The Janus Point: A New Theory of Time

by Julian Barbour

Overview

In a universe filled by chaos and disorder, one physicist makes the radical argument that the growth of order drives the passage of time — and shapes the destiny of the universe.
 
Time is among the universe's greatest mysteries. Why, when most laws of physics allow for it to flow forward and backward, does it only go forward? Physicists have long appealed to the second law of thermodynamics, held to predict the increase of disorder in the universe, to explain this. In The Janus Point, physicist Julian Barbour argues that the second law has been misapplied and that the growth of order determines how we experience time. In his view, the big bang becomes the "Janus point," a moment of minimal order from which time could flow, and order increase, in two directions. The Janus Point has remarkable implications: while most physicists predict that the universe will become mired in disorder, Barbour sees the possibility that order — the stuff of life — can grow without bound.
 
A major new work of physics, The Janus Point will transform our understanding of the nature of existence.

Product Details

ISBN-13:	9780465095490
Publisher:	Basic Books
Publication date:	12/01/2020
Sold by:	Hachette Digital, Inc.
Format:	eBook
File size:	11 MB
Note:	This product may take a few minutes to download.

About the Author

Julian Barbour is the author of the highly regarded The Discovery of Dynamics and the bestseller The End of Time. He received his PhD in physics from the University of Cologne in 1968. He is a past visiting professor of physics at the University of Oxford and lives on the edge of the scenic Cotswolds, UK.

Table of Contents

Preface and Acknowledgements ix

Chapter 1 Time and Its Arrows 1

Chapter 2 Bare-Bones Thermodynamics 23

Chapter 3 Statistical Mechanics in a Nutshell 43

Chapter 4 Boltzmann's Tussle with Zermelo 59

Chapter 5 The Curious History of Boltzmann Brains 77

Chapter 6 The Janus Point 87

Chapter 7 The Minimal Model 101

Chapter 8 The Foundations of Dynamics 113

Chapter 9 The Complexity of Shapes 139

Chapter 10 Shape Space 147

Chapter 11 A Role Reversal 155

Chapter 12 This Most Beautiful System 165

Chapter 13 Two Kinds of Dynamical Laws 173

Chapter 14 A Blindfolded Creator 181

Chapter 15 An Entropy-Like Concept for the Universe 191

Chapter 16 A Glimpse of the Big Bang? 207

Chapter 17 The Big Bang in General Relativity 245

Chapter 18 The Large-Scale Structure of the Universe 263

Chapter 19 The Creation of Structure in the Universe 285

Chapter 20 What Does It All Mean? 319

List of Illustrations 333

Notes 335

Bibliography 363

Index 369

Editorial Reviews

"The origin of the arrow of time is arguably the most important conceptual problem in cosmology, and the prospect that it can be solved in a universe where time flows 'backward' in the far past is as exciting as it is provocative. In this engaging book, Julian Barbour conveys this excitement admirably, complete with just a bit more detail than professional physicists usually share with the public."
―Sean Carroll, author of From Eternity to Here

"Julian Barbour's infectious enthusiasm for the big ideas in physics is addictive. He has a complete mastery of the history of ideas yet a remarkable lightness and clarity in explaining what are profound concepts. The Janus Point is controversial and gripping, an extraordinary introduction to his view of the universe."―Pedro G. Ferreira, author of The Perfect Theory

"By abandoning the prejudice that particles (atoms, stars...) are confined in a box, Julian Barbour has discovered an unexpected and remarkably simple feature of Newtonian dynamics. It is the basis of his seductive and eloquently presented explanation of the history of the universe, even time itself. Is his cosmology correct? 'Time' will tell."―Michael Victor Berry, Melville Wills Professor of Physics (Emeritus), Bristol University

"Julian Barbour has no peer when it comes to explaining scientific ideas in a way that is accessible without being simplistic. For good measure he has a talent for using quotes from Shakespeare and other literary sources in a manner that actually helps to elucidate key points. In The Janus Point he tackles subject matter that is notoriously challenging even to scientists, and explains it in a way that gave me new insights and understanding even though I studied these topics in a classroom a long time ago. This is a fitting sequel to his earlier work and helps to pull together several big ideas that some of us have been watching with fascination for decades."―Neal Stephenson, author of Snow Crash

"Julian Barbour is a profound and original thinker, with the boldness to tackle some of nature's deepest problems. He is also a fine writer, and this renders his book — despite its conceptual depth — accessible to anyone who has pondered the mysteries of space and time. It's a distillation of the author's prolonged investigations, and the insights that he offers deserve wide readership."―Martin Rees, author of On the Future

"Julian Barbour is well known for his brilliant study of physics history, The Discovery of Dynamics. The Janus Point includes a similar history of thermodynamics, statistical mechanics and the arrow of time. But for me the main point of the book was to show history-in-the-making. His 'shape dynamics' is a project to recast the foundations of all of cosmology, gravity, thermodynamics and the arrow of time. The book has given me a lot to ponder. As Gauss said of Riemann's habilitation lecture, '[it] exceeded my expectations.'"―Bill Unruh, professor of physics, University of British Columbia

"In this delightful, provocative book, Julian Barbour shares his learned insights and passion about deep questions of time, change, and the origin of the universe with all its creative variety. A cosmic physics adventure, enlivened with history and poetry."―Theodore A. Jacobson, professor of physics, University of Maryland

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