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首版內容介紹瞭宇宙本性最前沿的知識。微觀和宏觀世界觀測技術領域方麵10年來的進展證明瞭霍金教授的許多理論預言。他為瞭把觀測的新知識介紹給讀者,重寫瞭前言,全麵更新瞭原版的內容,並新增瞭一章有關蟲洞和時間旅行的激動人心的課題。 內容簡介
#1 NEW YORK TIMES BESTSELLER
A landmark volume in science writing by one of the great minds of our time, Stephen Hawking’s book explores such profound questions as: How did the universe begin—and what made its start possible? Does time always flow forward? Is the universe unending—or are there boundaries? Are there other dimensions in space? What will happen when it all ends?
Told in language we all can understand, A Brief History of Time plunges into the exotic realms of black holes and quarks, of antimatter and “arrows of time,” of the big bang and a bigger God—where the possibilities are wondrous and unexpected. With exciting images and profound imagination, Stephen Hawking brings us closer to the ultimate secrets at the very heart of creation.
本書是“推動叢書”輯的一種。 時間有初始嗎?它又將在何地終結呢?宇宙是無限的還是有限的? 霍金教授遨遊到外層空間奇異領域,對遙遠星係、黑洞、誇剋、大統一理論、“帶味”粒子和“自鏇”粒子、反物質、“時間箭頭”等進行瞭深入探討--其齣乎意外的含義引起瞭人們的極大興趣。他揭示瞭當日益膨脹的宇宙崩潰時,時間倒溯引起人們不安的可能性,那時宇宙分裂成11維空間,一種“沒有邊界”的宇宙理論可能取代大爆炸理論和上帝,上帝--也許曾是造萬物時主要推動者,也會因這些新發現而日漸範圍變窄。
《時間簡史》對我們這些喜用言語錶達甚於方程式錶達的讀者而言是一本裏程碑式的佳書。她齣於一個對人類思想有傑齣貢獻者之手,這是一本對知識無限追求之作,是對時空本質之謎不懈探討之作。 作者簡介
Stephen Hawking is Lucasian Professor of Mathematics at the University of Cambridge; his other books for the general reader include A Briefer History of Time, Black Holes and Baby Universes and The Universe in a Nutshell.
史蒂芬·霍金(Stephen W.Hawking),1942年齣生於伽利略逝世的三百周年紀念日。他現任劍橋大學盧卡斯數學教授(一度曾為牛頓所任),並廣被尊崇為繼愛因斯坦以來傑齣的理論物理學傢。 精彩書評
“[Hawking] can explain the complexities of cosmological physics with an engaging combination of clarity and wit. . . . His is a brain of extraordinary power.”— The New York Review of Books
“This book marries a child’s wonder to a genius’s intellect. We journey into Hawking’s universe while marvelling at his mind.”— The Sunday Times (London)
“Masterful.”— The Wall Street Journal
“Charming and lucid . . . [A book of] sunny brilliance.”— The New Yorker
“Lively and provocative . . . Mr. Hawking clearly possesses a natural teacher’s gifts—easy, good-natured humor and an ability to illustrate highly complex propositions with analogies plucked from daily life.”— The New York Times
“Even as he sits helpless in his wheelchair, his mind seems to soar ever more brilliantly across the vastness of space and time to unlock the secrets of the universe.”— Time 前言/序言
Chapter One
Our picture of the universe
A well-known scientist (some say it was Bertrand Russell) once gave a public lecture on astronomy. He described how the earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: “What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise.” The scientist gave a superior smile before replying, “What is the tortoise standing on?” “You’re very clever, young man, very clever,” said the old lady. “But it’s turtles all the way down!”
Most people would find the picture of our universe as an infinite tower of tortoises rather ridiculous, but why do we think we know better? What do we know about the universe, and how do we know it? Where did the universe come from, and where is it going? Did the universe have a beginning, and if so, what happened before then? What is the nature of time? Will it ever come to an end? Can we go back in time? Recent breakthroughs in physics, made possible in part by fantastic new technologies, suggest answers to some of these longstanding questions. Someday these answers may seem as obvious to us as the earth orbiting the sun–or perhaps as ridiculous as a tower of tortoises. Only time (whatever that may be) will tell.
As long ago as 340 B.C. the Greek philosopher Aristotle, in his book On the Heavens, was able to put forward two good arguments for believing that the earth was a round sphere rather than a flat plate. First, he realized that eclipses of the moon were caused by the earth coming between the sun and the moon. The earth’s shadow on the moon was always round, which would be true only if the earth was spherical. If the earth had been a flat disk, the shadow would have elongated and elliptical, unless the eclipse always occurred at a time when the sun was directly under the center of the disk. Second, the Greeks knew from their travels that the North Star appeared lower in the sky when viewed in the south than it did in more northerly regions. (Since the North Star lies over the North Pole, it appears to be directly above an observer at the North Pole, but to someone looking from the equator, it appears to lie just at the horizon. From the difference in the apparent position of the North Star in Egypt and Greece, Aristotle even quoted an estimate that the distance around the earth was 400,000 stadia. It is not known exactly what length a stadium was, but it may have been about 200 yards, which would make Aristotle’s estimate about twice the currently accepted figure. The Greeks even had a third argument that the earth must be round, for why else does one first see the sails of a ship coming over the horizon, and only later see the hull?
Aristotle thought the earth was stationary and that the sun, the moon, the planets, and the stars moved in circular orbits about the earth. He believed this because he felt, for mystical reasons, that the earth was the center of the universe, and that circular motion was the most perfect. This idea was elaborated by Ptolemy in the second century A.D. into a complete cosmological model. The earth stood at the center, surrounded by eight spheres that carried the moon, the sun, the stars, and the five planets known at the time, Mercury, Venus, Mars, Jupiter, and Saturn (Fig 1.1). The planets themselves moved on smaller circles attached to their respective spheres in order to account for their rather complicated observed paths in the sky. The outermost sphere carried the so-called fixed stars, which always stay in the same positions relative to each other but which rotate together across the sky. What lay beyond the last sphere was never made very clear, but it certainly was not part of mankind’s observable universe.
Ptolemy’s model provided a reasonably accurate system for predicting the positions of heavenly bodies in the sky. But in order to predict these positions correctly, Ptolemy had to make an assumption that the moon followed a path that sometimes brought it twice as close to the earth as at other times. And that meant that the moon ought sometimes to appear twice as big as at other times! Ptolemy recognized this flaw, but nevertheless his model was generally, although not universally, accepted. It was adopted by the Christian church as the picture of the universe that was in accordance with Scripture, for it had the great advantage that it left lots of room outside the sphere of fixed stars for heaven and hell.
A simpler model, however, was proposed in 1514 by a Polish priest, Nicholas Copernicus. (At first, perhaps for fear of being branded a heretic by his church, Copernicus circulated his model anonymously.) His idea was that the sun was stationary at the center and that the earth and the planets moved in circular orbits around the sun. Nearly a century passed before this idea was taken seriously. Then two astronomers–the German, Johannes Kepler, and the Italian, Galileo Galilei–started publicly to support the Copernican theory, despite the fact that the orbits it predicted did not quite match the ones observed. The death blow to the Aristotelian/Ptolemaic theory came in 1609. In that year, Galileo started observing the night sky with a telescope, which had just been invented. When he looked at the planet Jupiter, Galileo found that it was accompanied by several small satellites or moons that orbited around it. This implied that everything did not have to orbit directly around the earth, as Aristotle and Ptolemy had thought. (It was, of course, still possible to believe that the earth was stationary at the center of the universe and that the moons of Jupiter moved on extremely complicated paths around the earth, giving the appearance that they orbited Jupiter. However, Copernicus’s theory was much simpler.) At the same time, Johannes Kepler had modified Copernicus’s theory, suggesting that the planets moved not in circles but in ellipses (an ellipse is an elongated circle). The predictions now finally matched the observations.
As far as Kepler was concerned, elliptical orbits were merely an ad hoc hypothesis, and a rather repugnant one at that, because ellipses were clearly less perfect than circles. Having discovered almost by accident that elliptical orbits fit the observations well, he could not reconcile them with his idea that the planets were made to orbit the sun by magnetic forces. An explanation was provided only much later, in 1687, when Sir Isaac Newton published his Philosophiae Naturalis Principia Mathematica, probably the most important single work ever published in the physical sciences. In it Newton not only put forward a theory of how bodies move in space and time, but he also developed the complicated mathematics needed to analyze those motions. In addition, Newton postulated a law of universal gravitation according to which each body in the universe was attracted toward every other body by a force that was stronger the more massive the bodies and the closer they were to each other. It was this same force that caused objects to fall to the ground. (The story that Newton was inspired by an apple hitting his head is almost certainly apocryphal. All Newton himself ever said was that the idea of gravity came to him as he sat “in a contemplative mood” and “was occasioned by the fall of an apple.”) Newton went on to show that, according to his law, gravity causes the moon to move in an elliptical orbit around the earth and causes the earth and the planets to follow elliptical paths around the sun.
The Copernican model got rid of Ptolemy’s celestial spheres, and with them, the idea that the universe had a natural boundary. Since “fixed stars” did not appear to change their positions apart from a rotation across the sky caused by the earth spinning on its axis, it became natural to suppose that the fixed stars were objects like our sun but very much farther away.
Newton realized that, according to his theory of gravity, the stars should attract each other, so it seemed they could not remain essentially motionless. Would they not all fall together at some point? In a letter in 1691 to Richard Bentley, another leading thinker of his day, Newton argued that his would indeed happen if there were only a finite number of stars distributed over a finite region of space. But he reasoned that if, on the other hand, there were an infinite number of stars, distributed more or less uniformly over infinite space, this would not happen, because there would not be any central point for them to fall to.
This argument is an instance of the pitfalls that you can encounter in talking about infinity. In an infinite universe, every point can be regarded as the center, because every point has an infinite number of stars on each side of it. The correct approach, it was realized only much later, is to consider the finite situation, in which the stars all fall in on each other, and then to ask how things change if one adds more stars roughly uniformly distributed outside this region. According to Newton’s law, the extra stars would make no difference at all to the original ones on average, so the stars would fall in just as fast. We can add as many stars as we like, but they will still always collapse in on themselves. We now know it is impossible to have an infinite static model of the universe in which gravity is always attractive.
It is an interesting reflection on the general climate of thought before the twentieth century that no one had suggested that the universe was expanding or contracting. It was generally accepted that either the universe had existed forever in an unchanging state, or that it had been created at a finite time in the past more or less as we observe it today. In part this may have been due to...
宇宙的編織:對時間與空間的深度探索 作者:[此處留空,或填寫虛構的作者名] 裝幀:精裝 頁數:約 600 頁 --- 導言:在寂靜的星空中追問存在的本質 自人類第一次仰望夜空,那無垠的黑暗中閃爍的無數光點,便引發瞭最古老、最深刻的疑問:我們從何處來?宇宙的邊界在哪裏?時間,這條似乎永恒流淌的河流,究竟是真實的,還是僅僅是我們感知的一種幻象? 本書並非對既有理論的簡單羅列,而是一次對宇宙結構、時間本質以及人類認知局限性的深刻哲學與科學之旅。它旨在邀請讀者,暫時放下日常瑣碎,與我們一同潛入物理學的最前沿,去觸摸那些定義瞭“實在”的深層代碼。我們將從最宏大的尺度——可觀測宇宙的邊緣——開始,逐步深入到最微小的尺度——量子場的振動之中,力圖描繪一幅既符閤嚴謹數學邏輯,又充滿詩意想象的宇宙全景圖。 第一部分:空間幾何的重塑——從歐幾裏得到黎曼 我們對空間的直覺建立在日常生活的三維歐幾裏得幾何之上:平行綫永不相交,三角形內角和恒為 180 度。然而,當我們將視野投嚮星際尺度,或者試圖理解引力的本質時,這一直覺便開始瓦解。 本部分將詳細探討非歐幾何的誕生與意義。我們不僅會迴顧高斯對麯麵幾何的開創性工作,更會深入解析黎曼幾何如何為愛因斯坦的廣義相對論提供瞭必要的數學框架。引力不再被視為一種力,而是時空本身的幾何屬性——物質和能量彎麯瞭它所處的時空結構,而我們所感受到的“運動”,本質上是在這個彎麯時空中沿著“測地綫”的自然路徑。我們將用直觀的類比和嚴格的數學推導相結閤的方式,剖析時空度規張量的含義,理解黑洞周圍極端彎麯的幾何形態,以及光綫如何在引力透鏡效應中被“扭麯”。 此外,我們還將探討時空維度本身的可能性。從卡魯紮-剋萊因理論對第五維的初步設想,到現代弦理論中對額外緊緻維度的需求,空間的概念正在被不斷拓寬,挑戰著我們對“方嚮”的傳統理解。 第二部分:時間的箭與宇宙的演化 時間,這個我們最熟悉卻最難捉摸的概念,是本書的核心議題之一。我們體驗到的時間是單嚮的——雞蛋可以碎裂,但無法自行復原。物理學中的“時間之箭”指嚮何方? 我們將從熱力學第二定律(熵增定律)齣發,探究宏觀世界中時間不可逆性的根源。隨後,我們將檢視微觀物理定律的“時間對稱性”,分析為何粒子層麵的基本作用力似乎並不區分過去與未來,並討論這在量子力學中引發的深刻矛盾。 隨後,我們將轉嚮宇宙學的宏大敘事。從普朗剋時間尺度開始,我們追蹤宇宙的膨脹曆史。哈勃常數的測量、宇宙微波背景輻射(CMB)的精妙結構,如何共同構建瞭我們對大爆炸模型的信心?我們不僅會分析標準Lambda-CDM模型的成功之處,更會聚焦於模型中的未解之謎:暴脹理論試圖解釋的初始奇點問題、暗物質的引力證據、以及暗能量所代錶的驅動宇宙加速膨脹的神秘負壓。這些現象要求我們超越經典時空觀,擁抱一個動態的、不斷演化的宇宙劇場。 第三部分:量子的深淵與實在的邊界 當我們試圖將引力(宏觀的幾何學)與量子力學(微觀的概率論)統一起來時,我們便觸及瞭現代物理學的“聖杯”——量子引力的難題。 本部分將深入探索量子場論(QFT)的基本框架,理解物質粒子如何被視作基本場的激發態。我們將討論不確定性原理的哲學含義,以及測量行為在構建實在中所扮演的角色。波函數的坍縮、量子糾纏現象——愛因斯坦所稱的“幽靈般的超距作用”——如何挑戰瞭我們對定域性(Locality)的認知? 最終,我們將考察當前最有希望統一兩大理論的嘗試。圈量子引力(LQG)如何嘗試將時空本身“量子化”,使其不再是連續的背景,而是由離散的“量子時空原子”構成?而弦理論則提齣,所有基本粒子都是一維能量弦的不同振動模式,這一理論對多維空間和超對稱性的要求,極大地擴展瞭我們對可能性宇宙的想象。這些前沿理論的數學結構,揭示瞭時間與空間在普朗剋尺度下可能呈現齣的完全不同的、甚至顛覆性的麵貌。 結論:人類心智與無限的交匯 本書的旅程從可見的星空延伸到不可見的量子泡沫,最終導嚮一個核心命題:我們對宇宙的理解,是否受限於我們自身的感知結構?當我們試圖用有限的數學工具去描述無限的實在時,我們究竟是在發現宇宙的內在真理,還是僅僅在構建一個最自洽的“故事”? 通過對這些宏大主題的細緻梳理,本書旨在為嚴肅的科學愛好者提供一個全麵、深入且具有前瞻性的視角,去思考我們所處的這個宇宙——關於它的起源、它的結構、以及它那令人敬畏的、尚未完全揭示的最終命運。這是一部關於“我們是誰,我們在哪裏”的終極探索。