The term virtual is a concept applied in many fields with somewhat differing connotations, and also denotations. Colloquially, 'virtual' has a similar meaning to 'quasi-' or 'pseudo-' (prefixes which themselves have quite different meanings), meaning something that is almost something else, particularly when used in the adverbial form, e.g. "He's virtually ^* my boyfriend." __NOTOC__

Physics

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• Virtual particles—Particles that exist for a period of time which is not enough to mathematically define their energy.
• Virtual work

Computing

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• Virtual memory—Memory which may not physically exist, but is made to appear so by software:
• Virtual machines—Software based partitions of a single computer that function as if they were independent computers.
• Virtual function—allows a derived class to override functions in classes it inherits from
• Virtualization—The concept of establishing and managing virtual machines or other virtual resources that share phyical computing hardware.
• Virtual reality—A popular sci-fi/IT concept
• Virtual host—A function of modern webservers that allows more than one website to be hosted on the same server

Philosophy

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Numerous philosophers have advanced conceptions of the virtual.

The current definition, that can hardly be distinguished from "potential," originates in medieval Scolastics and the pseudo-Latin "virtualis." Most prominent of these in contemporary philosophy has been Gilles Deleuze, who uses the term virtual to refer to something that every object carries with it, which is neither its reality nor merely what it could have been, but rather what it is imagined to be. "Virtual" is therefore taken to mean a potential state that could become actual. "Virtual" is not opposed to "real" but to "actual," whereas "real" is opposed to "possible."

Recently this conception of the virtual has been challenged and another core meaning has been elicited (Denis Berthier, "Meditations on the real and the virtual" - in French). It is based both upon science (virtual image), technology (virtual world), and etymology (derivation from virtue - Latin virtus). At the same ontological level as "possible," "real," or "potential," "virtual" is defined as that which is not real but displays the full qualities of the real - in a plainly actual - i.e. not potential - way. The prototypical case is a reflection in a mirror: it is already there, whether I am here to see it; it is not waiting for any kind of actualization. This definition allows one to understand that real effects can be issued from a virtual object, so that our perception of it and our whole relation to it are fully real. It explains that virtual reality can be used to cure phobies - which remains contradictory in any conception for which the virtual is a kind of potential.

Work Teams

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Internet technology fostered the environment for virtual work in teams, with members who may never meet each other in person. Communicating by phone and email, with workproducts shared electronically, virtual teams produce results without being co-located.

Quantum field theory | Virtuell | Virtuel | Virtueel | Virtual | Virtualnost