16
A Brief Overview of the Big Bang Theory of
the Universe
To see the role of neutrinos in the universe in the past, present, and future,
we need to have an overview of the basic features in the evolution of the
universe. The universe is now about 13 billion years old, starting from the
moment of the “Big Bang.” It went through many stages in its evolution
that eventually created all the known features that we see today, such as
galaxies, stars, and various elements in different abundances. So how did it
all happen? There have been many people thinking about these issues for the
past century, starting with Einstein, De Sitter, Lemaitre, Hubble, Friedmann,
Robertson, and Walker, just to name a few. The universe provides a setting
that is unlikely to be achievable in the laboratory, but the ideas that went into
our understanding of the universe have been inspired by many phenomena
that have been observed in the laboratory. For example, the change of water
to steam or ice to water is a common phenomenon known as phase transition
in physics, and similar phenomena are expected to have occurred in the early
stages of the universe.
16.1 Big Bang Theory vs. Steady State Theory
The first part of the struggle to understand the details of the universe started
with uncovering the overall nature of its evolution. There have been several
theories regarding the evolution of the universe, but two most popular rival
theories until few decades ago were: (1) the Big Bang theory and (2) steady
state theory. The first one was proposed by Belgian priest and physicist George
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer
Nature Switzerland AG 2021
R. N. Mohapatra, The Neutrino Story: One Tiny Particle’s Grand Role in the Cosmos,
https://doi.org/10.1007/978-3-030-51846-2_16
123
A Brief Overview of the Big Bang Theory of
the Universe
To see the role of neutrinos in the universe in the past, present, and future,
we need to have an overview of the basic features in the evolution of the
universe. The universe is now about 13 billion years old, starting from the
moment of the “Big Bang.” It went through many stages in its evolution
that eventually created all the known features that we see today, such as
galaxies, stars, and various elements in different abundances. So how did it
all happen? There have been many people thinking about these issues for the
past century, starting with Einstein, De Sitter, Lemaitre, Hubble, Friedmann,
Robertson, and Walker, just to name a few. The universe provides a setting
that is unlikely to be achievable in the laboratory, but the ideas that went into
our understanding of the universe have been inspired by many phenomena
that have been observed in the laboratory. For example, the change of water
to steam or ice to water is a common phenomenon known as phase transition
in physics, and similar phenomena are expected to have occurred in the early
stages of the universe.
16.1 Big Bang Theory vs. Steady State Theory
The first part of the struggle to understand the details of the universe started
with uncovering the overall nature of its evolution. There have been several
theories regarding the evolution of the universe, but two most popular rival
theories until few decades ago were: (1) the Big Bang theory and (2) steady
state theory. The first one was proposed by Belgian priest and physicist George
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer
Nature Switzerland AG 2021
R. N. Mohapatra, The Neutrino Story: One Tiny Particle’s Grand Role in the Cosmos,
https://doi.org/10.1007/978-3-030-51846-2_16
123