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Various examples of physical phenomena
Various examples of physical phenomena

Physics is the natural science that studies matter, its fundamental constituents, 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, with its main goal being to understand how the universe behaves. A scientist who specializes in the field of physics is called a physicist.

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 these and other 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. (Full article...)

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Portrait by Jakob Emanuel Handmann (1753)
Portrait by Jakob Emanuel Handmann (1753)

Leonhard Euler (/ˈɔɪlər/ OY-lər, German: [ˈɔʏlɐ] (listen); 15 April 1707 – 18 September 1783) was a Swiss mathematician, physicist, astronomer, geographer, logician and engineer who founded the studies of graph theory and topology and made pioneering and influential discoveries in many other branches of mathematics such as analytic number theory, complex analysis, and infinitesimal calculus. He introduced much of modern mathematical terminology and notation, including the notion of a mathematical function. He is also known for his work in mechanics, fluid dynamics, optics, astronomy and music theory.

Euler is held to be one of the greatest mathematicians in history and the greatest of the 18th century. A statement attributed to Pierre-Simon Laplace expresses Euler's influence on mathematics: "Read Euler, read Euler, he is the master of us all." Carl Friedrich Gauss remarked: "The study of Euler's works will remain the best school for the different fields of mathematics, and nothing else can replace it." Euler is also widely considered to be the most prolific; his 866 publications as well as his correspondences are collected in the Opera Omnia Leonhard Euler which, when completed, will consist of 81 quarto volumes. He spent most of his adult life in Saint Petersburg, Russia, and in Berlin, then the capital of Prussia. (Full article...)
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  • John von Neumann in the 1940s
    John von Neumann in the 1940s
  • Image 2 Bruno Benedetto Rossi (/ˈrɒsi/; Italian: [ˈrossi]; 13 April 1905 – 21 November 1993) was an Italian experimental physicist. He made major contributions to particle physics and the study of cosmic rays. A 1927 graduate of the University of Bologna, he became interested in cosmic rays. To study them, he invented an improved electronic coincidence circuit, and travelled to Eritrea to conduct experiments that showed that cosmic ray intensity from the West was significantly larger than that from the East. Forced to emigrate in October 1938 due to the Italian racial laws, Rossi moved to Denmark, where he worked with Niels Bohr. He then moved to Britain, where he worked with Patrick Blackett at the University of Manchester. Finally he went to the United States, where he worked with Enrico Fermi at the University of Chicago, and later at Cornell University. Rossi stayed in the United States, and became an American Citizen. (Full article...)
  • A sample of multiwalled carbon nanotubes with 3–15 walls, mean inner diameter 4 nm, mean outer diameter 13–16 nm, length 1-10+ micrometers.
    A sample of multiwalled carbon nanotubes with 3–15 walls, mean inner diameter 4 nm, mean outer diameter 13–16 nm, length 1-10+ micrometers.
  • Elda Emma Anderson, physicist and health researcher
    Elda Emma Anderson, physicist and health researcher
  • Image 5Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases which arise from electromagnetic forces between atoms. More generally, the subject deals with "condensed" phases of matter: systems of many constituents with strong interactions between them. More exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, and the Bose–Einstein condensate found in ultracold atomic systems. Condensed matter physicists seek to understand the behavior of these phases by experiments to measure various material properties, and by applying the physical laws of quantum mechanics, electromagnetism, statistical mechanics, and other theories to develop mathematical models.The diversity of systems and phenomena available for study makes condensed matter physics the most active field of contemporary physics: one third of all American physicists self-identify as condensed matter physicists, and the Division of Condensed Matter Physics is the largest division at the American Physical Society.  The field overlaps with chemistry, materials science, engineering and nanotechnology, and relates closely to atomic physics and biophysics. The theoretical physics of condensed matter shares important concepts and methods with that of particle physics and nuclear physics. (Full article...)
    Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases which arise from electromagnetic forces between atoms. More generally, the subject deals with "condensed" phases of matter: systems of many constituents with strong interactions between them. More exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, and the Bose–Einstein condensate found in ultracold atomic systems. Condensed matter physicists seek to understand the behavior of these phases by experiments to measure various material properties, and by applying the physical laws of quantum mechanics, electromagnetism, statistical mechanics, and other theories to develop mathematical models.

    The diversity of systems and phenomena available for study makes condensed matter physics the most active field of contemporary physics: one third of all American physicists self-identify as condensed matter physicists, and the Division of Condensed Matter Physics is the largest division at the American Physical Society. The field overlaps with chemistry, materials science, engineering and nanotechnology, and relates closely to atomic physics and biophysics. The theoretical physics of condensed matter shares important concepts and methods with that of particle physics and nuclear physics. (Full article...)
  • Image 6A tamper is an optional layer of dense material surrounding the fissile material. It  is used in nuclear weapon design to reduce the critical mass of a nuclear weapon and to delay the expansion of the reacting material through its inertia. Due to its inertia it delays the thermal expansion of the fissioning fuel mass, keeping it supercritical for longer. Often the same layer serves both as tamper and as neutron reflector.  The weapon disintegrates as the reaction proceeds and this stops the reaction, so the use of a tamper makes for a longer-lasting, more energetic, and more efficient explosion. The yield can be further enhanced through the use of a fissionable tamper.The first nuclear weapons used heavy natural uranium or tungsten carbide tampers, but a heavy tamper necessitates a larger high-explosive implosion system, and makes the entire device larger and heavier. The primary stage of a modern thermonuclear weapon may instead use a lightweight beryllium reflector, which is also transparent to X-rays when ionized, allowing the primary's energy output to escape quickly to be used in compressing the secondary stage. More exotic tamper materials such as gold are used for special purposes like emitting large amounts of X-rays or maximizing or minimizing radioactive fallout. (Full article...)
    A tamper is an optional layer of dense material surrounding the fissile material. It is used in nuclear weapon design to reduce the critical mass of a nuclear weapon and to delay the expansion of the reacting material through its inertia. Due to its inertia it delays the thermal expansion of the fissioning fuel mass, keeping it supercritical for longer. Often the same layer serves both as tamper and as neutron reflector. The weapon disintegrates as the reaction proceeds and this stops the reaction, so the use of a tamper makes for a longer-lasting, more energetic, and more efficient explosion. The yield can be further enhanced through the use of a fissionable tamper.

    The first nuclear weapons used heavy natural uranium or tungsten carbide tampers, but a heavy tamper necessitates a larger high-explosive implosion system, and makes the entire device larger and heavier. The primary stage of a modern thermonuclear weapon may instead use a lightweight beryllium reflector, which is also transparent to X-rays when ionized, allowing the primary's energy output to escape quickly to be used in compressing the secondary stage. More exotic tamper materials such as gold are used for special purposes like emitting large amounts of X-rays or maximizing or minimizing radioactive fallout. (Full article...)
  • Rainwater in 1975
    Rainwater in 1975
  • A simulated particle collision in the LHC.
    A simulated particle collision in the LHC.
  • Image 9An antimetric electrical network is an electrical network that exhibits anti-symmetrical electrical properties. The term is often encountered in filter theory, but it applies to general electrical network analysis. Antimetric is the diametrical opposite of symmetric; it does not merely mean "asymmetric" (i.e., "lacking symmetry").  It is possible for networks to be symmetric or antimetric in their electrical properties without being physically or topologically symmetric or antimetric. (Full article...)
    An antimetric electrical network is an electrical network that exhibits anti-symmetrical electrical properties. The term is often encountered in filter theory, but it applies to general electrical network analysis. Antimetric is the diametrical opposite of symmetric; it does not merely mean "asymmetric" (i.e., "lacking symmetry"). It is possible for networks to be symmetric or antimetric in their electrical properties without being physically or topologically symmetric or antimetric. (Full article...)
  • Figure 1. The light path through a Michelson interferometer. The two light rays with a common source combine at the half-silvered mirror to reach the detector. They may either interfere constructively (strengthening in intensity) if their light waves arrive in phase, or interfere destructively (weakening in intensity) if they arrive out of phase, depending on the exact distances between the three mirrors.
    Figure 1. The light path through a Michelson interferometer. The two light rays with a common source combine at the half-silvered mirror to reach the detector. They may either interfere constructively (strengthening in intensity) if their light waves arrive in phase, or interfere destructively (weakening in intensity) if they arrive out of phase, depending on the exact distances between the three mirrors.
  • Vice Admiral John T. Hayward
    Vice Admiral John T. Hayward
  • George T. Reynolds' Los Alamos wartime security badge
    George T. Reynolds' Los Alamos wartime security badge
  • Rudolf Peierls in 1966
    Rudolf Peierls in 1966
  • Neddermeyer's ID badge photo from Los Alamos
    Neddermeyer's ID badge photo from Los Alamos
  • A waterspout near Florida. The two flares with smoke trails near the bottom of the photograph are for indicating wind direction and general speed.
    A waterspout near Florida. The two flares with smoke trails near the bottom of the photograph are for indicating wind direction and general speed.

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Fundamentals: Concepts in physics | Constants | Physical quantities | Units of measure | Mass | Length | Time | Space | Energy | Matter | Force | Gravity | Electricity | Magnetism | Waves

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

Specific fields: Acoustics | Astrophysics | Atomic physics | Molecular physics | Optical physics | Computational physics | Condensed matter physics | Nuclear physics | Particle physics | Plasma physics

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Background: Physicists | History of physics | Philosophy of physics | Physics education | Physics journals | Physics organizations

Other: Physics in fiction | Physics lists | Physics software | Physics stubs

Physics topics

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
Quantum 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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