Classical physics
Classical physics refers to theories of physics that predate modern, more complete, or more widely applicable theories. If a currently accepted theory is considered to be "modern," and its introduction represented a major paradigm shift, then the previous theories, or new theories based on the older paradigm, will often be referred to as belonging to the realm of "classical" physics.[citation needed] As such, the definition of a classical theory depends on context. Classical physical concepts are often used when modern theories are unnecessarily complex for a particular situation. Most usually classical physics refers to pre-1900 physics, while modern physics refers to post-1900 physics which incorporates elements of quantum mechanics and relativity.[1] Contents 1 Overview 2 Comparison with modern physics 3 Computer modeling and manual calculation, modern and classic comparison 4 References 5 See also Overview[edit] Part of a series of articles about Classical mechanics F → = m a → displaystyle vec F =m vec a Second law of motion History Timeline Branches Applied Celestial Continuum Dynamics Kinematics Kinetics Statics Statistical Fundamentals Acceleration Angular momentum Couple D'Alembert's principle Energy kinetic potential Force Frame of reference Inertial frame of reference Impulse Inertia / Moment of inertia Mass Mechanical power Mechanical work Moment Momentum Space Speed Time Torque Velocity Virtual work Formulations Newton's laws of motion Analytical mechanics Lagrangian mechanics Hamiltonian mechanics Routhian mechanics Hamilton–Jacobi equation Appell's equation of motion Udwadia–Kalaba equation Koopman–von Neumann mechanics Core topics Damping (ratio) Displacement Equations of motion Euler's laws of motion Fictitious force Friction Harmonic oscillator Inertial / Non-inertial reference frame
Motion (linear) Newton's law of universal gravitation Newton's laws of motion Relative velocity Rigid body dynamics Euler's equations Simple harmonic motion Vibration Rotation Circular motion Rotating reference frame Centripetal force Centrifugal force reactive Coriolis force Pendulum Tangential speed Rotational speed Angular acceleration / displacement / frequency / velocity Scientists Galileo Huygens Newton Kepler Horrocks Halley Euler d'Alembert Clairaut Lagrange Laplace Hamilton Poisson Daniel Bernoulli Johann Bernoulli Cauchy v t e Classical theory has at least two distinct meanings in physics. In the context of quantum mechanics, classical theory refers to theories of physics that do not use the quantisation paradigm, which includes classical mechanics and relativity.[2] Likewise, classical field theories, such as general relativity and classical electromagnetism, are those that do not use quantum mechanics.[3] In the context of general and special relativity, classical theories are those that obey Galilean relativity.[4] Depending on point of view, among the branches of theory sometimes included in classical physics are variably: Classical mechanics Newton's laws of motion Classical Lagrangian and Hamiltonian formalisms
Comparison with modern physics[edit]
In contrast to classical physics, "modern physics" is a slightly
looser term which may refer to just quantum physics or to 20th and
21st century physics in general.
A computer model would use quantum theory and relativistic theory only Today a computer performs millions of arithmetic operations in seconds
to solve a classical differential equation, while Newton (one of the
fathers of the differential calculus) would take hours to solve the
same equation by manual calculation, even if he were the discoverer of
that particular equation.
Computer modeling is essential for quantum and relativistic physics.
Classic physics is considered the limit of quantum mechanics for large
number of particles. On the other hand, classic mechanics is derived
from relativistic mechanics. For example, in many formulations from
special relativity, a correction factor (v/c)2 appears, where v is the
velocity of the object and c is the speed of light. For velocities
much smaller than that of light, one can neglect the terms with c2 and
higher that appear. These formulas then reduce to the standard
definitions of Newtonian kinetic energy and momentum. This is as it
should be, for special relativity must agree with Newtonian mechanics
at low velocities. Computer modeling has to be as real as possible.
^ Weidner and Sells, Elementary Modern
See also[edit]
Glossary of classical physics Semiclassical physics v t e Branches of physics Divisions Applied Experimental Theoretical Energy Motion Thermodynamics Mechanics Classical Ballistics Lagrangian Hamiltonian Continuum Celestial Statistical Solid Fluid Quantum Waves Fields Gravitation Electromagnetism Optics Geometrical Physical Nonlinear Quantum Quantum field theory Relativity Special General By speciality Accelerator Acoustics Astrophysics Nuclear Stellar Heliophysics Solar Space Astroparticle Atomic–molecular–optical (AMO) Communication Computational Condensed matter Mesoscopic Solid-state Soft Digital Engineering Material Mathematical Molecular Nuclear Particle Phenomenology Plasma Polymer Statistical
Biophysics Virophysics Biomechanics Medical physics Cardiophysics Health physics Laser medicine Medical imaging Nuclear medicine Neurophysics Psychophysics
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