This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
The Burn was a galaxy-wide disastrous event that occurred in roughly 3069, in which most dilithium mysteriously went inert, causing the detonation of every active warp core. The event caused widespread death and destruction, made dilithium an even more sought-after resource, and led to the near-collapse of the United Federation of Planets.
Around the mid-30th century, the dilithium supply in the Milky Way Galaxy began to dry up. The Federation issued a mandate to its member worlds to start trials on alternate warp drive designs that did not require dilithium, but none proved reliable. (DIS: "People of Earth")
The most promising project was SB-19, developed by the Vulcans and Romulans of Ni'Var. SB-19 would have allowed starships to be transported across thousands of light years in an instant, obviating the need for warp drive. As part of the project, sensors were scattered across dozens of light years of subspace. Though Ni'Var's scientists ultimately concluded that SB-19 was too dangerous to continue developing, the Federation denied their request to shutter the program because it was the most promising dilithium alternative being pursued at the time. (DIS: "Unification III")
Cause and event
In 3064, the KSF Khi'eth embarked on a mission to investigate a "dilithium nursery" in the Verubin Nebula. During the mission, the ship crashed on Theta Zeta, a planet composed of dilithium, at the center of the nebula. One of the Khi'eth's Kelpien crew members, Doctor Issa, was pregnant and later gave birth to Su'Kal. Su'Kal's cells acclimatized in utero to the dilithium, developing a connection to it.
Knowing she and her crewmates were dying, Issa created an elaborate holoprogram designed to educate and nurture Su'Kal and mask the crew's condition from him. In roughly 3069, however, Su'Kal was severely traumatized when he saw his mother die of radiation poisoning, resulting in an emotional outburst that caused a subspace shockwave that destabilized refined dilithium, causing it to suddenly become inert. (DIS: "Su'Kal", "That Hope Is You, Part 2") Because dilithium was used to regulate matter-antimatter reactions, this caused any ship with an active warp core to lose antimatter containment, resulting in a warp core breach. Countless ships were destroyed, including most belonging to the Federation, and millions of lives were lost. (DIS: "That Hope Is You, Part 1", "People of Earth", "Die Trying") The Burn also decimated the population of Trill symbionts. (DIS: "Forget Me Not")
The event damaged subspace in some regions as well. The orbit of Kwejian's moon shifted as a result, causing extreme tides that unleashed swarms of sea locusts on the planet's harvest. (DIS: "The Sanctuary")
Following the disaster, the Federation was unable to determine what caused it, nor did it know if it would occur again. The Vulcans of Ni'Var believed that SB-19 caused the Burn, and the planet seceded from the Federation in 3089 despite the Romulans' desire to remain. Around the same time, the people of Earth, feeling an urgency to protect their planet, also seceded. The Federation and Starfleet subsequently relocated their headquarters from Earth to a large space station simply called Federation Headquarters. (DIS: "People of Earth", "Unification III")
By 3188, the Federation, an organization that had nearly lasted a millennium and held 350 member worlds at its peak, had largely collapsed as a galactic superpower. As of 3189, it only retained 38 member worlds that Fleet Admiral Charles Vance was aware of, and was in conflict with the Emerald Chain crime syndicate. (DIS: "That Hope Is You, Part 1", "Far From Home", "Die Trying")
In 3189, the USS Discovery began a new investigation of the cause of the Burn. Although the Burn appeared to occur everywhere simultaneously, analysis of various black boxes found that it took time to travel across the galaxy, and ultimately led to its point of origin in the Verubin Nebula. Discovery located the wreck of the Khi'eth in the nebula and made contact with Su'Kal. While in contact with Discovery's away team, a holographic Kelpien monster frightened Su'Kal, nearly causing another Burn. The away team rescued Su'Kal from the Khi'eth, preventing the possibility of another Burn. At the same time, the dilithium throughout Theta Zeta's structure allowed the Federation to finally recover from the Burn, and multiple worlds that had seceded either rejoined, including Trill, or considered rejoining, including Ni'Var. (DIS: "Scavengers", "Unification III", "The Sanctuary", "Su'Kal", "That Hope Is You, Part 2")
Ships destroyed by the Burn
- Gav'Nor (DIS: "Unification III")
- USS Giacconi (NCC-316608) (DIS: "Scavengers")
- USS Yelchin (NCC-4774-E) (DIS: "People of Earth")
- At least 4 Eisenberg-class ships (DIS: "People of Earth")
- At least 3 Intrepid-class ships (DIS: "People of Earth")
- At least 7 Armstrong-type ships (DIS: "People of Earth")
- At least 3 Courage-class ships (DIS: "People of Earth")
- At least 3 Saturn-class ships (DIS: "People of Earth")
- At least 2 Angelou-class ships (DIS: "People of Earth")
- Several NCC-325019 type ships (DIS: "People of Earth")