The pulse wave torpedo is a type of starship-mounted projectile weapon. In the mid-23rd century, a Vulcan science vessel attempted to seal a subspace rupture in the Hanoli system using a pulse wave torpedo. Unfortunately, the attempt failed and the rupture expanded exponentially, obliterating the entire system.
In 2369, the crew of Deep Space 9 attempted a similar procedure when another rupture seemingly appeared near the station. It was hoped their attempt would be more successful, as modern pulse wave torpedoes allow for much greater control over flux density. (DS9: "If Wishes Were Horses")
Another line from the episode placed this incident in the mid-22nd century.