The first three billion years of cosmic time were the prime epoch of galaxy formation. Characterising galaxies at this epoch is therefore crucial to achieving a major goal of modern astrophysics: to understand how galaxies such as our Milky Way emerged from the primordial density fluctuations in the early Universe and how they evolved through cosmic time. Recent major international investments in observing facilities such as the Atacama Large Millimetre Array (ALMA) and the James Webb Space Telescope (JWST) promise to provide the next leap in our understanding of this topic. This volume gathers the scientific contributions to the International Astronomical Union Symposium 352, which was devoted to this topic. The community of theoretical and observational experts discuss how we can make the most of ALMA and JWST synergies in advancing our understanding of galaxy evolution in the young Universe.

Dark matter is a fundamental component of the standard cosmological model, but in spite of four decades of increasingly sensitive searches, no-one has yet detected a single dark-matter particle in the laboratory. An alternative cosmological paradigm exists: MOND (Modified Newtonian Dynamics). Observations explained in the standard model by postulating dark matter are described in MOND by proposing a modification of Newton's laws of motion. Both MOND and the standard model have had successes and failures - but only MOND has repeatedly predicted observational facts in advance of their discovery. In this volume, David Merritt outlines why such predictions are considered by many philosophers of science to be the 'gold standard' when it comes to judging a theory's validity. In a world where the standard model receives most attention, the author applies criteria from the philosophy of science to assess, in a systematic way, the viability of this alternative cosmological paradigm.

Following their New York Times-bestselling graphic novel Feynman, Jim Ottaviani and Leland Myrick deliver a gripping biography of Stephen Hawking, one of the most important scientists of our time. From his early days at the St Albans School and Oxford, Stephen Hawking's brilliance and good humor were obvious to everyone he met. A lively and popular young man, it's no surprise that he would later rise to celebrity status. At twenty-one he was diagnosed with ALS, a degenerative neuromuscular disease. Though the disease weakened his muscles and limited his ability to move and speak, it did nothing to limit his mind. He went on to do groundbreaking work in cosmology and theoretical physics for decades after being told he had only a few years to live. He brought his intimate understanding of the universe to the public in his 1988 bestseller, A Brief History of Time. Soon after, he added pop-culture icon to his accomplishments by playing himself on shows like Star Trek, The Simpsons, and The Big Bang Theory, and becoming an outspoken advocate for disability rights. In Hawking, writer Jim Ottaviani and artist Leland Myrick have crafted an intricate portrait of the great thinker, the public figure, and the man behind both identities.

Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory

A new edition of the New York Times bestseller—now a three-part Nova special on PBS-TV coming in Fall 2003: a fascinating and thought-provoking journey through the mysteries of space, time, and matter.

Now with a new preface (not in any other edition) that will review the enormous public reception of the relatively obscure string theory—made possible by this book and an increased number of adherents amongst physicists—The Elegant Universe "sets a standard that will be hard to beat" (New York Times Book Review). Brian Greene, one of the world's leading string theorists, peels away the layers of mystery surrounding string theory to reveal a universe that consists of eleven dimensions, where the fabric of space tears and repairs itself, and all matter—from the smallest quarks to the most gargantuan supernovas—is generated by the vibrations of microscopically tiny loops of energy.

Today physicists and mathematicians throughout the world are feverishly working on one of the most ambitious theories ever proposed: superstring theory. String theory, as it is often called, is the key to the Unified Field Theory that eluded Einstein for more than thirty years. Finally, the century-old antagonism between the large and the small-General Relativity and Quantum Theory-is resolved. String theory proclaims that all of the wondrous happenings in the universe, from the frantic dancing of subatomic quarks to the majestic swirling of heavenly galaxies, are reflections of one grand physical principle and manifestations of one single entity: microscopically tiny vibrating loops of energy, a billionth of a billionth the size of an atom. In this brilliantly articulated and refreshingly clear book, Greene relates the scientific story and the human struggle behind twentieth-century physics' search for a theory of everything.

Through the masterful use of metaphor and analogy, The Elegant Universe makes some of the most sophisticated concepts ever contemplated viscerally accessible and thoroughly entertaining, bringing us closer than ever to understanding how the universe works.

"[A] delightful, lucid introduction to the greatest problem in all of physics, the quest to unify all the laws of nature. Greene does a masterful job in presenting complex materials in a lively, engaging manner. Highly recommended to anyone who has ever gazed at the heavens and wondered, as Einstein did, if God had a choice in making the universe."—Michio Kaku, author of Hyperspace and Visions

"Everyone who is curious about the horizons of theoretical physics—past, present, and future—will enjoy this book."—Edward Witten, Institute for Advanced Study

"[A] beautifully crafted account of string theory—a theory that appears to be a most promising waystation on the road to an ultimate theory of everything. His book gives a clear, simple, yet masterful account that makes a complex theory very accessible to nonscientists but is also a delightful; read for the professional."—David M. Lee, professor of physics, Cornell University

"[A] tour-de-force of science writing. Perhaps more than any other popular-level account, this book peels away layers of detail and reveals the stunning essence of cutting-edge physics. With a rare blend of scientific integrity and literary flair, the author takes us on a whirlwind journey to the forefront of the search for the ultimate theory of the universe."—Shing-Tung Yau, Harvard University; Fields Medalist, winner of the National Medal of Science

"Greene goes beyond Kaku's book [Beyond Einstein], exploring the ideas and recent developments with a depth and clarity I wouldn't have thought possible. Like Simon Singh in "Fermat's Enigma," he has a rare ability to explain even the most evanescent ideas in a way that gives at least the illusion of understanding....Rather than recycling the tired old set pieces science writers too often fall back upon, he develops one fresh new insight after another....In the great tradition of physicists writing for the masses, The Elegant Universe sets a standard that will be hard to beat."—New York Times Book Review, 21 February 1999, George Johnson

"Do you lie awake a night wondering about superstrings, hidden dimensions and the quest for an ultimate theory of the universe? If so, you should browse Brian Greene's The Elegant Universe...[A] well-written account—without equations—from the forefront of cosmology and physics."—American Scientist, March/April 1999

"Greene does an admirable job of translating a wholly mathematical endeavor into visual terms. Throughout his work, he writes with poetic eloquence and style."—Washington Post Book World, Marcia Bartusiak, 7 March 1999

"Brian Greene...makes the terribly complex theory of strings accessible to all. He possesses a remarkable gift for using the everyday to illustrate what may be going on in dimensions beyond our feeble human perception."—Publishers Weekly, 11 January 1999

"Compulsively readable....Greene threatens to do for string theory what Stephen Hawking did for black holes."—New York

"As rewarding as it gets....A thrilling ride through a lovely landscape."—Los Angeles Times

A sweeping tour of the infrared universe as seen through the eyes of NASA's Spitzer Space Telescope Astronomers have been studying the heavens for thousands of years, but until recently much of the cosmos has been invisible to the human eye. Launched in 2003, the Spitzer Space Telescope has brought the infrared universe into focus as never before. Michael Werner and Peter Eisenhardt are among the scientists who worked for decades to bring this historic mission to life. Here is their inside story of how Spitzer continues to carry out cutting-edge infrared astronomy to help answer fundamental questions that have intrigued humankind since time immemorial: Where did we come from? How did the universe evolve? Are we alone? In this panoramic book, Werner and Eisenhardt take readers on a breathtaking guided tour of the cosmos in the infrared, beginning in our solar system and venturing ever outward toward the distant origins of the expanding universe. They explain how astronomers use the infrared to observe celestial bodies that are too cold or too far away for their light to be seen by the eye, to conduct deep surveys of galaxies as they appeared at the dawn of time, and to peer through dense cosmic clouds that obscure major events in the life cycles of planets, stars, and galaxies. Featuring many of Spitzer's spectacular images, More Things in the Heavens provides a thrilling look at how infrared astronomy is aiding the search for exoplanets and extraterrestrial life, and transforming our understanding of the history and evolution of our universe.

Venus draws a beautiful pentagram around Earth every eight years. Jupiter's two largest moons draw a perfect four-fold flower. The Planets grandly play out the slow Music of the Spheres. Is there a secret structure hidden in the Solar System? Packed with great illustrations and serious research from many sources, this internationally bestselling little book by cosmologist John Martineau will instantly retune your cosmological circuits to the extraordinary and primary patterns behind Life, the Universe and Everything. WOODEN BOOKS are small but packed with information. "Fascinating" FINANCIAL TIMES. "Beautiful" LONDON REVIEW OF BOOKS. "Rich and Artful" THE LANCET. "Genuinely mind-expanding" FORTEAN TIMES. "Excellent" NEW SCIENTIST. "Stunning" NEW YORK TIMES. Small books, big ideas.

Written by an international leader in the field, this is a coherent and accessible account of the concepts that are now vital for understanding cutting-edge work on supermassive black holes. These include accretion disc misalignment, disc breaking and tearing, chaotic accretion, the merging of binary supermassive holes, the demographics of supermassive black holes, and the defining effects of feedback on their host galaxies. The treatment is largely analytic and gives in-depth discussions of the underlying physics, including gas dynamics, ideal and non-ideal magnetohydrodynamics, force-free electrodynamics, accretion disc physics, and the properties of the Kerr metric. It stresses aspects where conventional assumptions may be inappropriate and encourages the reader to think critically about current models. This volume will be useful for graduate or Masters courses in astrophysics, and as a handbook for active researchers in the field. eBook formats include colour figures while print formats are greyscale only.

A scientific and globetrotting exploration of the physics experiments changing the ways we understand our universe. Why is the universe expanding? What is the nature of dark matter? Do other universes exist? In this timely and original book, science writer Anil Ananthaswamy embarks on a global journey to some of the world's most inhospitable and dramatic research sites to witness first-hand the audacious physics experiments conducted to answer profound questions about the nature of the universe. From the Atacama Desert in the Chilean Andes to the European Southern Observatory's Very Large Telescope on Mount Paranal to deep inside an abandoned iron mine in Minnesota and to the East Antarctic Ice Sheet, Ananthaswamy weaves together stories about the people and places at the heart of this cosmological research. While explaining the immense questions that scientists are trying to answer, Ananthaswamy provides an accessible and unique portrait of the universe and our quest to understand it. An atmospheric, engaging and illuminating read, The Edge of Physics depicts science as a human process and brings cosmology with all its rarefied concepts down to earth. ***PRAISE FOR THE EDGE OF PHYSICS*** 'A travelogue that celebrates the blood, sweat and tears that drive our understanding of the universe.' Guardian 'An excellent book. The author has a great knack of making difficult subjects comprehensible. I thoroughly enjoyed it.' Sir Patrick Moore 'A remarkable narrative that combines fundamental physics with high adventure.' New Scientist 'The ultimate physics-adventure travelogue... brilliant.' Physics World 'A grand tour of modern day cosmology's sacred places... evocative... engaging... refreshing... a taste of science in the heroic mode.' BBC Sky at Night 'Clean, elegant prose, humming with interest.' Robert MacFarlene 'An accomplished and timely overview of modern cosmology and particle astrophysics.' Nature

What is time? The Janus Point offers a ground-breaking solution to one of the greatest mysteries in physics. For over a century, the greatest minds have sought to understand why time seems to flow in one direction, ever forward. In The Janus Point, Julian Barbour offers a radically new answer: it doesn't. At the heart of this book, Barbour provides a new vision of the Big Bang - the Janus Point - from which time flows in two directions, its currents driven by the expansion of the universe and the growth of order in the galaxies, planets and life itself. What emerges is not just a revolutionary new theory of time, but a hopeful argument about the destiny of our universe. 'Both a work of literature and a masterpiece of scientific thought' Lee Smolin, author of The Trouble with Physics 'Profound...original...accessible to anyone who has pondered the mysteries of space and time' Martin Rees, Astronomer Royal 'Takes on fundamental questions, offering a new perspective on how the Universe started and where it may be headed' Science Magazine

The essential introduction to modern string theory-now fully expanded and revised String Theory in a Nutshell is the definitive introduction to modern string theory. Written by one of the world's leading authorities on the subject, this concise and accessible book starts with basic definitions and guides readers from classic topics to the most exciting frontiers of research today. It covers perturbative string theory, the unity of string interactions, black holes and their microscopic entropy, the AdS/CFT correspondence and its applications, matrix model tools for string theory, and more. It also includes 600 exercises and serves as a self-contained guide to the literature. This fully updated edition features an entirely new chapter on flux compactifications in string theory, and the chapter on AdS/CFT has been substantially expanded by adding many applications to diverse topics. In addition, the discussion of conformal field theory has been extensively revised to make it more student-friendly. The essential one-volume reference for students and researchers in theoretical high-energy physics Now fully expanded and revised Provides expanded coverage of AdS/CFT and its applications, namely the holographic renormalization group, holographic theories for Yang-Mills and QCD, nonequilibrium thermal physics, finite density physics, and entanglement entropy Ideal for mathematicians and physicists specializing in theoretical cosmology, QCD, and novel approaches to condensed matter systems An online illustration package is available to professors

In this vibrant, eye-opening tour of milestones in the history of our universe, Chris Impey guides us through space and time, leading us from the familiar sights of the night sky to the dazzlingly strange aftermath of the Big Bang. What if we could look into space and see not only our place in the universe but also how we came to be here? As it happens, we can. Because it takes time for light to travel, we see more and more distant regions of the universe as they were in the successively greater past. Impey uses this concept "look-back time" to take us on an intergalactic tour that is simultaneously out in space and back in time. Performing a type of cosmic archaeology, Impey brilliantly describes the astronomical clues that scientists have used to solve fascinating mysteries about the origins and development of our universe. The milestones on this journey range from the nearby to the remote: we travel from the Moon, Jupiter, and the black hole at the heart of our galaxy all the way to the first star, the first ray of light, and even the strange, roiling conditions of the infant universe, an intense and volatile environment in which matter was created from pure energy. Impey gives us breathtaking visual descriptions and also explains what each landmark can reveal about the universe and its history. His lucid, wonderfully engaging scientific discussions bring us to the brink of modern cosmology and physics, illuminating such mind-bending concepts as invisible dimensions, timelessness, and multiple universes. A dynamic and unforgettable portrait of the cosmos, How It Began will reward its readers with a deeper understanding of the universe we inhabit as well as a renewed sense of wonder at its beauty and mystery."

Professor Sir Roger Penrose's work, spanning fifty years of science, with over five thousand pages and more than three hundred papers, has been collected together for the first time and arranged chronologically over six volumes, each with an introduction from the author. Where relevant, individual papers also come with specific introductions or notes. Many important realizations concerning twistor theory occurred during the short period of this third volume, providing a new perspective on the way that mathematical features of the complex geometry of twistor theory relate to actual physical fields. Following on from the nonlinear graviton construction, a twistor construction was found for (anti-)self-dual electromagnetism allowing the general (anti-)self-dual Yang-Mills field to be obtained. It became clear that some features of twistor contour integrals could be understood in terms of holomorphic sheaf cohomology. During this period, the Oxford research group founded the informal publication, Twistor Newsletter. This volume also contains the influential Weyl curvature hypothesis and new forms of Penrose tiles.

How do we resolve conflicts when fundamental sources of knowledge and belief-such as science and theology-are involved? In God's Two Books, Kenneth Howell offers a historical analysis of how sixteenth- and seventeenth-century astronomers and theologians in Northern Protestant Europe used science and religion to challenge and support one another. Howell reveals that the cosmological schemes developed during this era remain monumental solutions to the enduring problem of how theological interpretation and empirical investigation interact with one another. "Writing history requires a constant shedding of our misconceptions about the past," says Howell. God's Two Books reshapes our understanding of the interaction of cosmological thought and biblical interpretation in the emerging astronomy of the Scientific Revolution by analyzing new texts and offering interpretations that cast old materials in a new light. The central argument of this compelling book is that the use of the Bible in early modern cosmology is considerably more complex and subtle than has previously been recognized. Drawing on the writings of Lutheran and Calvinist astronomers, natural philosophers, and theologians, Howell analyzes several underlying patterns of interpretation which affected how these historical figures viewed the mutual interaction of the books of nature and Scripture. He argues that while they differed on how the disciplines of astronomy, physics, and theology should relate to one another, most thinkers shared the common goal of finding and explaining the true system of the universe. Howell introduces the notion of a convergent realism to describe Protestant intellectuals' approach to incorporating empirical and theological perspectives into a holistic version of the universe. They believed the sacred page was relevant to cosmology but denied that the Bible had scientific content. At the same time, these thinkers argued that the theological truths expressed in the Bible were interwoven into nature in subtle, yet revealing, ways. Their resulting interpretations show continuity with Catholic thinkers and discard oversimplifications such as literal versus figurative hermeneutics or Copernican versus anti-Copernican cosmologies. Among Howell's many original contributions in this cogent study is a distinctive approach to Kepler's exegesis of nature and an introduction to the debate of many Calvinist thinkers who have previously received little attention.

This is a concise introduction to modern astrophysics for physicists, with a focus on galaxy dynamics and the discovery of dark matter halos in galaxies. Part I summarizes important discoveries in observational astronomy and astrophysics, in a manner accessible to those who are new to the topic. Building on this foundation, Part II describes the study of dark matter and provides more detail on galactic dynamics. Important physical concepts that form the basis of key astrophysical phenomena are explained, avoiding unnecessary technicalities and complex derivations. The approach is semi-empirical and emphasizes the importance of key measurements and observations in formulating fundamental theoretical questions and developing their solutions. Students are encouraged to develop a deep understanding of major discoveries and contemporary research topics, beyond the simple application of practical models and formulae, as a bridge to more advanced study in astrophysics.

This is a substantially revised and updates new edition of a classic introductory textbook. Although there are a wealth of cosmology texts at postgraduate level, Cosmology remains the classic introduction to modern cosmology for undergraduates. While designed as the main text for a course given at second or third year level, it is sufficiently self-contained for anyone with school science to understand. There is a strong emphasis on observational cosmology, with introductory chapters on the visible universe, our galaxy and other galaxies and the empirical basis for cosmological theory. After an account of the big bang model, there are chapters on the early stages of the big bang and galaxy formation. Finally, there are chapters on cosmological tests and on alternative theories. One feature of the book it its updated epilogue of twenty controversies on cosmology today. The latest results from the WMAP mission are included and a wealth of new material, including a stronger emphasis on the cosmological constant. It has an extensive glossary and the exercises have been substantially expanded. A stronger emphasis on the physical basis for cosmology is included throughout.

In CONSTELLATIONS, award-winning astronomy writer Govert Schilling takes us on an unprecedented visual tour of all 88 constellations in our night sky. Much more than just a stargazer's guide, CONSTELLATIONS is complete history of astronomy as told by Schilling through the lens of each constellation. The book is organized alphabetically by constellation. Profiles of each constellation include basic information such as size, visibility, and number of stars, as well as information on the discovery and naming of the constellation and associated lore. Beyond details about the constellation itself is information about every astronomical event that took place or discovery made in the vicinity of the constellation. In the constellation of Cygnus (the Swan) we encounter the location of the first confirmed black hole. A stop at Gemini (the Twins) is a chance to say hello to the dwarf planet Pluto, and in Orion (the hunter) we find the location of the first identified gamma-ray burst. Stunning star maps throughout the book by acclaimed star mapmaker Wil Tirion show us the exact location of every constellation, the details of its structure, as well as its surrounding astronomical neighbors.

Einstein's general theory of relativity can be a notoriously difficult subject for students approaching it for the first time, with arcane mathematical concepts such as connection coefficients and tensors adorned with a forest of indices. This book is an elementary introduction to Einstein's theory and the physics of curved space-times that avoids these complications as much as possible. Its first half describes the physics of black holes, gravitational waves and the expanding Universe, without using tensors. Only in the second half are Einstein's field equations derived and used to explain the dynamical evolution of the early Universe and the creation of the first elements. Each chapter concludes with problem sets and technical mathematical details are given in the appendices. This short text is intended for undergraduate physics students who have taken courses in special relativity and advanced mechanics.

An encapsulation in nine numbers of all that modern astronomy has learnt about the universe. These cosmic numbers appear to be independent characteristics of our universe and include its age, the Hubble constant (a measure of its rate of expression), and the density of matter in the universe. Only one of the nine numbers is known with real precision, and four of them only poorly known. Difficult ideas like the origin of the elements, the General Theory of Relativity, quantum theory, and the standard model of particle physics, ideas which underpin modern cosmology, are explained in a simple way. While most of what we know has been learnt during the 20th century, Rowan-Robinson provides a historical perspective, paying homage to the achievements of the Greeks, Renaissance astronomers, and the age of Newton. The book ends with predictions of when all nine numbers will be accurately known.

The origins of life on earth, the workings of the human mind, the mysteries of the Universe itself--profound questions such as these were once the province of philosophy and theology alone. Today they have become the staple--and indeed the hallmark--of the finest writing about science. And few science writers have tackled the big questions as persistently and as insightfully as astronomer John Barrow.
Now, in Between Inner Space and Outer Space, Barrow brings together dozens of essays that offer a sweeping account of his explorations along the boundary lines of science, philosophy, and religion. Here is an invigorating tour of topics such as cosmology, evolution, Grand Unified Theories, complexity and chaos, the nature of time, super string theory, quantum mechanics, particle physics, Big Bang theory, and much more. Barrow's range is remarkable. He examines, for instance, what science can tell us about our love of music or why certain paintings appeal to us. He recounts the dramatic discoveries made by the satellite COBE (Cosmic Background Explorer) and reveals what these findings tell us about the origins of the Cosmos. He discusses the debate over the nature of the universe waged by Stephen Hawking and Roger Penrose. And he offers a thoughtful review of E.O. Wilson's Consilience, seconding Wilson's criticism of social scientists who remain quite ignorant of the key insights made by the life sciences.
Leavened with a sprightly sense of humor, Between Inner Space and Outer Space illuminates modern science as it provides much food for thought about life's ultimate questions.

This book offers a systematic exposition of conformal methods and how they can be used to study the global properties of solutions to the equations of Einstein's theory of gravity. It shows that combining these ideas with differential geometry can elucidate the existence and stability of the basic solutions of the theory. Introducing the differential geometric, spinorial and PDE background required to gain a deep understanding of conformal methods, this text provides an accessible account of key results in mathematical relativity over the last thirty years, including the stability of de Sitter and Minkowski spacetimes. For graduate students and researchers, this self-contained account includes useful visual models to help the reader grasp abstract concepts and a list of further reading, making this an ideal reference companion on the topic. This title, first published in 2016, has been reissued as an Open Access publication on Cambridge Core.

Answers to science's most enduring questions from "Can I break the light-speed barrier like on Star Trek?" and "Is there life on other planets?" to "What is empty space made of?" This is an indispensable guide to physics that offers readers an overview of the most popular physics topics written in an accessible, irreverent, and engaging manner while still maintaining a tone of wry skepticism. Even the novice will be able to follow along, as the topics are addressed using plain English and (almost) no equations. Veterans of popular physics will also find their nagging questions addressed, like whether the universe can expand faster than light, and for that matter, what the universe is expanding into anyway. Gives a one-stop tour of all the big questions that capture the public imagination including string theory, quantum mechanics, parallel universes, and the beginning of time Explains serious science in an entertaining, conversational, and easy-to-understand way Includes dozens of delightfully groan-worthy cartoons that explain everything from special relativity to Dark Matter Filled with fascinating information and insights, this book will both deepen and transform your understanding of the universe.

With a focus on modified gravity this book presents a review of the recent developments in the fields of gravity and cosmology, presenting the state of the art, high-lighting the open problems, and outlining the directions of future research. General Relativity and the CDM framework are currently the standard lore and constitute the concordance paradigm of cosmology. Nevertheless, long-standing open theoretical issues, as well as possible new observational ones arising from the explosive development of cosmology in the last two decades, offer the motivation and lead a large amount of research to be devoted in constructing various extensions and modifications. In this review all extended theories and scenarios are first examined under the light of theoretical consistency, and are then applied in various geometrical backgrounds, such as the cosmological and the spherical symmetric ones. Their predictions at both the background and perturbation levels, and concerning cosmology at early, intermediate and late times, are then confronted with the huge amount of observational data that astrophysics and cosmology has been able to offer in the last two decades. Theories, scenarios and models that successfully and efficiently pass the above steps are classified as viable and are candidates for the description of Nature, allowing readers to get a clear overview of the state of the art and where the field of modified gravity is likely to go. This work was performed in the framework of the COST European Action "Cosmology and Astrophysics Network for Theoretical Advances and Training Actions" - CANTATA.

Kepler is a key figure in the development of modern astronomy. His work is also important in the history of philosophy and methodology of science as a whole. The present study is concerned with one of Kepler's major preoccupations, namely his search for the geometrical plan according to which God created the Universe. The author discusses how Kepler's cosmological theories, which embrace music and astrology as well as astronomy, are related to his other work. The subject will be of great interest to historians of science, mathematicians and astronomers as well as to historians of the late Renaissance.