Half an hour before arrival, Cass rolled onto her stomachand poked her head over the edge of the couch. Her engine’s exhaust wasa barely perceptible flicker, fainter than a methanol flame bydaylight, but she knew that if she reached down and placed her hand inthe stream of plasma, she’d rapidly lose any delusion that her Mimosanbody was indestructible.

She watched the Quietener growing beneath her, thesilvery sphere glinting Mimosa-blue. Surrounding it was a swarm ofsmaller, twinned spheres, unevenly colored and far less lustrous.Tethers, invisibly slender, allowed the twins to orbit each other,while ion jets balanced the slight tug of the Quietener’s gravity,keeping each pair’s center of mass fixed against the stars.

The Quietener made it possible to perform experimentsthat could never be carried out elsewhere. The right distribution ofmatter and energy could curve space-time in any manner that Einstein’sequations allowed, but creating a chosen state of quantum geometry wasa very different proposition. Rather than simply bending space-time inbulk, like a slab of metal in a foundry, it had to be controlled withthe same kind of precision as the particles in a two-slit interferenceexperiment. But the "particles" of geometry were twenty-five orders ofmagnitude smaller than atoms, and they could never be vaporized,ionized, or otherwise coaxed apart to be handled one by one. So thesame degree of delicacy had to be achieved with the equivalent of aten-tonne lump of iron.

Refining the starting material helped, and the Quietenerdid its best to screen out every form of impurity. Ordinary matter andmagnetic fields absorbed or deflected charged particles, while a shellof exotic nuclei, trapped by gamma-ray lasers in states from which theycould not decay without absorbing neutrinos, mopped up a greaterfraction of the billions wandering by than would have been stopped by agalaxy’s-worth of lead.