equal to the work done by the gravitational field in shrinking the fireball radius another meter. Thus the universe was eventually compressed to its limiting density, that of a nucleon, as it coasted in from the ignition perimeter at , initially at white dwarf density, without gaining additional energy. This would have yielded a lower spherical radius limit at nucleon density about equal to the radius of the orbit of Mars. The black body radiation field switched on at a temperature determined roughly from

,

containing many billions of times as much mass-energy ε from the infall kinetic energy as the entire nucleonic rest mass-energy. It was a bit like a man jumping on an elevator going down at constant velocity in the presence of radiation pressure ε/3. The energy release was rapid and ultimately explosive when the hard-core nucleonic potential caused a reflection shock wave that turned the infall around. Composed of dead galaxies of cold white dwarf material of the approximate density 3.55x10⁸ kg/m3, the universe mass fell into a sphere of radius 2000 AU, or 2.99x10¹4 meters, just 0.0316 light-years, before lighting up and coasting down to nucleon density radius over a period of several months at v < c. Subsequent calculations have shown that it took over 26.7244 years for the fireball to expand and cool enough for deuterium and helium to form, kicking in fusion energy, and the galaxies formed well over 3.542x10⁵ years after the reflection from nucleonic density, following the end of the radiation-dominated era at the time when radiation was decoupled from matter and the matter-dominated era began. These times are longer than many times you may read about elsewhere that were computed from approximate, non-relativistic models for the expansion of a universe of constant density. We find easy closed-form solutions to the approximate equations like

r = a(t)^{2 / 3}, with v = (2 / 3)a(t) ^{− 1 / 3} (matter-dominated era) and

r = b(t)^{1 / 2} , with v = (1 / 2)b(t) ^{− 1 / 2} (radiation-dominated era).

For both cases, it is easy to specify early times such that v >> c. These difficulties yielding short times to key early-universe events vanish when we use [16]

F = dp / dt = d / dt[m₀v / (1 − v² / c²)^{1 / 2}] = (GM / r²)[m₀ / (1 − v² / c²)^{1 / 2}],

as the basis of our calculations, neglecting a pressure term at first. Here the force is equal to the time-derivative of the special relativistic momentum p = m₀v / (1 − v² / c²)^{1 / 2}, and gravitating mass is equal to inertial mass m₀ / (1 − v² / c²)^{1 / 2}. Note that the equal falling of objects of different mass is preserved, so the principle of equivalance may still be applied. On the other hand, solutions are difficult to obtain in closed form then. However, one can easily show that velocities with v > c are never realized. We have gas- and radiation-ball theorems that give the radius R as a function of the temperature T in the form R(T). Then the expression t > R(T)/c gives the time for the expansion of the fireball to radius R(T) for any given early universe event temperature.

Our infall-before-bounce scheme insures that the basic conservation laws always hold true. I note that matter always falls in before supernovae, novae, or plantary nebula ejection occur, so it is natural to extend this to the Big Bang, equipping it with a preliminary Big Crunch and Crunch-Bang or Squeeze-Boom cosmic cycles. The matter-dominated era nucleons in the subsequent cooled Big Bang fireball are thought to be conserved across cosmic cycles hundreds of billions of years in length. - James A. Green, May 6, 2006 JamesAGreen 17:07, 6 May 2006 (UTC). See http://greenwdks.tripod.com/bigbangabundan.html for more on the Big Bang and the Big Crunch.

Why is it written:

It is believed to be responsible for the formation of hydrogen (H-1 or simply H), its isotope deuterium (H-2 or D), the helium isotopes ... etc

H-1 was not formed by nucleosynthesis, it is just protons, formed much earlier during the Big Bang. Right? BIL 20:20, 12 October 2006 (UTC)

[edit] p + p → d + π

Over on Plasma cosmology#Light elements abundance, Eric Lerner's theory is cited, that deuterium was formed by the above reaction between cosmic rays and cold protons. This article (BBN) makes it sound like everything had already been considered in the 70s. If anyone has a reference that specifically says this reaction was considered and rejected, it would make a very nice addition to the plasma cosmology article. (Of course, if a generation of cosmologists really overlooked this possibility, that would be even more delicious.) --Art Carlson 13:23, 7 November 2006 (UTC)

[edit] Question

When were all the other elements created? Gold, iron and the other metals? Could someone point me in the right direction? Thansk

Nucleosynthesis

[edit] Citation needed

The citation needed in the helium-4 section about ending the Big Bang nucleosynthesis crisis could be this from the Astrophysical Journal, University of Pennsylvania:

http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v508n2/36591/36591.web.pdf

Since I'm not familiar with the template for inserting sources that are periodicals, I hope someone will enter this reference. --Sir48 11:28, 12 February 2007 (UTC)

[edit] Request for comments: cited articles/article for general audience

A while ago, I made some changes to this article, adding a reference to the new WMAP measurements to the "Observational Tests" section and stressing the race between equilibrium and external change by expansion in the "Sequence of BBN section", adding as references two web articles by Achim Weiss (from the Max Planck Institute of Astrophysics in Munich). I also split the external links into technical links and those suitable for a general audience, and added a more general article by Weiss to the latter section.

Those were pretty much my first contributions to Wikipedia, and I hadn't progressed in reading the "How to" pages as much as I probably should have - anyway, I realize now that I should have declared a conflict of interest, since the three articles by Weiss are published on a website which I edit (Einstein Online). I think that my behaviour was as cautious and neutral as the guidelines suggest, and that I might be overdoing it by making this grand declaration here, but hey, I guess that's not up to me to decide - hence this request for comments. Markus Poessel 12:06, 5 April 2007 (UTC)

This really does not seem like a conflict of interest to me. Also, the material that was inserted seems reasonable, although I am not an expert on Big Bang nucleosynthesis. You may want to add references to refereed journal articles to supplement the existing references, but that is my only suggestion. Dr. Submillimeter 14:03, 5 April 2007 (UTC)

Thanks for your comment. At least for the observational tests, I've now added references to journal articles. Markus Poessel 19:49, 5 April 2007 (UTC)

Thanks for the help! I don't see any serious conflict of interest here, assuming we're not going to have *all* articles from your website down the road. Don't sweat the "grand declaration." It's considerate of you to check. Just don't let it stop you from being bold! Cheers, Gnixon 15:46, 6 April 2007 (UTC)

Thanks for the reassurance. I was certainly not planning on linking *all* articles, but I think a number of them would make good external links for the topics they address - don't worry, though, I'll follow proper procedure regarding those, proposing the additions on the respective talk pages and letting other Wikipedians decide. Markus Poessel 19:11, 7 April 2007 (UTC)