223 relations: A priori and a posteriori, Acceleration, Albert Einstein, American Journal of Physics, Ancient Roman units of measurement, Angle, Annalen der Physik, Apollo 15, Astronomical object, Astronomical unit, Atomic clock, Atomic nucleus, Avogadro constant, Ball, Binding energy, Black hole, Bohr radius, Caesium standard, Calculus, Calibration, Cambridge University Press, Canonical commutation relation, Canonical quantization, Carat (mass), Carbon-12, Causality, Cavendish experiment, Celestial spheres, Ceratonia siliqua, Classical electron radius, Classical mechanics, Closed system, Complex number, Compton wavelength, Condensed matter physics, Conservation of energy, Conversion of units, Cube (algebra), Curvature, Dark energy, David Scott, De motu corporum in gyrum, Deuterium, Dialogue Concerning the Two Chief World Systems, Dirac equation, Displacement (vector), Dover Publications, Drag (physics), Earth, Edmond Halley, ..., Effective mass (solid-state physics), Effective mass (spring–mass system), Eigenvalues and eigenvectors, Einstein field equations, Ellipse, Energy, Energy–momentum relation, Equivalence principle, Ernst Mach, Euler–Lagrange equation, Explanandum and explanans, Extension (metaphysics), Faster-than-light, Ferromagnetism, Fictitious force, Field (physics), Force, Frame of reference, Frank Wilczek, Free fall, Frequency, Friction, Galilean moons, Galileo Galilei, Gauss's law for gravity, General Conference on Weights and Measures, General relativity, Gerald Feinberg, Gravitational constant, Gravitational field, Gravitational lens, Gravitational time dilation, Gravity, Gravity of Earth, Gravity Probe B, Groove (engineering), Hamiltonian (quantum mechanics), Henri Poincaré, Higgs boson, Higgs mechanism, Hooke's law, House of Elzevir, If and only if, Imaginary number, Imperial units, Inclined plane, Inertia, Inertial frame of reference, International Bureau of Weights and Measures, International System of Quantities, International System of Units, Invariant mass, Isaac Newton, Johannes Kepler, John C. Baez, Kibble balance, Kilogram, Kinetic energy, Latent heat, Leaning Tower of Pisa, Loránd Eötvös, Lorentz covariance, Lorentz factor, Mass, Mass generation, Mass in special relativity, Mass versus weight, Mass–energy equivalence, Massive particle, Matter, Measure (mathematics), Melting point, Metrologia, Minkowski space, Modern physics, Momentum, Moon, Motion (physics), Natural units, Negative mass, Negative-index metamaterial, Net force, Newton (unit), Newton's law of universal gravitation, Newton's laws of motion, Nonlinear system, Nuclear fusion, Nucleon, Nuclide, Operationalization, Orbital period, Outline of physical science, Oxford University Press, Pair production, Parchment, Particle, Particle decay, Particle physics, Pedagogy, Percy Williams Bridgman, Perseus Books Group, Phantom energy, Phase transition, Philosophiæ Naturalis Principia Mathematica, Physical body, Physical property, Physics, Physics Today, Planck constant, Planck mass, Potential energy, Pound (force), Pound (mass), Prehistoric numerals, Proper acceleration, Proportionality (mathematics), Proposed redefinition of SI base units, Proton, Quantum, Quantum field theory, Radiation, Ratio, Real number, Resonance, Robert Hooke, Royal Society, Running Press, Rydberg constant, Scalar field, Schwarzschild radius, Scientific American, Semi-major and semi-minor axes, Sidereal year, Siliqua, Slug (unit), Solar mass, Solar System, Spacetime, Special relativity, Spectroscopy, Speed of light, Spring (device), Spring scale, Springer Nature, Square (algebra), Square root, Standard gravitational parameter, Standard Model, Stanford Encyclopedia of Philosophy, Stress–energy tensor, Stress–energy–momentum pseudotensor, Sun, Symmetry breaking, Tachyon, Tachyon condensation, Tachyonic field, Theoretical physics, Thermal energy, Thought experiment, Tonne, Torsion spring, Tycho Brahe, Unified atomic mass unit, University of Chicago Press, Vacuum, Velocity, Vincenzo Viviani, W. H. Freeman and Company, Wave function, Wavenumber, Weighing scale, Weight, Weightlessness. Expand index (173 more) » « Shrink index
The Latin phrases a priori ("from the earlier") and a posteriori ("from the latter") are philosophical terms of art popularized by Immanuel Kant's Critique of Pure Reason (first published in 1781, second edition in 1787), one of the most influential works in the history of philosophy.
In physics, acceleration is the rate of change of velocity of an object with respect to time.
Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics).
The American Journal of Physics is a monthly, peer-reviewed scientific journal published by the American Association of Physics Teachers and the American Institute of Physics.
The ancient Roman units of measurement were largely built on the Hellenic system, which in turn was built upon Egyptian and Mesopotamian influences.
In plane geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.
Annalen der Physik (English: Annals of Physics) is one of the oldest scientific journals on physics and has been published since 1799.
Apollo 15 was the ninth manned mission in the United States' Apollo program, the fourth to land on the Moon, and the eighth successful manned mission.
An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.
The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun.
An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.
In chemistry and physics, the Avogadro constant (named after scientist Amedeo Avogadro) is the number of constituent particles, usually atoms or molecules, that are contained in the amount of substance given by one mole.
A ball is a round object (usually spherical but sometimes ovoid) with various uses.
Binding energy (also called separation energy) is the minimum energy required to disassemble a system of particles into separate parts.
A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.
The Bohr radius (a0 or rBohr) is a physical constant, approximately equal to the most probable distance between the nucleus and the electron in a hydrogen atom in its ground state.
The caesium standard is a primary frequency standard in which electronic transitions between the two hyperfine ground states of caesium-133 atoms are used to control the output frequency.
Calculus (from Latin calculus, literally 'small pebble', used for counting and calculations, as on an abacus), is the mathematical study of continuous change, in the same way that geometry is the study of shape and algebra is the study of generalizations of arithmetic operations.
Calibration in measurement technology and metrology is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy.
Cambridge University Press (CUP) is the publishing business of the University of Cambridge.
In quantum mechanics (physics), the canonical commutation relation is the fundamental relation between canonical conjugate quantities (quantities which are related by definition such that one is the Fourier transform of another).
In physics, canonical quantization is a procedure for quantizing a classical theory, while attempting to preserve the formal structure, such as symmetries, of the classical theory, to the greatest extent possible.
The carat (ct) (not to be confused with the karat, sometimes spelled carat, a unit of purity of gold alloys), is a unit of mass equal to 200 mg (0.2 g; 0.007055 oz) and is used for measuring gemstones and pearls.
Carbon-12 is the more abundant of the two stable isotopes of carbon (Carbon-13 being the other), amounting to 98.93% of the element carbon; its abundance is due to the triple-alpha process by which it is created in stars.
Causality (also referred to as causation, or cause and effect) is what connects one process (the cause) with another process or state (the effect), where the first is partly responsible for the second, and the second is partly dependent on the first.
The Cavendish experiment, performed in 1797–1798 by British scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate values for the gravitational constant.
The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus, and others.
Ceratonia siliqua, known as the carob tree or carob bush, St John's-bread, locust bean (not African locust bean), or simply locust-tree, is a flowering evergreen tree or shrub in the pea family, Fabaceae.
The classical electron radius is a combination of fundamental physical quantities that define a length scale for problems involving electrons interacting with electromagnetic radiation.
Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars and galaxies.
A closed system is a physical system that does not allow certain types of transfers (such as transfer of mass and energy transfer) in or out of the system.
A complex number is a number that can be expressed in the form, where and are real numbers, and is a solution of the equation.
The Compton wavelength is a quantum mechanical property of a particle.
Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter.
In physics, the law of conservation of energy states that the total energy of an isolated system remains constant, it is said to be ''conserved'' over time.
Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors.
In arithmetic and algebra, the cube of a number is its third power: the result of the number multiplied by itself twice: It is also the number multiplied by its square: This is also the volume formula for a geometric cube with sides of length, giving rise to the name.
In mathematics, curvature is any of a number of loosely related concepts in different areas of geometry.
In physical cosmology and astronomy, dark energy is an unknown form of energy which is hypothesized to permeate all of space, tending to accelerate the expansion of the universe.
David Randolph Scott (born June 6, 1932) (Col, USAF, Ret.) is an American engineer, former NASA astronaut, retired U.S. Air Force officer and former test pilot.
De motu corporum in gyrum ("On the motion of bodies in an orbit") is the presumed title of a manuscript by Isaac Newton sent to Edmond Halley in November 1684.
Deuterium (or hydrogen-2, symbol or, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1).
The Dialogue Concerning the Two Chief World Systems (Dialogo sopra i due massimi sistemi del mondo) is a 1632 Italian-language book by Galileo Galilei comparing the Copernican system with the traditional Ptolemaic system.
In particle physics, the Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928.
A displacement is a vector whose length is the shortest distance from the initial to the final position of a point P. It quantifies both the distance and direction of an imaginary motion along a straight line from the initial position to the final position of the point.
Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward Cirker and his wife, Blanche.
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
Edmond (or Edmund) Halley, FRS (–) was an English astronomer, geophysicist, mathematician, meteorologist, and physicist.
In solid state physics, a particle's effective mass (often denoted) is the mass that it seems to have when responding to forces, or the mass that it seems to have when interacting with other identical particles in a thermal distribution.
In a real spring–mass system, the spring has a non-negligible mass m. Since not all of the spring's length moves at the same velocity v as the suspended mass M, its kinetic energy is not equal to \frac m v^2.
In linear algebra, an eigenvector or characteristic vector of a linear transformation is a non-zero vector that changes by only a scalar factor when that linear transformation is applied to it.
The Einstein field equations (EFE; also known as Einstein's equations) comprise the set of 10 equations in Albert Einstein's general theory of relativity that describe the fundamental interaction of gravitation as a result of spacetime being curved by mass and energy.
In mathematics, an ellipse is a curve in a plane surrounding two focal points such that the sum of the distances to the two focal points is constant for every point on the curve.
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
In physics, the energy–momentum relation, or relativistic dispersion relation, is the relativistic equation relating any object's rest (intrinsic) mass, total energy, and momentum: holds for a system, such as a particle or macroscopic body, having intrinsic rest mass, total energy, and a momentum of magnitude, where the constant is the speed of light, assuming the special relativity case of flat spacetime.
In the theory of general relativity, the equivalence principle is any of several related concepts dealing with the equivalence of gravitational and inertial mass, and to Albert Einstein's observation that the gravitational "force" as experienced locally while standing on a massive body (such as the Earth) is the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference.
Ernst Waldfried Josef Wenzel Mach (18 February 1838 – 19 February 1916) was an Austrian physicist and philosopher, noted for his contributions to physics such as study of shock waves.
In the calculus of variations, the Euler–Lagrange equation, Euler's equation, or Lagrange's equation (although the latter name is ambiguous—see disambiguation page), is a second-order partial differential equation whose solutions are the functions for which a given functional is stationary.
An explanandum (a Latin term) is a sentence describing a phenomenon that is to be explained, and the explanans are the sentences adduced as explanations of that phenomenon.
In metaphysics, extension signifies both 'stretching out' (Latin: extensio) as well as later 'taking up space', and most recently, spreading one's internal mental cognition into the external world.
Faster-than-light (also superluminal or FTL) communication and travel are the conjectural propagation of information or matter faster than the speed of light.
Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets.
A fictitious force (also called a pseudo force, d'Alembert force, or inertial force) is an apparent force that acts on all masses whose motion is described using a non-inertial frame of reference, such as a rotating reference frame.
In physics, a field is a physical quantity, represented by a number or tensor, that has a value for each point in space and time.
In physics, a force is any interaction that, when unopposed, will change the motion of an object.
In physics, a frame of reference (or reference frame) consists of an abstract coordinate system and the set of physical reference points that uniquely fix (locate and orient) the coordinate system and standardize measurements.
Frank Anthony Wilczek (born May 15, 1951) is an American theoretical physicist, mathematician and a Nobel laureate.
In Newtonian physics, free fall is any motion of a body where gravity is the only force acting upon it.
Frequency is the number of occurrences of a repeating event per unit of time.
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
The Galilean moons are the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto.
Galileo Galilei (15 February 1564Drake (1978, p. 1). The date of Galileo's birth is given according to the Julian calendar, which was then in force throughout Christendom. In 1582 it was replaced in Italy and several other Catholic countries with the Gregorian calendar. Unless otherwise indicated, dates in this article are given according to the Gregorian calendar. – 8 January 1642) was an Italian polymath.
In physics, Gauss's law for gravity, also known as Gauss's flux theorem for gravity, is a law of physics that is essentially equivalent to Newton's law of universal gravitation.
The General Conference on Weights and Measures (Conférence générale des poids et mesures – CGPM) is the supreme authority of the International Bureau of Weights and Measures (Bureau international des poids et mesures – BIPM), the inter-governmental organization established in 1875 under the terms of the Metre Convention (Convention du Mètre) through which Member States act together on matters related to measurement science and measurement standards.
General relativity (GR, also known as the general theory of relativity or GTR) is the geometric theory of gravitation published by Albert Einstein in 1915 and the current description of gravitation in modern physics.
Gerald Feinberg (27 May 1933, New York City – 21 April 1992, New York City) was a Columbia University physicist, futurist and populist author.
The gravitational constant (also known as the "universal gravitational constant", the "Newtonian constant of gravitation", or the "Cavendish gravitational constant"), denoted by the letter, is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's general theory of relativity.
In physics, a gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body.
A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer.
Gravitational time dilation is a form of time dilation, an actual difference of elapsed time between two events as measured by observers situated at varying distances from a gravitating mass.
Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward (or gravitate toward) one another.
The gravity of Earth, which is denoted by, refers to the acceleration that is imparted to objects due to the distribution of mass within Earth.
Gravity Probe B (GP-B) was a satellite-based mission which launched on 20 April 2004 on a Delta II rocket.
In manufacturing or mechanical engineering a groove is a long and narrow indentation built into a material, generally for the purpose of allowing another material or part to move within the groove and be guided by it.
In quantum mechanics, a Hamiltonian is an operator corresponding to the total energy of the system in most of the cases.
Jules Henri Poincaré (29 April 1854 – 17 July 1912) was a French mathematician, theoretical physicist, engineer, and philosopher of science.
The Higgs boson is an elementary particle in the Standard Model of particle physics.
In the Standard Model of particle physics, the Higgs mechanism is essential to explain the generation mechanism of the property "mass" for gauge bosons.
Hooke's law is a principle of physics that states that the force needed to extend or compress a spring by some distance scales linearly with respect to that distance.
Elzevir is the name of a celebrated family of Dutch booksellers, publishers, and printers of the 17th and early 18th centuries.
In logic and related fields such as mathematics and philosophy, if and only if (shortened iff) is a biconditional logical connective between statements.
An imaginary number is a complex number that can be written as a real number multiplied by the imaginary unit,j is usually used in Engineering contexts where i has other meanings (such as electrical current) which is defined by its property.
The system of imperial units or the imperial system (also known as British Imperial or Exchequer Standards of 1825) is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced.
An inclined plane, also known as a ramp, is a flat supporting surface tilted at an angle, with one end higher than the other, used as an aid for raising or lowering a load.
Inertia is the resistance of any physical object to any change in its position and state of motion.
An inertial frame of reference in classical physics and special relativity is a frame of reference in which a body with zero net force acting upon it is not accelerating; that is, such a body is at rest or it is moving at a constant speed in a straight line.
The International Bureau of Weights and Measures (Bureau international des poids et mesures) is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.
The International System of Quantities (ISQ) is a system based on seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
The invariant mass, rest mass, intrinsic mass, proper mass, or in the case of bound systems simply mass, is the portion of the total mass of an object or system of objects that is independent of the overall motion of the system.
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, astronomer, theologian, author and physicist (described in his own day as a "natural philosopher") who is widely recognised as one of the most influential scientists of all time, and a key figure in the scientific revolution.
Johannes Kepler (December 27, 1571 – November 15, 1630) was a German mathematician, astronomer, and astrologer.
John Carlos Baez (born June 12, 1961) is an American mathematical physicist and a professor of mathematics at the University of California, Riverside (UCR) in Riverside, California.
A Kibble balance (previously watt balance) is an electromechanical weight measuring instrument that measures the weight of a test object very precisely by the strength of an electric current and a voltage.
The kilogram or kilogramme (symbol: kg) is the base unit of mass in the International System of Units (SI), and is defined as being equal to the mass of the International Prototype of the Kilogram (IPK, also known as "Le Grand K" or "Big K"), a cylinder of platinum-iridium alloy stored by the International Bureau of Weights and Measures at Saint-Cloud, France.
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
Latent heat is thermal energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process — usually a first-order phase transition.
The Leaning Tower of Pisa (Torre pendente di Pisa) or simply the Tower of Pisa (Torre di Pisa) is the campanile, or freestanding bell tower, of the cathedral of the Italian city of Pisa, known worldwide for its unintended tilt.
Baron Loránd Eötvös de Vásárosnamény (vásárosnaményi báró Eötvös Loránd Ágoston or Loránd Eötvös,; 27 July 1848 – 8 April 1919), more commonly called Baron Roland von Eötvös in English literature, was an Austro-Hungarian physicist of ethnic Hungarian origin.
In relativistic physics, Lorentz symmetry, named for Hendrik Lorentz, is an equivalence of observation or observational symmetry due to special relativity implying that the laws of physics stay the same for all observers that are moving with respect to one another within an inertial frame.
The Lorentz factor or Lorentz term is the factor by which time, length, and relativistic mass change for an object while that object is moving.
Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.
In theoretical physics, a mass generation mechanism is a theory that describes the origin of mass from the most fundamental laws of physics.
Mass in special relativity incorporates the general understandings from the laws of motion of special relativity along with its concept of mass–energy equivalence.
In common usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities.
In physics, mass–energy equivalence states that anything having mass has an equivalent amount of energy and vice versa, with these fundamental quantities directly relating to one another by Albert Einstein's famous formula: E.
The term massive particle refers to particles which have real non-zero rest mass.
In the classical physics observed in everyday life, matter is any substance that has mass and takes up space by having volume.
In mathematical analysis, a measure on a set is a systematic way to assign a number to each suitable subset of that set, intuitively interpreted as its size.
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid at atmospheric pressure.
Metrologia is an international journal dealing with the scientific aspects of metrology.
In mathematical physics, Minkowski space (or Minkowski spacetime) is a combining of three-dimensional Euclidean space and time into a four-dimensional manifold where the spacetime interval between any two events is independent of the inertial frame of reference in which they are recorded.
Modern physics is the post-Newtonian conception of physics.
In Newtonian mechanics, linear momentum, translational momentum, or simply momentum (pl. momenta) is the product of the mass and velocity of an object.
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.
In physics, motion is a change in position of an object over time.
In physics, natural units are physical units of measurement based only on universal physical constants.
In theoretical physics, negative mass is matter whose mass is of opposite sign to the mass of normal matter, e.g. −1 kg.
Negative-index metamaterial or negative-index material (NIM) is a metamaterial whose refractive index for an electromagnetic wave has a negative value over some frequency range.
possible to determine the torque associated with the point of application of a net force so that it maintains the movement of jets of the object under theassociated torque, the net force, becomes the resultant force and has the same effect on the rotational mott as all actual forces taken together.
The newton (symbol: N) is the International System of Units (SI) derived unit of force.
Newton's law of universal gravitation states that a particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Newton's laws of motion are three physical laws that, together, laid the foundation for classical mechanics.
In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input.
In nuclear physics, nuclear fusion is a reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles (neutrons or protons).
In chemistry and physics, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus.
A nuclide (from nucleus, also known as nuclear species) is an atomic species characterized by the specific constitution of its nucleus, i.e., by its number of protons Z, its number of neutrons N, and its nuclear energy state.
In research design, especially in psychology, social sciences, life sciences, and physics, operationalization is a process of defining the measurement of a phenomenon that is not directly measurable, though its existence is indicated by other phenomena.
The orbital period is the time a given astronomical object takes to complete one orbit around another object, and applies in astronomy usually to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars.
Physical science is a branch of natural science that studies non-living systems, in contrast to life science.
Oxford University Press (OUP) is the largest university press in the world, and the second oldest after Cambridge University Press.
Pair production is the creation of an elementary particle and its antiparticle from a neutral boson.
Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats.
In the physical sciences, a particle (or corpuscule in older texts) is a small localized object to which can be ascribed several physical or chemical properties such as volume, density or mass.
Particle decay is the spontaneous process of one unstable subatomic particle transforming into multiple other particles.
Particle physics (also high energy physics) is the branch of physics that studies the nature of the particles that constitute matter and radiation.
Pedagogy is the discipline that deals with the theory and practice of teaching and how these influence student learning.
Percy Williams Bridgman (21 April 1882 – 20 August 1961) was an American physicist who won the 1946 Nobel Prize in Physics for his work on the physics of high pressures.
Perseus Books Group was an American publishing company founded in 1996 by investor Frank Pearl.
Phantom energy is a hypothetical form of dark energy satisfying the equation of state with w. It possesses negative kinetic energy, and predicts expansion of the universe in excess of that predicted by a cosmological constant, which leads to a Big Rip.
The term phase transition (or phase change) is most commonly used to describe transitions between solid, liquid and gaseous states of matter, and, in rare cases, plasma.
Philosophiæ Naturalis Principia Mathematica (Latin for Mathematical Principles of Natural Philosophy), often referred to as simply the Principia, is a work in three books by Isaac Newton, in Latin, first published 5 July 1687.
In physics, a physical body or physical object (or simply a body or object) is an identifiable collection of matter, which may be constrained by an identifiable boundary, and may move as a unit by translation or rotation, in 3-dimensional space.
A physical property is any property that is measurable, whose value describes a state of a physical system.
Physics (from knowledge of nature, from φύσις phýsis "nature") is the natural science that studies matterAt the start of The Feynman Lectures on Physics, Richard Feynman offers the atomic hypothesis as the single most prolific scientific concept: "If, in some cataclysm, all scientific knowledge were to be destroyed one sentence what statement would contain the most information in the fewest words? I believe it is that all things are made up of atoms – little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another..." and its motion and behavior through space and time and that studies the related entities of energy and force."Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." 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 most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of the human intellect in its quest to understand our world and ourselves."Physics is an experimental science. Physicists observe the phenomena of nature and try to find patterns that relate these phenomena.""Physics is the study of your world and the world and universe around you." Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over the last 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 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.
Physics Today is the membership magazine of the American Institute of Physics that was established in 1948.
The Planck constant (denoted, also called Planck's constant) is a physical constant that is the quantum of action, central in quantum mechanics.
In physics, the Planck mass, denoted by mP, is the unit of mass in the system of natural units known as Planck units.
In physics, potential energy is the energy possessed by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors.
The pound-force (symbol: lbf, sometimes lbf) is a unit of force used in some systems of measurement including English Engineering units and the British Gravitational System.
The pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement.
Counting in prehistory was first assisted by using body parts, primarily the fingers.
In relativity theory, proper acceleration is the physical acceleration (i.e., measurable acceleration as by an accelerometer) experienced by an object.
In mathematics, two variables are proportional if there is always a constant ratio between them.
The International Committee for Weights and Measures (CIPM) has proposed revised definitions of the SI base units, for consideration at the 26th General Conference on Weights and Measures (CGPM).
In physics, a quantum (plural: quanta) is the minimum amount of any physical entity (physical property) involved in an interaction.
In theoretical physics, quantum field theory (QFT) is the theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics.
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium.
In mathematics, a ratio is a relationship between two numbers indicating how many times the first number contains the second.
In mathematics, a real number is a value of a continuous quantity that can represent a distance along a line.
In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies.
Robert Hooke FRS (– 3 March 1703) was an English natural philosopher, architect and polymath.
The President, Council and Fellows of the Royal Society of London for Improving Natural Knowledge, commonly known as the Royal Society, is a learned society.
Running Press is an American publishing company and member of the Perseus Books Group.
The Rydberg constant, symbol R∞ for heavy atoms or RH for hydrogen, named after the Swedish physicist Johannes Rydberg, is a physical constant relating to atomic spectra, in the science of spectroscopy.
In mathematics and physics, a scalar field associates a scalar value to every point in a space – possibly physical space.
The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is a physical parameter that shows up in the Schwarzschild solution to Einstein's field equations, corresponding to the radius defining the event horizon of a Schwarzschild black hole.
Scientific American (informally abbreviated SciAm) is an American popular science magazine.
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the widest points of the perimeter.
A sidereal year (from Latin sidus "asterism, star") is the time taken by the Earth to orbit the Sun once with respect to the fixed stars.
The siliqua is the modern name given (without any ancient evidence to confirm the designation) to small, thin, Roman silver coins produced in the 4th century A.D. and later.
The slug is a derived unit of mass in the weight-based system of measures, most notably within the British Imperial measurement system and in the United States customary measures system.
The solar mass is a standard unit of mass in astronomy, equal to approximately.
The Solar SystemCapitalization of the name varies.
In physics, spacetime is any mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum.
In physics, special relativity (SR, also known as the special theory of relativity or STR) is the generally accepted and experimentally well-confirmed physical theory regarding the relationship between space and time.
Spectroscopy is the study of the interaction between matter and electromagnetic radiation.
The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.
A spring is an elastic object that stores mechanical energy.
A spring scale or spring balance or newton meter is a type of weighing scale.
Springer Nature is an academic publishing company created by the May 2015 merger of Springer Science+Business Media and Holtzbrinck Publishing Group's Nature Publishing Group, Palgrave Macmillan, and Macmillan Education.
In mathematics, a square is the result of multiplying a number by itself.
In mathematics, a square root of a number a is a number y such that; in other words, a number y whose square (the result of multiplying the number by itself, or) is a. For example, 4 and −4 are square roots of 16 because.
In celestial mechanics, the standard gravitational parameter μ of a celestial body is the product of the gravitational constant G and the mass M of the body.
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (the electromagnetic, weak, and strong interactions, and not including the gravitational force) in the universe, as well as classifying all known elementary particles.
The Stanford Encyclopedia of Philosophy (SEP) combines an online encyclopedia of philosophy with peer-reviewed publication of original papers in philosophy, freely accessible to Internet users.
The stress–energy tensor (sometimes stress–energy–momentum tensor or energy–momentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the stress tensor of Newtonian physics.
In the theory of general relativity, a stress–energy–momentum pseudotensor, such as the Landau–Lifshitz pseudotensor, is an extension of the non-gravitational stress–energy tensor which incorporates the energy–momentum of gravity.
The Sun is the star at the center of the Solar System.
In physics, symmetry breaking is a phenomenon in which (infinitesimally) small fluctuations acting on a system crossing a critical point decide the system's fate, by determining which branch of a bifurcation is taken.
A tachyon or tachyonic particle is a hypothetical particle that always moves faster than light.
Tachyon condensation is a process in particle physics in which a system can lower its energy by spontaneously producing particles.
A tachyonic field, or simply tachyon, is a field with an imaginary mass.
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena.
Thermal energy is a term used loosely as a synonym for more rigorously-defined thermodynamic quantities such as the internal energy of a system; heat or sensible heat, which are defined as types of transfer of energy (as is work); or for the characteristic energy of a degree of freedom in a thermal system kT, where T is temperature and k is the Boltzmann constant.
A thought experiment (Gedankenexperiment, Gedanken-Experiment or Gedankenerfahrung) considers some hypothesis, theory, or principle for the purpose of thinking through its consequences.
The tonne (Non-SI unit, symbol: t), commonly referred to as the metric ton in the United States, is a non-SI metric unit of mass equal to 1,000 kilograms;.
A torsion spring is a spring that works by torsion or twisting; that is, a flexible elastic object that stores mechanical energy when it is twisted.
Tycho Brahe (born Tyge Ottesen Brahe;. He adopted the Latinized form "Tycho Brahe" (sometimes written Tÿcho) at around age fifteen. The name Tycho comes from Tyche (Τύχη, meaning "luck" in Greek, Roman equivalent: Fortuna), a tutelary deity of fortune and prosperity of ancient Greek city cults. He is now generally referred to as "Tycho," as was common in Scandinavia in his time, rather than by his surname "Brahe" (a spurious appellative form of his name, Tycho de Brahe, only appears much later). 14 December 154624 October 1601) was a Danish nobleman, astronomer, and writer known for his accurate and comprehensive astronomical and planetary observations.
The unified atomic mass unit or dalton (symbol: u, or Da) is a standard unit of mass that quantifies mass on an atomic or molecular scale (atomic mass).
The University of Chicago Press is the largest and one of the oldest university presses in the United States.
Vacuum is space devoid of matter.
The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time.
Vincenzo Viviani (April 5, 1622 – September 22, 1703) was an Italian mathematician and scientist.
A wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system.
In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance.
Weighing scales (or weigh scales or scales) are devices to measure weight.
In science and engineering, the weight of an object is related to the amount of force acting on the object, either due to gravity or to a reaction force that holds it in place.
Weightlessness, or an absence of weight, is an absence of stress and strain resulting from externally applied mechanical contact-forces, typically normal forces (from floors, seats, beds, scales, etc.). Counterintuitively, a uniform gravitational field does not by itself cause stress or strain, and a body in free fall in such an environment experiences no g-force acceleration and feels weightless.
Active gravitational mass, Gravitating mass, Gravitational Mass, Gravitational mass, Gravitic mass, Imaginary mass, Inertial Mass, Inertial mass, Mass (physics), Mass Properties, Mass properties, Massed, Maſs, Metric mass, Metric unit of weight, Metric weight, Passive gravitational mass, Unit of mass, Units of mass, Weight (mass).