Preface 11 Part I Stars, Planets, and Life 15 1 The Size and Scale of the Universe 17 Neil deGrasse Tyson 2 From the Day and Night Sk y to Planetary Orbits 26 Neil deGrasse Tyson 3 Newton's Laws 42 Michael A. Strauss 4 How Stars Radiate Energy (I) 54 Neil deGrasse Tyson 5 How Stars Radiate Energy (II ) 71 Neil deGrasse Tyson 6 Stellar Spectra 81 Neil deGrasse Tyson 7 The Lives and Deaths of Stars (I) 93 Neil deGrasse Tyson 8 The Lives and Deaths of Stars (II ) 111 Michael A. Strauss 9 Why Pluto Is Not a Planet 126 Neil deGrasse Tyson 10 The Search for Life in the Galaxy 146 Neil deGrasse Tyson Part II Galaxies 171 11 The Interstellar Medium 173 Michael A. Strauss 12 Our Milk y Way 183 Michael A. Strauss 13 The Universe of Galaxies 197 Michael A. Strauss 14 The Expansion of the Universe 207 Michael A. Strauss 15 The Early Universe 222 Michael A. Strauss 16 Quasars and Supermassive Black Holes 241 Michael A. Strauss Part III Einstein and the Universe 255 17 Einstein's Road to Relativity 257 J. Richard Gott 18 Implications of Special Relativity 270 J. Richard Gott 19 Einstein's General Theory of Relativity 289 J. Richard Gott 20 Black Holes 300 J. Richard Gott 21 Cosmic Strings, Wormholes, and Time Travel 321 J. Richard Gott 22 The Shape of the Universe and the Big Bang 347 J. Richard Gott 23 Inflation and Recent Developments in Cosmology 374 J. Richard Gott 24 Our Future in the Universe 400 J. Richard Gott Acknowledgments 425 Appendix 1 Derivation of E = mc 2 427 Appendix 2 Bekenstein, Entropy of Black Holes, and Information 431 Notes 433 Suggested Reading 439 Index 441

A New York Times Bestseller One of Forbes.com's 10 Best Popular Science Books of 2016: Maths, Physics, Chemistry Honorable Mention for the 2017 PROSE Award in Cosmology and Astronomy, Association of American Publishers One of Ars Technica's 12 engrossing nonfiction books from 2016 One of Symmetry Magazine's Physics Books of 2016 One of Men's Journal's 40 Best Books of 2016 "Reading through is akin to receiving a private museum tour from an expert scientist... The authors present challenging content in accessible prose as they lead readers from our solar system to the edge of the visible universe, getting into the how and the what of just about everything there is to know about the cosmos... As Tyson, Strauss, and Gott explain the cutting-edge physics of multiverses, superstring theory, M-theory, and the benefits of colonizing space, even seasoned science readers will learn something new."--Publishers Weekly "As citizens of the cosmos, we are duty bound to explore it. So opine astrophysicists Neil deGrasse Tyson, Michael Struass, and Richard Gott, guides on this bracing expedition through dusty galactic hinterlands and the vast theoretical vistas of Albert Einstein's work."--Nature "All three [authors] write in informal, conversational tones, and the text is sprinkled with genuinely funny non sequiturs, such as a brief rumination on dwarfs versus dwarves and commentary on English-speaking aliens in Star Trek... What the book does very well is to present not just what we know about the universe but how we know it."--Science "An accessible and comprehensive overview of our universe by three eminent astrophysicists... An entertaining introduction to astronomy."--Kirkus "Three of the leading voices in astrophysics take us on a well-illustrated tour that includes Pluto, questions of intelligent life, and whether the universe is infinite."--Philadelphia Inquirer "The text is written in an informal and approachable style, referencing many popular-culture icons... This book will open up some of the newest and most sophisticated concepts in astrophysics to a general audience, helping all of us better understand the universe we live in."--Booklist "This book is anything but another ho-hum book on astrophysics... Unlike many popular scientific books that are very esoteric, this one is more like a conversation between expert and interested lay person... [Welcome to the Universe] will be a great read for any non-scientist but also science curious persons. It is certainly a good book for the teacher of science at any level as well as the high school and college student. Any reader will be able to see how some complex scientific thoughts fit together."--NSTA Recommends "Their laudable goal is communicating vast, cosmic ideas in ways that are accessible without being simplistic."--Washington Post "If you have a passing interest in astrophysics and would like to deepen it, this book is for you... An authoritative book written with humour and charm."--Marcus Chown, Times Higher Education "This is an important book. Part fascinating story, part reference book, and part astrophysical textbook, the work presents an information-rich summary of the current state of human knowledge of the cosmos... Reading this book, which packages many entertaining treatments of concepts in astronomy and astrophysics, will make you a whole lot smarter about how the universe works. It is highly recommended."--David Eicher, Astronomy.com "The authors remind us that even though people are not the center of the universe, we are an intelligent species able to measure, theorize, comprehend, and explore the limits of knowledge. An excellent introduction that will equip readers to follow current astronomical discoveries."--Library Journal "Well written with clear, helpful graphics and glossy pictures accompanying the text. This book would be ideal for those who want a slightly more technical read."--Dr. Chris North, BBC Sky at Night Magazine "Riveting questions fielded by three top astrophysicists in engaging style, with great illustrations and just a handful of equations. They may just have produced the best book about the universe in the universe."--New Scientist "Astrophysicists Neil deGrasse Tyson, Michael Strauss and J. Richard Gott team up for a readable survey of the universe, from our solar system's worlds to cosmic inflation and the multiverse. They don't stint on the details, and yes, there's some math involved, but it's well worth the journey."--Alan Boyle, GeekWire "Don't know the difference between a pulsar and a quasar? Pick up this endlessly fascinating book by three astrophysicists that provides a clear, readable introduction to the inner workings of our universe."--Men's Journal, a 40 Best Books of 2016 selection "Looking like a cross between a textbook and a coffee-table book, Welcome to the Universe is an extremely readable compilation of introductory astronomy lectures for non-science students... Their talks present physics with clarity and a little levity--with references to pop culture items such as Toy Story and Bill and Ted's Excellent Adventure. Gott even tackles time travel. What's not to like?"--Symmetry Magazine, a Physics Book of 2016 selection "Welcome to the Universe is going to turn your head around, because, frankly, what you think you know about the universe is probably wrong... Welcome to the Universe deserves numerous curtain calls for allowing the cosmos to embrace our existential thinking like a great Whitmanesque hug."--Peter Lewis, Philadelphia Inquirer "Learn about everything from the birth of the Universe and quasars to dark energy and exoplanets from three of the coolest guys you'll ever meet."--Annalee Newitz, Ars Technica "Welcome to the Universe is more than a breathtaking guide to the cosmos. It is a unique bridge between popular science and textbooks, admirably achieving Tyson's goal to 'empower you to understand the operations of nature.'"--Cosmos Magazine "A unique intergalactic voyage from our solar system to the outermost frontiers of the universe."--Lisa Kaaki, Arab News "This entertaining and enlightening book is an overview of the latest discoveries in astrophysics... The writing is witty yet informative, and the book is beautifully illustrated. [Welcome to the Universe] will appeal to all those who wish to learn more about the universe from three internationally prominent astrophysicists."--Forbes.com "In an informative and entertaining way, the book takes us from the latest discoveries to the edge of outer space, from planets, stars, galaxies, to black holes, wormholes, and time travel."--Wan Lixin, Shanghai Daily "The book's breadth is impressive. It starts with the basics (the size and scale of the universe) and finishes with a discussion of Einstein, general relativity, and the universe's fate... The book's strength is the authors' ability to write conversationally."--Air & Space Magazine

"The authors maintain the individual charms of their distinct voices chapter by chapter so the reader has the visceral sense of science shared, passed from one mind to another, almost as though through an oral history—ultimately, a warm welcome to the universe."—Janna Levin, author of Black Hole Blues and Other Songs from Outer Space"Readers will enjoy the big ideas in this lively and enjoyable book."—Robert P. Kirshner, author of The Extravagant Universe"All three of these authors are experts in the field, and they are also engaging writers. This is a very good book. There is nothing on the market that quite matches it."—Sean Carroll, author of The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World"As an astronomer, I admire the clever and artful way so much frontier cosmology is covered in this book. I enjoyed reading it immensely."—Chris Impey, coauthor of Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration