《Greene, BrianThe Elegant Universe (Quantum Theory, Superstring) (152 pp)》由会员分享，可在线阅读，更多相关《Greene, BrianThe Elegant Universe (Quantum Theory, Superstring) (152 pp)（120页珍藏版）》请在金锄头文库上搜索。
1、The Elegant Universe:PrefaceDuring the last thirty years of his life, Albert Einstein sought relentlessly for a so-called unified field theorya theory capable of describing natures forces within a single, all-encompassing, coherent framework. Einstein was not motivated by the things we often associa
2、te with scientific undertakings, such as trying to explain this or that piece of experimental data. Instead, he was driven by a passionate belief that the deepest understanding of the universe would reveal its truest wonder: the simplicity and power of the principles on which it is based. Einstein w
3、anted to illuminate the workings of the universe with a clarity never before achieved, allowing us all to stand in awe of its sheer beauty and elegance.Einstein never realized this dream, in large part because the deck was stacked against him: In his day, a number of essential features of matter and
4、 the forces of nature were either unknown or, at best, poorly understood. But during the past half-century, physicists of each new generationthrough fits and starts, and diversions down blind alleyshave been building steadily on the discoveries of their predecessors to piece together an ever fuller
5、understanding of how the universe works. And now, long after Einstein articulated his quest for a unified theory but came up empty-handed, physicists believe they have finally found a framework for stitching these insights together into a seamless wholea single theory that, in principle, is capable
6、of describing all physical phenomena. The theory, superstring theory, is the subject of this book. I wrote The Elegant Universe in an attempt to make the remarkable insights emerging from the forefront of physics research accessible to a broad spectrum of readers, especially those with no training i
7、n mathematics or physics. Through public lectures on superstring theory I have given over the past few years, I have witnessed a widespread yearning to understand what current research says about the fundamental laws of the universe, how these laws require a monumental restructuring of our conceptio
8、n of the cosmos, and what challenges lie ahead in the ongoing quest for the ultimate theory. I hope that, by explaining the major achievements of physics going back to Einstein and Heisenberg, and describing how their discoveries have grandly flowered through the breakthroughs of our age, this book
9、will both enrich and satisfy this curiosity.I also hope that The Elegant Universe will be of interest to readers who do have some scientific background. For science students and teachers, I hope this book will crystallize some of the foundational material of modern physics, such as special relativit
10、y, general relativity, and quantum mechanics, while conveying the contagious excitement of researchers closing in on the long-sought unified theory. For the avid reader of popular science, I have tried to explain many of the exhilarating advances in our understanding of the cosmos that have come to
11、light during the last decade. And for my colleagues in other scientific disciplines, I hope this book will give an honest and balanced sense of why string theorists are so enthusiastic about the progress being made in the search for the ultimate theory of nature.Superstring theory casts a wide net.
12、It is a broad and deep subject that draws on many of the central discoveries in physics. Since the theory unifies the laws of the large and of the small, laws that govern physics out to the farthest reaches of the cosmos and down to the smallest speck of matter, there are many avenues by which one c
13、an approach the subject. I have chosen to focus on our evolving understanding of space and time. I find this to be an especially gripping developmental path, one that cuts a rich and fascinating swath through the essential new insights. Einstein showed the world that space and time behave in astound
14、ingly unfamiliar ways. Now, cutting-edge research has integrated his discoveries into a quantum universe with numerous hidden dimensions coiled into the fabric of the cosmosdimensions whose lavishly entwined geometry may well bold the key to some of the most profound questions ever posed. Although s
15、ome of these concepts are subtle, we will see that they can be grasped through down-to-earth analogies. And when these ideas are understood, they provide a startling and revolutionary perspective on the universe.Throughout this book, I have tried to stay close to the science while giving the reader
16、an intuitive understandingoften through analogy and metaphorof how scientists have reached the current conception of the cosmos. Although I avoid technical language and equations, because of the radically new concepts involved the reader may need to pause now and then, to mull over a section here or ponder an explanation there, in order to follow the progression of ideas fully. A few sections of Part IV (focusing on the most recent developments) are a bit more abstract than the rest; I
