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According to current theories, the first nuclei were formed a few minutes after the Big Bang, through nuclear reactions in a process called Big Bang nucleosynthesis. [1] After about 20 minutes, the universe had expanded and cooled to a point at which these high-energy collisions among nucleons ended, so only the fastest and simplest reactions ...
In physical cosmology, Big Bang nucleosynthesis (also known as primordial nucleosynthesis, and abbreviated as BBN) [1] is a model for the production of light nuclei, deuterium, 3 He, 4 He, 7 Li, between 0.01s and 200s in the lifetime of the universe. [2] The model uses a combination of thermodynamic arguments and results from equations for the ...
Cosmic rays are highly energetic charged particles from beyond Earth, ranging from protons, alpha particles, and nuclei of many heavier elements. About 1% of cosmic rays also consist of free electrons. [citation needed] Cosmic rays cause spallation when a ray particle (e.g. a proton) impacts with matter, including other cosmic rays.
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. [1]
Hydrogen-1 is the most abundant nuclide, comprising roughly 92% of the atoms in the Universe, with helium-4 second at 8%. Other isotopes including 2 H, 3 H, 3 He, 6 Li, 7 Li, and 7 Be are much rarer; the estimated abundance of primordial lithium is 10 −10 relative to hydrogen. [ 7 ]
The new Sentinel nuclear weapons program is 81% over budget and is now estimated to cost nearly $141 billion, but the Pentagon is moving forward with the program, saying that given the threats ...
An inhomogeneous cosmology is a physical cosmological theory (an astronomical model of the physical universe's origin and evolution) which, unlike the dominant cosmological concordance model, assumes that inhomogeneities in the distribution of matter across the universe affect local gravitational forces (i.e., at the galactic level) enough to skew our view of the Universe. [3]
The exercise involved Russia's full nuclear "triad" of ground-, sea- and air-launched missiles. ... "I stress that we are not going to get involved in a new arms race, but we will maintain nuclear ...