New Ideas

1. New Ideas The geocentric model was nearly universally accepted until 1543 when Nicolaus Copernicus published his book entitled De revolutionibus orbium coelestium and was widely accepted into the next century. At around the same time, the findings of Vesalius corrected the previous anatomical teachings of Galen of Pergamon (129 - 217 AD), which were based upon the dissection of animals even though they were supposed to be a guide to the human body.

2. Andreas Vesalius (1514–1564) was an author of one of the most influential books on human anatomy, De humani corporis fabrica, also in 1543. French surgeon Ambroise Paré (c.1510–1590) is considered as one of the fathers of surgery; he was leader in surgical techniques and battlefield medicine, especially the treatment of wounds. Partly based on the works by the Italian surgeon and anatomist Matteo Realdo Colombo (c. 1516 - 1559), the anatomist William Harvey (1578–1657) described the circulatory system. Herman Boerhaave (1668–1738) is sometimes referred to as a "father of physiology" due to his exemplary teaching in Leiden and textbook 'Institutiones medicae' (1708). Advances in Anatomy

3. William Harvey (1 April 1578 – 3 June 1657) was an English physician who was the first person to describe completely and in detail the systemic circulation and properties of blood being pumped to the body by the heart. Before Harvey, Galen of Pergamon incompletely perceived the function of the heart, believing it a "productor of heat", while the function of its affluents, the arteries, was that of cooling the blood as the lungs "...fanned and cooled the heart itself". Circulatory System

4. Pierre Vernier (1580–1637) was inventor and eponym of the vernier scale used in measuring devices. Evangelista Torricelli (1608 – 1647) was an Italian physicist and mathematician. After Galileo's death in 1642, he succeed Galileo as the professor of mathematics in the University of Pisa. Torricelli's chief invention was the mercury barometer, which arose from solving a practical problem. Pump makers of the Grand Duke of Tuscany attempted to raise water to a height of 12 meters or more, but found that 10 meters was the limit with a suction pump. In 1643 he created a tube approximately one meter long, sealed at the top, filled it with mercury, and set it vertically into a basin of mercury. Torricelli also discovered Torricelli's Law, regarding the speed of a fluid flowing out of an opening, which was later shown to be a particular case of Bernoulli's principle. Modern Science

5. Although Franciscus Vieta (1540–1603) gave the first notation of modern algebra, John Napier (1550–1617) invented logarithms, and Edmund Gunter (1581–1626) created the logarithmic scales (lines, or rules) upon which slide rules are based. It was William Oughtred (1575–1660) who first used two such scales sliding by one another to perform direct multiplication and division; and thus is credited as the inventor of the slide rule in 1622. The Slide Rule

6. Blaise Pascal (1623–1662) invented the mechanical calculator in 1642. The introduction of his Pascaline in 1645 launched the development of mechanical calculators first in Europe and then all over the world. He also made important contributions to the study of fluid and clarified the concepts of pressure and vacuum by generalizing the work of Evangelista Torricelli. He wrote a significant treatise on the subject of projective geometry at the age of sixteen, and later corresponded with Pierre de Fermat (1601–1665) on probability theory, strongly influencing the development of modern economics and social science. Invention of the mechanical calculator

7. Denis Papin (1647–1712), a French-born physicist, mathematician and inventor, was best known for his pioneering invention of the steam digester, the forerunner of the steam engine and the pressure cooker. Abraham Darby (1678–1717) developed a method of producing high-grade iron in a blast furnace fuelled by coke rather than charcoal. This was a major step forward in the production of iron as a raw material for the Industrial Revolution. Thomas Newcomen (1664–1729) perfected a practical steam engine for pumping water, the Newcomen steam engine. Consequently, he can be regarded as a forefather of the Industrial Revolution. Steam Engine

8. Newcomen engines were used throughout Britain and Europe, principally to pump water out of mines, starting in the early 18th century. James Watt's later engine was an improved version. Although Watt is far more famous today, Newcomen rightly deserves the first credit for the widespread introduction of steam power. A Revolution

9. Nicolas Léonard Sadi Carnot (1796 – 1832) was a French physicist who, in his 1824 Reflections on the Motive Power of Fire, gave the first successful theoretical account of heat engines, now known as the Carnot cycle, thereby laying the foundations of the second law of thermodynamics. He is often described as the "Father of thermodynamics", being responsible for such concepts as Carnot efficiency, Carnot theorem, Carnot heat engine, and others. Sadi Carnot Carnot’s book apparently received very little attention from his contemporaries at first. The work only began to have a real impact when modernised by Émile Clapeyron, in 1834 and then further elaborated upon by Clausius and Kelvin, who together derived from it the notion of entropy and the second law of thermodynamics.

10. The concept of entropy developed in response to the observation that a certain amount of functional energy released from combustion reactions is always lost to dissipation or friction and is thus not transformed into useful work. Early heat-powered engines such as Thomas Savery's (1698), the Newcomen engine (1712) and the Cugnot steam tricycle (1769) were inefficient, converting less than two percent of the input energy into useful work output; a great deal of useful energy was dissipated or lost into what seemed like a state of immeasurable randomness. Over the next two centuries, physicists investigated this puzzle of lost energy; the result was the concept of entropy. History of Entropy

11. In 1803, mathematician Lazare Carnot (1753 - 1823) published a work entitled Fundamental Principles of Equilibrium and Movement. This work includes a discussion on the efficiency of fundamental machines, i.e. pulleys and inclined planes. Lazare Carnot saw through all the details of the mechanisms to develop a general discussion on the conservation of mechanical energy. Over the next three decades, Lazare Carnot’s theorem was taken as a statement that in any machine the accelerations and shocks of the moving parts all represent losses of moment of activity, i.e. the useful work done. From this Lazare drew the inference that perpetual motion was impossible. This loss of moment of activity was the first-ever rudimentary statement of the second law of thermodynamics and the concept of 'transformation-energy' or entropy, i.e. energy lost to dissipation and friction. Lazare Carnot

12. Lazare Carnot died in exile in 1823. During the following year Lazare’s son Sadi Carnot, having graduated from the École Polytechnique training school for engineers, wrote the Reflections on the Motive Power of Fire. In this paper, Sadi visualized an ideal engine in which the heat of caloric converted into work could be reinstated by reversing the motion of the cycle, a concept subsequently known as thermodynamic reversibility. Building on his father's work, Sadi postulated the concept that “some caloric is always lost”, not being converted to mechanical work. Hence any real heat engine could not realize the Carnot cycle's reversibility and was condemned to be less efficient. This lost caloric was a precursory form of entropy loss as we now know it. Though formulated in terms of caloric, rather than entropy, this was an early insight into the second law of thermodynamics. Sadi Carnot

13. The caloric theory was introduced by Antoine Lavoisier. Lavoisier developed the explanation of combustion in terms of oxygen in the 1770s. In 1783, Lavoisier proposed a 'subtle fluid' called caloric as the substance of heat. According to this theory, the quantity of this substance is constant throughout the universe, and it flows from warmer to colder bodies. Indeed, Lavoisier was one of the first to use a calorimeter to measure the heat changes during chemical reaction. Since heat was a material substance in caloric theory, and therefore could neither be created nor destroyed, conservation of heat was a central assumption.The introduction of the Caloric theory was also influenced by the experiments of Joseph Black related to the thermal properties of materials. Besides the caloric theory, another theory existed in the late eighteenth century that could explain the phenomena of heat: the kinetic theory. The two theories were considered to be equivalent at the time, but kinetic theory was the more modern one, as it used a few ideas from atomic theory and could explain both combustion and calorimetry. Caloric Theory

14. In 1798, Count Rumford published a report on his investigation of the heat produced while manufacturing cannons. He had found that boring a cannon repeatedly does not result in a loss of its ability to produce heat, and therefore no loss of caloric. This suggested that caloric could not be a conserved "substance". Rumford's experiment inspired the work of James Prescott Joule (1818 – 1889) and others. Joule was an English physicist and brewer. Joule studied the nature of heat, and discovered its relationship to mechanical work. This led to the theory of conservation of energy, which led to the development of the first law of thermodynamics. The SI derived unit of energy, the joule, is named after him. Later Developments

15. The first explicit statement of the first law of thermodynamics was given by Rudolf Clausius in 1850: "There is a state function E, called ‘energy’, whose differential equals the work exchanged with the surroundings during an adiabatic process." First Law of Thermodynamics Rudolf Clausius (1822 – 1888), was a German physicist and mathematician and is considered one of the central founders of the science of thermodynamics. By his restatement of Sadi Carnot's principle known as the Carnot cycle, he put the theory of heat on a truer and sounder basis. In 1865 he introduced the concept of entropy.

16. The second law of thermodynamics may be expressed in many specific ways, the most prominent classical statements being the original statement by Rudolph Clausius (1850), the formulation by Lord Kelvin (1851), and the definition in axiomatic thermodynamics by Constantin Carathéodory (1909). These statements cast the law in general physical terms citing the impossibility of certain processes. They have been shown to be equivalent. Clausius statement: No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature. Kelvin statement: No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work. Second Law of Thermodynamics

17. In 1865, Clausius gave irreversible heat loss in cyclic process a name: “I propose to name the quantity S the entropy of the system, after the Greek word, the transformation content. I have deliberately chosen the word entropy to be as similar as possible to the word energy: the two quantities to be named by these words are so closely related in physical significance that a certain similarity in their names appears to be appropriate.” Although Clausius did not specify why he chose the symbol "S" to represent entropy, it is arguable that Clausius chose "S" in honor of Sadi Carnot, to whose 1824 article Clausius devoted over 15 years of work and research. On the first page of his original 1850 article "On the Motive Power of Heat, and on the Laws which can be Deduced from it for the Theory of Heat", Clausius calls Carnot the most important of the researchers in the theory of heat. History of Entropy

18. In 1876, physicist J. Willard Gibbs, building on the work of Clausius, Hermann von Helmholtz and others, proposed that the measurement of "available energy" ΔG in a thermodynamic system could be mathematically accounted for by subtracting the "energy loss" TΔS from total energy change of the system ΔH. These concepts were further developed by James Clerk Maxwell. Later developments

19. Josiah Willard Gibbs (1839 – 1903) was an American theoretical physicist, chemist, and mathematician. He devised much of the theoretical foundation for chemical thermodynamics as well as physical chemistry. Yale University awarded Gibbs the first American Ph.D. in engineering in 1863, and he spent his entire career at Yale. In 1901, Gibbs was awarded the highest possible honor granted by the international scientific community of his day, granted to only one scientist each year: the Copley Medal of the Royal Society of London, for his greatest contribution of being "the first to apply the second law of thermodynamics to the exhaustive discussion of the relation between chemical, electrical, and thermal energy and capacity for external work." Josiah Willard Gibbs

20. In 1876, physicist J. Willard Gibbs, building on the work of Clausius, Hermann von Helmholtz and others, proposed that the measurement of "available energy" ΔG in a thermodynamic system could be mathematically accounted for by subtracting the "energy loss" TΔS from total energy change of the system ΔH. These concepts were further developed by James Clerk Maxwell. Later developments

21. Hermann von Helmholtz (1821 – 1894) was a German physician and physicist who made significant contributions to several widely varied areas of modern science. In physiology and psychology, he is known for his mathematics of the eye, theories of vision, ideas on the visual perception of space, color vision research, and on the sensation of tone and perception of sound. In physics, he is known for his theories on the conservation of energy, work in electrodynamics, chemical thermodynamics, and on a mechanical foundation of thermodynamics. The largest German association of research institutions, the Helmholtz Association, is named after him. Hermann von Helmholtz

22. In 1876, physicist J. Willard Gibbs, building on the work of Clausius, Hermann von Helmholtz and others, proposed that the measurement of "available energy" ΔG in a thermodynamic system could be mathematically accounted for by subtracting the "energy loss" TΔS from total energy change of the system ΔH. These concepts were further developed by James Clerk Maxwell. Later developments

23. James Clerk Maxwell (1831 – 1879) was a Scottish physicist and mathematician. Maxwell also helped develop the Maxwell–Boltzmann distribution, which is a statistical means of describing aspects of the kinetic theory of gases. These two discoveries helped usher in the era of modern physics, laying the foundation for such fields as special relativity and quantum mechanics. Maxwell is also known for presenting the first durable colour photograph in 1861 and for his foundational work on the rigidity of rod-and-joint frameworks like those in many bridges. James Clerk Maxwell

24. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and even optics into a consistent theory. Maxwell's equations demonstrated that electricity, magnetism and even light are all manifestations of the same phenomenon, namely the electromagnetic field. Subsequently, all other classic laws or equations of these disciplines became simplified cases of Maxwell's equations. Maxwell demonstrated that electric and magnetic fields travel through space in the form of waves, and at the constant speed of light. In 1865 Maxwell published A Dynamical Theory of the Electromagnetic Field. It was with this that he first proposed that light was in fact undulations in the same medium that is the cause of electric and magnetic phenomena. James Clerk Maxwell

25. In 1877, Ludwig Boltzmann formulated the alternative definition of entropy S defined as: S = kB lnΩ where kB is Boltzmann's constant and Ω is the number of microstates consistent with the given macrostate. Boltzmann saw entropy as a measure of statistical "mixedupness" or disorder. This concept was soon refined by J. Willard Gibbs, and is now regarded as one of the cornerstones of the theory of statistical mechanics. Statistical thermodynamic views

26. Ludwig Eduard Boltzmann (1844 – 1906) was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics. He was one of the most important advocates for atomic theory at a time when that scientific model was still highly controversial. Ludwig Boltzmann

27. Boltzmann's most important scientific contributions were in kinetic theory, including the Maxwell–Boltzmann distribution for molecular speeds in a gas. In addition, Maxwell–Boltzmann statistics and the Boltzmann distribution over energies remain the foundations of classical statistical mechanics. They are applicable to the many phenomena that do not require quantum statistics and provide a remarkable insight into the meaning of temperature. Much of the physics establishment did not share his belief in the reality of atoms and molecules — a belief shared, however, by Maxwell in Scotland and Gibbs in the United States. He had a long-running dispute with the editor of the preeminent German physics journal of his day, who refused to let Boltzmann refer to atoms and molecules as anything other than convenient theoretical constructs. Only a couple of years after Boltzmann's death, Perrin's studies of colloidal suspensions (1908–1909), based on Einstein's theoretical studies of 1905, confirmed the values of Avogadro's number and Boltzmann's constant, and convinced the world that the tiny particles really exist. Ludwig Boltzmann

28. The attempt to account for magnetic attraction as the working of a soul in the stone led to the first attack of human reason upon superstition and the foundation of philosophy. After the lapse of centuries, a new capacity of the lodestone became revealed in its polarity, or the appearance of opposite effects at opposite ends; then came the first utilization of the knowledge thus far gained, in the mariner's compass, leading to the discovery of the New World, and the throwing wide of all the portals of the Old to trade and civilization. In the 11th century, the Chinese scientist Shen Kuo (1031–1095) was the first person to write of the magnetic needle compass and that it improved the accuracy of navigation by employing the astronomical concept of true north, and by the 12th century the Chinese were known to use the lodestone compass for navigation. In 1187, Alexander Neckam was the first in Europe to describe the compass and its use for navigation. History of Magnetism

29. Magnetism was one of the few sciences which progressed in medieval Europe; for in the thirteenth century Peter Peregrinus conducted experiments on magnetism and wrote the first extant treatise describing the properties of magnets and pivoting compass needles. The dry compass was invented around 1300 by Italian inventor Flavio Gioja. Italian physician Gerolamo Cardano wrote about electricity in De Subtilitate (1550) distinguishing, perhaps for the first time, between electrical and magnetic forces. Toward the late 16th century, a physician, Dr. William Gilbert (1544 - 1603), in De Magnete, expanded on Cardano's work and invented the New Latin word electricus from ἤλεκτρον (elektron), the Greek word for "amber". History of Magnetism

30. Gilbert also discovered that a heated body lost its electricity and that moisture prevented the electrification of all bodies, due to the now well-known fact that moisture impaired the insulation of such bodies. He also noticed that electrified substances attracted all other substances indiscriminately, whereas a magnet only attracted iron. The many discoveries of this nature earned for Gilbert the title of founder of the electrical science. By investigating the forces on a light metallic needle, balanced on a point, he extended the list of electric bodies, and found also that many substances, including metals and natural magnets, showed no attractive forces when rubbed. Gilbert's work was followed up by Robert Boyle (1627—1691). Boyle was one of the founders of the Royal Society when it met privately in Oxford, and became a member of the Council after the Society was incorporated by Charles II. in 1663. He worked frequently at the new science of electricity. He left a detailed account of his researches under the title of Experiments on the Origin of Electricity. Boyle, in 1675, stated that electric attraction and repulsion can act across a vacuum. History of Electricity

31. The first electrostatic generators are called friction machines because of the friction in the generation process. A primitive form of frictional electrical machine was invented around 1663 by Otto von Guericke (German scientist 1602-1686), using a sulphur globe that could be rotated and rubbed by hand. It may not actually have been rotated during use, but inspired many later machines that used rotating globes. Isaac Newton suggested the use of a glass globe instead of a sulphur one. Francis Hauksbee (English scientist 1666-1713) improved the basic design. The Electric Machine

32. In 1729, Stephen Gray conducted a series of experiments that demonstrated the difference between conductors and non-conductors (insulators). He classified substances into two categories: "electrics" like glass, resin and silk and "non-electrics" like metal and water. "Electrics" conducted charges while "non-electrics" held the charge. Intrigued by Gray's results, in 1732, C. F. du Fay concluded that all objects except metals, animals, and liquids could be electrified by rubbing and that metals, animals and liquids could be electrified by means of an electric machine, thus discrediting Gray's "electrics" and "non-electrics" classification of substances. In 1737 Du Fay and Hawksbee independently discovered what they believed to be two kinds of frictional electricity; one generated from rubbing glass, the other from rubbing resin. From this, Du Fay theorized that electricity consists of two electrical fluids, "vitreous" and "resinous", that are separated by friction and that neutralize each other when combined.[34] This two-fluid theory would later give rise to the concept of positive and negative electrical charges devised by Benjamin Franklin. Electrics and Non-Electrics

33. The Leyden jar, a type of capacitor for electrical energy in large quantities, was invented independently by Ewald Georg von Kleist in 1744 and by Pieter van Musschenbroek in 1745—1746 at Leiden University (the latter location giving the device its name). William Watson, when experimenting with the Leyden jar, discovered in 1747 that a discharge of static electricity was equivalent to an electric current. The capacitive property, now and for many years availed of in the electric capacitor, was first observed by Von Kleist of Leyden in 1754. Leyden Jar

34. In 1752, Benjamin Franklin is frequently confused as the key luminary behind electricity. William Watson and Benjamin Franklin share the discovery of electrical potentials. Benjamin Franklin promoted his investigations of electricity and theories through the famous, though extremely dangerous, experiment of flying a kite through a storm-threatened sky. A key attached to the kite string sparked and charged a Leyden jar, thus establishing the link between lightning and electricity. Following these experiments he invented a lightning rod. It is either Franklin or Ebenezer Kinnersley of Philadelphia who is considered as the establisher of the convention of positive and negative electricity. Kite Experiment

35. To Franz Aepinus, a noted German scholar (1724–1802) is accorded the credit of having been the first to conceive the view of the reciprocal relationship of electricity and magnetism. In his work 'Tentamen Theoria Electricitatis et Magnetism,' published in he formulated a corresponding theory of magnetism excepting that in the case of magnetic phenomena the fluids only acted on the particles of iron. Henry Cavendish of London, England (1731-1810) independently conceived a theory of electricity nearly akin to that of Aepinus. He also (1784) was perhaps the first to utilize the electric spark to produce the explosion of hydrogen and oxygen in the proper proportions to produce pure water. About 1784 Charles-Augustin de Coulomb, a French physicist (1736 - 1806), devised the torsion balance, by means of which he discovered what is known as Coulomb's law; — The force exerted between two small electrified bodies varies inversely as the square of the distance; not as Aepinus in his theory of electricity had assumed, merely inversely as the distance. Electricity and Magnetism

36. In 1790 Prof. Luigi Alyisio Galvani on one occasion, while conducting experiments on "animal electricity," as he termed it, to which his attention had been turned by the twitching of a frog's legs in the presence of an electric machine, observed that the muscles of a frog which was suspended on an iron balustrade by a copper hook that passed through its dorsal column underwent lively convulsions without any extraneous cause. Hitherto the only electricity known was that developed by friction or rubbing, which was therefore termed frictional electricity. We now come to the era of galvanic or voltaic electricity. In 1800, Alessandro Volta (1745 – 1827, an Italian physicist) discovered that chemical reactions could be used to create positively charged anodes and negatively charged cathodes. Galvanic Electricity

37. In 1819 Hans Christian Ørsted of Copenhagen (1777 – 1851) discovered the deflecting effect of an electric current traversing a wire upon- a suspended magnetic needle. This discovery gave a clue to the subsequently proved intimate relationship between electricity and magnetism which was promptly followed up by André-Marie Ampère (1775 – June 1836) who shortly thereafter (1821) announced his celebrated theory of electrodynamics, relating to the force that one current exerts upon another, by its electro-magnetic effects. Ampere's Law

38. Georg Simon Ohm (1789 – 1854, a German physicist) used a galvanometer to measure current, and knew that the voltage between the thermocouple terminals was proportional to the junction temperature. He then added test wires of varying length, diameter, and material to complete the circuit. He found that his data could be modeled through a simple equation with variable composed of the reading from a galvanometer, the length of the test conductor, thermocouple junction temperature, and a constant of the entire setup. From this, Ohm determined his law of proportionality and published his results. In 1827, he announced the now famous law that bears his name. Ohm's Law

39. The discovery of electromagnetic induction was made almost simultaneously, although independently, by Michael Faraday (1791 – 1867, an English chemist and physicist) and Joseph Henry (1797 – 1878, an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution). While Faraday's early results preceded those of Henry, Henry was first in his use of the transformer principle. Henry's discovery of self-induction and his work on spiral conductors using a copper coil were made public in 1835, just before those of Faraday. Faraday and Henry

40. In 1864 James Clerk Maxwell of Edinburgh announced his electromagnetic theory of light, which was perhaps the greatest single step in the world's knowledge of electricity. Around 1862, Maxwell calculated that the speed of propagation of an electromagnetic field is approximately that of the speed of light. He considered this to be more than just a coincidence, and commented "We can scarcely avoid the conclusion that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena." Maxwell also showed that the equations predict the existence of waves of oscillating electric and magnetic fields that travel through empty space at a speed that could be predicted from simple electrical experiments. In his 1864 paper A Dynamical Theory of the Electromagnetic Field, Maxwell wrote, The agreement of the results seems to show that light and magnetism are affections of the same substance, and that light is an electromagnetic disturbance propagated through the field according to electromagnetic laws. Maxwell