
It should also be noted that the fact that the time independent equation takes the form of a simple eigenvalue problem (thus being more amenable to mathematical analysis) that makes it so useful. The conditions that must be met to enable this separation of variables arise very frequently in chemistry and physics. The second one is an eigenvalue equation, written commonly as Hψ = E ψ. Actually there are two different equations known as Schrödinger equation: The first is sometimes called the time-dependent, while the second is called the time independent equation, though in reality, it is simply an equation derived from the first using a mathematical technique known as separation of variables. Austrian physicist Erwin Schrödinger first proposed the equation in early 1926. It concerns the theory of measurement and decoherence.The Schrödinger equation is one of the fundamental equations of quantum mechanics and describes the spatial and temporal behavior of quantum-mechanical systems. The thought experiment known as " Schrödinger's cat" is one example among others of this. The Schrödinger equation is linear, and there is speculation on modifying it by adding non-linear terms in order to solve enigmas posed by quantum mechanics, such as the emergence of the classical state from the quantum state. Richard Feynman, explaining the theory of the ammonia maser to students at Caltech. String theory is largely based on this formulation. The Feynman formulation is not as general as the Dirac form for a state vector in Hilbert space, but it is the more flexible and practical when Yang-Mills fields and quantum cosmology are developed from quantum theory. The Schrödinger equation for a system of nuclei and their electrons.(Credit: Robert Laughlin).Īn alternative and very powerful formulation of the Schrödinger equation was given by Richard Feynman using his famous path integral. One of the most important properties of this equation in quantum mechanics is that it leads to the phenomenon of quantum entanglement. The Schrödinger equation governs all processes on a microscopic scale, and therefore the physics of molecules down to quarks, it should also cosmology, when the universe was the size of an elementary particle. This is actually just the application of Huygens' principle for a scalar wave to the scalar of the Schrödinger field in the phase space. These probability amplitudes interfere and their squares give the probability of observing the system with a precise value of its dynamic variables: energy, spin, momentum etc. To each possible process in the space of the states of the system, and in its phase space in the sense of analytical mechanics, there corresponds an amplitude of probabilities that the process will take place. This equation introduced complex numbers at a fundamental level to describe the state of a quantum system, and its solutions are probability amplitudes that the system when measured will be in a given state, proton or neutron, spin up or down etc. Paul Dirac (credit: AIP Emilio Sergè Visual Archives) Initially, it was not in relativistic form for particles, and it was Dirac again who found a generalisation for this. This also explains why the state vector l ψ > is sometimes called a wave function ψ (x) of the system.Īs its discoverer realised, it shows that the quantification of the energy of atomic systems results from formulation in terms of the Sturm Liouville problem, or the problem of eigenvalues for a linear differential operator H. Thus Schrödinger discovered a partial derivative equation describing a Hamiltonian mechanical system using a field scalar ψ propagating coordinates of this system in 6N dimensional space When applied to a particle in a field, it is akin to a wave equation in space and time, hence the name wave mechanics sometimes used for this particular and special form of quantum mechanics. It initially adopted the ideas of the mathematicians Hamilton and Félix Klein to extend De Broglie's theory of matter-waves.


The Schrödinger equation was established in primitive form in 1926 by Erwin Schrödinger and was generalised by Paul Dirac a few years later. It is written (ih/2 π) d l Ψ>/dt = Hl Ψ >

Its physical interpretation is generally taken within the Copenhagen interpretation of quantum mechanics. It is equivalent to an eigenvalue problem in the theory of Hilbert spaces as shown by John von Neumann. The Schrödinger equation is the basic equation in quantum mechanics describing the change over time of the state vector l ψ > of an arbitrary quantum system.
