The Big Bang Nucleosynthesis Homepage

One of the principle predictions of the standard Hot Big Bang model is the synthesis of light elements in the primordial universe. The references showing that stellar processes cannot account for the observed abundances are well know, and the calculations of Big Bang Nucleosynthesis (BBN) have been performed for decades. These calculations are very sensitive to some parameters that are measured in terrestrial experiments, and are constrained by the observations of astronomers.

There has been rapid improvement in both sets of measurments in the recent past. The improvement has been rapid enough that a quickly responsive forum for the latest implications of these measurments is appropriate. The goal of this Web site is to provide the needed fourm, and to serve as a clearing house for the latest information and speculation regarding BBN.

The organization of this site is simplistic, but it has not been written with a lay audience in mind. Since much of the information available is pictoral in nature, it is strongly suggested that a browser with graphic capabilities be used.

nucleon to photon ratio expansion parameter number of neutrino families
neutrino masses more massive nucleons exotic particles
other reactions The Big Picture References

If you have questions or comments about the site or the information contained in it, please send mail to:

John Phillips (

This site developed and maintained by the Astrophysics Theory Group of The Ohio State University.