History of physics

Table of contents 1 History of Physics 2 Antiquity 3 The Middle Ages & Islamic contibution to the Sciences 4 16th century 5 17th century 6 18th century 7 19th century 8 20th century 9 Developments since 1990 10 Developments since 2000

History of Physics

This article has changed substantially from its original form as the "Ridiculously Brief History of Physics" on the main Physics page. However, further work is needed to fill in some obvious gaps, and to include more detail about the development of physics (and, concurrently, astromomy and mathematics) in non-European cultures. It is intended that this article should grow to be a brief but comprehensive history of physics. The history on the Physics page should remain as a summary only.

This article is a work in progress: please add more material here

Antiquity

Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. Also a mystery was the character of the universe, such as the form of the Earth and the behavior of celestial objects such as the Sun and the Moon. Several theories were proposed, most of them were wrong, but this is part of the nature of the scientific enterprise, and even modern theories of quantum mechanics and relativity are considered merely as "theories that haven't broken yet". Physical theories in antiquity were largely couched in philosophical terms, and rarely verified by systematic experimental testing.

Typically the behaviour and nature of the world were explained by invoking the actions of gods. Around 200 BC, many Greek philosophers began to propose that the world could be understod as the result of natural processes. Many also challenged traditional ideas presented in mythology, such as the origin of the human species (anticipating the ideas of Charles Darwin), although this falls into the history of biology, not physics.

Due to the absence of advanced experimental equipment such as telescopes and accurate time-keeping devices, experimental testing of many such ideas was impossible or impractical. There were exceptions: for example, the Greek thinker Archimedes derived many correct quantitative descriptions of mechanics and also hydrostatics when, so the story goes, he noticed that his own body displaced a volume of water while he was getting into a bath one day. Another remarkable example was that of Eratosthenes, who deduced that the Earth was a sphere, and accurately calculated its circumference using the shadows of vertical sticks to measure the angle between two widely separated points on the Earth's surface. Greek mathematicians also proposed calculating the volume of objects like spheres and cones by dividing them into very thin disks and adding up the volume of each disk - anticipating the invention of integral calculus by almost two millennia.

Modern knowledge of these early ideas in physics, and the extent to which they were experimentally tested, is sketchy. Almost all direct record of these ideas was lost when the Library of Alexandria was destroyed, around 400 AD. Perhaps the most remarkable idea we know of from this era was the deduction by Aristarchus of Samos that the Earth was a planet that travelled around the Sun once a year, and rotated on its axis once a day (accounting for the seasons and the cycle of day and night), and that the stars were other, very distant suns which also had their own accompanying planets (and possibly, lifeforms upon those planets).

The discovery of the Antikythera mechanism points to a detailed understanding of movements of these astronomical objects, as well as a use of gear-trains that pre-dates any other known civilization's use of gears.

Regrettably, this period of inquiry into the nature of the world was eventually stifled by a tendency to accept the ideas of eminent philosophers, rather than to question and test those ideas. New discoveries, such as Pythagoras's deduction of the existence of irrational numbers[?], were suppressed, and technical knowledge was turned increasingly to the development of advanced weapons, rather than experimental investigations of nature. For one thousand years following the destruction of the Library of Alexandria, Ptolemy's (not to be confused with the Egyptian Ptolemies[?]) model of an Earth-centred universe with planets moving in perfect circular orbits was accepted as absolute truth.

We should mention physics and astronomy outside Europe at this stage, especially Mesoamerican, Babylonian, Arabic and Chinese astronomy. The Japanese were also very big on mathematical puzzles - it's not exactly physics but it might be a worthwhile aside, to make this history more balanced. We also need to include a lot about middle-eastern physics, here's a start...(The section Middle Ages)

The Middle Ages & Islamic contibution to the Sciences

When the power of Greek civilization was eclipsed by the Roman Empire, many Greek doctors began to practice medicine for the Roman elite, but sadly the physical sciences were not so well supported. Following the collapse of the Roman Empire, Europe entered the so-called Dark Ages, and almost all scientific research ground to a halt. The rise of Christianity saw the suppression and destruction of most classical Greek philosophy (along with Greek and Roman art, literature and religious iconography) as heretical and pagan. However in the middle east, many Greek natural philosophers were able to find support in the newly created Arab Caliphate (Empire), and the Islamic scholars built upon previous work in medicine, astronomy and mathematics while developing such new fields as alchemy (chemistry). The scholar Muhammad ibn Musa al-Khwarizmi gave his name to what we now call an algorithm, and the word algebra is derived from al-jabr, the beginning of the name of one of his publications in which he developed a system of solving quadratic equations, thus beginning Al-gebra.

Between the eighth and fifteenth centuries, in an era known as the the Golden Age of Islam, the only people doing decent work in science, philosophy or medicine were Muslims. Muslims not only preserved ancient learning, they also made substantial innovations. To really understand the contrast between past and present, lets’ look at what some modern Western Scholars have to say about past Muslim achievements in the sciences:

Robert Briffault, in the "Making of Humanity":

"It was under the influence of the arabs and Moorish revival of culture and not in the 15th century, that a real renaissance took place. North Africa, the Middle East and Islamic Spain, not Italy, was the cradle of the rebirth of Europe. After steadily sinking lower and lower into barbarism, Europe had reached the darkest depths of ignorance and degradation when cities of the Islamic world; Baghdad, Damascus, Cairo, Cordova, and Toledo, were growing centers of civilization and intellectual activity. It was there that this new life; science - arose; a life that was to grow into a new phase of human evolution."

"It was under the successors of the Muslims at the Oxford School that Roger Bacon learned Arabic and Arabic Sciences. Neither Roger Bacon nor later namesakes have any right to be credited with having invented the experimental method known today as Science. The experimental method was developed by Arab scientists at the 'House Of Wisdom' in Baghdad in the 8th and 9th centuries and Roger Bacon was no more than one student of Islamic Sciences and of this new scientific method, which he later introduced to Europe. He never wearied of declaring that the knowledge of Arabic and Arabic Sciences was for his contemporaries the only way to gain true knowledge".

"While Science is the most momentous contribution of Arab civilization to the modern world, its fruits were slow in ripening and unfortunately did not directly benefit its inventors. Not until long after Moorish culture had sunk back into its pre-Islamic twilight did the giant (Science), which it had given birth to, began to rise in its might. It was not science only which brought Europe back to life. Other and manifold influences from the civilization of Islam communicated its first glow to European Life.

George Sarton in the "Introduction to the History of Science" :

"During the reign of Caliph Al-Mamun (813-33 A.D.), the new concept of learning reached its climax. The monarch created in Baghdad a regular university called the 'House of Wisdom' for translation & research. It was equipped with a vast library and several laboratories. It was in these laboratories that the scientific method was born.

"The first mathematical transformation from the Greek conception of a static universe to the Islamic one of a dynamic, expanding universe was made by Al-Khwarizmi (780-850), the founder of modern Algebra as well as of the ‘Arab’ numerals the west uses today. He enhanced the purely arithmetical character of numbers as finite magnitudes by demonstrating their possibilities as elements of infinite manipulations and investigations of properties and relations".

"The importance of Khwarizmi's algebra was recognized, in the twelfth century, by the West, - when Girard of Cremona translated Khwarizmi’s theses into Latin. Until the sixteenth century this version was used in almost all European universities as the principal mathematical text book. But Khwarizmi's influence reached far beyond the universities. We find it reflected in the mathematical works of Leonardo Fibinacci of Pissa, Master Jacob of Florence, and of Leonardo da Vinci."

"One of the most famous exponents of Muslim universalism and an eminent figure in Islamic learning was Ibn Sina, known in the West as Avicenna (981-1037). For a thousand years he has retained his original renown as one of the greatest thinkers and medical scholars in history. His most important medical works are the Qanun (Canon) and a treatise on Cardiac drugs. The 'Qanun fil-Tibb' is an immense encyclopedia of medicine".

"We know that when, during the crusades, Europe at last began to establish hospitals, they were inspired by the Arabs of the near East, who had had hospitals for centuries....The first hospital in Paris, Les Quinze-vingt, was founded by Louis IX after his return from the crusade in 1254-1260."

"And then there was Al_kindi. (800-873 C.E.). In mathematics, he wrote four books on the number system and laid the foundation of a large part of modern arithmetic. He also contributed to spherical geometry to assist him in astronomical studies".

"Very little was known on the scientific aspects of music in his time. He was the first man in history to understand and write books on the role of mathematics in sound and in music. He was a prolific writer, the total number of books written by him was 241, the prominent among which were divided as follows: Astronomy 16, Arithmetic 11, Geometry 32, Medicine 22, Physics 12, Philosophy 22, Logic 9, Psychology 5, and Music 7.

He was known as Alkindus in Latin and a large number of his books were translated into Latin by Gherard of Cremona. Al-Kindi's influence on development of science and philosophy was significant in the revival of sciences in that period. In the Middle Ages, Cardano considered him as one of the twelve greatest minds on earth. His works, in fact, lead to further development of various subjects for centuries, notably physics, mathematics, medicine and music".

French Orientalist Dr. Gustav Lebon:

"It must be remembered that no science, either of Chemistry, Physics or any other, was discovered all of a sudden. The Arabs had established over one thousand years ago their laboratories in which they used to conduct experiments, called al-chemy, and published their discoveries, without which lavoisier (erroneously accredited by some westerners as being the founder of chemistry) would not have been able to produce anything in this field. It can be said without fear of contradiction that owing to the researches and experimentation of Muslim scientists, modern chemistry came into being and that it produced great results in the form of modern scientific inventions.

Joseph Hell in the "Arab Civilization":

"In the domain of trigonometry, the theory of Sine, Cosine and tangent is an heirloom of the Arabs. The brilliant epochs of Peurbach, of Regiomontanus, of Copernicus, cannot be recalled without reminding us of the fundamental labor of the Arab Mathematician Al-Battani, (858-929 A.D.)." (END)

The Arabs were accomplished in mathematics, chemistry, physics, medicine, philosophy, and most notably astronomy. Most Westerners think instantly of Copernicus, Galileo, or of the early Greek philosophers who worked to advance astronomical knowledge, but the contributions made by the Arabs are largely either overlooked or falsely assigned to later European astronomers. In reality, the golden era of Islamic astronomy that took place during the middle ages is of immense importance to the development of modern astronomy. Not only did the Arabs keep alive the works of the Greek and Indian astronomers before them, but they also improved upon and added to this knowledge in various significant ways. In addition, their translated works paved the way for the Copernican revolution.

Although there is no exact date for the beginning of the era of Arabic dominance in the realm of astronomy, it is generally agreed upon that by the end of the eighth century A.D. Islamic scholars had assimilated most of both Greek and Indian astronomy into their body of knowledge. They had translated many Greek texts and incorporated Greek theories into their own texts, all by the early 9th century A.D. It is hard to give an exact explanation of just how the Arabic interest in astronomy developed at this point, but there are many identifiable contributing factors. First of all, the sudden rise in astronomical interest occurred shortly after the remarkable expansion of the Islamic empire. This meant, among other things, that the invading Arabs had increased access to Greek astronomical texts which they could more easily translate. Secondly, a "renaissance of culture" is said to have occurred, starting in the beginning of the ninth century A.D. after the overthrow of the Umayyads by the Abbasids. This cultural rebirth is characterized mainly by an increased interest in the sciences (especially astronomy and chemistry) on behalf of the government. Rulers began to sponsor astronomical research through such activities as building observatories and funding scholars. Thus, the phenomenon may be at least partially explained by this conjunction of a succession of rulers who actively supported astronomical research and the increased availability of both Greek and Indian astronomical data, theories, and observations.

There are also numerous factors that must be looked at in order to understand why astronomy was so important to the people and rulers of the Islamic empire. The factor that is the most significant would be the connection between astronomy and the religion of Islam. Astronomy was imperative to the calculation of the Islamic calendar, which is lunar; it was the muslim arabs who developed the first correct lunar calendar in the world at this time. Astronomy was also necessary in the calculation of the correct times of prayer during the day, as well as the qibla, the direction to Mecca.

Luckily, this sudden burst in astronomical interest occurred at a time when astronomy was declining in Europe. The Roman empire was dissolving, and societies were beginning to focus more and more on Christianity and less and less on the works of the pagan Greeks. It is the prevailing opinion of most scholars that were it not for the assimilation of Greek astronomy by the Arabs, much of it would have been lost or at least forgotten. However, instead of having the extensive work of the Greeks and Indians stay static and unused throughout the middle ages, it was not only kept in use but significantly improved upon.

There are those who seem to be under the impression that all the Arabs ever contributed to astronomy was to have preserved the knowledge and observations of the Greeks during Europe's "Dark Ages", only to hand this information back to them at a later date so that the Europeans could continue advancing the science of astronomy. This, however, is entirely untrue. The Arabs advanced astronomy significantly during the middle ages. Not only did they take pre-existing theories and instruments and improve upon them, but they also invented entirely new theories and made their own discoveries. For example, although both the astrolabe and celestial globe were first invented by the Greeks in their original crude forms, far more sophisticated instruments were developed in medieval Islam. The astrolabe was ameliorated and fine-tuned so considerably that by the beginning of the tenth century it had been developed to the point that it could be used for approximately 300 problems in geography, spherical trigonometry, and mathematical astronomy, and to be "sophisticated enough to be useful for any latitude" [Anon.].

From this ongoing improvement of the astrolabe, the Arabs later developed an instrument called the quadrant. This instrument was sophisticated to the point that it was said to be useable to solve "all standard problems of spherical astronomy" [Anon.]. They also developed other new instruments as well, such as ones that could be used to determine the time of both day and night as well as the pendulum clock.

On a more theoretical basis, numerous inventions and discoveries were made in medieval Islam. We owe our current numerical system to them, as do we owe them most of our current knowledge of trigonometry. One great Islamic scientist alone, Abu'l-Wafa Muhammad al-Buzjani, is credited with introducing many new concepts into the field of trigonometry, the most important being the identification of the secant and cosecant. Scientists such as Abu al-Rayhan Muhammad Ahmad al-Biruni wrote many treatises on new mathematical and astronomical methods. This important Islamic astronomer, mathematician, and geographer who lived from 974 to 1048 A.D. invented several methods of representing the surface of a sphere on a plane, namely azimuthal equidistant projection and globular projection. Many others worked on making detailed observations of the heavens and using this data to develop mathematical equations and rules on the movements of celestial bodies, paying special attention to the movements of the moon. Other astronomers, such as Nasir al-Din al Tusi, undertook the task of reforming Ptolemaic astronomy. Overall, during the entire span of the middle ages there were many entirely new concepts introduced by the Arabs. By the end of the middle ages they had contributed immensely to the body of astronomical and mathematical knowledge.

A new school of thought emerged in the late 13th century that in itself constitutes a revolution. It is referred to as the Maragha Revolution, and it has been described as "an essential link to Copernican astronomy without which Copernican astronomy will be hard to explain" [Anon.]. The Maragha Revolution was, to put it simply, a rejection of many of Ptolemy's statements, and a sudden surge of new ideas and theories to replace incorrect Ptolemaic assertions. Thus, it turns out that the Arabs had come to many of the same conclusions as Copernicus well before Copernicus' time, although the astronomers of the Arabic Maragha school were still working within the confines of a geocentric model. Nonetheless, these astronomers were the ones who corrected many of Ptolemy's mistakes and made the first real moves towards the final realization of the true workings of the solar system. It is for this reason that many have firmly declared that Copernicus was influenced by the Arabic Maragha school.

In conclusion, the contributions made by the Arabs during the middle ages to the field of astronomy are not only great in number, but also in importance. This period served to enrich humanity's level of scientific understanding of the world. Medieval Islam accomplished very much in way of science and astronomy, from the beginning period of translation of Greek and Indian texts, through the golden era of new discoveries and refinement of pre-existing knowledge, right up until the time of the great European renaissance. Although we may tend to overlook and underemphasize this period in the evolution of humanity's knowledge, it nevertheless remains true that it was an era of huge importance.

The withdrawal of the Islamic empire from Mediterranean Europe (especially Spain) in the 15th century coincided with the dawn of the Renaissance. This "rebirth" of European culture was in part brought about by the re-discovery of those elements of ancient Greek, Indian, Chinese and Islamic culture preserved and further developed by Islam from the 8th to the 15th centuries, and translated by Christian Monks into Latin.

16th century

In the 16th century Nicholas Copernicus rediscovered the heliocentric model of the solar system devised by Aristarchus (which had been preserved by Arab scholars). He published this model, though due to fears that he would be persecuted by the church, the idea was presented as only a mathematical convenience for calculating the positions of planets, and not as an account of the true nature of the planetary orbits.

17th century

In the early 17th century Kepler formulated a model of the solar system based upon the five Platonic solids, in an attempt to explain why the orbits of the planets had the relative sizes they did. His access to extremely accurate astronomical observations by Tycho Brahe enabled him to determine that his model was inconsistent with the observed orbits. After a heroic seven-year effort to more accurately model the motion of the planet Mars (during which he laid the foundations of modern integral calculus) he concluded that the planets follow not circular orbits, but elliptical orbits with the Sun at one focus of the ellipse. This breakthrough overturned a millennium of dogma based on Ptolemy's idea of "perfect" circular orbits for the "perfect" heavenly bodies. Kepler then went on to formulate his three laws of planetary motion. He also proposed the first known model of planetary motion in which a force emanating from the Sun deflects the planets from their "natural" motion, causing them to follow curved orbits.

During the late 17th century, Galileo pioneered the use of experiment to validate physical theories, which is the key idea in the scientific method. Galileo's use of experiment, and Kepler's insistence that observational results must always take precedence over theoretical results brushed away the acceptance of dogma, and gave birth to an era where scientific ideas were openly discussed and rigorously tested. Galileo formulated and successfully tested several results in dynamics, in particular the Law of Inertia.

In 1687, Isaac Newton published the Principia Mathematica, detailing two comprehensive and successful physical theories: Newton's laws of motion, from which arise classical mechanics; and Newton's Law of Gravitation, which describes the fundamental force of gravity. Both theories agreed well with experiment. Classical mechanics would be exhaustively extended by Lagrange, Hamilton, and others, who produced new formulations, principles, and results. The Law of Gravitation initiated the field of astrophysics, which describes astronomical phenomena using physical theories.

We should include something here about Huygens' observations of Saturn's rings, and his debates with Newton about whether light was a wave or a particle.

18th century

From the 18th century onwards, thermodynamics was developed by Boyle, Young, and many others. In 1733, Daniel Bernoulli used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field of statistical mechanics. In 1798, Thompson demonstrated the conversion of mechanical work into heat.

19th century

In 1847 Joule stated the law of conservation of energy, in the form of heat as well as mechanical energy.

The behavior of electricity and magnetism was studied by Faraday, Ohm, and others. In 1855, Maxwell unified the two phenomena into a single theory of electromagnetism, described by Maxwell's equations. A prediction of this theory was that light is an electromagnetic wave. A more subtle part of Maxwell's deduction was that the observed speed of light does not depend on the speed of the observer, a premonition of the development of special relativity by Einstein.

In 1887 the Michelson-Morley experiment demonstrated with high reliability that contrary to the theory of the day, the Earth was not moving through a "luminiferous aether". This experiment was fundamental to Einstein's development of the theory of special relativity.

In 1895, Röntgen discovered X-rays, which turned out to be high-frequency electromagnetic radiation. Radioactivity was discovered in 1896 by Henri Becquerel, and further studied by the Pierre Curie and Marie Curie and others. This initiated the field of nuclear physics.

In 1897, Thomson discovered the electron, the elementary particle which carries electrical current in circuits.

20th century

The beginning of the 20th century brought the start of a revolution in physics. The long-held theories of Newton were shown not to be correct in all circumstances. Not only did quantum mechanics show that the laws of motion didn't hold on small scales, but even more disturbingly, general relativity showed that the fixed background of spacetime, on which both Newtonian mechanics and special relativity depended, could not exist.

In 1904, Thomson proposed the first model of the atom, known as the plum pudding model. (The existence of the atom had been proposed in 1808 by Dalton.)

In 1905, Einstein formulated the theory of special relativity, unifying space and time into a single entity, spacetime. Relativity prescribes a different transformation between reference frames than classical mechanics, necessitating the development of relativistic mechanics as a replacement for classical mechanics. In the regime of low (relative) velocities, the two theories agree. In 1915, Einstein extended special relativity to explain gravity with the general theory of relativity, which replaces Newton's law of gravitation. In the regime of low masses and energies, the two theories agree.

In 1911, Rutherford deduced from scattering experiments the existence of a compact atomic nucleus, with positively charged constituents dubbed protons. Neutrons, the neutral nuclear constituents, were discovered in 1932 by Chadwick.

Beginning in 1900, Planck, Einstein, Bohr, and others developed quantum theories to explain various anomalous experimental results by introducing discrete energy levels. In 1925, Heisenberg and Schrödinger formulated quantum mechanics, which explained the preceding quantum theories. In quantum mechanics, the outcomes of physical measurements are inherently probabilistic. The theory describes the calculation of these probabilities. It successfully describes the behavior of matter at small distance scales.

Quantum mechanics also provided the theoretical tools for condensed matter physics, which studies the physical behavior of solids and liquids, including phenomena such as crystal structures, semiconductivity, and superconductivity. The pioneers of condensed matter physics include Bloch, who created a quantum mechanical description of the behavior of electrons in crystal structures in 1928.

In 1929, Edwin Hubble published his discovery that the speed at which galaxies recede positively correlates with their distance. This is the basis for understanding that the universe is expanding.

During World War II, research was conducted by each side into nuclear physics, for the purpose of creating a nuclear bomb. The German effort, led by Heisenberg, did not succeed, but the Allied Manhattan Project reached its goal. In America, a team led by Fermi achieved the first man-made nuclear chain reaction in 1942, and in 1945 the world's first nuclear explosive was detonated in Alamagordo, New Mexico.

Quantum field theory was formulated in order to extend quantum mechanics to be consistent with special relativity. It achieved its modern form in the late 1940s with work by Feynman, Schwinger[?], Tomonaga[?], and Dyson. They formulated the theory of quantum electrodynamics, which describes the electromagnetic interaction.

Quantum field theory provided the framework for modern particle physics, which studies fundamental forces and elementary particles. In 1954, Yang[?] and Mills[?] developed a class of gauge theories[?], which provided the framework for the Standard Model. The Standard Model, which was completed in the 1970s, successfully describes almost all elementary particles observed to date.

we need more on cosmology, black holes and Stephen Hawking

Developments since 1990

Attempts to unify quantum mechanics and general relativity made signficant progress during the 1990s. At the close of the century, a Theory of everything was still not in hand, but some of its characteristics were taking shape. Loop quantum gravity, string theory, and black hole thermodynamics[?] all predicted quantized spacetime on the Planck scale.

please add to this

Developments since 2000

Gravity was shown to propagate at the speed of light, confirming one prediction of loop quantum gravity.

-- add stuff on convergence of superstring stuff to M-theory

See also: History of science and technology