约瑟夫·拉莫尔Joseph Larmor

约瑟夫·拉莫尔的父亲是Hugh Larmor，母亲是Anna Wright。Anna Wright是拉莫尔 Wright的女儿，而拉莫尔是以其外祖父的名字命名的。拉莫尔出生时，Hugh Larmor是个农民，但在拉莫尔大约六七岁时，他放弃了务农，成为贝尔法斯特一家杂货店的商人。拉莫尔是一个大家庭中的长子。

到拉莫尔该上学的年龄时，他的父母已搬到贝尔法斯特，因此他是在那座城市就读于皇家贝尔法斯特学术学院的。当时他是一个[1]：-

一个害羞、体弱[而]早熟的男孩……

离开学校后，拉莫尔在贝尔法斯特继续接受教育，在贝尔法斯特女王大学攻读文学学士和文学硕士学位。1877年，从女王大学毕业后，他前往剑桥大学圣弗瑞兹·约翰学院，在那里学习数学荣誉学位考试课程。1880年，他以高级数学荣誉学位考试一等及格者（Wrangler）（一等第一名学生）毕业，并获得史密斯奖第一名。有趣的是，与拉莫尔一样将对理解电子做出重要贡献的J J 汤姆孙，是第二名数学荣誉学位考试一等及格者（Wrangler）（在数学荣誉学位考试中仅次于拉莫尔）。

毕业后，拉莫尔被选为圣约翰学院的会士。此后不久，仍在1880年，他回到爱尔兰，被任命为戈尔韦女王学院的自然哲学教授。他在戈尔韦度过了五年，从1880年到1885年，然后于1885年回到剑桥的圣约翰学院担任讲师。他后来于1903年成为剑桥的卢卡斯数学讲席教授，该讲席因乔治·加布里埃尔·斯托克斯于同年2月去世而空缺。

拉莫尔的贡献出现在物理学发生重大革命的时代，经典物理学正被量子论和相对论所取代。他的贡献可以看作新旧物理学之间的桥梁。在[5]和[6]中，Buchwald描述了拉莫尔主要贡献的影响。其核心思想是最小作用量原理，这一原理在拉莫尔整个职业生涯的所有工作中都具有根本重要性，其含义最早由他在1884年发表于Proceedings of the London Mathematical Society的论文Least action as the fundamental formulation in dynamics and physics中提出。他在1894年至1897年间发表了三篇均题为A dynamical theory of the electric and luminiferous medium的论文。这些论文提出了他的电子理论，这一理论在1897年J J Thomson通过实验确认电子后当然获得了更大的分量。Buchwald将拉莫尔的这些论文置于背景之中：-

在1873年至1894年间，英美物理学家推崇一种理论，他们几乎都直接从J C 詹姆斯·克拉克·麦克斯韦的著作《电与磁通论》（1873年）中习得该理论。1897年之后，他们中只有少数人，包括奥利弗·赫维赛德，仍然坚持该理论。在这三年间（1894—1897），詹姆斯·克拉克·麦克斯韦电磁理论的最基本原理被抛弃，整个学科在拉莫尔与George 乔治·斐兹杰惹商讨后，以新的基础——电子——得以重建。……[他提出]电荷的唯一来源是粒子，这种粒子的流动唯一地构成传导电流，并且以太必须与物质严格分离……

Warwick在[15]中详细解释了拉莫尔如何发展他的理论。他将这一过程总结如下：-

……拉莫尔最初通过物理光学和热力学来处理地球运动问题，但……当他与剑桥之外的其它Maxwellians接触——尤其是与George 乔治·斐兹杰惹——他越来越将电磁理论作为其工作的基础。事实上，在引入电子之后，他开始将穿过以太的运动问题作为运动物体的电动力学问题来处理。在这一特定的电磁学背景下，拉莫尔面对Michelson-法兰克·莫雷实验的零结果问题，采纳了著名的乔治·斐兹杰惹-亨德里克·洛伦兹收缩假说，并成为第一位使用现在所谓的‘亨德里克·洛伦兹’变换的物理学家。

拉莫尔于1900年写了Aether and Matter（由贺拉斯·兰姆改名为Aether and no matter），这是1898年剑桥约翰·柯西·亚当斯奖的获奖作品。它纳入了我们上面提到的1894—1897年三篇主要论文的大部分工作。Warwick在[15]中写道：-

他1900年的著作《以太与物质》，剑桥大学出版社，剑桥，1900年，帮助建立了一个研究学派，该学派指导了剑桥数学电磁理论的发展，直到第一次世界大战结束。

然而沃里克15也写道：-

然而今天，拉莫尔在科学家中广为人知，仅仅是因为两个公式和一个定理，尽管这些确实正确地归功于他，但科学史家们认为它们与他的主要研究兴趣关系不大。事实上，最近关于拉莫尔科学工作的学术研究甚至都没有提到这些如今著名的公式和定理。

我们应该以沃里克为榜样，确保提到那些今天与拉莫尔的名字联系在一起的概念。这些是“拉莫尔进动”、“拉莫尔频率”、“拉莫尔定理”和“拉莫尔公式”。第一个解释了磁场中谱线的分裂和偏振。拉莫尔频率与电子在磁场中的轨道运动有关，并促使他假设电子围绕某个中心运动。他似乎是最早预测这种行为的人。拉莫尔定理是一个相关结果，涉及某种变换如何能使受电场和磁场作用的带电粒子的磁场变为零。他是第一个计算加速电子能量辐射率的人，为此他给出了拉莫尔公式，该公式根据电子的电荷和加速度给出了辐射功率。由于相对论效应，该公式在速度接近光速时失效。

拉莫尔当然没有急于接受当时正在发展的时空新观念。他[3]：-

……在科学观点上绝对是保守的。很难确定他对新进展（尤其是量子理论）欣赏到什么程度，因为他习惯于采取一种姿态，夸大自己的超然态度。他在阿尔伯特·爱因斯坦的引力理论上摇摆不定。有一小段时间他完全皈依，但后来又重新反对。最终，他不仅拒绝了空间弯曲，甚至拒绝了早期狭义相对论的观点。

当乔治乔治·加布里埃尔·斯托克斯和威廉开尔文（开尔文勋爵）去世时，拉莫尔担任了他们全集的编辑。他还在1921年出版了亨利·卡文迪什著作的新版本，詹姆斯·克拉克·麦克斯韦曾是原版的编辑。拉莫尔还投入了相当多的精力撰写乔治·加布里埃尔·斯托克斯（1903年）、约西亚·威拉德·吉布斯（1905年）和开尔文（1908年）的讣告。

拉莫尔于1932年从剑桥大学卢卡斯数学讲席退休。保罗·狄拉克接替了他的这一职位。随着健康状况恶化，拉莫尔返回爱尔兰，在唐郡霍利伍德度过了他的最后岁月。他终身未婚，亲近他的人形容他[1]：-

……一个谦逊、羞怯的人，不轻易与人建立亲密友谊，他的许多慷慨之举都是不事张扬地做出的。

达西・汤普森写道：-

拉莫尔也许朋友不多；但在他有生之年，以及他们健在之时，他从未失去任何一位朋友。

他于1884年成为伦敦数学会的成员，并为该学会做出了许多贡献，从1887年到1912年担任理事会成员。在理事会任职期间，他于1890年和1891年担任副主席，还从1892年到1914年担任该学会司库二十多年。他于1914年担任该学会主席，同年，该学会授予他奥古斯塔斯·德摩根奖章。

Royal Society于1892年选举拉莫尔为会士，他于1901年至1912年担任秘书。Royal Society于1915年授予他皇家奖章，并于1921年授予他科普利奖章。他受到多所大学的荣誉，授予他荣誉学位：都柏林、牛津、贝尔法斯特、格拉斯哥、阿伯丁、伯明翰、圣安德鲁斯、达勒姆和剑桥。他还被选为许多学术团体的成员，包括爱尔兰皇家科学院、American Academy of Arts and Sciences和Accademia dei Lincei。

拉莫尔于1909年被封为爵士，从1911年到1922年担任剑桥大学的议员。他于1912年在议会发表首次演讲，鉴于他的背景，他在关于爱尔兰自治的辩论中支持统一党人并不令人意外。然而，他在议会的主要贡献是特别大力支持大学，以及总体上支持教育。

拉莫尔积极参与学院事务，多年担任圣约翰学院理事会成员。在[9]中，讲述了一个关于他参与学院事务的趣闻：-

……他性情保守，甚至对诸如学院安装浴室（1920年）这类事情上的现代潮流也持质疑态度。“我们400年来都没有这些东西，为什么现在要开始用？”他曾在一次学院会议上这样说。然而一旦安装了这些新设施，他却成了经常使用者。每天清晨，他穿着在其他时候见不到的雨衣、戴着帽子，穿过桥前往新庭院浴室。

Joseph Larmor's father was Hugh Larmor and his mother was Anna Wright. Anna Wright was the daughter of Joseph Wright, and Joseph Larmor was named after his maternal grandfather. Hugh Larmor was a farmer at the time Joseph was born but he gave up farming when Joseph was around six or seven years old to become a trader with a grocer's shop in Belfast. Joseph was the eldest of a large family.

By the time Joseph was of an age to attend school, his parents had moved to Belfast so it was in that city that he attended the Royal Belfast Academical Institution. At this time he was [1]:-

A shy, delicate [and] precocious boy ...

After leaving school, Larmor continued his education in Belfast, studying for his B.A. and M.A. at Queen's University, Belfast. In 1877, having graduated from the Queen's University, he went to St John's College, Cambridge, where he studied the Mathematical Tripos. In 1880 he graduated as Senior Wrangler (the top First Class student) and he was first Smith's prizeman. It is interesting to note that J J Thomson, who like Larmor would make an important contribution to the understanding of the electron, was Second Wrangler (taking second place in the Mathematical Tripos examinations to Larmor).

After graduating Larmor was elected a Fellow of St John's College. Soon after this, still in the year 1880, he returned to Ireland when he was appointed as professor of Natural Philosophy at Queen's College, Galway. He spent five years, 1880 to 1885, teaching in Galway before he returned to St John's College, Cambridge, as a lecturer in 1885. He went on to become Lucasian Professor of Mathematics at Cambridge in 1903, the chair becoming vacant on the death of Stokes in February of that year.

Larmor's contributions came at a time when there were major revolutions in physics with the passing of classical physics to be replaced by quantum theory and relativity. His contributions can be seen as a bridge between the old and the new physics. In [5] and [6] Buchwald describes the impact of Larmor's major contributions. The main underlying idea was the principle of least action, which would be of fundamental importance in all Larmor's work throughout his career, and its implications were first set out by him in his paper Least action as the fundamental formulation in dynamics and physics which he published in the Proceedings of the London Mathematical Society in 1884. He published three papers all entitled A dynamical theory of the electric and luminiferous medium between 1894 and 1897. These papers presented his theory of the electron, which of course gained further weight in 1897 when J J Thomson experimentally identified the electron. Buchwald puts these papers by Larmor in context:-

Between 1873 and 1894 British and American physicists were proponents of a theory which they almost all learned directly from J C Maxwell's book Treatise on electricity and magnetism (1873). After 1897 only a few among them, including Heaviside, still adhered to that theory. During these three years (1894-97) the most basic principles of Maxwell's theory of electromagnetism were abandoned, and the entire subject was reconstructed on a new foundation - the electron - by Joseph Larmor in consultation with George FitzGerald. ... [He proposed that] the only source of charge is a particle, that the flow of such particles uniquely constitutes the current of conduction, and that the ether must be strictly separated from matter ...

Warwick in [15] explains in detail how Larmor developed his theory. He summarises the process as follows:-

... Larmor initially tackled the problem of the earth's motion through physical optics and thermodynamics, but ... as he made contact with other Maxwellians beyond Cambridge - especially with George FitzGerald - he came increasingly to make electromagnetic theory fundamental to his work. Indeed, following the introduction of the electron, he began to approach the problem of motion through the ether as one in the electrodynamics of moving bodies. In this specifically electromagnetic context, Larmor confronted the problem of the null result of the Michelson-Morley experiment, adopted the famous FitzGerald-Lorentz contraction hypothesis, and became the first physicist to employ what are now called the 'Lorentz' transformations.

Larmor wrote Aether and Matter in 1900 (renamed by Lamb Aether and no matter ) which was a winning entry for the Adams Prize at Cambridge in 1898. It incorporated much of the work of the three major papers of 1894-1897 we referred to above. Warwick writes in [15]:-

His book of 1900, Aether and matter, Cambridge University Press, Cambridge, 1900, helped to establish a research school that guided the development of mathematical electromagnetic theory in Cambridge until the end of World War I.

However Warwick [15] also writes:-

Today, however, Larmor is widely remembered by scientists for just two formulae and one theorem which, although correctly attributed to him, have been seen by historians of science as tangential to his main research interests. Indeed, none of the recent scholarly studies of Larmor's scientific work even mention the now famous formulae and theorem.

We should take Warwick's lead and make sure that we mention those concepts to which Larmor's name is attached today. These are the 'Larmor precession', the 'Larmor frequency', 'Larmor's theorem' and 'Larmor's formula'. The first explains the splitting and polarisation of the spectral lines in a magnetic field. The Larmor frequency relates to electrons orbiting in a magnetic field and led him to postulate electrons as orbiting around some centre. He appears to have been the first to predict this behaviour. Larmor's theorem is a related result concerning how a certain transformation can negate the magnetic field for a charged particle subject to electric and magnetic fields. He was the first to calculate the rate of energy radiation from an accelerating electron and for this he gave Larmor's formula which gives the power radiated in terms of the electron's charge and acceleration. The formula breaks down for velocities close to the speed of light due to relativistic effects.

However, Larmor certainly did not rush to embrace the new ideas of space time which were being developed. He [3]:-

... was decidedly conservative in his scientific views. It was difficult to ascertain how much he appreciated the new developments (especially quantum theory), because he was accustomed to adopt a pose which exaggerated his aloofness. He wavered much over Einstein's theory of gravitation. For a short time he became a full convert, but afterwards relapsed into opposition. In the end he rejected, not only the curvature of space, but even the standpoint of the earlier special theory of relativity.

When George Stokes and William Thomson (Lord Kelvin) died, Larmor acted as an editor for their complete works. He also brought out a new version of Henry Cavendish's works in 1921, Maxwell had been the editor for the original publication. Larmor also put considerable effort into writing obituaries of Stokes (1903), Gibbs (1905), and Thomson (1908).

Larmor retired from the Lucasian Chair of Mathematics at Cambridge in 1932. He was succeeded in this position by Dirac. With his health deteriorating, Larmor returned to Ireland where he spent his final years at Holywood, County Down. He never married and was described by those close to him as [1]:-

... an unassuming, diffident man who did not readily form close friendships and whose numerous acts of generosity were performed without publicity.

D'Arcy Thompson wrote:-

Larmor made few friends, perhaps; but while he lived, and they lived, he lost none.

He became a member of the London Mathematical Society in 1884 and he contributed much to the Society being a council member from 1887 until 1912. During his period on the council he was vice president in 1890 and 1891 and also served as treasurer of the Society for over twenty years from 1892 until 1914. He was president of the Society in 1914 and, in the same year, he was awarded the De Morgan Medal by the Society.

The Royal Society elected Larmor as a Fellow 1892 and he served as secretary from 1901 to 1912. The Royal Society awarded him its Royal Medal in 1915 and its Copley Medal in 1921. He was honoured by various universities who awarded him honorary degrees: Dublin, Oxford, Belfast, Glasgow, Aberdeen, Birmingham, St Andrews, Durham and Cambridge. He was also elected to membership of many learned societies including the Royal Irish Academy, the American Academy of Arts and Sciences, and the Accademia dei Lincei.

Knighted in 1909, Larmor served as MP for the University of Cambridge from 1911 to 1922. He made his maiden speech in Parliament in 1912 when, not surprisingly given his background, he supported the Unionists in a debate on Irish home rule. His main contributions in Parliament, however, were to give strong support to universities in particular, and education in general.

Larmor was active in college affairs, being a member of the council of St John's College for many years. In [9] a nice story is told of his involvement in College affairs:-

... he was conservative in temperament, questioning modern trends even in such matters as the installation of baths in the College (1920). "We have done without them for 400 years, why begin now?", he once said at a College meeting. Yet once the innovation were made he was a regular user. Morning by morning in a mackintosh and cap, in which he was not seen at other times, he found his way across the bridge to the New Court baths.