دانلود کتاب فضازمان کیهانی

Big or small, young or old, we all marvel at the splendor of our Universe. We are struck by its unfathomable extent and agonize over the mystery of its birth. In a sense, our ancestors have been cosmologists from the beginning of written history, probably even earlier. Each succeeding civilization forges its own framework for understanding our place in the cosmos, whether it be immanent, transcendent, or physicalist. At its very foundation, our communion with nature meanders back and forth as new ideas and discoveries rescind broken concepts and sculpt their replacements. Without doubt, however, the greatest revolution in this subject was inspired by the development of the general theory of relativity. Indeed, many trace the foundation of modern cosmology to the year 1917, when Einstein himself applied his description of space interlaced with time to the cosmic setting, shortly after completing his landmark work with the notable mathematicians David Hilbert and Emmy Noether. As it turned out, Einstein’s initial ideas on this topic were incorrect, but his proposal established an important foundation for later thinking. The steps that have brought us from that inauspicious beginning to where we are today tell one of the most remarkable stories in all of science. And many books have been written in the past century to chronicle various stages in this development, especially in recent decades when a cascade of new observational discoveries seemingly threatens to overwhelm our lagging theoretical understanding. But rarely has any of these works focused on the very backbone of modern cosmology—the cosmic spacetime. As we shall document in this book, the evidence we have today compels us to cease merely using the Friedmann-Lemaˆitre-Robertson-Walker (FLRW) metric—one of the most famous solutions to Einstein’s equations—and instead initiate a deeper probe into the nature of spacetime on the grandest scale.