Обсуждение:История физики

Материал из Википедии — свободной энциклопедии

[править] Актуальность

Переносить статью из ЭСБЕ на эту тему это как говорится жжошь! Ни ядерной физики, ни лазеров, ни квантовой физики, ни релятивистской... :( Имеет ли смысл викифицировать? --Morpheios Melas 11:42, 12 января 2006 (UTC)

Такое убожество давно не читал. —ТЖА.

Эту статью спасти невозможно. -- vald 09:02, 11 апреля 2006 (UTC)

Ну зря Вы так, в качестве введения, не перегруженного информацией, вполне подходит. -- Astellar, 23 апреля 2006.

Добавлен раздел введение и куча фотографий знаменитых физиков. Вроде ничего пока. -- Vald 17:56, 29 апреля 2006 (UTC)

Давайте en переведем лучше, я ее медленно один сейчас уже перевожу. За неделю очень даже можно. ))) --Matist Krusoe 06:39, 11 июня 2006 (UTC)

Да, пожалуйста, любые улучшения будут только приветствоваться. А вот, на всякий случай, русские ссылки: Летопись познания - Vald 13:34, 20 июня 2006 (UTC)

[править] История физики

Рост физики не только оказывал воздействие на идеи о материальном мире, математике и философии, но также и преобразовывал человеческое общество, путем совершенствования его технологий, в целом. Физика - это не только знания, но и, что даже скорее больше, практический опыт. Научная революция, начавшаяся примерно году этак в 1600, является удобной границей между древней мыслью и классической физикой. Год 1900 - начало более современной физики. Появились новые вопросы, которые и сегодня еще очень далеки от своего завершения. Все больше пробле связано с эволющией Вселенной, с ее ранними этапами, с природой вакуума, и, наконец, с окончательной природой свойств податомных цастиц. Частичные теории являются в настоящее время лучшими, что физика может предложить в настоящее время. Список неразрешенных проблем в физике постоянно множится; однако,

"Мы больше атома, но, кажется, уже знаем о нем все." - Ричард Фейман

[править] Ранняя физика

По природе своей, человек - существо любопытное. Еще с древних пор его начали интересовать вещи, казавшиеся ранее обыденными, относящиеся к окрудающему миру. Тогда давно основной причиной этого любопытства, скорее всего, был страх. И лишь немногих это интересовало из-за чистого любопытства, любопытства ради любопытства. Действительно, почему, например происходит притяжение, почему разные материалы имеют разные свойства? Ну почему же солнце заходит с одной стороны, а восходит с другой?! Люди всегда интересовались миром. Многие свойства природы приписывались богам. Неправильные теории преобретали свойства религии. Их передавали из поколения в поколения. Многие теории того времени были в значительной степени изложены в форме философских срок. Мало было людей, готовых в них сомневаться. Тем более на том этапе развития наличие любой теории или отсутствие таковой большого влияния на жизнь не оказывало. Были люди, готовые дойти до края зели. Чтобы убедиться в нем! Кто эти люди? Сумасшедшие? Эксперементаторы! Это будущие физики!

[править] Индийские вклады

Оригинальный вариант скрыт в комментариях.

В позднюю Vedic эру (c 9 по 6 столетие до н.э), астроном Яджнаволкья (Yajnavalkya), в своей Shatapatha Brahmana, упомянуто раннее понятие гелиоцентр (heliocentrism), в котором Земля была круглой, и Солнце являлось "центром сфер". Он измерил растояния от Луны и Солнца до Земли в 108 деаметров самих объектов. Эти значения практически совпадают с современными: для Луны - 110.6, и для Солнца - 107.6.

Индусы представляли мир состоящим из пяти основных элементов: земля, огонь, воздух, вода и эфир/пространство. Позже, с 6-ого столетия до н.э, они сформулировали теорию атома, начиная с Kanada и Pakudha Katyayana. Поклонники теории полагали, что атом состоит элементов, до 9 элементов в каждом атоме, каждый элемент имеет до 24 свойств. Они развивали следующие теории, о том как атомы могут объединяться, реагировать, вибрировать, перемещаться и выполнять другие действия. Так ж разрабатывались теории того, как атомы могут сформировать двойные молекулы, которые объединяются далее, чтобы сформировать еще большие молекулы, и как частицы сначала объединяются в пары, и затем группа в трио пар, которые являются наименьшими видимыми единицами материи. Эти схождения с современными атомными теориями потрясают воображение. Еще у индусов атомы были делимыми частицами, до чего мы догадались лишь дару сотен лет назад, и что положило начало всей ядерной энергетики.

Принцип относительности (чтобы не быть перепутать с теорией относительности Эйншеина) был доступен в зачаточной форме с 6-ого столетия до н.э в древнем индийском философском понятии "sapekshavad", буквально "теория относительности" на Санскрите.

Две школы, Samkhya и Vaisheshika, развивали теории света с 6-ого 5-ого столетия до н.э. Согласно школе Samkhya, свет - один из пяти фундаментальных элементов, из которых появляются более тяжелые элементы, появляются уже позже. Школа Vaisheshika определила движение в терминах немгновенного движения физических атомов. Лучи света были выбраны быть потоком высоких скоростных атомов огня, которые могут проявлять различные особенности в зависимости от скорости и мер этих частиц. [2] Буддисты Дигнга (5-ое столетие) и Dharmakirti (7-ое столетие) развивали теорию света, состоящего из частиц энергии, подобных современному понятию фотонов.

Почетный австралийский специалист по индийской культуре (indologist) A. L. Basham заключил, что "они были блестящими образными объяснениями физической структуры мира, и по большей части, согласились с открытиями современной физики."

В 499, астроном-математик Арьябхата (Aryabhata) представлял на обсуждение детальную модель гелиоцентрисской солнечной системы тяготения, где планеты вращаются вокруг своей оси (сменяя таким образом день и ночь) и имеют элиптическую орбиту (преобретая таким образом зиму и лето). Удивительно, что в такой системе луна не являлась источником света, а только отражала солнечный свет от своей поверхности. Арьябхата также правильно объяснил причины солнечных и лунных затмений и предсказал их времена, дал радиусы планетарных орбит вокруг Солнца, и точно измерил длины дня, звездного года, и диаметра Земли. Brahmagupta, в его Brahma Sputa Siddhanta в 628, представляет гравитацию как силу притяжения и показывает закон притяжения.

Особенно важный индийский вклад был индусскоарабскими цифрами. Современная позиционная система цифры (индусская-арабская система цифры) и ноль числа была сначала развита в Индии, наряду с тригонометрическими функциями синуса и косинуса. Эти математические события, наряду с индийскими событиями в физике, были приняты Исламским Калифатом, после чего и начали распространяться по Европе и другим частям света.

[править] Китайский вклад

В 1115 году до н.э, в Китае был первым изобретен изобрел первый редукционный механизм, the South Pointing Chariot, это было также первым использованием дифференциальной передачи.

Китаец "Мо Чинг" в III веке до н.э стал автором ранней версии закона движения Ньютона.

""Прекращение движения происходит из-за противодействующей силы... Если не будет никакой противостоящей силы ..., то движение никогда не закончится. Это верно настолько же, как и то, что бык не лошадь." "

Более поздние вклады китая включают изобретения бумаги, печатного дела, пороха, и компаса. Китайцы первыми "открыли" отрицательные числа, которые оказали сильное влияние на развитие физики и математики.

[править] Греческий и Эллинистический вклады

Western physics began with eminent Greek pre-Socratic philosophers such as Thales, Anaximander, possibly Pythagoras, Heraclitus, Anaxagoras, Empedocles and Philolaus, many of whom were involved in various schools. For example, Anaximander and Thales belonged to the Milesian school.

Plato, briefly and Aristotle at length, continued these studies of nature in their works, the earliest surviving complete treatises dealing with natural philosophy. Democritus, a contemporary, was of the school of Atomists who attempted to characterize the nature of matter.

Due to the absence of advanced experimental equipment such as telescopes and accurate time-keeping devices, experimental testing of physical hypotheses was impossible or impractical. There were exceptions and there are anachronisms: 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, using methods resembling integral calculus.

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 traveled 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, except that of ancient China.

An early version of the steam engine, Hero's aeolipile was only a curiosity which did not solve the problem of transforming its rotational energy into a more usable form, not even by gears. The Archimedes screw is still in use today, to lift water from rivers onto irrigated farmland. The simple machines were unremarked, with the exception (at least) of Archimedes' elegant proof of the law of the lever. Ramps were in use several millennia before Archimedes, to build the Pyramids.

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. Pythagoras himself is said to have tried to suppress knowledge of the existence of irrational numbers, discovered by his own school, because they did not fit his number mysticism. 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 in which the planets are assumed to each move in a small circle, called an epicycle, which in turn moves along a larger circle called a deferent, was accepted as absolute truth.

[править] Персидский и Исламский вклад

With civilization dominated 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 saw a decline in interest in classical culture which some have called the Dark Ages, though modern scholars do not use this phrase, and almost all scientific research ground to a halt.

In the Middle East however, many Greek and Hellenistic natural philosophers were able to find support for their work, and Islamic scholars built upon their previous work in astronomy and mathematics while developing such new fields as alchemy (chemistry). After the Arabs conquered Persia, many scientists arose among the Persians, who preserved Hellenistic physics, which faded away in Europe at the time, and studied Indian physics after conquering parts of India. The Persians, as well as the Arabs, went on to make many improvements on the Indian and Hellenistic concepts.

A Persian scientist Mohammad al-Fazari invented the astrolabe, an astronomical instrument and analog computer that was important in locating and predicting the positions of the Sun, Moon, planets and stars. Muḥammad ibn Mūsā al-Ḵwārizmī gave his name to what we now call an algorithm, and developed modern algebra, which was derived from the Arabic word al-jabr from the title of his treatise Hisab al-jabr w’al-muqabala.

The Persian scientist Alhazen Abu Ali al-Hasan ibn al-Haytham (c. 965-1040), also known as Alhazen, developed a broad theory that explained vision, using geometry and anatomy, which stated that each point on an illuminated area or object radiates light rays in every direction, but that only one ray from each point, which strikes the eye perpendicularly, can be seen. The other rays strike at different angles and are not seen. He used the example of the pinhole camera, which produces an inverted image, to support his argument. This contradicted Ptolemy's theory of vision that objects are seen by rays of light emanating from the eyes. Alhazen held light rays to be streams of minute particles that travelled at a finite speed. He improved Ptolemy's theory of the refraction of light, and went on to discover the laws of refraction.

He also carried out the first experiments on the dispersion of light into its constituent colors. His major work Kitab-at-Manazir was translated into Latin in the Middle Ages, as well his book dealing with the colors of sunset. He dealt at length with the theory of various physical phenomena like shadows, eclipses, the rainbow. He also attempted to explain binocular vision, and gave a correct explanation of the apparent increase in size of the sun and the moon when near the horizon. Through these extensive researches on optics, is considered as the father of modern optics.

Al-Haytham also correctly argued that we see objects because the sun's rays of light, which he believed to be streams of tiny particles travelling in straight lines, are reflected from objects into our eyes. He understood that light must travel at a large but finite velocity, and that refraction is caused by the velocity being different in different substances. He also studied spherical and parabolic mirrors, and understood how refraction by a lens will allow images to be focused and magnification to take place. He understood mathematically why a spherical mirror produces aberration.

Смотри также: List of Iranian scientists and scholars

[править] Средневековый Европейский вклад

In the 12th century, the birth of medieval university and the rediscovery of the works of ancient philosophers through contact with the Arabs, during the process of Reconquista and the Crusades, started an intellectual revitalization of Europe.

By the 13th century, precursors of the modern scientific method can be seen already on Robert Grosseteste's emphasis on mathematics as a way to understand nature and on the empirical approach admired by Roger Bacon.

Bacon conducted experiments into optics, although much of it was similar to what had been done and was being done at the time by Arab scholars. He did make a major contribution to the development of science in medieval Europe by writing to the Pope to encourage the study of natural science in university courses and compiling several volumes recording the state of scientific knowledge in many fields at the time. He described the possible construction of a telescope, but there is no strong evidence of his having made one. He recorded the manner in which he conducted his experiments in precise detail so that others could reproduce and independently test his results - a cornerstone of the scientific method, and a continuation of the work of researchers like Al Battani.

In the 14th century, some scholars, such as Jean Buridan and Nicolas Oresme, started to question the received wisdom of Aristotle's mechanics. In particular, Buridan developed the theory of impetus which was the first step towards the modern concept of inertia.

In his turn, Oresme showed that the reasons proposed by the physics of Aristotle against the movement of the earth were not valid and adduced the argument of simplicity for the theory that the earth moves, and not the heavens. In the whole of his argument in favor of the earth's motion Oresme is both more explicit and much clearer than that given two centuries later by Copernicus. He was also the first to assume that color and light are of the same nature and the discoverer of the curvature of light through atmospheric refraction; even though, up to now, the credit for this latter achievement has been given to Hooke.

In spite of this pause, the 15th century saw the artistic flourishing of the Renaissance. The rediscovery of ancient texts was improved when many Byzantine scholars had to seek refuge in the West after the fall of Constantinople in 1453. Meanwhile, the invention of printing was to democratize learning and allow a faster propagation of new ideas. All that paved the way to the Scientific Revolution, which may also be understood as a resumption of the process of scientific change halted around the middle of the 14th century.

[править] Современная физика

Конец XVI века послужил началом современной науки. Он может рассмативаться и как расцвет Ренессанса и как путь к современной цивилизации. Частично это было вызвано повторным открытием достижений древней греческой, индийской, китайской и исламской культуры, сохраненной, а в дальнейшем дополненой Исламским миром от VIII до XV столетия, и перевело христианскими монахами на латинский, типа "Альмагеста" (Almagest).

Современная наука началась всего с нескольких исследователей, а позже развилась в целое движение, не остановившееся и до наших дней. Начинаясь с Астрономии, принципы натуральной философии формируются в фундаментальный законы физики, которые были изложены и развиты в последующих столетиях. К XIX столетию, в физике начинается сегментация, появляются новые ответвления. Исследования преобретают более узкий характер, хотя результаты их по преднему переплетены логической общностью физики.

[править] XVI столетье

In the 16th century Nicolaus Copernicus revived Aristarchus' heliocentric model of the solar system in Europe (which survived primarily in a passing mention in The Sand Reckoner of Archimedes). When this model was published at the end of his life, it was with a preface by Andreas Osiander that piously represented it as only a mathematical convenience for calculating the positions of planets, and not an account of the true nature of the planetary orbits.

In England William Gilbert (1544-1603) studied magnetism and published a seminal work, De Magnete (1600), in which he thoroughly presented his numerous experimental results.

[править] XVII столетье

In the early 17th century Johannes 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.

The first quantitative estimate of the speed of light was made in 1676 by Ole Rømer, by timing the motions of Jupiter's satellite Io with a telescope.

During the early 17th century, Galileo Galilei pioneered the use of experiment to validate physical theories, which is the key idea in the scientific method. Galileo's use of experiment, and the insistence of Galileo and Kepler that observational results must always take precedence over theoretical results (in which they followed the precepts of Aristotle if not his practice), 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, including the correct law of accelerated motion, the parabolic trajectory, the relativity of unaccelerated motion, and an early form of 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. The Law of Gravitation initiated the field of astrophysics, which describes astronomical phenomena using physical theories.

[править] XVIII столетье

From the 18th century onwards, thermodynamic concepts were developed by Robert Boyle, Thomas Young, and many others, concurrently with the development of the steam engine, onward into the next century. In 1733, Daniel Bernoulli used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field of statistical mechanics. Benjamin Thompson demonstrated the conversion of unlimited mechanical work into heat.

In 1746 an important step in the development of electricy was taken in the invention of the Leyden jar, a capacitor, that could store and discharge electrical charge in a controlled way. Benjamin Franklin effectively used them in his researches into the nature of electricity in 1752.

In about 1788, Joseph Louis Lagrange elaborated an important new formulation of mechanics using the calculus of variations, the principle of least action and the Euler-Lagrange equations.

[править] XIX век

In a letter to the Royal Society in 1800, Alessandro Volta described his invention of the electric battery, thus providing for the first time the means to generate a constant electric current, and opening up a new field of physics for investigation.

The behavior of electricity and magnetism was studied by Michael Faraday, Georg Ohm, Hans Christian Ørsted, and others. Faraday, who began his career in chemistry working under Humphry Davy at the Royal Institution, demonstrated that electrostatic phenomena, the action of the newly discovered electric pile or battery, electrochemical phenomena, and lightning were all different manifestations of electrical phenomena. Faraday further discovered in 1821 that electricity can cause rotational mechanical motion, and in 1831 discovered the principle of electromagnetic induction, by which means mechanical motion is converted into electricity. Thus it was Faraday who laid the foundations for both the electric motor and the electric generator.

In 1855, James Clerk 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. The discovery of the Hall effect in 1879 gave the first direct evidence that the carrier of electricity was negatively charged.

In 1847 James Prescott Joule stated the law of conservation of energy, in the form of heat as well as mechanical energy. However, the principle of conservation of energy had been suggested or enunciated in various forms by perhaps a dozen German, French, British and other scientists during the first half of the 19th Century. About the same time, entropy and the second law of thermodynamics were first clearly described in the work of Rudolf Clausius. In 1875 Ludwig Boltzmann made the important connection between the number of possible states that a system could occupy and its entropy. With two installments in 1876 and 1878, Josiah Willard Gibbs developed much of the theoretical formalism for thermodynamics, and a decade later firmly laid the foundation for statistical mechanics — much of which Ludwig Boltzmann had independently invented.

Classical mechanics was given a new formulation by William Rowan Hamilton, in 1833 with the introduction of what is now called the Hamiltonian, which a century gave an entry to wave mechanical formulation of quantum mechanics.

Dimensional analysis was used for the first time in 1878 by Lord Rayleigh who was trying to understand why the sky is blue.

In 1887 the Michelson-Morley experiment was conducted and it was interpreted as counter to the general held theory of the day, that the Earth was moving through a "luminiferous aether". The development of what later became Einstein's Special Theory of Relativity provided a complete explanation which did not require an aether, and was consistent with the results of the experiment. Albert Abraham Michelson and Edward Morley were not fully convinced of the non-existence of the aether. Morley conducted further experiments with Dayton Miller with improved interferometers, again giving null results.

In 1887, Nikola Tesla investigated X-rays using his own devices as well as Crookes tubes. In 1895, Wilhelm Conrad Röntgen observed and analysed X-rays, which turned out to be high-frequency electromagnetic radiation. Radioactivity was discovered in 1896 by Henri Becquerel, and further studied by Pierre and Marie Curie and others. This initiated the field of nuclear physics.

In 1897, J.J. Thomson and Philipp Lenard studied cathode rays. Thomson deduced that were negatively charged particles, which he called "corpuscles", which came to be called electrons. Lenard showed that the particles ejected in the photoelectric effect were the same as those in cathode rays, and that their energy was independent of the intensity of the light, but was greater for short wavelengths of the incident light.

[править] XX век

Начало XX века можно назвать революцией в физике.

В 1904, Томсон предложил первую модель атома, известный как модель сливового пудинга, где атом представлял собой положительно заряженное тело, с равномерно перемешанными в нем электронами (т.к. электрон открыли, а ядро еще нет). Существование атомов различных масс было предложено в 1808 Джоном Дальтоном, чтобы объяснить закон многократных пропорций (the law of multiple proportions). Конвергенция различных оценок числа Авогадро предоставила решающее доказательство для атомистической теории. В 1911, Эрнест Резерфорд, проводя эксперименты по рассеянию альфа-частиц атомами, обнаружил отклонения от модели сливового пудинга. Так появилась более современная теория теория компактного ядра атома. Позже, в 1913 Нильсом Бором была опубликована первая квантово механическая модель атома, Боровская модель. Сэр W. H. Bragg и его сын сэр W. L. Bragg, в том же 1913 году, начал изучения атомной структуры кристаллического вещества при помощи дифракции рентгеновских лучей. Нейтрон, входивший в состав атомного ядра, был обнаружен в 1932 Джеймсом Чедвиком.

Преобразования Лоренса, фундаментальные уравнения специальной теории относительности, были изданы в 1897 и 1900 и также Джозеф Лармор и Хенриком Лоренцем в 1899 и 1904. Они оба показали, что уравнения Максвелла были инвариантными при переходе от одной системы отсчета к другой. В 1905, Эйнштейн сформулировал специальную теорию относительности, объединяя пространство и время в неразрывное целое, пространственно-временной континуум. В 1915, Эйнштейн опубликовал общую теорию относительности, которая провозглашала эквивалентность гравитационной и инертной массы. Как результат Общей теории относительности - гравитационный коллапс в черных дырах, который был предсказан еще двумя столетиями ранее, но объяснен только Робертом Оппенгеймером. Важные частные решения полевого уравнения Эйнштейна были найдены Карлом Швочилдичем (Karl Schwarzschild) в 1915 и Ройем Керром только в 1963.

According to Cornelius Lanczos, any physical law which can be expressed as a variational principle describes an expression which is self-adjoint^[1] or Hermitian. Thus such an expression describes an invariant under a Hermitian transformation. Felix Klein's Erlangen program attempted to identify such invariants under a group of transformations. Noether's theorem identified the conditions under which the Poincaré group of transformations (what is now called a gauge group) for general relativity define conservation laws. The relationship of these invariants (the symmetries under a group of transformations) and what are now called conserved currents, depends on a variational principle, or action principle. Noether's papers made the requirements for the conservation laws precise. Noether's theorem remains right in line with current developments in physics to this day.

В 1900 такие ученые, как Макс Планк, Альберт Эйнштейн, Нильс Бор, и другие начали развивать квантовую теорию. В 1925 Волфганг Паули вводит принцип исключения Паули, а также такие понятия как спин элементарной частицы и фермион. В том же году Эрвин Шрденджер фомульрует волновую механику (wave mechanics), который содержит последовательные математические метод для описания большого разнообразия физических моделей, типа частицы в коробке (particle in a box) и квантовый гармонический маятник (quantum harmonic oscillator), которые до него небыли решены. Гейзенберг, в том же 1925 году, описывает альтернативный математический метод, названный матричная механика, который, как оказалось, был эквивалентном волновой механике. В 1928 Пол Дирак дает релятивистскую формулировку, основанную на матричной механике Гейзенберга, и предсказал существование позитрона, таким образом основывая квантую электродинамику.

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 understanding condensed matter physics, which studies the physical behavior of solids and liquids, including phenomena such as electrical conductivity in crystal structures. The pioneers of condensed matter physics include Felix Bloch, who created a quantum mechanical description of the behavior of electrons in crystal structures in 1928. Much of the behavior of solids was elucidated within a few years with the discovery of the Fermi surface which was based on the idea of the Pauli exclusion principle applied to systems having many electrons.

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. Thus, the universe must have been smaller and therefore hotter in the past. By the 1940s, researchers like George Gamow proposed the Big Bang theory^[2], evidence for which was discovered in 1964^[3]; Enrico Fermi and Fred Hoyle were among the doubters in the 1940s and 1950s. Hoyle had dubbed Gamow's theory the Big Bang in order to debunk it. Today, it is one of the principal results of cosmology.

In 1934, the Italian physicist Enrico Fermi had discovered strange results when bombarding uranium with neutrons, which he believed at first to have created transuranic elements. In 1939, it was discovered by the chemist Otto Hahn and the physicist Lise Meitner that what was actually happening was the process of nuclear fission, whereby the nucleus of uranium was actually being split into two pieces, releasing a considerable amount of energy in the process. At this point it became clear to a number of scientists independently that this process could potentially be harnessed to produce massive amount of energy, either as a civilian power source or as a weapon. Leó Szilárd actually filed a patent on the idea of a nuclear chain reaction in 1934. In America, a team led by Fermi and Szilárd achieved the first man-made nuclear chain reaction in 1942 in the world's first nuclear reactor, and in 1945 the world's first nuclear explosive was detonated at Trinity Site, north of Alamogordo, New Mexico. After the war, central governments would become the primary sponsors of physics. The scientific leader of the Allied project, theoretical physicist Robert Oppenheimer, noted the change of the imagined role of the physicist when he noted in a speech that:

"In some sort of crude sense, which no vulgarity, no humor, no overstatement can quite extinguish, the physicists have known sin, and this is a knowledge which they cannot lose."

Though the process had begun with the invention of the cyclotron by Ernest O. Lawrence in the 1930s, nuclear physics in the postwar period entered into a phase of what historians have called "Big Science", requiring costly huge accelerators and particle detectors, and large collaborative laboratories to test open new frontiers. The primary patron of physics became central governments, who recognized that the support of "basic" research could sometimes lead to technologies useful to both military and industrial applications. Toward the end of the twentieth century, a European collaboration of 20 nations, CERN, became the largest particle physics laboratory in the world.

Another "big science" was the science of ionized gases, plasma, which had begun with Crookes tubes late in the 19th century. Large international collaborations over the last half of the twentieth century embarked on a long range effort to produce commercial amounts of electricity through fusion power, which remains a distant goal.

Further understanding of the physics of metals, semiconductors and insulators led a team of three men at Bell labs, William Shockley, Walter Brattain and John Bardeen in 1947 to the first transistor and then to many important variations, especially the bipolar junction transistor. Further developments in the fabrication and miniaturization of integrated circuits in the years to come produced fast, compact computers that came to revolutionize the way physics was done--simulations and complex mathematical calculations became possible that were undreamed of even a few decades previous.

The discovery of nuclear magnetic resonance in 1946 led to many new methods for examining the structures of molecules and became a very widely used tool in analytical chemistry, and it gave rise to an important medical imaging technique, magnetic resonance imaging.

Starting in 1960 the military establishment of the United States began using atomic clocks to construct the global positioning system which in 1984 achieved its full configuration of 24 satellites in low earth orbits. This came to have many important civilian and scientific uses as well.

Superconductivity, discovered in 1911 by Kamerlingh Onnes, was shown to be a quantum effect and was satisfactorily explained in 1957 by Bardeen, Cooper, and Schrieffer. A family of high temperature superconductors, based on cuprate perovskite, were discovered in 1986, and their understanding remains one of the major outstanding challenges for condensed matter theorists.

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 Richard Feynman, Julian Schwinger, Sin-Itiro Tomonaga, and Freeman Dyson. This provided the framework for modern particle physics, which studies fundamental forces and elementary particles. In 1954, Yang Chen Ning and Robert Mills developed a class of gauge theories, which provided the framework for the Standard Model. This was largely completed in the 1970s and successfully describes almost all elementary particles observed to date.

In 1974 Stephen Hawking discovered the spectrum of radiation emanating during the collapse of matter into black holes. These mysterious objects became objects of intense interest to astrophysicists and even the general public in the latter part of the twentieth century.

Attempts to unify quantum mechanics and general relativity made significant 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. String theory, loop quantum gravity and black hole thermodynamics all predicted quantized spacetime on the Planck scale.

A number of new efforts to understand the physical world arose in the last half of the twentiety century that generated widespread interest: fractals and scaling, self-organized criticality, complexity and chaos, power laws and noise, networks, non-equilibrium thermodynamics, sandpiles, nanotechnology, cellular automata and the anthropic principle were only a few of these important topics.