苏布拉马尼扬·钱德拉塞卡Subrahmanyan Chandrasekhar

苏布拉马尼扬·钱德拉塞卡一生都被称为Chandra。他的父亲是C 钱德拉塞卡 Ayyar，母亲是Sitalaksmi Aiyar。他的父亲是一名印度政府审计员，工作是审计西北铁路，来自一个拥有马德拉斯（现金奈）附近一些土地的婆罗门家庭。Chandra来自一个大家庭，有两个姐姐、三个弟弟和四个妹妹。当Chandra还小的时候，他的父母搬到了马德拉斯（现金奈），随着他长大，他被鼓励寻求教育，以便跟随父亲进入政府服务。然而Chandra想成为一名科学家，他的母亲鼓励他走这条路。他的榜样是他的伯父Sir Chandrasekhara Venkata Raman，后者因1928年发现拉曼散射和拉曼效应而于1930年获得诺贝尔奖，拉曼效应是当一束光被分子偏转时发生的光波长变化。关于Chandra与伯父交换的一些信件，见[15]。

钱德拉就读于马德拉斯大学管区学院，还在那里读本科时他就写出了第一篇研究论文。这篇论文发表在Proceeding of the Royal Society上，是由拉尔夫·福勒提交的。同样在管区学院与钱德拉一起的还有Lalitha Doraiswamy，她是一个家庭的女儿，这个家庭住在马德拉斯钱德拉家附近。他们此时订婚了。钱德拉获得了印度政府提供的奖学金，资助他在英国学习，1930年他离开印度，前往英国剑桥大学三一学院学习。1933年至1937年，他在剑桥进行研究，但1936年他回到印度，于9月11日与Lalitha结婚。Mestel写道[2]：-

他们的婚姻是例外，是双方自主选择而非包办。Lalitha的家庭也非常重视教育，婚前她曾担任学校校长。在两人共同生活的五十九年里，她始终是钱德拉塞卡坚定的支持者。这段婚姻没有子女。

1936年他们回到剑桥，但次年钱德拉加入了芝加哥大学的教职，此后他一生都在那里工作。起初他在威斯康星州芝加哥大学所属的叶凯士天文台工作。后来他搬到芝加哥市内的大学校园工作。第二次世界大战期间，他在马里兰州阿伯丁试验场的弹道研究实验室工作。写于1943年的两份报告显示了他当时正在研究的问题类型：第一份是On the decay of plane shock waves，第二份是The normal reflection of a blast wave。

1952年，他被任命为芝加哥大学Morton D Hull杰出服务教授。尽管那时钱德拉已在美国工作15年，但他和妻子此前都没有取得公民身份。然而，第二年两人都成为美国公民，并非常融入这个国家的生活。1964年，当钱德拉被提供剑桥的讲席时，他立即回复说他不感兴趣，从而拒绝了一个他年轻时本会认为最令人向往的职位。

钱德拉塞卡发表了约400篇论文和许多书籍。他的研究兴趣异常广泛，但我们可以将它们分为主题和他专注于这些特定主题的大致时期。首先，他从1929年到1939年研究恒星结构，包括白矮星理论，然后从1939年到1943年研究恒星动力学。接着，他从1943年到1950年研究辐射转移理论和氢负离子的量子理论，随后从1950年到1961年研究流体动力学和磁流体动力学稳定性。在20世纪60年代的大部分时间里，他研究平衡椭球图形的平衡和稳定性，但在此期间他也开始研究广义相对论、辐射反应过程和相对论恒星稳定性等主题。从1971年到1983年期间，他研究黑洞的数学理论，然后在他生命的最后时期，他研究碰撞引力波理论。

1930年，钱德拉表明，质量超过太阳质量1.4倍的恒星（现在称为钱德拉塞卡极限）必须以坍缩成密度极大的物体而结束其生命，这种物体与当时已知的任何物体都不同。他说：-

……人们只能推测其他可能性……

即诸如黑洞之类的物体。然而，这项工作导致了钱德拉与亚瑟·爱丁顿之间的争论，后者将钱德拉的工作描述为：-

……几乎是对相对论性退化公式的归谬法。

亚瑟·爱丁顿当时是相对论方面的顶尖专家，他认为：-

……根本不存在相对论性退化这回事！

钱德拉塞卡因与亚瑟·爱丁顿的争论而深感沮丧，这在一定程度上影响了他此后一生的治学方式。许多年后，钱德拉塞卡于1983年被授予诺贝尔物理学奖——

……以表彰他对恒星结构与演化具有重要意义的物理过程的理论研究。

他在The Mathematical Theory of Black Holes（1983）中描述了这项工作。他说：-

……探索广义相对论物理内容的方式之一，是让自己对其美学基础的感受力来引导问题的表述，并坚信其数学结构具有和谐的一致性。

他的其他著作包括An Introduction to the Study of Stellar Structure（1939年）、Principles of Stellar Dynamics（1942年）、Radiative Transfer（1950年）、Plasma Physics（1960年）、Hydrodynamic and Hydromagnetic Stability（1961年）、Ellipsoidal Figures of Equilibrium（1969年）、Truth and Beauty: Aesthetics and Motivations in Science（1987年）和Newton's Principia for the Common Reader（1995年）。这些著作在数学天文学中发挥了重要作用。例如，一位评论者写道Hydrodynamic and Hydromagnetic Stability:-

……作者在其热不稳定性和旋转不稳定性的主要论题的处理上无人能及。

此外，对Principles of Stellar Dynamics的评论正确地指出：-

这本书写得异常清晰……[它]应该能激发天文学家、数学家和物理学家的兴趣。

钱德拉塞卡于1962年被授予伦敦皇家学会的皇家奖章：-

……以表彰他在数学物理方面的杰出研究，特别是那些与有磁场和无磁场流体中对流运动的稳定性有关的研究。

Royal Society也在1984年授予他科普利奖章：-

...以表彰他在理论物理学方面的杰出工作，包括恒星结构、辐射理论、流体动力学稳定性和相对论。

从1952年到1971年，钱德拉塞卡担任Astrophysical Journal 的编辑。该期刊最初是芝加哥大学的地方出版物，但其地位逐渐提升，成为美国天文学会的全国性出版物，随后成为领先的国际期刊。

钱德拉塞卡因其杰出贡献获得了许多荣誉，其中一些我们已在上文提及，例如1983年的诺贝尔物理学奖、1962年皇家学会的皇家奖章和1984年的科普利奖章。然而，我们还应该提到，他被授予太平洋天文学会的布鲁斯奖章、National Academy of Sciences（美国）的亨利·德雷珀奖章以及皇家天文学会的金奖章。

钱德拉于1980年退休，但继续居住在芝加哥，并于1985年被授予荣休教授。他继续发表发人深省的演讲，例如他在1994年林道诺贝尔奖得主会议上发表的Newton and Michelangelo。他比较了米开朗基罗在西斯廷教堂的壁画和艾萨克·牛顿的Principia：-

...在更广泛的背景下，探讨科学家和艺术家在各自创造性追求中的动机是否有任何相似之处。

类似风格的其它演讲包括Shakespeare, Newton and Beethoven or patterns of creativity和The perception of beauty and the pursuit of science。

钱德拉塞卡在85岁高龄、生命最后几个月仍保持活跃，并出版了他最后一部重要著作Newton's Principia for the Common Reader。这部著作出版后不久，他因心力衰竭去世，葬于芝加哥。他的妻子Lalitha尚在世。让我们引用Tayler在[20]中的话结束这篇传记：-

[钱德拉塞卡]是一位经典应用数学家，其研究主要应用于天文学，像他这样的人大概再也见不到了。

Subrahmanyan Chandrasekhar was known throughout his life as Chandra. His father was C Subrahmanyan Ayyar and his mother was Sitalaksmi Aiyar. His father, an Indian government auditor whose job was to audit the Northwest Railways, came from a Brahman family which owned some land near Madras (now Chennai), India. Chandra came from a large family, having two older sisters, three younger brothers and four younger sisters. When Chandra was still young his parents moved to Madras (now Chennai) and, as he grew up, he was encouraged to seek an education which would see him following his father into government service. However Chandra wanted to be a scientist and his mother encouraged him to follow this route. He had a role model in his paternal uncle Sir Chandrasekhara Venkata Raman who went on to win the Nobel prize in 1930 for his 1928 discovery of Raman scattering and the Raman effect, which is a change in the wavelength of light occurring when a beam of light is deflected by molecules. See [15] for some letters Chandra exchanged with his uncle.

Chandra studied at Presidency College, University of Madras, and he wrote his first research paper while still an undergraduate there. The paper was published in the Proceeding of the Royal Society where it had been submitted by Ralph Fowler. Also at Presidency College with Chandra was Lalitha Doraiswamy, who was the daughter of a family living close to where Chandra's family lived in Madras. They became engaged to marry at this time. Chandra obtained a scholarship from the Indian government to finance his studies in England, and in 1930 he left India to study at Trinity College, Cambridge, England. From 1933 to 1937 he undertook research at Cambridge, but he returned to India in 1936 to marry Lalitha on 11 September. Mestel writes [2]:-

Their marriage, exceptionally, was by mutual choice rather than by arrangement. Lalitha's family was also very interested in education, and before her marriage she worked as a school headmistress. She was an ever-present support for Chandrasekhar during their fifty-nine years together. There were no children of the marriage.

They returned to Cambridge in 1936 but in the following year Chandra joined the staff at the University of Chicago where he was to remain for the rest of his life. At first he worked in Yerkes Observatory, part of the University of Chicago in Wisconsin. Later he moved to work on the university campus in the city of Chicago. During World War II he worked in the Ballistic Research Laboratories at the Aberdeen Proving Ground in Maryland. Two reports, written in 1943, show the type of problems he was working on at this time: the first is On the decay of plane shock waves while the second is The normal reflection of a blast wave.

He was honoured with being appointed Morton D Hull distinguished service professor of the University of Chicago in 1952. Although by that time Chandra had been working in the United States for 15 years, neither he nor his wife had taken out citizenship earlier. However, both became American citizens in the following year and became very much integrated into the life of the country. When Chandra was offered a chair at Cambridge in 1964 he replied by return that he was not interested, so turning down a position which as a young man he would have found the most desirable.

Chandrasekhar published around 400 papers and many books. His research interests were exceptionally broad but we can divide them into topics and rough periods when he was concentrating on these particular topics. First he studied stellar structure, including the theory of white dwarfs, from 1929 to 1939, then stellar dynamics from 1939 to 1943. Next he looked at the theory of radiative transfer and the quantum theory of the negative ion of hydrogen from 1943 to 1950, followed by hydrodynamic and hydromagnetic stability from 1950 to 1961. During most of the 1960s he studied the equilibrium and the stability of ellipsoidal figures of equilibrium but during this period he also began work on topics from general relativity, the radiation reaction process, and the stability of relativistic stars. During the period from 1971 to 1983 he undertook research into the mathematical theory of black holes, then for the last period of his life he worked on the theory of colliding gravitational waves.

In 1930 Chandra showed that a star of a mass greater than 1.4 times that of the Sun (now known as the Chandrasekhar's limit) had to end its life by collapsing into an object of enormous density unlike any object known at that time. He said:-

... one is left speculating on other possibilities ...

namely objects such as black holes. However, this work led to a controversy between Chandra and Eddington who described Chandra's work as:-

... almost a reductio ad absurdum of the relativistic degeneracy formula.

Eddington, who was a leading expert on relativity at this time, argued that:-

... there is no such thing as relativistic degeneracy!.

Chandra was very frustrated by the controversy with Eddington and to a certain extent it influenced the way that he worked through the rest of his life. Many years later Chandra was awarded the Nobel prize for Physics in 1983-

... for his theoretical studies of the physical processes of importance to the structure and evolution of the stars.

He described this work in The Mathematical Theory of Black Holes (1983). He said that:-

... one of the ways in which one may explore the physical content of the general theory of relativity is to allow one's sensibility to its aesthetic base guide in the formulation of problems with conviction in the harmonious coherence of its mathematical structure.

His other books include An Introduction to the Study of Stellar Structure (1939), Principles of Stellar Dynamics (1942), Radiative Transfer (1950), Plasma Physics (1960), Hydrodynamic and Hydromagnetic Stability (1961), Ellipsoidal Figures of Equilibrium (1969), Truth and Beauty: Aesthetics and Motivations in Science (1987), and Newton's Principia for the Common Reader (1995). These texts have played a major role in mathematical astronomy. For example a reviewer wrote of Hydrodynamic and Hydromagnetic Stability:-

... the author has no peer in the treatment of his main topics of thermal and rotational instability.

Also the review of Principles of Stellar Dynamics rightly asserts:-

The book is written with exceptional clarity ... [It] should prove stimulating to astronomer, mathematician and physicist.

Chandrasekhar was awarded the Royal Medal of the Royal Society of London in 1962:-

... in recognition of his distinguished researches in mathematical physics, particularly those related to the stability of convective motions in fluids with and without magnetic fields.

The Royal Society also awarded him their Copley Medal in 1984:-

... in recognition of his distinguished work on theoretical physics, including stellar structure, theory of radiation, hydrodynamic stability and relativity.

From 1952 until 1971 Chandrasekhar was editor of the Astrophysical Journal . This journal was originally a local University of Chicago publication, but it grew in stature to become national publication of the American Astronomical Society, then a leading international journal.

Chandrasekhar received many honours for his outstanding contributions some of which, such as the Nobel prize for Physics in 1983, the Royal Society's Royal Medal of 1962 and their Copley Medal of 1984, we have mentioned above. We should also mention, however, that he was honoured with the Bruce medal of the Astronomical Society of the Pacific, the Henry Draper medal of the National Academy of Sciences (United States), and the Gold Medal of the Royal Astronomical Society.

Chandra retired in 1980 but continued to live in Chicago where he was made professor emeritus in 1985. He continued to give thought-provoking lectures such as Newton and Michelangelo which he delivered at the 1994 Meeting of Nobel Laureates held in Lindau. He compared Michelangelo's frescoes in the Sistine Chapel and Newton's Principia :-

... in the larger context of whether there is any similarity in the motivations of scientists and artists in their respective creative quests.

Other lectures in a similar vein include Shakespeare, Newton and Beethoven or patterns of creativity and The perception of beauty and the pursuit of science.

Chandrasekhar remained active and published in final major book Newton's Principia for the Common Reader at 85 years of age in the final months of his life. Shortly after publication of this work he died from heart failure and was buried in Chicago. He was survived by his wife Lalitha. Let us end this biography by quoting the words of Tayler from [20]:-

[Chandrasekhar] was a classical applied mathematician whose research was primarily applied in astronomy and whose like will probably never be seen again.