This article is from the Star Trek Tech FAQ, by Joshua Bell inexorabletash@hotmail.com with numerous contributions by others.
As you may have guessed, the .tech community was less than impressed
with "Threshold" [VOY] in which Voyager - a ship running low on
supplies, with half its crew dead, stranded away from repair or
research facilities, on the other side of the Galaxy from the
Federation - manages to upgrade one of its never-ending supply of
shuttles to make a Transwarp flight, something that has defied the
best minds in the Federation for a century. Things go
higglety-pigglety after that, and many people (including some of the
production crew) just pretend it didn't happen.
Forgiving that, however, the episode's technobabble isn't too bad. The
Voyager crew mention how Warp 10 = Infinite Speed = being everywhere
at once. An interesting tidbit is that once Transwarp drive is active,
the shuttle's speed registers at Warp 10.
 
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