Doctor Serova was a Hekaran scientist (warp field theorist) who believed that the use of high warp drive was damaging the fabric of subspace. She convinced her brother, Rabal, that there was possible truth in her theories, but their report submitted to the Federation Science Council was dismissed for lacking conclusive evidence.
In 2370, she sacrificed her own life to prove her theories by causing a warp core breach of her ship in the Hekaras Corridor, resulting in the formation of a subspace rift. The Federation imposed a speed limit for its vessels until the limitations could be overcome. (TNG: "Force of Nature")