Also, in Deepness in the Sky, it goes into the Qeng Ho's practice of broadcasting an encyclopedia of general technology throughout known space, to accelerate pl

Also, in Deepness in the Sky, it goes into the Qeng Ho's practice of broadcasting an encyclopedia of general technology throughout known space, to accelerate planets' development until they were advanced enough to trade with. It's sub-light, but so is travel, at least in that zone.