And so the grav wave, once the promise of near certain death, had become the secret to faster, cheaper, and safer hyper voyages. Captains who had avoided them like the plague now actively sought them out, cruising between them on impeller drive where necessary, and the network of surveyed grav waves had grown apace.

There had still been a few problems. The most bothersome was that grav waves were layers of focused gravity, subject to areas of reverse flow and unpredictable bouts of “turbulence” along the interfaces of opposed flows or where one wave impinged upon another. Such turbulence could destroy a ship, but it was almost more frustrating that no one could take full advantage of the potential of the Warshawski sail (or, for that matter, the impeller drive) because no human could survive the accelerations which were theoretically possible.

Improved Warshawskis had tended to offset the first difficulty by extending their detection range and warning ships of turbulence. With enough warning time, a ship could usually trim its sails to ride through turbulence by adjusting their density and “grab factor,” though failure to trim in time remained deadly, which was why Sirius’s claim of tuner flutter had been so serious. A captain still had to see it coming, but the latest generation detectors could detect a grav wave at as much as eight light-minutes and spot turbulence within a wave at up to half that range. The problem of acceleration tolerance, on the other hand, had remained insoluble for over a standard century, until Dr. Shigematsu Radhakrishnan, probably the greatest hyper physicist after Warshawski herself, devised the inertial compensator.

Radhakrishnan had also been the first to hypothesize the existence of wormhole junctions, but the compensator had been his greatest gift to mankind’s diaspora. The compensator turned the grav wave (natural or artificial) associated with a vessel into a sump into which it could dump its inertia. Within the safety limits of its compensator, any accelerating or decelerating starship was in a condition of internal free-fall unless it generated its own gravity, but the compensator’s efficiency depended on two factors: the area enclosed in its field and the strength of the grav wave serving as its sump. Thus a smaller ship, with a smaller compensator field area, could sustain a higher acceleration from a given wave strength, and the naturally-occurring and vastly more powerful grav waves of hyper-space allowed for far higher accelerations under Warshawski sail than could possibly be achieved under impeller drive in normal-space.

Even with the acceleration rates the compensator permitted, no manned vessel could maintain a normal-space velocity above eighty percent of light-speed, for the particle and radiation shielding to survive such velocities simply did not exist. The highest safe speed in hyper was still lower, little more than .6 c due to the higher particle charges and densities encountered there, but the closer congruity of points in normal-space meant a ship’s apparent velocity could be many times light-speed. Equipped with Warshawski sails, gravity detectors, and the inertial compensator, a modern warship could attain hyper accelerations of up to 5,500 g and sustain apparent velocities of as much as 3,000 c. Merchantmen, on the other hand, unable to sacrifice as much onboard mass to the most powerful possible sails and compensators the designer could squeeze in, remained barred from the highest hyper bands and most powerful grav waves and were lucky to make more than 1,200 c, though some passenger liners might go as high as 1,500.