Redshift Academy

Wolfram Alpha:         

  Search by keyword:  

Astronomy

-
Astronomical Distance Units .
-
Celestial Coordinates .
-
Celestial Navigation .
-
Location of North and South Celestial Poles .

Chemistry

-
Avogadro's Number
-
Balancing Chemical Equations
-
Stochiometry
-
The Periodic Table .

Classical Physics

-
Archimedes Principle
-
Bernoulli Principle
-
Blackbody (Cavity) Radiation and Planck's Hypothesis
-
Center of Mass Frame
-
Comparison Between Gravitation and Electrostatics
-
Compton Effect .
-
Coriolis Effect
-
Cyclotron Resonance
-
Dispersion
-
Doppler Effect
-
Double Slit Experiment
-
Elastic and Inelastic Collisions .
-
Electric Fields
-
Error Analysis
-
Fick's Law
-
Fluid Pressure
-
Gauss's Law of Universal Gravity .
-
Gravity - Force and Acceleration
-
Hooke's law
-
Ideal and Non-Ideal Gas Laws (van der Waal)
-
Impulse Force
-
Inclined Plane
-
Inertia
-
Kepler's Laws
-
Kinematics
-
Kinetic Theory of Gases .
-
Kirchoff's Laws
-
Laplace's and Poisson's Equations
-
Lorentz Force Law
-
Maxwell's Equations
-
Moments and Torque
-
Nuclear Spin
-
One Dimensional Wave Equation .
-
Pascal's Principle
-
Phase and Group Velocity
-
Planck Radiation Law .
-
Poiseuille's Law
-
Radioactive Decay
-
Refractive Index
-
Rotational Dynamics
-
Simple Harmonic Motion
-
Specific Heat, Latent Heat and Calorimetry
-
Stefan-Boltzmann Law
-
The Gas Laws
-
The Laws of Thermodynamics
-
The Zeeman Effect .
-
Wien's Displacement Law
-
Young's Modulus

Climate Change

-
Keeling Curve .

Cosmology

-
Baryogenesis
-
Cosmic Background Radiation and Decoupling
-
CPT Symmetries
-
Dark Matter
-
Friedmann-Robertson-Walker Equations
-
Geometries of the Universe
-
Hubble's Law
-
Inflation Theory
-
Introduction to Black Holes .
-
Olbers' Paradox
-
Penrose Diagrams
-
Planck Units
-
Stephen Hawking's Last Paper .
-
Stephen Hawking's PhD Thesis .
-
The Big Bang Model

Finance and Accounting

-
Amortization
-
Annuities
-
Brownian Model of Financial Markets
-
Capital Structure
-
Dividend Discount Formula
-
Lecture Notes on International Financial Management
-
NPV and IRR
-
Periodically and Continuously Compounded Interest
-
Repurchase versus Dividend Analysis

Game Theory

-
The Truel .

General Relativity

-
Accelerated Reference Frames - Rindler Coordinates
-
Catalog of Spacetimes .
-
Curvature and Parallel Transport
-
Dirac Equation in Curved Spacetime
-
Einstein's Field Equations
-
Geodesics
-
Gravitational Time Dilation
-
Gravitational Waves
-
One-forms
-
Quantum Gravity
-
Relativistic, Cosmological and Gravitational Redshift
-
Ricci Decomposition
-
Ricci Flow
-
Stress-Energy Tensor
-
Stress-Energy-Momentum Tensor
-
Tensors
-
The Area Metric
-
The Equivalence Principal
-
The Essential Mathematics of General Relativity
-
The Induced Metric
-
The Metric Tensor
-
Vierbein (Frame) Fields
-
World Lines Refresher

Lagrangian and Hamiltonian Mechanics

-
Classical Field Theory .
-
Euler-Lagrange Equation
-
Ex: Newtonian, Lagrangian and Hamiltonian Mechanics
-
Hamiltonian Formulation .
-
Liouville's Theorem
-
Symmetry and Conservation Laws - Noether's Theorem

Macroeconomics

-
Lecture Notes on International Economics
-
Lecture Notes on Macroeconomics
-
Macroeconomic Policy

Mathematics

-
Amplitude, Period and Phase
-
Arithmetic and Geometric Sequences and Series
-
Asymptotes
-
Augmented Matrices and Cramer's Rule
-
Basic Group Theory
-
Basic Representation Theory
-
Binomial Theorem (Pascal's Triangle)
-
Building Groups From Other Groups
-
Completing the Square
-
Complex Numbers
-
Composite Functions
-
Conformal Transformations .
-
Conjugate Pair Theorem
-
Contravariant and Covariant Components of a Vector
-
Derivatives of Inverse Functions
-
Double Angle Formulas
-
Eigenvectors and Eigenvalues
-
Euler Formula for Polyhedrons
-
Factoring of a3 +/- b3
-
Fourier Series and Transforms .
-
Fractals
-
Gauss's Divergence Theorem
-
Grassmann and Clifford Algebras .
-
Heron's Formula
-
Index Notation (Tensors and Matrices)
-
Inequalities
-
Integration By Parts
-
Introduction to Conformal Field Theory .
-
Inverse of a Function
-
Law of Sines and Cosines
-
Line Integrals, ∮
-
Logarithms and Logarithmic Equations
-
Matrices and Determinants
-
Matrix Exponential
-
Mean Value and Rolle's Theorem
-
Modulus Equations
-
Orthogonal Curvilinear Coordinates .
-
Parabolas, Ellipses and Hyperbolas
-
Piecewise Functions
-
Polar Coordinates
-
Polynomial Division
-
Quaternions 1
-
Quaternions 2
-
Regular Polygons
-
Related Rates
-
Sets, Groups, Modules, Rings and Vector Spaces
-
Similar Matrices and Diagonalization .
-
Spherical Trigonometry
-
Stirling's Approximation
-
Sum and Differences of Squares and Cubes
-
Symbolic Logic
-
Symmetric Groups
-
Tangent and Normal Line
-
Taylor and Maclaurin Series .
-
The Essential Mathematics of Lie Groups
-
The Integers Modulo n Under + and x
-
The Limit Definition of the Exponential Function
-
Tic-Tac-Toe Factoring
-
Trapezoidal Rule
-
Unit Vectors
-
Vector Calculus
-
Volume Integrals

Microeconomics

-
Marginal Revenue and Cost

Particle Physics

-
Feynman Diagrams and Loops
-
Field Dimensions
-
Helicity and Chirality
-
Klein-Gordon and Dirac Equations
-
Regularization and Renormalization
-
Scattering - Mandelstam Variables
-
Spin 1 Eigenvectors .
-
The Vacuum Catastrophe

Probability and Statistics

-
Box and Whisker Plots
-
Categorical Data - Crosstabs
-
Chebyshev's Theorem
-
Chi Squared Goodness of Fit
-
Conditional Probability
-
Confidence Intervals
-
Data Types
-
Expected Value
-
Factor Analysis
-
Hypothesis Testing
-
Linear Regression
-
Monte Carlo Methods
-
Non Parametric Tests
-
One-Way ANOVA
-
Pearson Correlation
-
Permutations and Combinations
-
Pooled Variance and Standard Error
-
Probability Distributions
-
Probability Rules
-
Sample Size Determination
-
Sampling Distributions
-
Set Theory - Venn Diagrams
-
Stacked and Unstacked Data
-
Stem Plots, Histograms and Ogives
-
Survey Data - Likert Item and Scale
-
Tukey's Test
-
Two-Way ANOVA

Programming and Computer Science

-
Hashing
-
How this site works ...
-
More Programming Topics
-
MVC Architecture
-
Open Systems Interconnection (OSI) Standard - TCP/IP Protocol
-
Public Key Encryption

Quantum Computing

-
The Qubit .

Quantum Field Theory

-
Creation and Annihilation Operators
-
Field Operators for Bosons and Fermions
-
Lagrangians in Quantum Field Theory
-
Path Integral Formulation
-
Relativistic Quantum Field Theory

Quantum Mechanics

-
Basic Relationships
-
Bell's Theorem
-
Bohr Atom
-
Clebsch-Gordan Coefficients .
-
Commutators
-
Dyson Series
-
Electron Orbital Angular Momentum and Spin
-
Entangled States
-
Heisenberg Uncertainty Principle
-
Ladder Operators .
-
Multi Electron Wavefunctions
-
Pauli Exclusion Principle
-
Pauli Spin Matrices
-
Photoelectric Effect
-
Position and Momentum States
-
Probability Current
-
Schrodinger Equation for Hydrogen Atom
-
Schrodinger Wave Equation
-
Schrodinger Wave Equation (continued)
-
Spin 1/2 Eigenvectors
-
The Differential Operator
-
The Essential Mathematics of Quantum Mechanics
-
The Observer Effect
-
The Quantum Harmonic Oscillator .
-
The Schrodinger, Heisenberg and Dirac Pictures
-
The WKB Approximation
-
Time Dependent Perturbation Theory
-
Time Evolution and Symmetry Operations
-
Time Independent Perturbation Theory
-
Wavepackets

Semiconductor Reliability

-
The Weibull Distribution

Solid State Electronics

-
Band Theory of Solids .
-
Fermi-Dirac Statistics .
-
Intrinsic and Extrinsic Semiconductors
-
The MOSFET
-
The P-N Junction

Special Relativity

-
4-vectors .
-
Electromagnetic 4 - Potential
-
Energy and Momentum, E = mc2
-
Lorentz Invariance
-
Lorentz Transform
-
Lorentz Transformation of the EM Field
-
Newton versus Einstein
-
Spinors - Part 1 .
-
Spinors - Part 2 .
-
The Lorentz Group
-
Velocity Addition

Statistical Mechanics

-
Black Body Radiation
-
Entropy and the Partition Function
-
The Harmonic Oscillator
-
The Ideal Gas

String Theory

-
Bosonic Strings
-
Extra Dimensions
-
Introduction to String Theory
-
Kaluza-Klein Compactification of Closed Strings
-
Strings in Curved Spacetime
-
Toroidal Compactification

Superconductivity

-
BCS Theory
-
Introduction to Superconductors
-
Superconductivity (Lectures 1 - 10)
-
Superconductivity (Lectures 11 - 20)

Supersymmetry (SUSY) and Grand Unified Theory (GUT)

-
Chiral Superfields
-
Generators of a Supergroup
-
Grassmann Numbers
-
Introduction to Supersymmetry
-
The Gauge Hierarchy Problem

The Standard Model

-
Electroweak Unification (Glashow-Weinberg-Salam)
-
Gauge Theories (Yang-Mills)
-
Gravitational Force and the Planck Scale
-
Introduction to the Standard Model
-
Isospin, Hypercharge, Weak Isospin and Weak Hypercharge
-
Quantum Flavordynamics and Quantum Chromodynamics
-
Special Unitary Groups and the Standard Model - Part 1 .
-
Special Unitary Groups and the Standard Model - Part 2
-
Special Unitary Groups and the Standard Model - Part 3 .
-
Standard Model Lagrangian
-
The Higgs Mechanism
-
The Nature of the Weak Interaction

Topology

-

Units, Constants and Useful Formulas

-
Constants
-
Formulas
Last modified: May 6, 2020

Position Creation and Annihilation Operators for Bosons -------------------------------------------------------- Notation: Capital Ψ is used to denote field operators and ψ is used for wavefunctions. Field operators create or destroy a particle at a particular point in space. Field operators act by applying the Fourier transform to the creation and annihilation operators. Ψ(x) = Σkα(k)exp(ikx) where α(k) is equivalent to the amplitude term in QM and, Ψ*(x) = Σkα*(k)exp(-ikx) Compare these to the QM case: ψ(x) = ΣAmψm m Where ψm are othornormal basis vectors of the form exp(ikx) and Am are the Fourier coefficients. Therefore, in QFT the Fourier coefficients are replaced by the creation and annihilation operators. Now introduce time: Ψ(x,t) = Σka-exp(i(kx - ωt)) ... annihilates a particle at position x. and, Ψ(x,t) = Σka+exp(-i(kx - ωt)) ... creates a particle at position x. Ψ(x,t) and Ψ(x,t) are quantum fields. Summary: a+(k) - creation operator for momenta, k Ψ(x) - creation operator for position, x a-(k) - annihilation operator for momenta, k Ψ(x)  - annihilation operator for position, x Examples: Pre-existing photon, n(5) = 1 |0 0 0 0 1 0 0> Create a new photon in momentum state k = 3 at x. Thus, n(3) -> 1, n(5) = 1 Σka+(3)exp(-i3x)|0 0 0 0 1 0 0> => e-i3x|0 0 1 0 1 0 0> Create another new photon in momentum state k = 5 at the same x. Thus, n(5) -> 2 Σka+(5)exp(-i5x)|0 0 1 0 1 0 0> => √2e-i5x|0 0 1 0 2 0 0> The factor of √2 comes from a+|n> = √(n+1)|n+1> Creation and annihilation operators on bra vectors: The rule for the creation and annihilation operators when they operate on bra vectors is the opposite of the case for ket vectors. Thus, the creation operator acts on a bra as an annihilation operator and vice versa. <n|a+ => <n-1|√n and <n|a- => <n+1|√n+1 Consider the following scattering processes: t k2 | \ | \ | | \| g = coupling contant that measures the strength of | /| the scattering (measured experimentally). | / | | / | | k1 | -------------------- x x=0 ΨΨ|k1> => |k2> The probability that k1 results in k2 is given by: |<k2Ψ|k1>|2 We will just calculate the |...|: <k2|g∫dtΣda+(d)exp(iω2t)Σea-(f)exp(-iω1t)|k1> after setting x = 0 <k2|g∫dta+(k2)exp(iω2t)a-(k1)exp(-iω1t)|k1> <0|g∫dtexp(i(ω2 - ω1)t)|0> <0|gδ(ω2 - ω1)|0> ∴ hω2 = hω1 ... conservation of energy k2 k3 \ / \ / \/ / g / / ki Follow the same procedure as above: ΨΨΨ|k1> => |k2k3> <k2k3ΨΨ|k1> <k2k3|g∫dxΣda+(d)exp(-ik3x)Σea+(e)exp(-ik2x)Σfa-(f)exp(ik1x)|k1> after setting t = 0 <k2k3|g∫dxa+(k3)exp(-ik3x)a+(k2)exp(-ik2x)a-(k1)exp(ik1x)|k1> <0| = 1 when k1 - k2 - k3 or 0 otherwise |0> ∴ hk1 - hk2 - hk3 = 0 ... conservation of momentum Time Dependent Schrodinger equation for a field: Differentiate, Ψ w.r.t. t and x: ∂Ψ/∂t = Σk(-iω)a-(k)exp(i(kx - ωt)) ∂Ψ/∂x = Σk(ik)a-(k)exp(i(kx - ωt)) ∂2Ψ/∂x2 = Σk(ik)2a-(k)exp(i(kx - ωt)) So we can write: ∂Ψ/∂t/∂2Ψ/∂x2 = Σk(-iω)a-(k)exp(i(kx - ωt))/Σk(ik)2a-(k)exp(i(kx - ωt))   = (-iω)/(ik)2 Which leads to:   (ik)2∂Ψ/∂t = (-iω)∂2Ψ/∂x2   k2∂Ψ/∂t = (iω)∂2Ψ/∂x2 Now E = hω = p2/2m = h2k2/2m Therefore k2 = 2mω/h (2mω/h)∂Ψ/∂t/∂ = (iω)∂2Ψ/∂x2 ∂Ψ/∂t =(ih/2m)∂2Ψ/∂x2 Note: In both cases we could have equally integrated over position/time to demonstrate conservation of momentum and conservation of energy respectively. What is the meaning of ∫Ψ(x)Ψ(x)dx ? circle with length L = ∫LΣma+(m)e-imxΣna-(n)einxdx = ∫LΣma+(m)Σna-(n)ei(n-m)xdx = LΣma+(m)a-(m) - occupation number is a+(m)a-(m) = the number of particles Ψ(x)Ψ(x) is interpreted as the density of particles at x Position Creation and Annihilation Operators for Fermions ---------------------------------------------------------- Bosons can occur in the same state state; Fermions cannot (Pauli Exclusion Principle). Fermions can only have 0 or 1 in a state. We define new position creation and annihilation operators as: Ψ(x,t) = Σkc-exp(i(kx - ωt)) and, Ψ(x,t) = Σkc+exp(-i(kx - ωt)) Heisenberg Uncertainty Principle in QFT --------------------------------------- Analagous to the relationship in QM, the position creation and annihilation operators are Fourier transforms of each other. Thus : Ψ(x)± = Σka(k)±exp(±ikx) and a(k)± = ΣΨ(x)±exp(±ikx) This shows that to create a state of definite position, it is necessary to sum over many momentum states. Conversely, to create a state of definite momentum it is necessary to sum over many position states.