Dilithium (Star Trek)
In the Star Trek fictional universe, dilithium is an invented material which serves as a controlling agent in the matter-antimatter reactors. In the original series, dilithium crystals were rare and could not be replicated, making the search for them a recurring plot element. According to a periodic table shown during a Next Generation episode, it has the atomic number 87, which in reality belongs to francium, and the chemical symbol Dt.
Description and usage
This section describes a work or element of fiction in a primarily in-universe style. (February 2019)
Dilithium is depicted as an extremely hard crystalline mineral that occurs naturally on some planets. It is believed that this material exists in more than three dimensions at the same time and this is somehow related to its properties. When placed in a high-frequency electromagnetic field, eddy currents are induced in its structure which keep charged particles away from the crystal lattice. This prevents it from reacting with antimatter when so energized, because the antimatter particles never actually touch it. Therefore, it is used to contain and regulate the annihilation reaction of matter and antimatter in a starship's warp core, which otherwise would explode from the uncontrolled annihilation reaction. Though low-quality artificial crystals can be grown or replicated, they are limited in the power of the reaction they can regulate without fragmenting, and are therefore largely unsuitable for warp drive applications. Due to the need for natural dilithium crystals for interstellar travel, deposits of this material are – much like real-world equivalents such as oil – a highly contested resource, and as such, dilithium crystals have led to more interstellar conflict than all other reasons combined.
In the original series, dilithium crystals were rare and could not be replicated. In Star Trek IV: The Voyage Home, Spock re-crystallized a Klingon Bird of Prey's decaying dilithium through exposure to high-energy photons as generated by 20th century fission reactors - although it was pointed out that not only was the method of re-crystalization itself hazardous, but the 20th century nuclear reactors needed for the photons were no longer used in the 23rd century.
As depicted on the show, the streams of matter (deuterium gas) and antimatter (anti-deuterium) directed into crystallized dilithium are unbalanced – there is usually much more matter in the stream than antimatter. The annihilation reaction heats the excess deuterium gas, which produces plasma for the nacelle(s) and allows faster than light travel. In addition, most starships use this plasma as a power source for the ship's systems; in the series Star Trek: Enterprise (2001–2005), this was referred to as an electro-plasma system (a backronym of the term "EPS", which was used in all other series except the original series) to refer to a ship's or station's power system. The specific details of this reaction were officially established in the Star Trek: The Next Generation (1987–1994) series and technical manual; in earlier works, it is not clearly defined.
Dilithium is a member of the fictional hypersonic series of elements, according to a periodic table graphic seen in episodes of Star Trek: The Next Generation and Star Trek: Deep Space Nine (1993–1999). The dilithium crystal structure is 2(5)6 dilithium 2(:)l diallosilicate 1:9:1 heptoferranide, according to the Star Trek: The Next Generation Technical Manual (1991).