约瑟夫·普拉托Joseph Plateau

约瑟夫·普拉托 的父亲是一位具有绘画花卉天赋的艺术人。他希望 普拉托 从事艺术职业，他的学业也是为此目的安排的。在小学表现出色后，普拉托 被送到美术学院。然而，普拉托 在十四岁时成为孤儿，父亲去世，母亲已于一年前去世。普拉托 母亲的一位兄弟，一位律师，M Thirion 先生，接手抚养 普拉托 和他的两个姐妹。普拉托 在这段时间患了重病，有一段时间无法上美术学院。然而，一旦康复，他就恢复了课程。

虽然美术学院的训练主要是在艺术方面，但 普拉托 的兴趣在于科学。他对物理学充满热情，晚上用自己制作的仪器进行实验。这些不仅仅是为了自娱自乐，因为年轻的 普拉托 正在表演以娱乐观众。在这方面，他将表演技巧与灵巧的展示和出色的理解结合在一起。普拉托 于 1817 年进入布鲁塞尔的雅典娜神殿学校完成中学教育。在那里，他有幸受教于 阿道夫·凯特勒，后者于 1819 年被任命为雅典娜神殿学校的初等数学讲席。雅典娜神殿学校的一位同学 皮埃尔·弗朗索瓦·韦吕勒，为 普拉托 提供了可以花许多时间进行深入科学讨论的人，而两人都受到他们的老师 阿道夫·凯特勒 的强烈鼓励，后者成为了他们的朋友。正是 阿道夫·凯特勒 安排了 普拉托 和他的朋友们经常参观国家天文台，这激发了他对天文学的兴趣。

1822 年，普拉托 以优异成绩从雅典娜神殿学校毕业。他的导师建议他在列日大学学习文学和哲学，目的是继续学习法律。当然，他的监护人是律师，所以法律在某种程度上是自然的选择。然而，尽管 普拉托 在这些科目上表现出色，但它们并不是他感兴趣的科目。他觉得别无选择，只能听从建议，并确实获得了文学和哲学学士学位，然后获得了法律学士学位。他已经决定完成这个课程，然后注册学习他真正热爱的科目。他正是这样做的，在列日大学学习数学和物理课程。

普拉托 现在需要负责供养他的姐妹们，而他认真对待这一责任。他没有专注于攻读数学和物理学的博士学位，而是在列日雅典中学担任数学中学教师；他还担任妹妹 Joséphine 的家庭教师。尽管有所有这些职责，普拉托 仍然能够在两年内写出一篇杰出的学位论文，并于 1829 年 6 月 3 日获得博士学位 [4]：-

他的学位论文是对光在眼睛上所能施加的印象之性质的一项卓越研究。不幸的是，同年 [1829]，他对实验的热情促使他进行了一项非常危险的实验，即在大约二十五秒内直视明亮的太阳。在那次不慎行为很久之后，他的眼睛仍然受到刺激。

健康问题意味着他被迫辞去在列日雅典中学的教学职位，并搬到布鲁塞尔，在那里他很快获得了由 M Gaggia 经营的一所学院的教授职位。在布鲁塞尔的一个好处是他可以加入围绕 阿道夫·凯特勒 聚集的年轻科学家圈子。正是通过 阿道夫·凯特勒 的影响，普拉托 于 1835 年被提供根特大学物理学特别教授职位。作为大学教师、研究人员和科学推动者，他都极为成功。1840 年 8 月 27 日，他与 Augustine- Thérèse- Fanny Clavareau 结婚；他们有两个儿子 Félix 和 Ernest，以及一个女儿 Alice。事实上，1840 年对 普拉托 来说还因另一个原因而重要，因为在那一年他首次开始实验，这些实验将引导他研究极小曲面。我们将在下面进一步说明这一点。

普拉托 在 1829 年进行了凝视太阳的实验，直到 1841 年他一直保持着合理的视力。在那一年，他开始遭受眼部炎症。起初，他视力模糊，眼前有许多黑点飘动。随后两年的治疗无效，到 1843 年他已完全失明。麦可·法拉第 后来写道：-

……尽管普拉托的肉体仍深陷于一个悲伤而深沉的夜晚的黑暗之中，但他心智的洞察力却变得比以往任何时候都更为敏锐，这将引领他走向最辉煌的发现，并为比利时科学赢得不朽的荣耀。

尽管当时因失明已无法授课，普拉托仍于1844年6月29日被任命为根特大学正教授。

普拉托的第一项主要贡献与他关于人眼颜色感知的博士工作有关。他在提交学位论文之前的1828年发表了一篇关于这个主题的重要文章。1830年，他做出了一项卓越的发现，为此他应该得到更多的赞誉。他发现，通过旋转圆盘上的孔观察一个周期性运动的物体，以适当的速度旋转圆盘可以使物体看起来静止。当然，这就是所有观看运动图片的原理。这个装置被称为Phenakistiscope（有多种拼写），可以被视为最早的移动媒体娱乐形式之一。它在THIS LINK的Google涂鸦中受到庆祝。

他发表的下一项关于视觉主题的工作涉及眼睛以互补色保留彩色物体印象的机制。

然而，在数学中，他最被人们铭记的是普拉托问题。这项研究的起点是在1840年，当时一个仆人将油洒进一个装满水和酒精混合物的容器中。普拉托注意到油滴在混合物中形成了完美的球体。然后他进行了一系列实验，重复最初的事故，但也研究了当水和酒精混合物旋转时油滴的形状。他后来使用肥皂水和甘油的溶液，将线框轮廓浸入其中，注意到形成的表面是极小曲面。他没有数学技能从理论上研究这个问题，但卡尔·魏尔斯特拉斯、波恩哈德·黎曼和赫尔曼·阿曼杜斯·施瓦茨研究了这个最终由杰西·道格拉斯和蒂博尔·拉多解决的问题。普拉托还写了一些关于数论的数学文章，并与阿道夫·凯特勒合写了一篇文章。

实验的更多细节在THIS LINK。

关于他的性格，Grosjean和Rassias在[4]中写道：-

他性格活泼幽默，记忆力很少让他失望，而且与大多数人相反，随着年龄增长，他的记忆力变得惊人。他喜欢拜访学者，也喜欢在家中欢迎他们。……他到了老年，除了失明之外，身体和精神状态都极佳。

普拉托获得了许多荣誉。他于1834年4月15日当选为比利时皇家科学院（Académie Royale des Sciences, des Lettres et des Beaux Arts）的通讯院士，并于1836年12月15日当选为正式院士。他曾两次获得数学和物理学五年奖，第一次是在1854年，表彰他在1849-53年期间的工作，第二次是在1869年，表彰他在1864-68年期间的工作。1841年12月13日，他被授予利奥波德勋章骑士称号，后来于1859年11月15日晋升为军官，最终于1872年5月28日晋升为司令。

Joseph Plateau's father was an artistic man with a great talent for painting flowers. He wanted Joseph to follow an artistic career and his schooling was arranged with this aim. After excelling at primary school, Joseph was sent to the Academy of Fine Arts. However Joseph became an orphan at the age of fourteen when his father died, his mother having died one year earlier. A brother of Joseph's mother who was a lawyer, a M Thirion, took over bringing up Joseph and his two sisters. Joseph had a serious illness around this time and for a while could not attend the Academy. However, once he had recovered he resumed his course.

Although the training at the Academy was mainly in the arts, Plateau's interests were in science. He was enthusiastic about physics and carried out experiments in the evenings with apparatus which he had constructed himself. These were not simply for his own amusement, for the young Plateau was putting on a show to entertain an audience. In this he combined showmanship with a display of dexterity and excellent understanding. Plateau entered the Athenaeum in Brussels in 1817 to complete his secondary education. There he was fortunate to be taught by Adolphe Quetelet who was appointed to the chair of elementary mathematics at the Athenaeum in 1819. A fellow pupil at the Athenaeum, Pierre Verhulst, provided someone with whom Plateau could spend many hours in deep scientific discussions, while both were strongly encouraged by their teacher Quetelet who became their friend. It was Quetelet who arranged for Plateau and his friends to frequently visit the National Observatory which encouraged his interest in astronomy.

In 1822 Plateau graduated from the Athenaeum having achieved outstanding success. His tutor advised him to study literature and philosophy at the University of Liège with the aim of going on to study law. Of course his guardian was a lawyer so law was in some ways a natural choice. However, although Plateau had shown great ability in these subjects, they were not the ones which interested him. He felt he had no choice but to follow the advice and indeed obtained a bachelor's degree in literature and philosophy and then a bachelor's degree in law. He had already decided that he would complete this course but then register to study the subjects which he really loved. He did just that, studying courses in mathematics and physics at the University of Liège.

Plateau now was responsible for providing for his sisters and he took this responsibility seriously. Rather than concentrate on working for a doctorate in mathematics and physics, he took a job as a secondary school teacher of mathematics at the Athenaeum of Liège; he also acted as a tutor for his sister Joséphine. Despite having all these duties, Plateau was still able to write an outstanding doctoral dissertation in a period of two years and he was awarded a doctorate on 3 June 1829 [4]:-

His thesis was a remarkable study of the properties of the impressions which light can exercise on the eye. Unfortunately, the same year [1829], his ardour for experimentation pushed him to carry out a very dangerous experiment consisting in looking directly into the bright sun during approximately twenty-five seconds. A long time after that imprudence, his eyes were still irritated.

Health problems meant he was forced to resign from his teaching position at the Athenaeum in Liège and he moved to Brussels where he soon was given the position of professor in a College run by M Gaggia. An advantage of being in Brussels was that he could join the circle of young scientists who gathered round Quetelet. It was through Quetelet's influence that Plateau was offered the position of extraordinary professor of physics at the University of Ghent in 1835. He was highly successful both as a university teacher, researcher and as a promoter of science. On 27 August 1840 he married Augustine- Thérèse- Fanny Clavareau; they had two sons Félix and Ernest, and a daughter Alice. In fact 1840 was important for another reason for Plateau, for in that year he first began experiments which would lead him to study minimal surfaces. We shall say more about this below.

Although Plateau had carried out his experiment of staring at the sun in 1829, he had retained reasonable vision until 1841. In that year he began to suffer with inflammation of his eyes. At first he suffered from blurring of vision with many black spots floating about in front his sight. Treatment during the following two years was ineffective and by 1843 he had become totally blind. Faraday later wrote:-

... although bodily Plateau remained plunged in the darkness of a sad profound night, the perspicacity of his mind, having become more intensive than ever, was to lead to the most brilliant discoveries and to conquer for Belgium science an immortal glory.

Despite now being unable to teach because of his blindness, Plateau was made a full professor at the University of Ghent on 29 June 1844.

Plateau's first major contributions were related to the work of his doctorate on perceptions of colour by the human eye. He published an important article on this topic in 1828 before submitting his doctoral dissertation. In 1830 he made a remarkable discovery for which he should receive much more credit. He discovered that by observing a periodically moving object through a hole in a rotating disk, it was possible to make the object appear stationary by rotating the disk at a suitable speed. Of course this is the principle which underlies all viewing of moving pictures. This device was called the Phenakistiscope (with various spellings) and can be regarded as one of the first forms of moving media entertainment. It is celebrated in the Google doodle at THIS LINK.

The next work he published on the topic of vision related to the mechanism by which eye retains an impression of a coloured object in the complementary colour.

He is best remembered in mathematics, however, for Plateau Problems. The starting point for this investigation was in 1840 when a servant spilt oil into a container filled with a mixture of water and alcohol. Plateau noticed that the drops of oil formed into perfect spheres in the mixture. He then carried out a series of experiments repeating the original accident but also investigating the shape of the drops of oil when the mixture of water and alcohol is rotating. He later used a solution of soapy water and glycerine and dipped wire contours into it, noting that the surfaces formed were minimal surfaces. He did not have the mathematical skills to investigate the problem theoretically but Weierstrass, Riemann and Schwarz worked on the problem which was finally solved by Douglas and Radó. Plateau also wrote some mathematical articles on number theory and wrote a joint article with Quetelet.

More details of the experiments are at THIS LINK.

As to his character Grosjean and Rassias write in [4]:-

He had a vivid and humorous character, his memory seldom let him down, and in contrast to most people, it became prodigious as he grew older. He was fond of visiting scholars and liked to welcome them at his home. ... he reached old age, bodily and mentally in excellent state, exception made for his blindness.

Plateau received many honours. He was elected a corresponding member of the Royal Belgium Academy of Science (Académie Royale des Sciences, des Lettres et des Beaux Arts) on 15 April 1834 and was elected a full member on 15 December 1836. He was awarded the quinquennial prize for Mathematics and physics twice, first in 1854 for his work over the period 1849-53, then for a second time in 1869 for his work over the period 1864-68. On 13 December 1841 he was named Knight of the Order of Leopold, later being promoted to officer on 15 November 1859 and finally to commander on 28 May 1872.