The term cloud model can refer to two quite different things. First it can refer to the electron cloud model (ECM). It can, however, also refer to the style of computing called cloud computing.
The electron cloud model refers to a name given to the results of using Schrödinger’s equation to do a probabilistic location of an electron in a hydrogen atom. The equation was developed by Austrian theoretical physicist Erwin Schrödinger in 1926. The paper in which he published the equation was revolutionary, especially in the realm of quantum mechanics, and he was awarded the Nobel Prize for this work in 1933, two years prior to proposing the thought experiment known as the Schrödinger’s cat thought experiment.
The Cloud Model gets its name from the appearance of the probability function showing where the electron in question is likely to be found. The nucleus of the atom is shown as a central dot and the probabilistic positions of where the electron has been and is likely to be are shown as tiny dots which appear to form a cloud around the nucleus. Schrödinger’s equation predicts the locations given by the 1913 atomic model proposed by Danish physicist Niels Bohr. The equation has applications in various subspecialties of physics.
The cloud model of computing is a way of allocating resources that represents a shift in the established practice for building up technology capabilities. In the model that has heretofore been used, an individual, company, school, or other entity provided its own infrastructure, platform, and software. This meant that each entity had its own computers, possibly its own server, its own software, its own information technology team and security specialists or relied on an Internet Service Provider (ISP), for some small number of these services.
The cloud model looks to virtualized resources that are—as much as possible–provided over the Internet. This means that what used to be property is now reconfigured as service. This has led to the terms that reflect this shift: IaaS—infrastructure as a service; PaaS—platform as a service; and SaaS—software as a service.
This model is considered helpful in that entities both avoid capital expenditure and only pay for resources that they actually use. Cloud computing services are offered by Adobe®, ThinkFree®, Microsoft®, Google, IBM, Amazon, and Sun Microsystems, among others. The model, however, raises concerns because control of data is off-site and clients are made dependent on the providers.
