Lecture

Big Bang Nucleosynthesis: Cosmic Evolution and Reactions

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Description

This lecture covers the fundamental concepts of Big Bang nucleosynthesis (BBN) and its implications for the early universe. It begins with a review of the general picture of BBN, emphasizing the abundance of light elements formed during this period. The instructor discusses the equilibrium conditions and the finite reaction rates that affect the abundance of elements like hydrogen, helium, and deuterium. Saha's equation is introduced to explain the relationship between temperature and particle densities. The lecture also addresses the role of neutrinos and their decoupling from matter, which is crucial for understanding the thermal history of the universe. The instructor highlights the significance of the cosmic microwave background (CMB) as evidence of BBN and its connection to the observed elemental abundances. The discussion includes the baryon-to-photon ratio and its implications for the formation of elements. The lecture concludes with a focus on nuclear reactions and binding energies, providing a comprehensive overview of the processes that shaped the early universe.

Official source

Ontological neighbourhood

Physics

Nuclear physics: Topics in nuclear physics

Astronomy

Astrophysics: Physical cosmology

Related concepts (32)

Big Bang nucleosynthesis

In physical cosmology, Big Bang nucleosynthesis (also known as primordial nucleosynthesis, and abbreviated as BBN) is the production of nuclei other than those of the lightest isotope of hydrogen (hydrogen-1, 1H, having a single proton as a nucleus) during the early phases of the universe. This type of nucleosynthesis is thought by most cosmologists to have occurred from 10 seconds to 20 minutes after the Big Bang.

Cosmic neutrino background

The cosmic neutrino background (CNB or CνB) is the universe's background particle radiation composed of neutrinos. They are sometimes known as relic neutrinos. The CνB is a relic of the Big Bang; while the cosmic microwave background radiation (CMB) dates from when the universe was 379,000 years old, the CνB decoupled (separated) from matter when the universe was just one second old. It is estimated that today, the CνB has a temperature of roughly 1.95K. As neutrinos rarely interact with matter, these neutrinos still exist today.

Chronology of the universe

The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, with an uncertainty of around 21 million years at the 68% confidence level. For the purposes of this summary, it is convenient to divide the chronology of the universe since it originated, into five parts.

Cosmology

Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term cosmology was first used in English in 1656 in Thomas Blount's Glossographia, and in 1731 taken up in Latin by German philosopher Christian Wolff, in Cosmologia Generalis. Religious or mythological cosmology is a body of beliefs based on mythological, religious, and esoteric literature and traditions of creation myths and eschatology. In the science of astronomy, cosmology is concerned with the study of the chronology of the universe.

Universe

The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. According to this theory, space and time emerged together 13.787billion years ago, and the universe has been expanding ever since the Big Bang. While the spatial size of the entire universe is unknown, it is possible to measure the size of the observable universe, which is approximately 93 billion light-years in diameter at the present day.

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