A single foglet of Utility Fog; this model has twelve arms, arranged in a dodecahedral shape
A collective of mesobots or nanobots ("foglets") that link together into a complex network in the air, able to work together to exert force in any direction or transmit information between each other. Utility fog can be used to simulate any environment, essentially providing a real life environment with the transformational capabilities of virtual reality. This gives users almost complete control over their physical environment. Used both by hyperturings and archailects (as part of an angelnet or other distributed network) and by lesser toposophics. Users do not have be SI:1 or higher, although many are. Crude forms of Utility Fog were available during the Interplanetary Age, but fully functional fog was not widely available until 1010 AT.
In microgravity environments a quite thin (ankle-deep) layer of utility fog can replace gravity as a method of keeping people oriented in a common fashion, establishing a false sense of up and down (for instance). In addition utility fog can be used within a zero gravity environment to prevent objects and users from drifting and tumbling.
Utility Fog civilizations, with intelligent individuals who exist as distributed entities within the fog, have evolved a number of times, but rarely last more than a few centuries before transcending. One of the very few stable ones is Nimbus.
Utility fog in use can consume considerable power, and produce considerable waste heat; for this reason the fog must be used in the most efficient way possible for any particular purpose. This requires sophisticated control systems, which are generally distributed throughout the fog itself. Sophisticated imaging technology such as phased array projectors are often incorporated into the fog, often on or near the surface layers, allowing the fog to display a range of images and to replicate a range of environments. Using phased array projectors, utility fog can even become apparently transparent or invisible.
Colloquially, utility fog is often known as u-fog or ufog, and variants thereof, in various Anglic dialects.
Related technologies include utility sand, which uses larger robot units comparable in size to a sand grain, and modubots and blockbots which use even larger scale units, all of which can replicate some or most of the qualities of utility fog.
Angelnet Fog - Text by John B One side effect of large amounts of low-tech utility fog (or other lower-tech nanites) in a terran-standard atmosphere has come to be called 'Angelnet Fog'. Effectively, each nanite or microbot acts as the seed for a raindrop, with water coalescing out of the atmosphere onto its surface. This tends (in poorly regulated angelnets) to lead to high degrees of mist and fog at ground level. It can be an interesting phenomenon to fly into an angelnetted city from above the angelnetting, seeing large, odd-shaped 'columns' of fog, only later to realize that what you're seeing is the angelnet fog surrounding various buildings.
Fog Swarm Projection - Text by M. Alan Kazlev A rl projection of physical objects and entities through the behavior of trillions of foglets. Fog swarms can be seamlessly merged with virch environments to create a continuum from totally virtual to totally rl.
Plasmic Furniture - Text by M. Alan Kazlev Furniture based on limited utility fog which allows it to reshape itself fluidly into whatever shapes is desired. Design involves mainly selecting the right behavioral parameters for it to predict the desires of its owners and when not in use form aesthetically pleasing "resting shapes".