I just watched [S7E25 "All Good Things ..." of Star Trek: The Next Generation](http://www.imdb.com/title/tt0111281/?ref_=nm_flmg_act_93) which I believe is the final episode of the series. In this episode, Captain Beverly Picard tells the crew to pilot her medical ship into the Neutral Zone at Warp 13. In a separate episode of ST: Voyager (actual episode unknown to me), the characters Tom Paris and Harry Kim talk about not being able to break the Warp 10 barrier for some reason. This is toward the end of the series. Is there any explanation in the Star Trek Universe which explains this seeming difference? This especially confuses me because ST:V (1995-2001) started the year after ST:TNG ended (1987-1994). I would think it would be produced with these story lines in mind. Is there any explanation for this?