Bubbles were first developed in LY 400 by a Sorreter named Koichi. They are a medium which is used for many spell devices, some of which were invented within a few years of the introduction of the medium, while others (such as t-mail) didn't come until much later (see "spell devices" for a more comprehensive listing of bubble uses). Other uses include scrying, audio and/or visual recordings, illumination, etc. The medium itself is made of a substance which is created through a mixture of science and magic, to "format" it for the subsequent casting of a specific spell upon the device. A bubble is something like a thin, hollow orb of glass, about the size of a marble, when inert, but which expands to any of various sizes when activated. The substance is also unbreakable (once magically formatted), but can be made to vanish by a voice command; though some bubbles are disposable, and automatically vanish when their use is completed.
There are also devices called bubble-screens, which are made of the same substance as regular bubbles and which have had a similar spell cast upon them, but which are actually flat, and remain one size (typically a large rectangle which hangs on a wall). Initially these were rare, used only by the very wealthy, usually for t-mail conference calls. In 912, public bubble-screens were set up in selected locations in each village, to be used as a worldwide public address system, though when not being used for that, they can also be used as theatre screens for the showing of news or entertainment. Bubble-screens may contain both audio and visual properties, though they can also be supplemented by bubble-speakers which transmit audio in conjunction with the bubble-screens' visual displays. Bubble-speakers may also be used independently of bubble-screens for purely audio "bubblecasts." (Bubble-speakers work in conjunction with recording bubbles or with magic microphones, which were invented in 911.) Audio bubblecasts are sometimes referred to as "radio," a term borrow from Earth.
While both news and music bubblecasts are free for anyone to listen to, some bubble-screens have been enclosed in indoor theatres, so that people will have to pay to see audio/visual "movies" (another term borrowed from Earth) or some concerts. Bubblecasts which are free to the public are paid for by the public fund, which in turn receives money from anyone wishing to use the PA system to bubblecast advertisements for their business, such as stores, restaurants, etc.
In 913, devices called "home-PA bubbles" began to gain popularity. These were much like the bubble-screens once used exclusively for t-mail by relatively few people, but the new "multimedia" devices could be used as not only a permanent (non-vanishing) alternative to t-mail bubbles (which are still commonly used away from the house), but also for receiving bubblecasts of radio, news, movies (which in the home may be called "television"), and so forth. They also came to be used for transmitting text, especially after the development of typewriters. In 914, enhanced-capacity recording bubbles were developed to serve as "databases," which led to the establishment of the Sylph Swarm, a network for sharing all kinds of data with people around the world.