I am sort of puzzled - whatever made this story win a Hugo Award? This is among of the more muddled & incomprehensible pieces from Niven!
Story summary.Dr Julian Forward is from high gravity human colony world called Jinx. Because of high gravity, its natives have a body build rather heavy compared to earthlings - sometimes making them butts of jokes. These jokes have ensured that Julian has an inferiority complex. But he is a talented scientist. Decides to take it on the world. He is based on "Forward Station" - a research facility in the outer reaches of Sol, & is running a space piracy racket from there.
His technique is rather exotic. If there is comprehensible physics to it, it went over my head. But here it is.
Creation of the universe also created many "quantum black holes" - very tiny ones - of atomic scale in size, & of mass about that of an asteroid. One such lives within the vicinity of Sol. Julian has not only located it, but tamed it with a complex device called "Grabber". It's normally parked at its alloted place outside the asteroid housing the research station.
He has space mining tugs that can drag this black hole around! When in looting mood, he parks them near the trading routes used by ships moving between earth & colony worlds. When there is an incoming unarmed ship with booty (traveling at interstellar speed!), he can guide this black hole through a path that will make the ship's drive vanish!!!
His men will then board the ship, loot it, & throw the ship & its crew into the black hole! And then tug the black hole back to its parking place!
Of course, there are heroes that will bring the villain to book. Sigmund Ausfaller, Carlos Wu, & Beowulf Shaeffer are coming from Jinx in an armed ship disguised as harmless trading ship - as a sort of bait. When they are attacked, they lose their hyperdrive (but not normal space drive). Carlos is a physicist who has an idea of what happened, but won't tell anyone. He will make some calls, & contrive an appointment with Julian on his research station - not far from current location of space ship (minus its hyperdrive)..
After some James Bond movie style action at research station, heroes will escape somewhat damaged but recoverable, while the villains & their research station is eaten up by the black hole.
We are also treated, during story build up, to a lot of trivia about Jinx. I found these boring, but your tastes might differ.
Fact sheet."The Borderland of Sol", short story, review
First published: Analog, January 1975.
Winner of Hugo Award 1976 in novelette category