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Various examples of physical phenomena

Physics (from Ancient Greek: φυσική (ἐπιστήμη), romanizedphysikḗ (epistḗmē), lit. 'knowledge of nature', from φύσις phýsis 'nature') is the natural science that studies matter, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.

Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over much of the past two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the Scientific Revolution in the 17th century these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy.

Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism, solid-state physics, and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.

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Amalie Emmy Noether (German: [ˈnøːtɐ]; 23 March 1882 – 14 April 1935) was a German mathematician who made important contributions to abstract algebra and theoretical physics. She invariably used the name "Emmy Noether" in her life and publications. She was described by Pavel Alexandrov, Albert Einstein, Jean Dieudonné, Hermann Weyl and Norbert Wiener as the most important woman in the history of mathematics. As one of the leading mathematicians of her time, she developed the theories of rings, fields, and algebras. In physics, Noether's theorem explains the connection between symmetry and conservation laws.

Noether was born to a Jewish family in the Franconian town of Erlangen; her father was a mathematician, Max Noether. She originally planned to teach French and English after passing the required examinations, but instead studied mathematics at the University of Erlangen, where her father lectured. After completing her dissertation in 1907 under the supervision of Paul Gordan, she worked at the Mathematical Institute of Erlangen without pay for seven years. At the time, women were largely excluded from academic positions. In 1915, she was invited by David Hilbert and Felix Klein to join the mathematics department at the University of Göttingen, a world-renowned center of mathematical research. The philosophical faculty objected, however, and she spent four years lecturing under Hilbert's name. Her habilitation was approved in 1919, allowing her to obtain the rank of Privatdozent. Read more...
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False-color photo of the Sun as seen in ultraviolet light
  • ... that neutron stars are so dense (10¹⁷ kg/m³) that a teaspoonful (5 mL) would have ten times the mass of the total human population?

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Ampere Andre 1825.jpg
Engraving of André-Marie Ampère
Born(1775-01-20)20 January 1775
Died10 June 1836(1836-06-10) (aged 61)
Marseille, France
Known forAmpère's circuital law, Ampère's force law
Scientific career
InstitutionsÉcole Polytechnique
André-Marie Ampère signature.svg

André-Marie Ampère (20 January 1775 – 10 June 1836) was a French physicist and mathematician who is generally regarded as one of the main founders of the science of classical electromagnetism, which he referred to as "electrodynamics". The electric current unit of measurement known as the ampere is named after him.

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James Chadwick at the 1933 Solvay Conference. Chadwick had discovered the neutron the year before while working at Cavendish Laboratory.

The discovery of the neutron and its properties was central to the extraordinary developments in atomic physics in the first half of the 20th century. Early in the century, Ernest Rutherford developed a crude model of the atom, based on the gold foil experiment of Hans Geiger and Ernest Marsden. In this model, atoms had their mass and positive electric charge concentrated in a very small nucleus. By 1920 chemical isotopes had been discovered, the atomic masses had been determined to be (approximately) integer multiples of the mass of the hydrogen atom, and the atomic number had been identified as the charge on the nucleus. Throughout the 1920s, the nucleus was viewed as composed of combinations of protons and electrons, the two elementary particles known at the time, but that model presented several experimental and theoretical contradictions.

The essential nature of the atomic nucleus was established with the discovery of the neutron by James Chadwick in 1932 and the determination that it was a new elementary particle, distinct from the proton. Read more...

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Basic physics: Mechanics | Electromagnetism | Statistical mechanics | Thermodynamics | Quantum mechanics | Theory of relativity | Optics | Acoustics

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Classical physics traditionally includes the fields of mechanics, optics, electricity, magnetism, acoustics and thermodynamics. The term Modern physics is normally used for fields which rely heavily on quantum theory, including quantum mechanics, atomic physics, nuclear physics, particle physics and condensed matter physics. General and special relativity are usually considered to be part of modern physics as well.

Fundamental Concepts Classical Physics Modern Physics Cross Discipline Topics
Continuum Solid Mechanics Fluid Mechanics Geophysics
Motion Classical Mechanics Analytical mechanics Mathematical Physics
Kinetics Kinematics Kinematic chain Robotics
Matter Classical states Modern states Nanotechnology
Energy Chemical Physics Plasma Physics Materials Science
Cold Cryophysics Cryogenics Superconductivity
Heat Heat transfer Transport Phenomena Combustion
Entropy Thermodynamics Statistical mechanics Phase transitions
Particle Particulates Particle physics Particle accelerator
Antiparticle Antimatter Annihilation physics Gamma ray
Waves Oscillation Quantum oscillation Vibration
Gravity Gravitation Gravitational wave Celestial mechanics
Vacuum Pressure physics Vacuum state physics Quantum fluctuation
Random Statistics Stochastic process Brownian motion
Spacetime Special Relativity General Relativity Black holes
Quanta Quantum mechanics Quantum field theory Quantum computing
Radiation Radioactivity Radioactive decay Cosmic ray
Light Optics Quantum optics Photonics
Electrons Solid State Condensed Matter Symmetry breaking
Electricity Electrical circuit Electronics Integrated circuit
Electromagnetism Electrodynamics Quantum Electrodynamics Chemical Bonds
Strong interaction Nuclear Physics Quantum Chromodynamics Quark model
Weak interaction Atomic Physics Electroweak theory Radioactivity
Standard Model Fundamental interaction Grand Unified Theory Higgs boson
Information Information science Quantum information Holographic principle
Life Biophysics Quantum Biology Astrobiology
Conscience Neurophysics Quantum mind Quantum brain dynamics
Cosmos Astrophysics Cosmology Observable universe
Cosmogony Big Bang Mathematical universe Multiverse
Chaos Chaos theory Quantum chaos Perturbation theory
Complexity Dynamical system Complex system Emergence
Quantization Canonical quantization Loop quantum gravity Spin foam
Unification Quantum gravity String theory Theory of Everything

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