In 2269, a team of 127 Federation scientists, led by Professor K'mtu Ketoract, were working on a top secret experiment entitled "Project Omega" at a classified research center in the Lantauro sector. The project's goal was to create an inexhaustible energy source which would end all needs for all other sources of energy, hence the name Omega. The research showed a single molecule of Omega contained the same power as a warp core which led Ketoract to believe a small chain of Omega molecules could sustain a civilization for countless years. Ketoract, along with various cosmologists, theorized that the Omega molecule once existed in nature for an infinitesimal period of time at the exact moment of the big bang. Ketoract even postulated Omega was the primal source of energy for the explosion that began our universe.
The scientists were able to synthesize a single Omega molecule but only for a fraction of a second before it destabilized, destroying the research center and killing all 127 scientists. An unexpected secondary effect was the rupture of subspace extending out 3.2 light-years. Through further theoretical tests, Starfleet Command concluded a chain reaction involving a handful of Omega molecules could devastate and/or destroy subspace throughout an entire quadrant causing warp travel to become an impossibility and causing all space faring civilizations to stagnate and die.
Starfleet, in an attempt to keep all information of the destruction of the research center and the subspace rupture secret, suppressed all knowledge of the experiment and fabricated the story of a natural phenomena occurring in the Lantauro sector which causes the lack of warp travel in a radius of 3.2 light-years.
Starfleet, in 2270, then enacted the Omega Directive. Named after the last letter in the Greek alphabet and chosen to represent a threat not only to the Federation but to the entire galaxy, the Omega Directive states any and all Omega molecules found are to be destroyed at all costs. Starfleet's reasoning is since Omega is believed to be the most powerful substance known to exist, information of it should not fall into the wrong hands. Starfleet then restricted access to the Omega to Federation Captains and Flag Officers and then only on a need to know basis. When an Omega molecule is encountered, all other priorities are to be rescinded and Starfleet is to be informed of the discovery. Starfleet will the send in a specialized team authorized to use whatever means necessary to deal with the crisis and destroy the molecule/s.