It had been discovered early on that translating into the alpha band, the lowest of the hyper bands, at a velocity greater than thirty percent that of light was suicide, yet people had continued to kill themselves for centuries in efforts to translate at speeds higher than that. Not because they were suicidal, but because such a low velocity had severely limited the usefulness of hyper travel.

The translation into or out of any given band of hyper-space was a complex energy transfer that cost the translating vessel most of its original velocity—as much as ninety-two percent of it, in the case of the alpha band. The energy loss dropped slightly with each “higher” hyper band, but its presence remained a constant, and for over five standard centuries, all hyper ships had relied on reaction drives.

There were limits to the amount of reaction mass a ship could carry, and hydrogen catcher fields didn’t work in the extreme conditions of hyper-space. That had effectively limited ships to the very lowest (and “slowest”) hyper bands, since no one could carry enough reaction mass to recover velocity after multiple translations. It also explained why more stubborn inventors had persisted in their costly efforts to translate at higher velocities in order to maintain as much starting velocity in hyper-space as possible. It had taken over two hundred years for the .3 c limitation to be fully accepted, and even today, some hyper physicists continued to search for a way around it.

Even after one had resolved the problems of safe translation speeds, however, there was the question of navigation. Hyper-space wasn’t like normal-space. The laws of relativistic physics applied at any given point in hyper, but as a hypothetical observer looked outward, his instruments showed a rapidly increasing distortion. Maximum observation range was barely twenty light-minutes under ideal conditions; beyond that, the gravity-warped chaos of hyper and its highly charged particles and extreme background radiation made instruments utterly unreliable. Which, of course, meant that astrogation fixes were impossible, and a ship that couldn’t see where it was going seldom came home again.

The answer to that one had been the hyper log, the interstellar equivalent of the ancient inertial guidance systems developed on Old Earth long before the Diaspora. Early-generation hyper logs hadn’t been all that accurate, but they’d at least given astrogators a rough notion of where they were. That had been far better than anything that had come before, yet even with the hyper log, so many ships never returned that only survey vessels used hyper-space. Survey crews had been small, fantastically well-paid, and probably just a bit crazy, but they’d kept hyper travel in use until, eventually, one or two of them encountered what had killed so many other starships and survived to tell about it.

Hyper space itself was best considered as a compressed dimension which corresponded on a point-by-point basis to normal-space but placed those points in much closer congruity and so “shortened” the distance between them. In fact, there were multiple “bands,” or associated but discrete dimensions, of hyper space. The “higher” the band, the shorter the distance between points in normal-space, the greater the apparent velocity of ships traveling through it… and the higher the cumulative energy cost to enter it.