This book picks up where the last book, Underwood, T. G. (2023). General Relativity, left off, addressing the omission that "A fundamental theoretical explanation for the weak attractive gravitational force between matter is also long overdue." We know less about gravity than any other force. The purpose of this book is to try to fill that void. Part I reviews contributions to the understanding of the effects of gravity, starting with extracts from Kepler and Newton. Part I also describes alternative forms of Newton's law provided by Gauss's law for gravity, and Poisson's equation. Part II addresses "What is Gravity?". It begins by reviewing Einstein's unsuccessful attempts at producing a classical unified field theory, a unified theory of electromagnetism and gravity, between 1923 until he died in 1955. But then it moves on to consider quantum entanglement, or some form of entanglement between matter, as a potential source of gravity and to examine the origin of gravity according to the Big Bang theory. In an attempt to answer the question: "Why does matter attract matter?", facts related to gravity and other forces of nature are listed and reviewed. The underlying cause of gravity remains elusive. From this analysis it is most likely to be found in the initial creation of matter and expansion of the universe, not in quantum theory, nor in a unified theory of electromagnetism and gravity. This appears to suggest that gravity resulted from some form of entanglement between matter after it was driven apart in the expansion of the universe following the Big Bang. The existence of a very large amount of energy at the time of the origin of the current universe, makes the idea of a universe in which gravitational attractive forces eventually overcome the forces causing the expansion of the universe particularly attractive, in that it provides an explanation for this energy and for the Big Bang without invoking dark matter or dark energy. The gravitational field at the at the surface of the universe, is approximately equal to the gravitational constant.
Underwood, Trevor: - "Trevor Underwood was born in England in 1943, and became a US citizen in 2004. He earned a M.A. in mathematics and physics at Cambridge University, in 1965, and a M.Sc. in economics at the London School of Economics in 1967, followed by further graduate studies in international economics at the University of Rochester, NY, and at Harvard University, between 1967 and 1969. He worked for the Bank of England, the International Monetary Fund, and the UK Treasury and was a UK Advisor to the Committee of Twenty on Reform of the International Monetary System, between 1969 and 1973. He founded a treasury consultancy business in 1974 and a treasury software company in 1976, which he continued to run until 2017. In 2008 he returned to scientific research, initially on human evolution. In November 2015, he published a paper "A new model of human dispersal" on bioRxiv.org, the online preprint archive for biology run by Cold Spring Harbor Laboratory. Between December 2015 and November 2019, he worked on climate science, during which time he wrote six climate science papers. In November 2019, these were published in a book "The Surface Temperature of the Earth", distributed by Lulu.com. He then returned to theoretical physics to review progress since he left Cambridge in 1965, in particular on electromagnetic radiation, matter and gravity. In December 2021, he published a spin-off from this research, "Urbain Le Verrier on the Movement of Mercury - annotated translations", distributed by Lulu.com. In April 2023, he published "Quantum Electrodynamics - annotated sources. Volumes I and II"; in June 2023, "Special Relativity"; in November 2023, "General Relativity", and in March 2024, "Gravity", also distributed by Lulu.com."
