Fisika

Fisika (tina Basa Yunani φυσικός (physikos): natural, tina φύσις (physis): Alam) mangrupa élmu Alam tina jihat nu panglegana. Fisikawan ngulik paripolah jeung interaksi zat jeung gaya. Hukum fisika umumna diwujudkeun dina rupa hubungan matematis.
Fisika raket pisan hubunganana jeung élmu alam séjén, utamana kimia, élmu molekul jeung senyawa kimia nu dibentukna. Kimia mirip pisan jeung fisika, utamana dina mékanika kuantum, térmodinamika jeung éléktromagnétisme. Ngan, ku sabab fénoména kimiawi nu kompléks jeung kacida lobana ngajadikeun kimia salawasna dianggap salaku disiplin nu misah.
Di handap ieu hiji ihtisar sub-widang jeung konsép utama dina fisika, disusul tepus ku ringkesan sajarah fisika jeung sub-widangna. Béréndélan jejer nu leuwih lengkep ogé aya.
Catetan: di handap ieu mangrupa ihtisar ringkes tumuwuhna fisika. Pikeun leuwih jéntré, baca artikel utama subjék ieu, Sajarah fisika.
Geus ti jaman baheula manusa nyoba neuleuman paripolah zat: naha apel bet ragrag kana taneuh, naha barang nu béda boga sipat nu béda, jeung saterusna. Ogé ngeunaan karakter mayapada, samodél bentuk Bumi jeung paripolah celestial object samodél panonpoé jeung bulan. Sababaraha téori geus diajukeun, tétéla lolobana salah. Téori-téori ieu umumna kedal dina istilah filosofis, teu kungsi dibuktikeun maké uji éksperimén nu sistematis. There were exceptions and there are anachronisms: for example, the Greek thinker Archimedes derived many correct quantitative descriptions of mechanics and hydrostatics.
Munggaran abad ka-17, Galiléo naratas dipakéna ékspérimén pikeun ngabuktikeun téori-téori fisik, nu jadi ide konci dina métode ilmiah. Galiléo geus sacara suksés ngarumuskeun jeung nguji sababaraha hasil panalungtikan ngeunaan dinamika, utamana Hukum Inersia. Dina taun 1687, Newton published the Principia Mathematica, detailing two comprehensive and successful physical théories: Newton's laws of motion, from which arise classical mechanics; and Newton's Law of Gravitation, which describes the fundamental force of gravity. Both théories 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 théories.
From the 18th century onwards, thermodynamics was developed by Boyle, Young, and many others. In 1733, 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 héat, and in 1847 Joule stated the law of conservation of energy, in the form of héat 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 théory of electromagnetism, described by Maxwell's equations. A prediction of this théory was that light is an electromagnetic wave.
In 1895, Roentgen discovered X-rays, which turned out to be high-frequency electromagnetic radiation. Radioactivity was discovered in 1896 by Henri Becquerel, and further studied by 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. In 1904, he proposed the first modél 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 théory of special relativity, unifying space and time into a single entity, spacetime. Relativity prescribes a different transformation between reference frames than classical mechanics; this necessitated the development of relativistic mechanics as a replacement for classical mechanics. In the regime of low (relative) velocities, the two théories 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 énérgies, the two théories agree.
In 1911, Rutherford deduced from scattering experiments the existence of a compact atomic nucleus, with positively charged constituents dubbed protons. Neutrons, the neutral nucléar constituents, were discovered in 1932 by Chadwick.
Beginning in 1900, Planck, Einstein, Bohr, and others developed quantum théories to explain various anomalous experimental results by introducing discrete energy levels. In 1925, Heisenberg and 1926, Schrödinger and Dirac formulated quantum mechanics, which explained the preceding quantum théories. In quantum mechanics, the outcomes of physical méasurements are inherently probabilistic; the théory describes the calculation of these probabilities. It successfully describes the behavior of matter at small distance scales.
Quantum mechanics also provided the théoretical 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 créated a quantum mechanical description of the behavior of electrons in crystal structures in 1928.
During World War II, reséarch was conducted by éach side into nuclear physics, for the purpose of créating a nuclear bomb. The German effort, led by Heisenberg, did not succeed, but the Allied Manhattan Project réached its goal. In America, a téam led by Fermi achieved the first man-made nuclear chain reaction in 1942, and in 1945 the world's first nuclear explosive was detonated at Trinity site, néar Alamogordo, New Mexico.
Quantum field theory was formulated in order to extend quantum mechanics to be consistent with special relativity. It achieved its modérn form in the late 1940s with work by Feynman, Schwinger, Tomonaga, and Dyson. They formulated the théory of quantum electrodynamics, which describes the electromagnetic interaction.
Quantum field théory provided the framework for modérn 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 modél, which was completed in the 1970s, successfully describes almost all elementary particles observed to date.
As of 2003, reséarch is progressing on a large number of fields of physics.
In condensed matter physics, the biggest unsolved théoretical problem is the explanation for high-temperature superconductivity. Strong efforts, largely experimental, are being put into making workable spintronics and quantum computers.
In particle physics, the first pieces of experimental evidence for physics beyond the Standard Model have begun to appéar. Foremost amongst this are indications that neutrinos have non-zero mass. These experimental results appéar to have solved the long-standing solar neutrino problem in solar physics. The physics of massive neutrinos is currently an aréa of active théoretical and experimental reséarch. In the next several yéars, particle accelerators will begin probing energy scales in the TeV range, in which experimentalists are hoping to find evidence for the higgs boson and supersymmetric particles.
Théoretical attempts to unify quantum mechanics and general relativity into a single théory of quantum gravity, a program ongoing for over half a century, has yet to béar fruit. The current léading candidates are M-theory and loop quantum gravity.
Many astronomical phenomena have yet to be explained, including the existence of ultra-high energy cosmic rays and the anomalous rotation rates of galaxies. Théories that have been proposed to resolve these problems include doubly-special relativity, modified Newtonian dynamics, and the existence of dark matter. In addition, the cosmological predictions of the last several decades have been contradicted by recent evidence that the expansion of the universe is accelerating.
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See the definition of physical.
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