In physics, two wave sources are coherent if their frequency and waveform are identical. Coherence is an ideal property of waves that enables stationary (i.e., temporally or spatially constant) interference. It contains several distinct concepts, which are limiting cases that never quite occur in reality but allow an understanding of the physics of waves, and has become a very important concept in quantum physics. More generally, coherence describes all properties of the correlation between physical quantities of a single wave, or between several waves or wave packets. Interference is the addition, in the mathematical sense, of wave functions. A single wave can interfere with itself, but this is still an addition of two waves (see Young's slits experiment). Constructive or destructive interference are limit cases, and two waves always interfere, even if the result of the addition is complicated or not remarkable. When interfering, two waves can add together to create a wave of greater amplitude than either one (constructive interference) or subtract from each other to create a wave of lesser amplitude than either one (destructive interference), depending on their relative phase. Two waves are said to be coherent if they have a constant relative phase. The amount of coherence can readily be measured by the interference visibility, which looks at the size of the interference fringes relative to the input waves (as the phase offset is varied); a precise mathematical definition of the degree of coherence is given by means of correlation functions. Spatial coherence describes the correlation (or predictable relationship) between waves at different points in space, either lateral or longitudinal. Temporal coherence describes the correlation between waves observed at different moments in time. Both are observed in the Michelson–Morley experiment and Young's interference experiment. Once the fringes are obtained in the Michelson interferometer, when one of the mirrors is moved away gradually from the beam-splitter, the time for the beam to travel increases and the fringes become dull and finally disappear, showing temporal coherence. Similarly, in a double-slit experiment, if the space between the two slits is increased, the coherence dies gradually and finally the fringes disappear, showing spatial coherence. In both cases, the fringe amplitude slowly disappears, as the path difference increases past the coherence length. (Wikipedia).
http://www.teachastronomy.com/ Cosmology is the study of the universe, its history, and everything in it. It comes from the Greek root of the word cosmos for order and harmony which reflected the Greek belief that the universe was a harmonious entity where everything worked in concert to
From playlist 22. The Big Bang, Inflation, and General Cosmology
Covariance (1 of 17) What is Covariance? in Relation to Variance and Correlation
Visit http://ilectureonline.com for more math and science lectures! To donate:a http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 We will learn the difference between the variance and the covariance. A variance (s^2) is a measure of how spread out the numbers of
From playlist COVARIANCE AND VARIANCE
What Are Covalent Bonds | Properties of Matter | Chemistry | FuseSchool
What Are Covalent Bonds | Properties of Matter | Chemistry | FuseSchool Learn the basics about covalent bonds, when learning about properties of matter. When similar atoms react, like non-metals combining with other non-metals, they share electrons. This is covalent bonding. Non-metals
From playlist CHEMISTRY
What is a Coordinate Covalent Bond?
This chemistry video tutorial provides a basic introduction into coordinate covalent bond. Line any covalent bond, electrons are shared. However, in a coordinate covalent bond, one atom donates both electrons that contribute to the formation of the bond. A lewis acid lewis base reaction
From playlist New AP & General Chemistry Video Playlist
This educational video delves into how you quantify a linear statistical relationship between two variables using covariance! #statistics #probability #SoME2 This video gives a visual and intuitive introduction to the covariance, one of the ways we measure a linear statistical relation
From playlist Summer of Math Exposition 2 videos
From playlist Courses and Series
Estimation of Coherence and Cross Spectra
http://AllSignalProcessing.com for more great signal-processing content: ad-free videos, concept/screenshot files, quizzes, MATLAB and data files. Averaging approaches for estimating coherence and cross spectra, analogous to Welch's averaged periodogram estimator of the power spectrum.
From playlist Estimation and Detection Theory
Trigonometry 7 The Cosine of the Sum and Difference of Two Angles
A geometric proof of the cosine of the sum and difference of two angles identity.
From playlist Trigonometry
Physics 35 Coulomb's Law (1 of 8)
Visit http://ilectureonline.com for more math and science lectures! In this three part lecture, I will introduce you to Coulomb's law, which describes the electric force between two charged particles or objects. It's format is similar to Newton's law of gravity, though Coulomb's constant
From playlist MOST POPULAR VIDEOS
Giulio Chiribella: New applications of coherent states in quantum information theory
Abstract: Coherent states have been long known for their applications in quantum optics and atomic physics. In recent years, a number of new applications have emerged in the area of quantum information theory. In this talk I will highlight two such applications. The first is the comparison
From playlist Mathematical Physics
Quantum-to-Classical Transition of the Primordial Perturbations by Andreas Albrecht
PROGRAM: PHYSICS OF THE EARLY UNIVERSE - AN ONLINE PRECURSOR ORGANIZERS: Robert Brandenberger (McGill University, Montreal, Canada), Jerome Martin (Institut d'Astrophysique de Paris, France), Subodh Patil (Instituut-Lorentz for Theoretical Physics, Leiden, Netherlands) and L Sriramkumar (
From playlist Physics of The Early Universe - An Online Precursor
Extended kq-representation and bi-coherent states by Fabio Bagarello
DATE: 04 June 2018 to 13 June 2018 VENUE:Ramanujan Lecture Hall, ICTS Bangalore Non-Hermitian Physics-"Pseudo-Hermitian Hamiltonians in Quantum Physics (PHHQP) XVIII" is the 18th meeting in the series that is being held over the years in Quantum Physics. The scope of the program on Non-H
From playlist Non-Hermitian Physics - PHHQP XVIII
UXSS 2016 - Dr. Agostino Marinelli
Dr. Agostino Marinelli from SLAC National Accelerator Laboratory presents "Introduction to the Physics of Free Electron Lasers" on June 13, 2016 at the Ultrafast X-ray Summer Seminar, hosted by Stanford PULSE Institute at SLAC National Accelerator Laboratory.
From playlist Stanford PULSE Institute
Long-Range Coupling of Spins with Microwave-Frequency Photons by Jason Petta
PROGRAM NON-HERMITIAN PHYSICS (ONLINE) ORGANIZERS: Manas Kulkarni (ICTS, India) and Bhabani Prasad Mandal (Banaras Hindu University, India) DATE: 22 March 2021 to 26 March 2021 VENUE: Online Non-Hermitian Systems / Open Quantum Systems are not only of fundamental interest in physics a
From playlist Non-Hermitian Physics (ONLINE)
21. Two-photon Excitation II and Coherence I
MIT 8.421 Atomic and Optical Physics I, Spring 2014 View the complete course: http://ocw.mit.edu/8-421S14 Instructor: Wolfgang Ketterle In this lecture, the professor explained some cases of two-photon processes and started to discuss about coherence. License: Creative Commons BY-NC-SA M
From playlist MIT 8.421 Atomic and Optical Physics I, Spring 2014
James Stasheff (8/31/22): Homotopy coherence - theme and variations
This survey will be semi-historical and idiosyncratic with the topics covered determined by the knowledge and taste of the authors, but we hope it will provide some links that may not be common knowledge between the various aspects of the theory of homotopy coherence and, in particular, to
From playlist AATRN 2022
Turbulent origin of Magnetic fields in Galaxies and clusters by Kandaswamy Subramanian
Program Cosmology - The Next Decade ORGANIZERS : Rishi Khatri, Subha Majumdar and Aseem Paranjape DATE : 03 January 2019 to 25 January 2019 VENUE : Ramanujan Lecture Hall, ICTS Bangalore The great observational progress in cosmology has revealed some very intriguing puzzles, the most i
From playlist Cosmology - The Next Decade
EEVblog 1443 - They Don't Teach This in School! (Coherence)
A follow-up video to the Electrodynamic Shaker, showing you the critical importance of Coherence measurement. Something you'll only get taught in the school of hard knocks! Using the Ling Electrodynamic shaker, a measurement accelerometer, and a Dynamic Signal Analyser to set up a vibratio
From playlist Vibration Measurement
Covariance Definition and Example
What is covariance? How do I find it? Step by step example of a solved covariance problem for a sample, along with an explanation of what the results mean and how it compares to correlation. 00:00 Overview 03:01 Positive, Negative, Zero Correlation 03:19 Covariance for a Sample Example
From playlist Correlation
Modulating Statistics of Light by Zubizarreta Casalengua
PROGRAM NON-HERMITIAN PHYSICS (ONLINE) ORGANIZERS: Manas Kulkarni (ICTS, India) and Bhabani Prasad Mandal (Banaras Hindu University, India) DATE: 22 March 2021 to 26 March 2021 VENUE: Online Non-Hermitian Systems / Open Quantum Systems are not only of fundamental interest in physics a
From playlist Non-Hermitian Physics (ONLINE)