Gravity's End was a proto-universe phenomenon in which matter created by a Big Bang in a parallel universe was deposited in the universe. Located near the Omega Maelstrom, Gravity's End was the only proto-universe phenomenon known to the United Federation of Planets. The phenomenon was known for its extremely high energy output, which exceeded that of 100 G-type stars.
Espoir Station was constructed in the mid 23rd century to observe and collect data on Gravity's End. In 2269 an extremist faction of the Vardaine led by Doctor Ies Bredell. Bredell, seeking to destroy the Federation, was able to build a superweapon near the station designed to collect energy from Gravity's End and fire a beam capable of destroying a planet.
In an alternate future timeline Ies Bredell was able to fire the weapon at Earth. This destroyed the planet and causing the collapse of the Federation. During the explosion the starship USS Alexander was thrown into a timewarp, which sent it back in time eight days. The USS Enterprise (NCC-1701) encountered the heavily damaged Alexander, and Captain Lucas Rayner tried to warn the Enterprise what had happened. However the damage inflicted by the Big Bang Weapon and the timewarp was too much, and the Alexander exploded.
The Enterprise then traveled to Espoir Station to investigate the threat, and was able to prevent Bredell from firing his weapon. The weapon was destroyed by the Enterprise's phasers. (TOS video game: Judgment Rites)