# Index of physics articles (O)

The index of physics articles is split into multiple pages due to its size.
To navigate by individual letter use the table of contents below.

## Index of physics articles

* 0–9
* A
* B
* C
* D
* E
* F
* G
* H
* I
* J
* K
* L
* M
* N
* O
* P
* Q
* R
* S
* T
* U
* V
* W
* X
* Y
* Z

## O

* OECC
* OPAL detector
* OPERA experiment
* OSA Fellow
* OSO 3
* OSO 7
* OVRO 40 meter Telescope
* OZI Rule
* Oak Ridge National Laboratory
* Oberth effect
* Objective (optics)
* Oblique correction
* Oblique shock
* Oblique wing
* Observable
* Observable universe
* Observational cosmology
* Observer (general relativity)
* Observer (quantum physics)
* Observer (special relativity)
* Observer effect (physics)
* Ocean gyre
* Ocean thermal energy conversion
* Oceanography
* Ocellus Lucanus
* Octavio Novaro
* Odd molecule
* Odd sympathy
* Oersted
* Oersted Medal
* Ofer Biham
* Ofer Lahav
* Off-axis optical system
* Oganesson
* Ogden Rood
* Ohm
* Ohm's law
* Ohmic contact
* Ohnesorge number
* Oil drop experiment
* Okorokov effect
* Ola Hunderi
* Olaf Dreyer
* Olami–Feder–Christensen model
* Olav Holt
* Olbers' paradox
* Old quantum theory
* Oldroyd-B model
* Ole Jacob Broch
* Oleg D. Jefimenko
* Oleg Firsov
* Oleg Losev
* Oleg Sushkov
* Olexander Smakula
* Olga Kennard
* Olinto De Pretto
* Oliver E. Buckley Condensed Matter Prize
* Oliver Heaviside
* Oliver Lodge
* Olli Lounasmaa
* Olympia Academy
* Omega baryon
* Omega meson
* On-Line Isotope Mass Separator
* On Physical Lines of Force
* On shell and off shell
* On the Shoulders of Giants (book)
* On the movement of small particles suspended in a stationary liquid demanded by the molecular-kinetic theory of heat
* One-electron universe
* One-loop Feynman diagram
* One-way speed of light
* Onium
* Online refuelling
* Onsager reciprocal relations
* Onset of deconfinement
* Oops-Leon
* Oort constants
* Opacity (optics)
* Opalescence
* Open-pool Australian lightwater reactor
* OpenFOAM
* OpenScientist
* Open Source Physics
* Open quantum system
* Open shell
* Operator (physics)
* Operator product expansion
* Oppenheimer–Phillips process
* Optic crystals
* Optical Fiber Technology
* Optical Gravitational Lensing Experiment
* Optical Physics
* Optical Review
* Optical Society
* Optical Society of Japan
* Optical aberration
* Optical amplifier
* Optical autocorrelation
* Optical axis
* Optical black hole
* Optical brightener
* Optical cavity
* Optical chopper
* Optical circulator
* Optical coating
* Optical coherence tomography
* Optical communication
* Optical conductivity
* Optical contact bonding
* Optical depth
* Optical downconverter
* Optical equivalence theorem
* Optical feedback
* Optical field
* Optical flat
* Optical force
* Optical format
* Optical lattice
* Optical lens design
* Optical levitation
* Optical medium
* Optical metamaterial
* Optical microsphere
* Optical modulator
* Optical modulators using semiconductor nano-structures
* Optical neural network
* Optical parametric amplifier
* Optical parametric oscillator
* Optical path
* Optical path length
* Optical phenomenon
* Optical phonon
* Optical physics
* Optical power
* Optical properties of carbon nanotubes
* Optical pulsar
* Optical pumping
* Optical reader
* Optical rectification
* Optical ring resonators
* Optical rotatory dispersion
* Optical scalars
* Optical science
* Optical sciences
* Optical sectioning
* Optical sine theorem
* Optical superresolution
* Optical switch
* Optical telescope
* Optical theorem
* Optical train
* Optical transition radiation
* Optical tweezers
* Optical window
* Optically stimulated luminescence
* Opticks
* Optics
* Optics & Photonics News
* Optics (physics)
* Optics Classification and Indexing Scheme
* Optics Communications
* Optics Express
* Optics Letters
* Optics and Photonics News
* Optics and Spectroscopy
* Optik (journal)
* Optoelectric nuclear battery
* Optoelectronics
* Optofluidics
* Optomechanics
* Orb (optics)
* Orbit
* Orbit (dynamics)
* Orbit equation
* Orbit phasing
* Orbital angular momentum multiplexing
* Orbital angular momentum of light
* Orbital decay
* Orbital eccentricity
* Orbital elements
* Orbital inclination
* Orbital integral
* Orbital mechanics
* Orbital motion
* Orbital motion (quantum)
* Orbital node
* Orbital period
* Orbital plane (astronomy)
* Orbital state vectors
* Orbiting body
* Orbitrap
* Ordal Demokan
* Order and disorder (physics)
* Order operator
* Ordered exponential
* Orders of magnitude (charge)
* Orders of magnitude (density)
* Orders of magnitude (energy)
* Orders of magnitude (entropy)
* Orders of magnitude (force)
* Orders of magnitude (length)
* Orders of magnitude (luminous flux)
* Orders of magnitude (magnetic field)
* Orders of magnitude (mass)
* Orders of magnitude (power)
* Orders of magnitude (pressure)
* Orders of magnitude (radiation)
* Orders of magnitude (resistance)
* Orders of magnitude (specific energy density)
* Orders of magnitude (specific heat capacity)
* Orders of magnitude (temperature)
* Orders of magnitude (voltage)
* Orest Khvolson
* Oreste Piccioni
* Orfeu Bertolami
* Organic field-effect transistor
* Organic nonlinear optical materials
* Organic photorefractive materials
* Organic superconductor
* Orientifold
* Orifice plate
* Origin of avian flight
* Ornstein–Zernike equation
* Orr–Sommerfeld equation
* Orso Mario Corbino
* OrthoCAD Network Research Cell
* Orthobaric density
* Orthometric height
* Orthomode transducer
* Orthorhombic crystal system
* Orthovoltage X-rays
* Osborne Reynolds
* Oscar Lanford
* Oscar Sala
* Oscar W. Greenberg
* Oscillation
* Oscillator linewidth
* Oscillator phase noise
* Oscillatory universe
* Oscillon
* Osculating orbit
* Oseen's approximation
* Oseen equations
* Oskar Heil
* Oskar Klein
* Oskar Klein Memorial Lecture
* Oskar Ritter
* Osmosis
* Osoaviakhim-1
* Ostro
* Ostwald ripening
* Ostwald–Freundlich equation
* Otoacoustic emission
* Ottaviano-Fabrizio Mossotti
* Otto Bastiansen
* Otto Hahn
* Otto Haxel
* Otto Klemperer (physicist)
* Otto Kratky
* Otto Laporte
* Otto Laporte Award
* Otto Lehmann (physicist)
* Otto Lummer
* Otto Robert Frisch
* Otto Scherzer
* Otto Schmitt
* Otto Stern
* Otto Wiener (physicist)
* Otto cycle
* Otto von Guericke
* Otto Øgrim
* Our Mr. Sun
* Outdoor–indoor transmission class
* Outflow channels
* Outhouse (unit)
* Outline of applied physics
* Outline of astronomy
* Outline of geophysics
* Outline of physical science
* Outline of physics
* Ouzo effect
* Over/under cable coiling
* Overflow (software)
* Overlap matrix
* Overtone
* Owen Chamberlain
* Owen Willans Richardson
* Oxford Calculators
* Oxford Electric Bell
* Oxide thin-film transistor
* Oxsensis
* Oxygen-burning process
* Oxygen permeability
* Oyo Buturi
* Øyvind Grøn
* Ozsváth–Schücking metric