In this thesis, I first review the fundamentals of Einstein's theory of gravity in four-dimensional spacetimes, and then develop the general formulas of thin shells in this theory. Applying these formulas to spherically symmetric thin shells, I study the gravitational collapse of dust clouds in the background of dark energy. To solve the relevant equations, I develop a computer program, and investigate four representative cases, in which one is without dark energy and the others are with. I find that in all the four cases black holes can be formed from the gravitational collapse of the dust cloud.

A black hole is a region in space where the gravitational pull is so strong that nothing, not even light, can escape from it. This occurs when a massive amount of matter is compressed into a very small area, creating a powerful gravitational field. Black holes form through various processes that involve the collapse of massive astronomical objects and the merging of smaller black holes. One primary method is the stellar collapse. Stars, during their lifecycle, fuse hydrogen into helium in their cores. When the hydrogen is depleted, they begin fusing heavier elements until iron is produced. For stars more than 20 times the mass of the Sun, the end of this fusion process leads to a supernova explosion. The core of the star collapses rapidly due to gravity, and if the core's mass is sufficiently large (typically more than about three times the mass of the Sun), it will continue collapsing into a singularity, forming a stellar-mass black hole. Another way black holes can form is through accretion and growth. A compact object like a neutron star or a white dwarf can accumulate matter from a companion star or its surroundings. As this matter accumulates, the mass of the compact object increases, and it may eventually reach a critical mass where it collapses into a black hole.

The formation of the first supermassive black holes is one of the main open questions in our understanding of high-redshift structure formation. In this book, we aim to provide a summary of state-of-the-art modern research on this topic, exploring the formation of massive black holes from a fluid-dynamical, stellar-dynamical and chemical perspective. The book thus presents a solid theoretical foundation, a comparison with current observations and future observational perspectives with upcoming missions such as the Square Kilometre Array, the European Extremely Large Telescope, the Euclid satellite as well as possible detections via gravitational waves.

Black holes are one of the most fascinating predictions of general relativity. They are the natural product of the complete gravitational collapse of matter and today we have a body of observational evidence supporting the existence of black holes in the Universe. However, general relativity predicts that at the center of black holes there are spacetime singularities, where predictability is lost and standard physics breaks down. It is widely believed that spacetime singularities are a symptom of the limitations of general relativity and must be solved within a theory of quantum gravity. Since we do not have yet any mature and reliable candidate for a quantum gravity theory, researchers have studied toy-models of singularity-free black holes and of singularity-free gravitational collapses in order to explore possible implications of the yet unknown theory of quantum gravity. This book reviews all main models of regular black holes and non-singular gravitational collapses proposed in the literature, and discuss the theoretical and observational implications of these scenarios.

This book consists of two titles, which are the following: Galaxies - Galaxies are dynamic entities, constantly evolving through processes like mergers, collisions, and interactions with neighboring galaxies. When galaxies merge, their stars, gas, and dust can undergo dramatic transformations, leading to the formation of new stars and restructuring of the galaxy's shape. These interactions can trigger intense bursts of star formation and feed supermassive black holes at the galaxies' centers, leading to the emission of powerful jets of radiation. Supermassive Black Hole - Black holes form through various processes that involve the collapse of massive astronomical objects and the merging of smaller black holes. One primary method is the stellar collapse. Stars, during their lifecycle, fuse hydrogen into helium in their cores. When the hydrogen is depleted, they begin fusing heavier elements until iron is produced. For stars more than 20 times the mass of the Sun, the end of this fusion process leads to a supernova explosion. The core of the star collapses rapidly due to gravity, and if the core's mass is sufficiently large (typically more than about three times the mass of the Sun), it will continue collapsing into a singularity, forming a stellar-mass black hole.

Your author decided to write this book about the Big Bang & Black Holes after attending a Caltech Associates dinner in which Dr. Sean Carroll gave a dynamic talk entitled: The Origin of the Universe and the Arrow of Time. During his lecture Dr. Carroll mentioned the Baby Universes concept of Stephen Hawking, a theory described in this book.

How did the universe begin? Where do galaxies come from? Where do the material particles we are made of come from? Today we have only provisional answers to such questions, but this will improve dramatically over the next ten years, predicts astronomer Gribbin. He focuses on what we think we know about ten issues and explains how cutting-edge research may yield solutions in the very near future. He explores ideas concerning the creation of the universe, the possibility of other forms of life, and the fate of the expanding cosmos. He examines "theories of everything," including grand unified theories and string theory, and he discusses the Big Bang theory, the origin of structure and patterns of matter in the galaxies, dark mass and dark energy, the future of Earth and the Sun, and the possibility that the universe might expand forever.--From publisher description.