A Collection of Biographies with special emphasis on Geophysics by Wolfgang A. Lenhardt Lenhardt – Biographies 1 Foreword This presentation of biographies is far from complete and kept very brief for each person relevant to geophysics. Most texts are taken from Wikipedia and respective links are stated at the bottom of each page. The biographies are sorted in chronological order according respective years of birth and show pictures (when possible from their haydays) of these scientists and engineers. Their countries of birth and death are given in historical context (England <> G.B. >> U.K., Prussia <> Germany, Austro-Hungarian Empire >> Austria, Yugoslavia <> Serbia, Croatia, etc.) thus might to appear erratic, but are deemed to be correct. It seems appropriate to mention the many achievements in geophysics which were not accomplished by a single person alone – as it happens in all other scientific disciplines. Therefore, collaborations are briefly addressed in some slides. In addition, the sequence of biographies is supplemented by slides describing two significant natural events, which altered almost immediately the course of geophysical understanding of our planet. Each person has been allocated a specific main achievement or topic related to geophysics. Sometimes, these allocations are incomplete, like for e.g. Gauss, Laplace or Young, which were truly multi-talented. Hence, some of the headlines might be considered not to the point by some readers. I apologize for that. Please let me know, where I did very wrong. [email protected] Vienna/Austria 21st of December, 2020 Lenhardt – Biographies 2 Brief Overview of Plate Tectonics 13th cent. Petrus Peregrinus Compass 1596 Abraham Ortelius Geographer, shapes of continents match! 1600 William Gilbert Earth magnetism 1635 Henry Gellibrand Secular variation (movement of geomagnetic field) 1735 Pierre Bouguer Abnormal gravity at Chimborazo (Andes) 1831-1843 Carl Friedrich Gauss Separation of the inner and outer Earth‘s magnetic field 1858 Antonio Snider-Pellegrini Similarities of fossils in coal seams 1895 Pierre Curie Loss of magnetism of rocks at high temperatures 1906 Bernard Brunhes Inversion of magnetic field 1908 Frank Bursley Taylor Geology, movement of continents, shape 1915 Alfred Wegener “Die Entstehung der Kontinente und Ozeane” 1926 Harold Jeffreys Rejects continental drift 1927 Arthur Holmes Drift, convection due to heat 1933 Kiyoo Wadati Deep earthquakes in Japan 1937 Alexander du Toit “Our Wandering Continents“, South Africa 1941 Beno Gutenberg & Charles Frederic Richter Subduction? - Already half of the geologists accept continental drift 1950 Patrick Blackett & Keith Runcorn Local magnetic field orientation relates to continental drift 1959/1962 Harry Hess Sea floor topography, “Sea Floor Spreading“ 1963 Drummond Mathews & Frederick Vine Local inversions of magnetic field at sea floor (Carlsberg Ridge) 1963/65 John Tuzo-Wilson Hotspots und transform-faults in oceans Lenhardt – Biographies 3 Ptolemeic World – 2nd century After Ptolemy's book Geography, written c. 150. Based on an inscription in several of the earliest surviving manuscripts, it is traditionally credited to Agathodaemon of Alexandria (2nd century A.D). See also: https://en.wikipedia.org/wiki/Ptolemy%27s_world_map Lenhardt – Biographies 4 Deep Time Aristotle (384 in Stagira/Macedonia – 322 BC in Euboea/Macedonia) was a Greek philosopher and polymath during the Classical period in Ancient Greece. He was the founder of the Lyceum and the Peripatetic School of Philosophy and Aristotelian tradition. Along with his teacher Plato, he has been called the “Father of Western Philosophy”. His writings cover almost all subjects such as physics, biology, zoology, metaphysics, logic, ethics, esthetics, poetry, theatre, music, rhetoric, psychology, linguistics, economics, politics and government. Aristotle provided a complex synthesis of the various philosophies existing prior to him, and it was above all from his teachings that the West inherited its intellectual lexicon, as well as problems and methods of inquiry. As a result, his philosophy has exerted a unique influence on almost every form of knowledge in the West and it continues to be a subject of contemporary philosophical discussion. Meanwhile, many of Aristotle’s findings (e.g. the speed of a free falling object depends on its weight) have been disproved. The philosopher Bertrand Russell argued that “almost every serious intellectual advance has had to begin with an attack on some Aristotelian doctrine”. Russell called Aristotle's ethics “repulsive”, and labelled his logic ”as definitely antiquated as Ptolemaic astronomy”. Russell stated that these errors made it difficult to do historical justice to Aristotle, until one remembered what an advance he made upon all of his predecessors. Geosciences: Aristotle was one of the first people to record any geological observations. He stated that geological change was too slow to be observed in one person's lifetime. The geologist Charles Lyell noted that Aristotle described such change, including “lakes that had dried up” and “deserts that had become watered by rivers”, giving as examples the growth of the Nile delta since the time of Homer, and "the upheaving of one of the Aeolian islands, previous to a volcanic eruption“. Hence, he anticipated the concept of “deep time” which was put forward by John McPhee in 1981. See also: https://de.wikipedia.org/wiki/Aristoteles https://en.wikipedia.org/wiki/Deep_time Lenhardt – Biographies 5 Earth Size Eratosthenes of Cyrene (c. 276 BC in Cyrene/today Libya – c. 195/194 BC in Alexandria/Egypt) was a Greek polymath: a mathematician, geographer, astronomer, poet, and music theorist. He was a man of learning, becoming the chief librarian at the Library of Alexandria. His work is comparable to what is now known as the study of geography, and he introduced some of the terminology still used today. He is best known for being the first person to calculate the circumference of the Earth, which he did by comparing angles of the mid-day Sun at two places, a known North-South distance apart. His calculation was remarkably accurate. He was also the first to calculate the tilt of the Earth's axis, again with remarkable accuracy. Additionally, he may have accurately calculated the distance from the Earth to the Sun and invented the leap day. He created the first global projection of the world, incorporating parallels and meridians based on the available geographic knowledge of his era. Eratosthenes was the founder of scientific chronology; he endeavoured to revise the dates of the chief literary and political events from the conquest of Troy. Eratosthenes dated “The Sack of Troy” to 1183 BC. In number theory, he introduced the sieve of Eratosthenes, an efficient method of identifying prime numbers. He was a figure of influence in many fields. According to an entry in the Suda (a 10th century encyclopedia), his critics scorned him, calling him Beta (the second letter of the Greek alphabet) because he always came in second in all his endeavors. Nonetheless, his devotees nicknamed him Pentathlos after the Olympians who were well rounded competitors, for he had proven himself to be knowledgeable in every area of learning. Eratosthenes yearned to understand the complexities of the entire world. See also: https://en.wikipedia.org/wiki/Eratosthenes Lenhardt – Biographies 6 Seismoscope Zhang Heng (張衡; AD 78 in Nanyang/China – 139 in Luoyang/China), formerly romanized as Chang Heng, was a Chinese polymathic scientist and statesman from Nanyang who lived during the Han dynasty. Educated in the capital cities of Luoyang and Chang'an, he achieved success as an astronomer, mathematician, seismologist, hydraulic engineer, inventor, geographer, cartographer, ethnographer, artist, poet, philosopher, politician, and literary scholar. In 132, Zhang introduced an intricate seismoscope to the court, which he claimed could detect the precise cardinal direction of a distant earthquake. On one occasion his device indicated that an earthquake had occurred in the northwest. As there was no perceivable tremor felt in the capital his political enemies were briefly able to relish the failure of his device, until a messenger arrived shortly afterwards to report that an earthquake had occurred about 400 km to 500 km northwest of Luoyang in Gansu province. During the Han Dynasty, many learned scholars — including Zhang Heng — believed in the “oracles of the winds”. These oracles of the occult observed the direction, force, and timing of the winds, to speculate about the operation of the cosmos and to predict events on Earth. These ideas influenced Zhang Heng's views on the cause of earthquakes. See also: https://en.wikipedia.org/wiki/Zhang_Heng Lenhardt – Biographies 7 Compass Petrus Peregrinus de Maricourt or Pierre Pelerin de Maricourt (French), or Peter Peregrinus of Maricourt (1240 in Maricourt/France – date of death and place not known), was a 13th-century French scholar who conducted experiments on magnetism and wrote the first extant treatise describing the properties of magnets. His work is particularly noted for containing the earliest detailed discussion of freely pivoting compass needles, a fundamental component of the dry compass soon to appear in medieval navigation. He also wrote a treatise on the construction and use of a universal astrolabe. The Epistola de magnete is divided into two parts. Part One discusses the physical (but not the occult) properties of the lodestone (= magnetite)