The Evolution Of Physics 1v521q

The Evolution of Physics: The Growth of Ideas From Early Concepts to Relativity and Quanta is a science book for the lay reader, by Albert Einstein and Leopold Infeld, tracing the development of ideas in physics. It was originally published in 1938 byCambridge University Press. It was a popular success,[1] and was featured in a Time magazine cover story. Contents [hide] 

1 Background of collaboration

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2 Book's point of view

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3 Contents

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4 Reception and reviews o

4.1 Partial list of reviews

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5 See also

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6 References

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7 External links

Background of collaboration[edit] Einstein agreed to write the book partly as a way to help Infeld financially. [2] Infeld collaborated briefly in Cambridge with Max Born, before moving to Princeton, where he worked with Einstein at the Institute for Advanced Study. Einstein tried to get Infeld a permanent position there, but failed.[3] Infeld came up with a plan to write a history of physics with Einstein, which was sure to be successful, and split the royalties. When he went to Einstein to pitch the idea, Infeld became incredibly tongue-tied, but he was finally able to stammer out his proposal. “This is not at all a stupid idea,” Einstein said. "Not stupid at all. We shall do it." The book was published by Simon & Schuster.

Book's point of view[edit] In the book, Einstein pushed his realist approach to physics in defiance of much of quantum mechanics. Belief in an “objective reality,” the book argued, had led to great scientific advances throughout the ages, thus proving that it was a useful concept even if not provable. “Without the belief that it is possible to grasp reality with our theoretical constructions, without the belief in the inner harmony of our world, there could be no

science,” the book declared. “This belief is and always will remain the fundamental motive for all scientific creation.” In addition, Einstein used the text to defend the utility of field theories amid the advances of quantum mechanics. The best way to do that was to view particles not as independent objects but as a special manifestation of the field itself: "Could we not reject the concept of matter and build a pure field physics? We could regard matter as the regions in space where the field is extremely strong. A thrown stone is, from this point of view, a changing field in which the states of the greatest field intensity travel through space with the velocity of the stone."[4]

Contents[edit] The book has four chapters: The Rise of The Mechanical View, The Decline of the Mechanical View, Field, Relativity, and Quanta. The third chapter (Field, Relativity) examines lines of force starting with gravitational fields (i.e., a physical collection of forces), moving on to descriptions of electric and magnetic fields. The authors explain that they are attempting to "translate familiar facts from the language of fluids...into the new language of fields." They state that the Faraday, Maxwell, and Hertz experiments led to modernphysics. They describe how "The change of an electric field produced by the motion of a charge is always accompanied by a magnetic field."

Evolution of Physics Greek Contributions The earliest history of physics is interrelated with that of the other sciences. A number of contributions were made during the period of Greek civilization, dating from Thales and the early Ionian natural philosophers in the Greek colonies of Asia Minor (6th and 5th cent. B.C.). Democritus (c.460–370 B.C.) proposed an atomic theory of matter and extended it to other phenomena as well, but the dominant theories of matter held that it was formed of a few basic elements, usually earth, air, fire, and water. In the school founded by Pythagoras of Samos the principal concept was that of number; it was applied to all aspects of the universe, from planetary orbits to the lengths of strings used to sound musical notes. The most important philosophy of the Greek period was produced by two men at Athens, Plato (427–347 B.C.) and his student Aristotle (384–322 B.C.); Aristotle in particular had a critical influence on the development of science in general and physics

in particular. The Greek approach to physics was largely geometrical and reached its peak with Archimedes (287–212 B.C.), who studied a wide range of problems and anticipated the methods of the calculus. Another important scientist of the early Hellenistic period, centered in Alexandria, Egypt, was the astronomer Aristarchus (c.310–220 B.C.), who proposed a heliocentric, or sun-centered, system of the universe. However, just as the earlier atomic theory had not become generally accepted, so too the astronomical system that eventually prevailed was the geocentric system proposed by Hipparchus (190–120 B.C.) and developed in detail by Ptolemy (A.D. 85–A.D. 165). Preservation of Learning With the ing of the Greek civilization and the Roman civilization that followed it, Greek learning ed into the hands of the Muslim world that spread its influence from the E Mediterranean eastward into Asia, where it picked up contributions from the Chinese (papermaking, gunpowder) and the Hindus (the place-value decimal number system with a zero), and westward as far as Spain, where Islamic culture flourished in Córdoba, Toledo, and other cities. Little specific advance was made in physics during this period, but the preservation and study of Greek science by the Muslim world made possible the revival of learning in the West beginning in the 12th and 13th cent. The Scientific Revolution The first areas of physics to receive close attention were mechanics and the study of planetary motions. Modern mechanics dates from the work of Galileo and Simon Stevin in the late 16th and early 17th cent. The great breakthrough in astronomy was made by Nicolaus Copernicus, who proposed (1543) the heliocentric model of the solar systemthat was later modified by Johannes Kepler (using observations by Tycho Brahe) into the description of planetary motions that is still accepted today. Galileo gave his to this new system and applied his discoveries in mechanics to its explanation. The full explanation of both celestial and terrestrial motions was not given until 1687, when Isaac Newton published his Principia [Mathematical Principles of Natural Philosophy]. This work, the most important document of the Scientific Revolution of the 16th and 17th cent., contained Newton's famous three laws of motion and showed how the principle of universal gravitation could be used to explain the behavior not only of falling bodies on the earth but also planets and other celestial bodies in the heavens. To arrive at his results, Newton invented one form of an entirely new branch of mathematics, the calculus (also invented independently by G. W. Leibniz), which was to become an essential tool in much of the later development in most branches of physics. Other branches of physics also received attention during this period. William Gilbert, court physician to Queen Elizabeth I, published (1600) an important work on magnetism, describing how the earth itself behaves like a giant magnet. Robert Boyle (1627–91) studied the behavior of gases enclosed in a chamber and formulated the gas law named for him; he also contributed to physiology and to the founding of modern chemistry.

Newton himself discovered the separation of white light into a spectrum of colors and published an important work on optics, in which he proposed the theory that light is composed of tiny particles, or corpuscles. This corpuscular theory was related to the mechanistic philosophy presented early in the 17th cent. by René Descartes, according to which the universe functioned like a mechanical system describable in of mathematics. A rival theory of light, explaining its behavior in of Waves, was presented in 1690 by Christian Huygens, but the belief in the mechanistic philosophy together with the great weight of Newton's reputation was such that the wave theory gained relatively little until the 19th cent. Development of Mechanics and Thermodynamics During the 18th cent. the mechanics founded by Newton was developed by several scientists and received brilliant exposition in the Analytical Mechanics (1788) of J. L. Lagrange and the Celestial Mechanics (1799–1825) of P. S. Laplace. Daniel Bernoulli made important mathematical studies (1738) of the behavior of gases, anticipating the kinetic theory of gases developed more than a century later, and has been referred to as the first mathematical physicist. The accepted theory of heat in the 18th cent. viewed heat as a kind of fluid, called caloric; although this theory was later shown to be erroneous, a number of scientists adhering to it nevertheless made important discoveries useful in developing the modern theory, including Joseph Black (1728–99) and Henry Cavendish (1731–1810). Opposed to this caloric theory, which had been developed mainly by the chemists, was the less accepted theory dating from Newton's time that heat is due to the motions of the particles of a substance. This mechanical theory gained in 1798 from the cannon-boring experiments of Count Rumford (Benjamin Thompson), who found a direct relationship between heat and mechanical energy. In the 19th cent. this connection was established quantitatively by J. R. Mayer and J. P. Joule, who measured the mechanical equivalent of heat in the 1840s. This experimental work and the theoretical work of Sadi Carnot, published in 1824 but not widely known until later, together provided a basis for the formulation of the first two laws of thermodynamics in the 1850s by William Thomson (later Lord Kelvin) and R. J. E. Clausius. The first law is a form of the law of conservation of energy, stated earlier by J. R. von Mayer and Hermann Helmholtz on the basis of biological considerations; the second law describes the tendency of energy to be converted from more useful to less useful forms. The atomic theory of matter had been proposed again in the early 19th cent. by the chemist John Dalton and became one of the hypotheses of the kinetic-molecular theory of gases developed by Clausius and James Clerk Maxwell to explain the laws of thermodynamics. The kinetic theory in turn led to the statistical mechanics of Ludwig Boltzmann and J. W. Gibbs. Advances in Electricity, Magnetism, and Thermodynamics

The study of electricity and magnetism also came into its own during the 18th and 19th cents. C. A. Coulomb had discovered the inverse-square laws of electrostatics and magnetostatics in the late 18th cent. and Alessandro Volta had invented the electric battery, so that electric currents could also be studied. In 1820, H. C. Oersted found that a current-carrying conductor gives rise to a magnetic force surrounding it, and in 1831 Michael Faraday (and independently Joseph Henry) discovered the reverse effect, the production of an electric potential or current through magnetism (see induction); these two discoveries are the basis of the electric motor and the electric generator, respectively. Faraday invented the concept of the field of force to explain these phenomena and Maxwell, from c.1856, developed these ideas mathematically in his theory of electromagnetic radiation. He showed that electric and magnetic fields are propagated outward from their source at a speed equal to that of light and that light is one of several kinds of electromagnetic radiation, differing only in frequency and wavelength from the others. Experimental confirmation of Maxwell's theory was provided by Heinrich Hertz, who generated and detected electric waves in 1886 and verified their properties, at the same time foreshadowing their application in radio, television, and other devices. The wave theory of light had been revived in 1801 by Thomas Young and received strong experimental from the work of A. J. Fresnel and others; the theory was widely accepted by the time of Maxwell's work on the electromagnetic field, and afterward the study of light and that of electricity and magnetism were closely related. Birth of Modern Physics By the late 19th cent. most of classical physics was complete, and optimistic physicists turned their attention to what they considered minor details in the complete elucidation of their subject. Several problems, however, provided the cracks that eventually led to the shattering of this optimism and the birth of modern physics. On the experimental side, the discoveries of X rays by Wilhelm Roentgen (1895), radioactivity by A. H. Becquerel (1896), the electron by J. J. Thomson (1897), and new radioactive elements by Marie and Pierre Curie raised questions about the supposedly indestructible atom and the nature of matter. Ernest Rutherford identified and named two types of radioactivity and in 1911 interpreted experimental evidence as showing that the atom consists of a dense, positively charged nucleus surrounded by negatively charged electrons. Classical theory, however, predicted that this structure should be unstable. Classical theory had also failed to explain successfully two other experimental results that appeared in the late 19th cent. One of these was the demonstration by A. A. Michelson and E. W. Morley that there did not seem to be a preferred frame of reference, at rest with respect to the hypothetical luminiferous ether, for describing electromagnetic phenomena. Relativity and Quantum Mechanics In 1905, Albert Einstein showed that the result of the Michelson-Morley experiment could be interpreted by assuming the equivalence of all inertial (unaccelerated) frames

of reference and the constancy of the speed of light in all frames; Einstein's special theory of relativity eliminated the need for the ether and implied, among other things, that mass and energy are equivalent and that the speed of light is the limiting speed for all bodies having mass. Hermann Minkowski provided (1908) a mathematical formulation of the theory in which space and time were united in a four-dimensional geometry of space-time. Einstein extended his theory to accelerated frames of reference in his general theory (1916), showing the connection between acceleration and gravitation. Newton's mechanics was interpreted as a special case of Einstein's, valid as an approximation for small speeds compared to that of light. Although relativity resolved the electromagnetic phenomena conflict demonstrated by Michelson and Morley, a second theoretical problem was the explanation of the distribution of electromagnetic radiation emitted by a blackbody; experiment showed that at shorter wavelengths, toward the ultraviolet end of the spectrum, the energy approached zero, but classical theory predicted it should become infinite. This glaring discrepancy, known as the ultraviolet catastrophe, was solved by Max Planck's quantum theory (1900). In 1905, Einstein used the quantum theory to explain the photoelectric effect, and in 1913 Niels Bohr again used it to explain the stability of Rutherford's nuclear atom. In the 1920s the theory was extensively developed by Louis de Broglie, Werner Heisenberg, Wolfgang Pauli, Erwin Schrödinger, P. A. M. Dirac, and others; the new quantum mechanics became an indispensable tool in the investigation and explanation of phenomena at the atomic level. Particles, Energy, and Contemporary Physics Dirac's theory, which combined quantum mechanics with the theory of relativity, also predicted the existence of antiparticles. During the 1930s the first antiparticles were discovered, as well as other particles. Among those contributing to this new area of physics were James Chadwick, C. D. Anderson, E. O. Lawrence, J. D. Cockcroft, E. T. S. Walton, Enrico Fermi, and Hideki Yukawa. The discovery of nuclear fission by Otto Hahn and Fritz Strassmann (1938) and its explanation by Lise Meitner and Otto Frisch provided a means for the large-scale conversion of mass into energy, in accordance with the theory of relativity, and triggered as well the massive governmental involvement in physics that is one of the fundamental facts of contemporary science. The growth of physics since the 1930s has been so great that it is impossible in a survey article to name even its most important individual contributors. Among the areas where fundamental discoveries have been made more recently are solid-state physics, plasma physics, and cryogenics, or low-temperature physics. Out of solid-state physics, for example, have come many of the developments in electronics (e.g., the transistor and microcircuitry) that have revolutionized much of modern technology. Another development is the maser and laser (in principle the same device), with applications ranging from communication and controlled nuclear fusion experiments to atomic clocks and other measurement standards.

The Ancient Philosophers

3500 BC to 350 BC

During the Bronze Age, the first civilisations grew up in The Middle East. Later, in the Iron Age, The Persians, Egyptians, Greeks and Romans spread this culture through conquests and trade. Meanwhile, the Chinese were observing the heavens and starting their own culture and science.

Sumerians - City builders and arithmeticians (c. 3500 BC to 2000 BC)

The Sumerians lived in Mesopotamia. This region of fertile plains between the Tigris and the Euphrates is now mostly in modern Iraq. Here the Sumerians built the first advanced civilisation in great cities with istrations, legal systems and irrigation. They developed methods of writing and counting - in base 60.

In around 2300 BC, the Sumerians were invaded by the Akkadians. Between them, they invented the abacus and a basic arithmetic with addition, subtraction and versions of multiplication and division. The Sumerians were displaced by the Babylonians in around 2000 BC. But they ed on their systems of counting and arithmetic.

The Ancient Egyptians picked up Sumerian ideas on numbers The Babylonians invaded Sumeria and inherited their number system Ancient Egyptians - Love geometry? Go to Ancient Egypt (c. 3000 BC to 320 BC)

Egyptian civilisation grew up around the Nile Delta from around 3000 BC. The Ancient Egyptians wrote using hieroglyphics drawn on papyrus or carved into stone. Many examples survive, including some mathematical ones.

Being hieroglyphic, the Egyptian number system had no zero and was not suited to multiplication or division. However, they found ways around this.

Their mathematics was very practical - usually to do with engineering projects or trade. However, they set and solved what we would recognise as algebraic problems. For example, 'a quantity added to a quarter of that quantity becomes 15. What is the quantity?'.

The Egyptians used a lot of geometry (due to the limitations of their number system) and probably ed to Pythagoras the theorem that was named after him. They are well known for the engineering triumph of the pyramids.

In about 3000 BC, they produced a very early calendar that had 365 days in the year and in around 1470 BC, Thutmosis III put up the 'Needle of Cleopatra' in Hliopolis. The needle's shadow was used to calculate the time, seasons and solstices.

The Ancient Egyptians picked up Sumerian ideas on numbers. Trade with the Babylonians meant a sharing of numbers and geometry. Greek philosophers like Thales were famliar with Egyptian geometry. The theorem to which Pythagoras gave his name was known to the Egyptians. Euclid would have been strongly influenced by the long Egyptian tradition in geometry. Babylonians - Conquerors of Sumeria and number pinchers (c. 2000 BC to 100 BC)

The Babylonians invaded Sumeria in about 2100 BC. They set up their capital in Babylon, whose few ruins can be seen in the Iraqui desert south of Baghdad.

Babylonians inherited the Sumerian number system, counting in base 60. They divided the day into the hours, minutes and seconds that we use today. So we still count in base 60 - with 60 seconds in a minute and 60 minutes in an hour.

Although at first there was no representation of zero (so 536 would be the same as 5036), they began to leave a space, then used a symbol for zero in about 300 BC. Much later, this led to all sorts of mathematical possibilities - like multiplication and long division - which could not be done using Roman numerals or Egyptian hieroglyphics.

Even without zero, they devised ingenious methods to help them multiply or divide two numbers. For example, they could multiply two numbers using the formula ab = [(a + b)2 - (a - b)2]/4 and a stone tablets, or table, of squares.

Trade with the Ancient Egyptians meant a sharing of numbers and geometry. The Babylonians took the Sumerians' numbers as well as their country. Greek philosophers like Thales were famliar with Babylonian number systems. The theorem to which Pythagoras gave his name was well known to the Babylonians. Thales of Miletus, philosopher - Played with a feather and some elektron? (c. 625 BC to 546 BC)

Greek philosopher, born in Miletus, Asia Minor, now Turkey.

Thales is best known for discovering static electricity and, as one of the Seven Wise Men, an early philosopher.

Thales' aim was to understand the nature of the physical world without relying on mythology or dogma. Instead, he questioned ideas and tried to understand phenomena - including heavenly ones. He became famous for predicting the eclipse of the Sun that occurred on May 28, 585 BC.

The story is that he noticed that he could pick up feathers with a piece of amber - so long as he rubbed it with cat fur. The effect took its name from the Greek for amber elektron. From this, we get the modern words - electricity and electron.

Thales left no writings; knowledge of him is derived from an in the Metaphysics of Aristotle.

Thales would have been familiar with the geometry of the Ancient Egyptians Pythagoras built on the philosophy of Thales Thales would have studies the number ideas of the Babylonians Democritus developed some of Thales ideas Aristotle was familiar with Thales philosophy William Gilbert coined the name electron 2000 years after Thales' experiments. Pythagoras, philosopher and mathematician - Numbers, maths and music were all he needed (c. 569 BC to 475 BC)

Philosopher and mathematician born on the island of Samos.

Not much is known about the life of Pythagoras, except that he founded a community in Croton, southern Italy. He believed that we can understand the order of the world with the aid of mathematics and astronomy. As he put it: 'all is number'.

He proposed, in The Music of the Spheres that the movement of the planets was mathematically related to musical sounds. The connections that he established between music, astronomy, geometry and arithmetic exist to this day and remained strong until quite recently.

Pythagoras was best known for working out what we know as 'Pythagoras' Theorem'. Although, this was already known to the Egyptians and Babylonians, Pythagoras was probably the first to provide a rigorous proof.

The Egyptians knew, but probably never proved, his triangle theorem.

The Babylonians knew, but probably never proved, Pythagoras' triangle theorem. Pythagoras built on the philosophical ideas of Thales. Aristotle went to Plato's academy and Plato was strongly influenced by Pythagoras' followers. Ptolemy formalised ideas about planets 400 years later The geometry of the Greeks - including Pythagoras - was essential to the Arab mathematicians who followed them. Anaxagoras, philosopher - A philosopher with real nous (c. 490 BC to 428 BC)

Greek philosopher, born in Clazomenae (now Turkey).

Anaxagoras explained his philosophy in Peri Physeos (On Nature), but only fragments of the books have survived.

He thought that all matter started off as infinitesimally small atoms; order was produced out of this infinite chaos through the influence of nous (Greek for 'mind' or 'reason').

Anaxogoras believed that there were an infinite number of elements at a time when the accepted view was that there were only four: fire, earth, air and water. He was the first person to explain correctly the reason for eclipses.

He set the scene for Democritus to develop his ideas of atoms and his doctrine of nous was adopted by Aristotle, who said that he sounded like the only sober man in a chorus of drunks.

In 450 BC Anaxagoras was imprisoned for suggesting that the Sun was not a god but a hot stone.

Aristotle adopted Anaxagoras' doctrine of nous.

Anaxagoras' ideas on atoms were developed by Democritus Two thousand years later, Anaxagoras' ideas on the Sun influenced Copernicus and Galileo who, like him, faced arrest for his work. Democritus, philosopher - A paper ripper (at least in his mind) (c. 460 BC to 370 BC)

Greek philosopher, born in Abdera, Thrace.

Democritus considered what would happen if you kept ripping up a piece of paper. He reasoned that, eventually, you would reach a point where you couldn't rip any more. The paper (and everything else) must be made of tiny, indivisible blocks of different shapes and sizes. He called these blocks atoms (which means uncuttable).

He developed this idea to say that all changes in matter came from changes in the motion of the atoms, or changes in the way that they are packed together.

Democritus was harshly criticised for his ideas. At a time when beliefs and superstitions dominated the world, his atom theory seemed odd. People found it hard to accept the idea that everything, including human existence, is a product of mere atom collisions. This would leave everything to chance. Of course, although the belief systems are different, there is still a divide between those who are and are not comfortable with their fate being determined by physical rather than divine rules.

Democritus also wrote on ethics, proposing happiness, or 'cheerfulness', as the highest good - a condition to be achieved through moderation, tranquillity, and freedom from fear. Later historians sometimes referred to him as the Laughing Philosopher.

Anaxagoras gave Democritus ideas on atoms. Aristotle was the next great Greek philosopher after Democritus. Democritus' ideas on atoms were developed by Al-Razi in the 9th century AD. Aristotle, philosopher - Teacher to Alexander the Great (384 BC to 322 BC)

Greek philosopher, born in Stagira in northeast Greece.

Aristotle believed that all knowledge must proceed directly from observation. He said that everything is made of the four elements (earth, fire air and water) which are only found on Earth. He later added another 'element' - ether, which surrounds heavenly bodies.

Aristotle made a distinction between what happened in the heavens (the celestial) and on the Earth (the terrestrial) . The heavens, being the domain of the gods, are ordered and stable; whereas the Earth is chaotic and changing under the influence of people. This distinction is still influential and it was Newton who broke its complete grip on philosophy when he proposed a Universal law of gravitation.

In his books On the Heavens, and Physics, he proposed a finite, spherical universe, with the Earth at its centre surrounded by concentric spheres which carry the planets and fixed stars. This geocentric theory of cosmology was the basis of European thought from the 12th century until it was challenged by Copernicus in the 1500's.

Aristotle is one of the 'big three' philosophers of ancient Greece (with Plato and Socrates). Socrates taught Plato, who in turn instructed Aristotle. After Plato's death, Aristotle travelled widely, teaching Alexander the Great, before founding his own school, The Lyceum, in Athens.

Democritus was the previous great Greek philosopher Archimedes studied in Alexandria which continued Aristotle's legacy. Euclid was based in Alexandria, which maintained Aristotle's legacy It wasn't until Copernicus nearly 2000 years later that Aristotle's ideas on the planets were replaced. Ibn Rushd took Aristotlean ideas into Europe in the Middle Ages, laying the foundations for the Renaissance.

Aristotle's ideas on the separateness of the celestial and terrestrial survived until Newton in the 17th century. Euclid, mathematician - The father of geometry (c.330 BC to 280 BC)

Greek mathematician who lived in Alexandria in Egypt.

Very little is known about Euclid's life except that he worked in Alexandria and published The Elements, the basic book on geometry.

He was probably educated in Athens by pupils of Plato. On moving to Alexandria, he would have had access to the Egyptians' strong tradition in geometry. In part, this would probably have been thanks to the Great Library in Alexandria, which was founded by Alexander the Great in 332 BC and housed over 7000 works.

Euclid's main work, The Elements, is a comprehensive treatise on mathematics. Its 13 volumes were used as a standard school text for the next 2300 years. Although much of it is probably original work, it is likely that he organised and explained more clearly ideas that were already in circulation. Nevertheless, because of The Elements and his work in this field, he is called the father of geometry.

Soon after Euclid, Eratosthenes (276 - 195 B.C.) developed the idea that the world is round and measured his latitude and the circumference of the Earth using the Sun's shadows.

Euclid built on and formalised much of the geometry of the Ancient Egyptians Archimedes studied in Alexandria and would have been the first of many students of Euclidian geometry. Ptolemy would have studied Euclid in Alexandria. Al Biruni would have studied Euclid's geometry

Although Euclid wouldn't have overlapped with Aristotle, the Greek's legacy would be felt in Alexandria. Archimedes, Sicilian philosopher - Eureka, you've found him! (c. 287 BC to 212 BC)

Sicilian philosopher, who studied in Alexandria and worked in Italy.

We believe that Archimedes studied under followers of Euclid in Alexandria before returning to Italy where he spent the rest of his life.

He is known for his mathematical work and applying science to everyday life. He worked out the principle of levers, calculated the surface areas and volumes of solids and invented a machine, the Archimedes screw, for raising water. This is still used in many parts of the world.

Legend has it that Archimedes discovered his famous principle of displacement while taking a bath, shouting 'Eureka!' ('I have found it!').

When the Romans laid siege to Syracuse he designed catapults and machines to keep them at bay for years. When the Romans finally got into the city, Archimedes was killed by a soldier.

Archimedes studied in Alexandria and would have studied with Euclid's successors Claudius Ptolemaeus (Ptolemy), astronomer- A model, but not as we know it (c.85 AD to 168 AD)

Greek astronomer who worked in Alexandria

Ptolemy is another ancient about whom we know very little. His name is part Roman (Claudius) and part Egyptian/Greek. So it is thought that his ancestors probably moved

from Greece to Alexandria in Egypt. One of them may have been granted Roman citizenship.

However, his work is well known because, by refining the geocentric model of Aristotle, he helped it to last for the next 1350 years. His mathematical model has a stationary earth at the centre with the stars, the Sun, the Moon and the 5 known planets all revolving around it.

His model was far better at predicting planetary positions than anything else produced in antiquity. It was so persuasive that it became the official Christian doctrine and guided all European thinking even after Copernicus suggested the Sun as the centre in around 1500.

His theories are preserved in a 13-volume work known as The Almagest.

Euclid's Elements would have been a standard text for Ptolemy Ptolemy's ideas of a geocentric Universe lasted until Copernicus Ptolemy's work on optics were next picked up by Al-Haytham 400 years later. Chinese Sun dial - A stick's shadow to track time (c. 2500 BC)

By putting a bamboo stick in the ground and tracking its shadow, the Chinese developed the first recorded example of a timepiece. With it, they could get a good estimate of the time of day.

However, as with many Chinese inventions, it didn't have any influence on the rest of the world. Sundials crop up in a number of places (and were probably developed independently) in around 300 BC

Shih Shen et al - Comets, stars and supernovae (613 BC to 200 BC)

Chinese astronomers observed and recorded many astronomical events including Halley's comet (in 613 BC) and the first recorded supernova (in 352 BC).

In around 300 BC, Shih Shen compiled the first map of the stars. About 200 years earlier, astronomers had recorded comets (referred to as broom stars) in an atlas called The Book of Silk, which was discovered in a tomb in 1976.

Zon Yan - Yin and Yang in science (c. 300 BC)

The ancient Chinese philosophy of Yin and Yang is based on opposites being complementary and yet in conflict. An example is day and night. Many of their features are the exact opposite to each other - light versus dark; warm versus cold. Nevertheless, they complement each other and without night, there would be no such idea as day.

In around 300 BC, the Chinese philosopher Son Yan integrated these ideas into the developing ideas of science - mainly astronomy.

Loadstone com- What is geomancy? (c. 220 BC)

From early in the first millennium BC, the Greeks, Romans, some Europeans and the Chinese knew of the magnetic properties of loadstone - i.e. that pieces of loadstone would attract and repel each other.

However, unlike the others, the Chinese realised that loadstone magnets all pointed in the same direction. So they had the basis of a primitive com for geomancy - to ensure that a house was facing in the correct direction - and for guidance.

However, loadstone comes were not very transportable and it wasn't until more like 200 AD that navigational comes were first used - again in China.