奥托·尤利耶维奇·施密特Otto Schmidt

奥托·尤利耶维奇·施密特的名字常被音译为Shmidt。当然，施密特听起来像是一个德国名字，而这正是施密特父系祖先的来源地。他们曾迁居到库尔兰，这是波罗的海沿岸的一个地区，在18世纪末成为俄罗斯帝国的一部分。该地区于1918年成为拉脱维亚的一部分。施密特的父亲Julius Fridrihovich 施密特试图靠经商谋生。施密特的母亲Anna Fridrihovna Ergli来自库尔兰的一个农民家庭；事实上，她与Julius相识是因为他们是近邻。考虑到这样的背景，人们可能会好奇家里说什么语言。令人惊讶的是，家里说三种语言：俄语、拉脱维亚语和德语。这是一个大家庭，施密特是五个孩子之一。

在施密特成长过程中，全家四处搬迁，试图改善境遇、寻求更好的生活，但施密特在莫吉廖夫、敖德萨和基辅的学校接受了良好的教育。这个男孩“表现出不寻常的好奇心和求知欲”，这促使他的家人让他接受良好的学术教育，而不是让他学一门手艺。鉴于家庭经济状况不佳，这意味着相当大的牺牲。1900年，他在莫吉廖夫开始接受教育，直接进入文理中学二年级，但全家很快搬到敖德萨，1901年他在那里的文理中学继续学业。他对学习的热忱体现在他去找敖德萨学校的校长想要学习古希腊语（他已经能流利使用拉丁语）。尽管学校里没有其他人对学习希腊语感兴趣，校长还是找到一位老师，在一对一的课堂上教施密特。另一次搬迁使全家于1907年来到基辅，施密特像整个求学期间一样，继续在课堂之外自学，特别是阅读经典书籍、学习外语和高等数学。1909年，他以金质奖章从基辅第二古典文理中学毕业，同年进入基辅大学物理数学系。

在大学里，施密特像求学期间一样继续长时间学习，常常通宵达旦。他师从一些杰出的数学家，如德米特里·格雷夫、B Ya Bukreev、G Y Pfeiffer、G K Suslov和V P Voronets。他的进步非常突出，在第二年的学习中，德米特里·格雷夫开始鼓励他从事研究。德米特里·格雷夫创立了基辅代数学派，在施密特就读期间，基辅是代数的领先中心。施密特的进步如此显著，以至于还在本科阶段，他就在1912-13年发表了三篇关于群论的优秀论文，包括Über die Zerlegung endlicher Gruppen in direkte unzerlegbare Faktoren Ⓣ（《论有限群分解为不可约直因子》）（1912年）和Sur les produits directs Ⓣ（《论直积》）（1913年）。第一篇论文为他赢得了一枚金质奖章。这些论文包含了今天所谓的沃尔夫冈·克鲁尔-施密特定理（有时也称为罗伯特·雷马克-沃尔夫冈·克鲁尔-施密特定理）。这比沃尔夫冈·克鲁尔版本的定理早了大约十四年，但施密特的版本发表于1912年1月，仅比罗伯特·雷马克的版本晚几个月，后者包含在他1911年的学位论文中。上述标题的1913年论文包含了一个新的更简短的证明。

他与Vera Yanitskaia结婚，并于1913年从基辅大学毕业。根据德米特里·格雷夫的推荐，他继续在基辅攻读硕士学位，并于1916年获得学位。同年，他出版了专著The abstract theory of groups，这是第一本同时包含有限群和无限群结果的群论书籍。书中有许多原创结果，特别是在施密特称之为特殊群的领域（特殊群是满足$G$的群，使得$G$的每个真子群$H$都有一个不同于$H$的正规化子）。由于这一杰出出版物，施密特被授予拉赫曼尼诺夫金质奖章。该书的第二版于1933年以俄语出版，第二版的英译本于1966年出版。获得硕士学位后，他被任命为基辅大学的privatdocent，开始了他的教学生涯。然而，1917年俄国革命的事件彻底改变了他职业生涯的方向。

第一次世界大战的事件已经对乌克兰，特别是基辅，产生了严重的后果。1914年末，俄罗斯对奥匈帝国取得了胜利，但在1915年春天，奥匈帝国重新夺回了乌克兰的部分地区，导致基辅大学疏散到萨拉托夫。施密特和大学的其他成员一样，在1915-16年间住在萨拉托夫，直到大学返回基辅后，他才开始了大学教师的职业生涯。然而，即使在他职业生涯的早期阶段，他也在教育和城市管理方面承担了领导职务。他被选为基辅高等教育教师协会的主席，并在1917年初帮助组织基辅市的粮食分配。1917年6月，他前往彼得格勒（当时圣彼得堡的名称）参加全俄高等教育大会。1917年3月，由于严重的粮食短缺，彼得格勒已经发生了骚乱，结果，沙皇被迫退位，成立了临时政府。7月14日，施密特被任命为粮食部的一名职员，但仍留在基辅大学的教职员工中。

1917年10月，布尔什维克发动了政变。粮食部被解散，成立了粮食人民委员部。施密特被任命为其中一个部门的负责人。次年3月，业务从彼得格勒迁至莫斯科，施密特也迁至莫斯科，他的第一个儿子弗拉基米尔·奥托维奇于1920年3月在那里出生。在20世纪20年代初，他承担了更多的职务，例如在教育人民委员部。他撰写了多份关于教育重组的报告，包括：The importance of vocational education；Problems of professional education；On higher education；和The reform of the school system。他的文章Mathematical laws of currency issue（1923年）讨论了货币供应问题，这是当时苏联政府的一个重要问题。然而，除了这些职务外，施密特于1920年开始在中学任教，同年，他被任命为林业学院的讲师。1923年，他成为莫斯科国立大学的数学教授，在那里他成为代数系的主任，并建立了一个活跃的群论学派。

1921年，施密特被任命为国家出版社的主任，在他的领导下，科学期刊和研究专著的出版重新开始。正是以这一身份，他计划承担一项巨大的任务，即制作一部重要的俄罗斯参考著作。1924年4月，他被任命为《大苏联百科全书》的主编。这是一项非常庞大的工程，除了招募众多科学家和艺术专家撰写文章外，施密特本人也在多年间撰写了大量文章。

小时候，施密特患有肺结核，尽管他恢复得很好，但疾病定期复发。1924年，他前往奥地利蒂罗尔接受治疗，其中一部分涉及爬山。这段经历使他成为了一名热衷的登山者，并于1928年率领一支苏德联合探险队探索了帕米尔高原的冰川，这是中亚的高地地区。探险队探索了费德琴科冰川地区，使得首次绘制出帕米尔西北部的精确地形图成为可能。尽管他有众多的任务和健康问题，他仍然能够产出相当重要的数学论文。1924年，他发表了Groups all of whose proper subgroups are special。我们已经注意到施密特使用了“特殊群”这一术语，并在上面给出了定义。在这篇论文中，他分类了所有真子群都是幂零的有限非幂零群。1927年夏天，他前往德国进行学术访问，并向哥廷根数学会提交了一篇关于具有链条件的无限群的重要论文。这篇论文发表在Mathematische Zeitschrift上，题为Über unendliche Gruppen mit endlicher Kette Ⓣ（关于具有有限链的无限群）（1929年）。

相当值得注意的是，我们还没有谈到施密特一生中今天最为人所知的事件，即他作为俄罗斯和西伯利亚北极的科学家和探险家的工作。1928年，他被任命为破冰船Sedov的负责人，进行了一次前往法兰士约瑟夫地群岛的科学探险，这是巴伦支海东北部由191个岛屿组成的群岛。许多岛屿是由1873年奥匈帝国探险队发现的（并以奥地利皇帝命名），但在1926年被苏联吞并。显然，苏联热衷于在其新吞并的土地上建立永久存在，但对苏联领导层来说，施密特是一个很好的选择，这是有原因的。他表现出自己是1917年俄国革命的坚定支持者，并在次年加入了布尔什维克。然而，他对斯大林在1924年列宁去世后带领苏联的方向感到不满。1928年，斯大林推出了符合其政治哲学但导致大范围饥荒的经济政策。在许多方面，值得注意的是，反对斯大林做法的施密特竟然幸存下来——斯大林的大多数反对者都被清除了。也许斯大林没有预料到他会从法兰士约瑟夫地群岛返回，但无论如何，就领导层而言，他已经不碍事了。

1928年的探险在法兰士约瑟夫地群岛建立了极地地球物理观测站并安全返回。两年后，施密特率领第二次探险前往同一目的地，再次乘坐破冰船Sedov，越过法兰士约瑟夫地群岛向北地群岛进发。这次探险中发现的一座岛屿以他们的领队施密特命名为施密特岛。1932年，他被任命为北方海航道中央管理局局长，该局是为开发东北航道而设立的，这是一条沿北海岸连接俄罗斯欧洲部分与西伯利亚的海上航线。

在一次探险指挥中，施密特于1932年从摩尔曼斯克出发，乘坐破冰船Sibiryakov（原为纽芬兰捕海豹汽船Bellaventure），试图从西向东航行东北航道。西比里亚科夫号绕过了北地群岛的北端，停靠了蒂克西和科雷马河口，但在到达白令海峡之前，在遇到的冰中失去了螺旋桨。它继续扬帆穿过海峡，到达了符拉迪沃斯托克。次年，施密特指挥了第二次探险，乘坐破冰船Chelyuskin，打算从西向东航行，然后沿同一路线返回。他们于1933年7月12日启航，船上有一百多人，包括妇女和儿童。在几乎从西边到达白令海峡时，它被困在冰中，冰最终压碎了船只，随后在楚科奇海沉没。探险队的大多数成员设法弃船并在冰上建立了营地。他们修建了一条着陆跑道，最终被多架飞机救起。施密特成为了民族英雄。许多报纸文章描述了他的功绩，广播节目和新闻短片也对他进行了报道：-

女孩们把从杂志上剪下的他的肖像挂在房间里。

1937年5月，施密特开始了另一次探险，这次是乘飞机从法兰士约瑟夫地群岛的一个岛屿出发。飞机降落在距离北极13英里内的冰上，他在那里建立了研究站“北极1号”。其他飞机运送了更多的人员和物资，之后施密特返回法兰士约瑟夫地群岛，然后返回莫斯科。1937年6月27日，在莫斯科以西15公里的图希诺机场，他的飞机降落，斯大林和政治局成员迎接了他，授予他苏联英雄称号和列宁勋章。随后，他又被带到克里姆林宫参加宴会，后来还设立了一枚特别的“金星”奖章，以授予他进一步的荣誉。然而，1937年晚些时候，北极1号研究站所在的冰漂向格陵兰，1938年2月，施密特乘坐破冰船成功执行了救援任务，接回了科学家们。施密特于1933年2月1日当选为苏联科学院通讯院士，1935年6月1日当选为正式院士。他敦促科学院成立理论地球物理研究所，该研究所于1938年成立。施密特在研究所成立时成为所长，并在此后十年担任该职务。1939年2月28日，他当选为苏联科学院副院长，任职至1942年3月24日。在这一职位上，他负责因二战期间德国入侵而被迫疏散和重建的学术机构。然而，他被约瑟夫·斯大林免去了在苏联科学院的职务，不久之后又被免去了《大苏联百科全书》的编辑职务。

1944年，施密特提出了关于太阳系起源的假说。他在1949年出版的Four lectures on the theory of the origin of the Earth一书中发表了这一理论。他的理论是，太阳在某个时候穿过一团尘埃和气体云，这团云被其引力吸引而捕获。云在旋转，并在引力作用下收缩，变得更加密集。尘埃粒子合并形成更大的天体，其引力吸引进一步物质，形成更大的天体。这一理论与先前提出的理论的主要区别之一是，行星形成时是寒冷的固体，而不是炽热的熔融状态。他提出，地球的变暖是由于其核心中元素的放射性衰变，因此释放出大量气体和水蒸气，这些气体和水蒸气凝结形成了海洋。他还发表了关于天文学问题的论文，如The theory of capture and statistical laws of the distribution of the orbits of double stars（俄文）（1948年）和The problem of capture in the three body problem（俄文）（1948年）。

我们绝不能给人留下施密特放弃了群论的印象，因为事实恰恰相反。例如，亚历山大·热纳季耶维奇·库罗什通过阅读施密特的论文并参加他1930年在莫斯科国立大学讲授的群论课程，受到影响而成为群论学家。施密特在职业生涯末期撰写的群论论文例子包括：Über die Frobenius-Gruppen Ⓣ（论费迪南德·格奥尔格·弗罗贝尼乌斯群）（1940年）、Groups with two classes of non-invariant subgroups（俄文）（1940年）、On infinite special groups（俄文）（1940年）和Infinite soluble groups（俄文）（1945年）。在提及他在群论方面的工作时，我们应该提到“施密特问题”——例如见[8]。这个问题问的是哪些无限群没有无限真子群。Szélpál在1949年证明，海因茨·普吕弗的拟循环群是唯一具有此性质的阿贝尔群。随后几年获得了许多其他结果，表明当施加比阿贝尔更弱的条件时，拟循环群是唯一的例子。Kostrikin [20]讨论了后续工作，包括A Yu Ol'shanskii于1982年发表的例子：-

对于每个足够大的素数p，存在一个无限群G，使得G的每个真子群的阶为p。

到施密特提出太阳系起源理论时，他的健康已开始严重恶化。从童年起就周期性影响他的肺结核已扩散到他的喉咙和肺部。他发现说话越来越困难，大部分时间在莫斯科附近和雅尔塔的疗养院度过。有时病情缓解，他能够在莫斯科和列宁格勒讲课。他继续工作，即使卧床不起，1951年他在莫斯科国立大学创立了地球物理系并被任命为系主任。1953年，他仍然能够在莫斯科国立大学新大楼的开幕式上讲课，但他不得不在莫斯科附近的兹韦尼哥罗德越来越多地卧床休息。在他生命的最后三个月里，他知道自己时日无多。他说：-

我感激赋予我的生命。有许多美好而有趣的事物！我不惧怕死亡。

我们在上面提到了授予施密特的许多荣誉。他被授予三枚列宁勋章、两枚红旗勋章、一枚红星勋章和几枚奖章。然而，我们应该通过列出更多保存他记忆的方式来表明他的英雄地位变得多么伟大。各种地理特征以他的名字命名：喀拉海的一个岛屿、新地岛北部的半岛、楚科奇海沿岸的一个海角、帕米尔山脉的一个山峰和一个山口。同样以他命名的还有苏联地球物理研究所、北极探险博物馆和一所中学。阿尔汉格尔斯克、基辅和利佩茨克都有以他命名的街道，莫吉廖夫也有一条城市大道。第一艘苏联科学破冰船于1979年下水，命名为Otto Schmidt。1995年，设立了施密特奖章，以表彰在北极研究和开发方面的杰出科学工作。一颗小行星（第2108号）以他的名字命名，月球上的一个陨石坑也是如此。

Otto Yulyevich Schmidt's name is often transliterated as Shmidt. Of course, Schmidt sounds like a German name and this is precisely where Otto Schmidt's ancestors on his father's side came from. They had moved to Courland, a region on the Baltic coast which had become part of the Russian Empire at the very end of the 18th century. The region became part of Latvia in 1918. Otto's father, Julius Fridrihovich Schmidt, tried to make a living trading goods. Otto's mother, Anna Fridrihovna Ergli, was from a farming family in Courland; in fact she met Julius since she was a near neighbour. One might wonder, given this background, what language was spoken in the home. Amazingly three languages were spoken, Russian, Latvian and German. It was a large family with Otto being one of five children.

The family moved around as Otto was growing up, trying to improve their fortunes and find a better life, but Otto was given a good educations at schools in Mogilev, Odessa and Kiev. The fact that the boy "showed uncommon curiosity and a desire for knowledge" had encouraged his family to give him a good academic education rather than have him learn a trade. Given the poor financial position of the family, this entailed a considerable sacrifice. It was in 1900 that he began his education in Mogilev, going straight into the second grade of the Gymnasium, but the family soon moved to Odessa where he continued his schooling at the Gymnasium in 1901. His passion for learning is illustrated by the fact that he approached the headmaster of the school in Odessa wanting to learn ancient Greek (he was already fluent in Latin). Although nobody else in the school was interested in studying Greek, the headmaster found a teacher to teach Schmidt in a class of one. Another move saw the family go to Kiev in 1907 and Schmidt, as he had done throughout his school years, continued with self-study outside the classroom, in particular reading classic books, studying foreign languages, and higher mathematics. He graduated from Classical Gymnasium No 2 in Kiev in 1909 with the Gold Medal and, in the same year, entered the Physics and Mathematics Faculty of Kiev University.

At university, Schmidt continued to work long hours as he had during his school years, often spending the whole night studying. He was taught by some outstanding mathematicians such as D A Grave, B Ya Bukreev, G Y Pfeiffer, G K Suslov and V P Voronets. His progress was outstanding and, in his second year of study, Dmitry Aleksandrovich Grave began to encourage him to undertake research. Grave had founded the Kiev school of algebra and, at the time Schmidt studied there, Kiev was the leading centre for algebra. Schmidt's progress was so marked that, while still an undergraduate, he published three excellent papers on group theory in 1912-13 including Über die Zerlegung endlicher Gruppen in direkte unzerlegbare Faktoren Ⓣ (1912) and Sur les produits directs Ⓣ (1913). The first of these papers earned him a gold medal. They contain what today is called the Krull-Schmidt theorem (or sometimes the Remak-Krull-Schmidt theorem). This is around fourteen years before Krull's version of the theorem but Schmidt's version was published in January 1912, only months after Remak's version which is contained in his 1911 doctoral thesis. The 1913 paper whose title is given above contains a new shorter proof.

He married Vera Yanitskaia and graduated from Kiev University in 1913. Following Grave's recommendation, he continued to study at Kiev for his Master's degree which he was awarded in 1916. In the same year, he published the monograph The abstract theory of groups which was the first group theory book to include results on both finite and infinite groups. There are many original results in the book, particularly in the area of what Schmidt called special groups (special groups are groups $G$ such that every proper subgroup $H$ of $G$ has a normaliser different from $H$). For this remarkable publication, Schmidt was awarded the Rakhmaninov Gold Medal. A second edition of the book was published in Russian in 1933 and an English translation of this second edition was published in 1966. Following the award of his Master's degree, he was appointed as a privatdocent at the University of Kiev and began his teaching career. The events of the Russian revolution of 1917, however, completely changed the direction of his career.

The events of World War I had already had severe consequences for Ukraine and Kiev in particular. Russia had won victories against Austro-Hungary in late 1914 but in the spring of 1915 Austro-Hungary had recaptured parts of Ukraine leading to an evacuation of Kiev University to Saratov. Schmidt had, like other members of the university, lived in Saratov during 1915-16 and it was only after the university returned to Kiev that he began his career as a university teacher. However, even at this early stage in his career he was undertaking leading administrative roles both in education and in running the city. He had been elected to chair the Society for Higher Education Teachers of Kiev and by early 1917 was also helping organise food distribution for the city of Kiev. In June 1917 he went to Petrograd (as St Petersburg was called at that time) to attend the All-Russian Congress on Higher Education. There had already been riots in Petrograd in March 1917 because of severe food shortages and, as a result, the Tsar was forced to abdicate and a Provisional Government set up. On 14 July Schmidt was appointed as a clerk in the Ministry of Food but remained on the staff of Kiev University.

In October 1917 the Bolsheviks staged a coup. The Ministry of Food was disbanded and the People's Commissariat for Food was set up. Schmidt was appointed as head of one of the divisions. In March of the following year operations were moved from Petrograd to Moscow and Schmidt relocated to Moscow where his first son Vladimir Ottovich was born in March 1920. In the early 1920s, he took on further roles such as in the People's Commissariat for Education. He produced several reports on the restructuring of education, including: The importance of vocational education; Problems of professional education; On higher education; and The reform of the school system. His article Mathematical laws of currency issue (1923) addressed the question of the money supply, an important problem for the Soviet government at the time. However, in addition to these roles, Schmidt began to teach in secondary schools in 1920 and, in the same year, he was appointed as a lecturer at the Forestry Institute. In 1923 he became a Professor of Mathematics at Moscow State University where he became Head of the Department of Algebra and set up an active school of group theory.

In 1921 Schmidt was appointed as director of the State Publishing House and under his leadership publishing of scientific journals and research monographs restarted. It was in this capacity that he planned to undertake a huge task of producing a major Russian reference work. In April 1924 he was appointed as editor-in-chief of the Great Soviet Encyclopaedia. This was a very large undertaking and, as well as enlisting numerous scientists and experts in the arts to write articles, Schmidt himself authored many articles over a period of many years.

As a child Schmidt had suffered from tuberculosis and, although he had made a good recovery, the illness recurred periodically. In 1924 he went to the Austrian Tyrol where he received treatment part of which involved climbing mountains. This experience led him to became a keen mountaineer and, in 1928, he headed a joint Soviet-German expedition which explored the glaciers of the Pamirs, the highland region of Central Asia. The expedition explored the region of the Fedchenko Glacier, making possible the first accurate topographical maps of the north-western Pamirs. Despite his numerous tasks and his health problems he was still able to produce mathematical papers of considerable importance. In 1924 he published Groups all of whose proper subgroups are special. We have already noted that Schmidt used the term 'special group' and given a definition above. In this paper he classified finite non-nilpotent groups all of whose proper subgroups are nilpotent. In the summer of 1927 he went to Germany on a research visit and delivered an important paper on infinite groups with chain conditions to the Göttingen Mathematical Society. This was published in Mathematische Zeitschrift as Über unendliche Gruppen mit endlicher Kette Ⓣ (1929).

It is rather remarkable that we still have not reached the events of Schmidt's life for which he is best known today, namely his work as a scientist and explorer of the Russian and Siberian Arctic. In 1928 he was put in charge of the icebreaker Sedov on a scientific expedition to Franz Josef Land, an archipelago of 191 islands in the northeastern Barents Sea. Many of the islands had been discovered by an Austro-Hungarian expedition in 1873 (and named after the Austrian emperor) but annexed by the Soviet Union in 1926. Clearly the Soviet Union was keen to establish a permanent presence in their newly annexed land but there was a reason why Schmidt was a good choice as far as the Soviet leadership was concerned. He had shown himself a strong supporter of the Russian revolution of 1917 and had joined the Bolsheviks in the following year. However, he was unhappy with the direction that Stalin took the Soviet Union after the death of Lenin in 1924. In 1928 Stalin brought in economic policies which fitted his political philosophy but caused widespread famine. In many ways it is remarkable that Schmidt, who opposed Stalin's approach, survived at all - most of Stalin's opponents were eliminated. Perhaps Stalin did not expect him to return from Franz Josef Land, but anyway he was out of the way as far as the leadership was concerned.

The 1928 expedition established the Polar Geophysical Observatory in Franz Josef Land and returned safely. Two years later Schmidt headed a second expedition to the same destination, again on the icebreaker Sedov, going beyond Franz Josef Land towards the Severnaya Zemlya. An island they discovered on this expedition was named Ostrov Shmidta, after their leader Schmidt. In 1932 he was appointed as head of the Central Administration of the Northern Sea Route which had been set up to develop the northeastern passage, a sea route along the north coast linking European Russia with Siberia.

In command of an expedition, Schmidt sailed on the ice-breaker Sibiryakov (originally the Newfoundland sealing steamer Bellaventure) setting out from Murmansk in 1932 in an attempt to navigate the northeastern passage from west to east. The Sibiryakov rounded the northern tip of Severnaya Zemlya, called at Tiksi and the mouth of the Kolyma, but lost its propeller in the ice it encountered before reaching the Bering Strait. It continued under sail through the Strait and reached Vladivostok. The following year Schmidt commanded a second expedition on the ice-breaker Chelyuskin intending to make the voyage from west to east and then return along the same route. They sailed on 12 July 1933 with over one hundred people, including women and children, on board. Having almost reached the Bering Strait from the west, it became stuck in ice which eventually crushed the vessel which then sank in the Chukchi Sea. Most of the members of the expedition had managed to abandon the ship and set up a camp on the ice. They constructed a landing strip and were eventually rescued by a number of airplanes. Schmidt became a national hero. Many newspaper articles described his exploits, radio programs featured him as did the newsreels:-

Girls hung portraits of him cut from magazines in their rooms.

In May 1937 Schmidt set off on another expedition, this time by aircraft from one of the Franz Josef Land islands. The airplane landed on the ice within 13 miles of the North Pole where he set up a research station "North Pole 1". Other airplanes flew out further men and supplies after which Schmidt returned to Franz Josef Land and then to Moscow. On 27 June 1937, at Tushino airfield 15 km west of Moscow where his plane landed, he was met by Stalin and members of the Politburo who honoured him with the title Hero of the Soviet Union and the Order of Lenin. He was then further honoured by being taken to a banquet in the Kremlin and later, a special medal "Gold Star" was established to award him a further distinction. However, later in 1937 the ice on which the research station North Pole 1 was set up drifted towards Greenland and, in February 1938, Schmidt mounted a successful rescue mission on an ice-breaker to bring back the scientists. Schmidt had been elected a corresponding member of the USSR Academy of Sciences on 1 February 1933 and a full member on 1 June 1935. He urged the Academy to found an Institute of Theoretical Geophysics which happened in 1938. Schmidt became director of the Institute on its foundation, a role he held for the following ten years. On 28 February 1939 he was elected vice-president of the USSR Academy of Sciences, a position he held until 24 March 1942. In this capacity he was responsible for the evacuation and reestablishment of academic institutions forced on the Soviet Union because of the German invasion during World War II. He was, however, removed from his role in the USSR Academy of Sciences by Joseph Stalin and shortly afterwards he was removed from the editorship of the Great Soviet Encyclopaedia.

In 1944 Schmidt proposed his hypotheses of the origin of the solar system. This theory he published in his 1949 book Four lectures on the theory of the origin of the Earth. His theory was that at some point the sun passed through a cloud of dust and gas which was captured by its gravitational attraction. The cloud was rotating and it contracted under gravity becoming more dense. Dust particles coalesced to form larger bodies whose gravitational attraction caused further material to be swept up forming larger bodies. One of the main differences of this theory from those which had been proposed earlier was that the planets formed as cold solid bodies rather than in a hot molten state. The warming of the Earth, he suggested, was due to radioactive decay of elements in its core which, as a consequence, released large amounts of gas and water vapour which condensed to form the oceans. He also published papers on astronomical problems such as The theory of capture and statistical laws of the distribution of the orbits of double stars (Russian) (1948) and The problem of capture in the three body problem (Russian) (1948).

We must not give the impression that Schmidt gave up group theory for nothing could be further from the truth. For example, A G Kurosh had been influenced to become a group theorist through reading Schmidt's papers and attending a group theory course he gave at Moscow State University in 1930. Examples of group theory papers that Schmidt wrote towards the end of his career include: Über die Frobenius-Gruppen Ⓣ (1940), Groups with two classes of non-invariant subgroups (Russian) (1940), On infinite special groups (Russian) (1940), and Infinite soluble groups (Russian) (1945). While mentioning his work in group theory, we should mention the "Schmidt problem" - see for example [8]. This asks which infinite groups have no infinite proper subgroups. Szélpál showed in 1949 that Prüfer's quasi-cyclic groups are the only abelian groups with this property. Many other results were obtained over the following years showing that the quasi-cyclic groups are the only examples when weaker conditions than abelian are imposed. Kostrikin [20] discusses subsequent work including the examples by A Yu Ol'shanskii published in 1982:-

For every sufficiently large prime p there exists an infinite group G such that every proper subgroup of G has order p.

By the time that Schmidt proposed his theory of the origin of the solar system his health had begun to seriously deteriorate. The tuberculosis which had periodically affected him from childhood had spread to his throat as well as his lungs. He found speaking increasingly difficult and spent much time in a sanatorium near Moscow, and one in Yalta. At times the condition eased and he was able to lecture in Moscow and Leningrad. He continued to work, even when confined to bed, and in 1951 he founded the Geophysical Department at Moscow State University and was appointed its head. In 1953 he was still able to lecture at the opening of a new building at Moscow State University but he had to spend increasing amounts of time in bed in Zvenigorod, near Moscow. During the last three months of his life he knew that he had little time left. He said:-

I am thankful for the life I was given. There were many good and many interesting things! I'm not afraid to die.

We have mentioned above many of the honours awarded to Schmidt. He was awarded three Orders of Lenin, two Orders of Red Banner, an Order of Red Star and several medals. However, we should indicate just how great his hero status became by listing further ways in which his memory has been preserved. Various geographical features have been named after him: an Island in the Kara Sea, the peninsula in the northern part of Novaya Zemlya, a cape on the coast of the Chukchi Sea, one of the peaks and a pass in the Pamir Mountains. Also named for him is the Institute of Earth Physics of the USSR, the Museum of Arctic Exploration, and a Gymnasium. There are streets in Archangel, Kiev, and Lipetsk named for him as well as an urban avenue in Mogilev. The first Soviet scientific icebreaker was launched in 1979 and named Otto Schmidt. In 1995 the Schmidt Medal was established for outstanding scientific work in research and development of the Arctic. A minor planet (No 2108) has been named after him, as has a crater on the moon.