Warning: contains pseudoscientific gibberish!!! Do not learn from this post
I did try long ago to build a history for Flat Black in which laser-pumped lightsails were used either to despatch colony ships or to establish an infrastructure for technologically primitive FTL (instantaneous) travel. But the Tau Ceti and the other colonies of the core got too far ahead of the periphery, the power requirements of the launch lasers scared me, and the inventor of FTL ended up with not enough legitimacy. So in this version you have the Ramotswe-Raerino modified Alcubierre warp encapsulator, or “flinger”. I don’t want to say too much about the Ramotswe-Raerino-Alcubierre warp bubble. Any statement about its physics would be mere corroborative detail, intended to add an air of artistic verisimilitude to an otherwise bald and unconvincing tale. The first problem with that is that a decorative statement (such as “the warp has such negative density of gravitational energy as to exactly match the mass of the ship and other contents, leaving the capsule with zero net mass”, or “all information about the interior of the capsule is temporarily unavailable to the outside universe, leaving conserved quantities such as mass, charge, entropy, and spin as property of the capsule’s surface”) always turns out to imply something that I don’t want, and that my friends with science degrees figure out for me while meaning to be helpful. The second problem is that a statement that sounds sciency to me with my sophomore physics is SoD-busting gibberish¹ to a reader or player who knows science. “Keep a still tongue in a wise head.”
So here’s what a flinger does, at the level of “set the date you want to go to with this dial, turn the machine on with this key, hold down this safety and press the green button”.
A Ramotswe-Raerino warp encapsulator (popularly “flinger”) is a large, delicate, and expensive piece of apparatus, several hundreds of kilometres long, consisting of myriads of field generators held in place by a framework, and with an open channel along its axis. You build them in orbit, and they only work properly
2.2 1.7 AU from Sol, because of gravity and tides. Accelerating or rotating a flinger is a pig of an operation, because all the pieces have to be precisely in place and orientation. If any of those kilometre-long struts bends, if any of those ten-kilometre stay cables stretches, the thing will need an expensive overhaul.
So you have a flinger in deep space. You point it at the star you want to travel to, replenish the consumables, put a spaceship in the middle, turn on the power and the computers, and press “go”. Machines start doing things, generators glow with what would be Cherenkov radiation if you weren’t in vacuum. Lines of sight through the flinger start rippling and quivering like heat haze. After a few tens of hours the distortions settle down to a regular pulsation that slows down like the beating of a guitar string coming into tune. When its frequency reaches zero there is a violent convulsion. The ship is gone. Many of the components of the flinger are white-hot. Some have failed. A vapour of coolant is spraying from ruptured lines. Almost everything is at least a few microns out of place. Cooling, refilling, checking, and adjusting everything to prepare for the next launch is automatic, but takes days.
What the flinger does is to “encapsulate” the ship (whatever is in the middle of it) in a Ramotswe-Raerino warp capsule, which is an exotic solution to the equations of General Relativity, kind of like an Alcubierre warp, but not all that much like it. “Have you heard of a Alcubierre warp?” “Yes.” “It’s not really like that.”
- A Ramotswe-Raerino warp travels at the speed of light
- The canonical form of an R-R capsule travels though flat space; the practical version is an approximate solution that travels through sufficiently-close-to-flat space. When it reaches sufficiently curved space it distorts, tears open, and ceases to be: an energetic event that is conspicuous to detectors
- A fully symmetrical R-R capsule goes “straight uphill” and “straight downhill” in a gravitational field, “straight on” in flat space. Travelling slantwise induces asymmetries that curve the path, distort the capsule, accelerate through feedback, and burst the warp. But you can calculate that backwards, setting a warp with carefully-calculated asymmetry out on a very slightly oblique path, just precisely adjusted become more symmetrical and straighten its course as the asymmetrical effects of oblique gravity work on it.
- A warp capsule cannot be steered once it is formed.
- A theoretically perfect warp capsule in flat space goes on forever, with no beginning and no end. The practical ones actually used only approximated that, and were unstable. They could be formed within Time, in curved space. They were unstable; they disintegrated in excessively curved space and unravelled in finite time.
- No time passes inside the warp between its formation and its rupture.
Bifrost was built in a elliptical solar orbit with its aphelion at
2.2 1.7 AU, non-rotating. That had a shorter period than a 2.2 1.7-AU orbit (which gave it more frequent launch windows), and by Kepler’s Third Law meant it was moving more slowly at aphelion, so it spent longer in the launch cone (more launches per window). But it had continual problems with precession and tidal effects. It worked, but at such cost that no-one did that again.
Later flingers were built in ~
2.2 1.7-AU circular orbits, rotating synchonously. Each one provided a potential service to any star within a narrow band of sky on either side of the plane of its orbit, for a week or two once every 2.2 years, approximately. The width of the band and the duration of the launch window were not hard-edged, but limited by the increasing instability of the capsules with increasing launch angle.
Flingers were expensive to build and comparatively cheap to run. The salvage value of a used flinger was small compared to its construction costs (sunk costs were large). And it was difficult and expensive to change their orbits once they were built². The result is that when a flinger was built to serve a colony project, if the project failed to live up to projections it was more economic to keep running the flinger for a short-run profit on variable costs than to liquidate it and crystallise the long-term losses.
Given any two destinations, a flinger could be built to serve them both at the same cost as a flinger that served only one. It was thus trivially easy to spread the cost of amortisation over two colonies.
Each flinger spent less than 2% of its time “pointed at” each colony it served. The rest of the time it was pointed at a little patch of sky dictated by timing the characteristics of its orbit. If another destination happened to be in that patch another potential launch service was available towards it, at no increase in the capital cost of the flinger. That meant that habitable worlds sometimes got their interstellar transport infrastructure built as a free side-effect of building transport infrastructure for somewhere else. Later, many habitable worlds were discovered in the accessible bands of existing flingers. Transport to those worlds could be had very cheaply.
As technology improved between AD 2059 and AD 2353, and as the flinger industry expanded, flingers gradually became significantly cheaper to build and run. Over the same span of time existing flingers became more valuable as new colonies were established in their ambits. Simultaneously, the steady discovery and confirmation of more habitable and terraformable planets meant that there were ever more opportunities to build a flinger that might serve multiple colonies. Usual practice after AD 2200 or so was to build each new flinger in such an orbit that it provided lucrative access to one of the established and desirable colonies, thus defraying the cost of providing access to a new colony (and, increasingly, incidental access to other low-demand colonies and yet-unsettled worlds).
The upshot of all that was that from AD 2250 or so there were lots of habitable worlds that were not attracting mainstream migrants, and to which JAFAL transport was available cheaply. While at the same time an increasing share of the population were coming to accept emigration. Secular and religious utopist and separatist projects found it ever easier to buy a planet and get there, requiring any ever-narrower base of support to do so.
¹ Like “Lord John Marbury” explaining his titles to Toby Zeigler in that episode of The West Wing.
² Inclination changes. Ugh.