This book features several of the significant scientific debates and controversies that helped develop space science in the early space era. The debates led to significant new understandings of the constituents and processes occurring beyond Earth’s atmosphere, and often opened new research directions. Scientific speculations with their resultant debates have played an important role in the development and furthering of research in general. The book thus has broad intellectual importance in illustrating how science advances. The book includes debates in the subject areas of heliophysics (physics in the cosmic region that covers particles and magnetic fields flowing from the Sun), Earth’s moon, solar system asteroids and comets, and the origin of cosmic gamma-ray bursts. A final chapter describes two important and surprising early scientific discoveries that involved no debates. The target audience for this book includes (a) active and retired space scientists, (b) space enthusiasts, and (c) students as supplemental (or even prime) reading in an introductory astronomy and/or space science course. The topics of the debates and controversies, their resolutions, and their pointing to further research and understanding of nature are of both historical and contemporary interest, appeal, and value.

This is a provocative account of the astounding new answers to the most basic philosophical question: Where did the universe come from and how will it end?

A respected physics professor and author breaks down the great debate over the Big Bang and the continuing quest to understand the fate of the universe. Today, the Big Bang is so entrenched in our understanding of the cosmos that to doubt it would seem crazy. But as Paul Halpern shows in Flashes of Creation, just decades ago its mere mention caused sparks to fly. At the center of the debate were Russian American physicist George Gamow and British astrophysicist Fred Hoyle. Gamow insisted that a fiery explosion explained how the elements of the universe were created. Attacking the idea as half-baked, Hoyle countered that the universe was engaged in a never-ending process of creation. The battle was fierce. In the end, Gamow turned out to be right -- mostly -- and Hoyle, along with his many achievements, is remembered for giving the theory the silliest possible name: "The Big Bang." Halpern captures the brilliance of both thinkers and reminds us that even those proved wrong have much to teach us about boldness, imagination, and the universe itself.

This textbook provides an introduction to gravitational lensing, which has become an invaluable tool in modern astrophysics, with applications that range from finding planets orbiting distant stars to understanding how dark matter and dark energy conspired to form the cosmic structures we see today. Principles of Gravitational Lensing begins with Einstein’s prediction that gravity bends light, and shows how that fundamental idea has spawned a rich field of study over the past century. The gravitational deflection of light was first detected by Eddington during a solar eclipse in May 1919, launching Einstein and his theory of relativity into public view. Yet the possibility of using the phenomenon to unlock mysteries of the Universe seemed remote, given the technology of the day. Theoretical work was carried out sporadically over the next six decades, but only with the discovery of the system Q0957+561 in 1979 was gravitational lensing transformed from a curiosity of general relativity into a practical observational tool. This book describes how the three subfields known as strong lensing, weak lensing, and microlensing have grown independently but become increasingly intertwined. Drawing on their research experience, Congdon and Keeton begin with the basic physics of light bending, then present the mathematical foundations of gravitational lensing, building up to current research topics in a clear and systematic way. Relevant background material from physics and mathematics is included, making the book self-contained. The derivations and explanations are supplemented by exercises designed to help students master the theoretical concepts as well as the methods that drive current research. An extensive bibliography guides those wishing to delve more deeply into particular areas of interest. Principles of Gravitational Lensing is ideal for advanced students and seasoned researchers looking to penetrate this thriving subject and even contribute research of their own.

Space is again in the headlines. E-billionaires Jeff Bezos and Elon Musk are planning to colonize Mars. President Trump wants a "Space Force" to achieve "space dominance" with expensive high-tech weapons. The space and nuclear arms control regimes are threadbare and disintegrating. Would-be asteroid collision diverters, space solar energy collectors, asteroid miners, and space geo-engineers insistently promote their Earth-changing mega-projects. Given our many looming planetary catastrophes (from extreme climate change to runaway artificial superintelligence), looking beyond the earth for solutions might seem like a sound strategy for humanity. And indeed, bolstered by a global network of fervent space advocates-and seemingly rendered plausible, even inevitable, by oceans of science fiction and the wizardly of modern cinema-space beckons as a fully hopeful path for human survival and flourishing, a positive future in increasingly dark times. But despite even basic questions of feasibility, will these many space ventures really have desirable effects, as their advocates insist? In the first book to critically assess the major consequences of space activities from their origins in the 1940s to the present and beyond, Daniel Deudney argues in Dark Skies that the major result of the "Space Age" has been to increase the likelihood of global nuclear war, a fact conveniently obscured by the failure of recognize that nuclear-armed ballistic missiles are inherently space weapons. The most important practical finding of Space Age science, also rarely emphasized, is the discovery that we live on Oasis Earth, tiny and fragile, and teeming with astounding life, but surrounded by an utterly desolate and inhospitable wilderness stretching at least many trillions of miles in all directions. As he stresses, our focus must be on Earth and nowhere else. Looking to the future, Deudney provides compelling reasons why space colonization will produce new threats to human survival and not alleviate the existing ones. That is why, he argues, we should fully relinquish the quest. Mind-bending and profound, Dark Skies challenges virtually all received wisdom about the final frontier.

This book introduces the Statistical Drake Equation where, from a simple product of seven positive numbers, the Drake Equation is turned into the product of seven positive random variables. The mathematical consequences of this transformation are demonstrated and it is proven that the new random variable N for the number of communicating civilizations in the Galaxy must follow the lognormal probability distribution when the number of factors in the Drake equation is allowed to increase at will. Mathematical SETI also studies the proposed FOCAL (Fast Outgoing Cyclopean Astronomical Lens) space mission to the nearest Sun Focal Sphere at 550 AU and describes its consequences for future interstellar precursor missions and truly interstellar missions. In addition the author shows how SETI signal processing may be dramatically improved by use of the Karhunen-Loève Transform (KLT) rather than Fast Fourier Transform (FFT). Finally, he describes the efforts made to persuade the United Nations to make the central part of the Moon Far Side a UN-protected zone, in order to preserve the unique radio-noise-free environment for future scientific use.

A BBC Sky at Night Best Astronomy and Space Book of the Year “[A] luminous guide to the cosmos...Jo Dunkley swoops from Earth to the observable limits, then explores stellar life cycles, dark matter, cosmic evolution and the soup-to-nuts history of the Universe.” —Nature “A grand tour of space and time, from our nearest planetary neighbors to the edge of the observable Universe...If you feel like refreshing your background knowledge...this little gem certainly won’t disappoint.” —Govert Schilling, BBC Sky at Night Most of us have heard of black holes and supernovas, galaxies and the Big Bang. But few understand more than the bare facts about the universe we call home. What is really out there? How did it all begin? Where are we going? Jo Dunkley begins in Earth’s neighborhood, explaining the nature of the Solar System, the stars in our night sky, and the Milky Way. She traces the evolution of the universe from the Big Bang fourteen billion years ago, past the birth of the Sun and our planets, to today and beyond. She then explains cutting-edge debates about such perplexing phenomena as the accelerating expansion of the universe and the possibility that our universe is only one of many. Our Universe conveys with authority and grace the thrill of scientific discovery and a contagious enthusiasm for the endless wonders of space-time.