Then a flash.
Another ship appeared ahead of the first. The newcomer was dented and dirty, with a patched hull and an awkward appearance. On its nose, faded letters spelled a single word.
The two ships passed each other in a tiny fraction of a second, their relative velocities so immense, there was only time for a brief transmission to pass from one to the other.
The transmission was of a man’s voice, and it said: *Your family is alive.*
Then the newcomer was gone, vanished into the distance.
Within the lonely ship, within the emerald cocoon and the swaddling flesh, there lay a woman. And though her eyes were closed and her skin was blue, and though her blood was ice and her heart was still—though all of that, a smile appeared upon her face.
And so she sailed on, content to hold and wait and there to sleep, to sleep in a sea of stars.
ADDENDUM
APPENDIX I. SPACETIME & FTL
Excerpt from the Entropic Principia (Revised)
… necessary to outline a brief overview of the fundamentals. Let this serve as a primer and quick reference guide for later, more serious studies.
FTL travel is the defining technology of our modern era. Without it, expansion beyond the Solar System would be impossible, barring centuries-long trips on generational ships or automated seed ships that would grow colonists in situ upon arrival. Even the most powerful fusion drives lack the delta-v to jet between the stars as we do now.
Although long theorized, superluminal travel did not become a practical reality until Ilya Markov codified the unified field theory (UFT) in 2107. Empirical confirmation followed soon afterward, and the first working prototype of an FTL drive was constructed in 2114.
Markov’s brilliance was in recognizing the fluidic nature of spacetime and demonstrating the existence of the different luminal realms, as outlined in the earlier, purely theoretical work of Froning, Meholic, and Gauthier around the turn of the twenty-first century. Prior to that, thinking was constrained by the limitations of general relativity.
Per Einstein’s formulations for special relativity (coupled with Lorentz transformations), no particle with real mass can accelerate to the speed of light. Not only would that require an infinite amount of energy, doing so would break causality, and as later, practical demonstrations have shown, the universe does not break causality on a non-quantum scale.
However, nothing in special relativity prevents a massless particle from always traveling the speed of light (i.e., a photon), nor from always traveling faster than light (i.e., a tachyon). And that is exactly what the math shows. By combining several of the equations of special relativity, the underlying relativistic symmetry between subluminal, luminal, and superluminal particles becomes clear. With regard to the superluminal, substituting relativistic mass for proper mass allows superluminal mass and energy to become definable, non-imaginary properties.
This provides us with our current model of physical space (fig. 1):
Figure 1: Positive energy vs. velocity
Here the v=c asymptote vertical represents the fluidic spacetime membrane (which has a negligible but non-zero thickness).
By examining this graph, a number of things will become immediately and intuitively clear. First, that just as a subluminal particle can never reach the speed of light c, neither can a superluminal particle. In normal, STL space, expending energy (e.g., shooting propellent out the back of your spaceship) can move you closer to the speed of light. So too in FTL space. However, in FTL space, the speed of light is the slowest possible speed, not the fastest, and you can never quite slow down to it, not as long as you possess mass.
Since increasing speed moves you away from c in FTL, there is no upper limit to tachyonic speeds, although there are practical limits, given the minimal level of energy needed to maintain particle integrity (remember, less energy = more speed in superluminal space). And while rest mass in subluminal space is real, positive, and increases due to special relativity as v approaches c; in luminal space, rest mass is zero and v always = c; and in superluminal space, rest mass is imaginary at v=c, but becomes real, positive, and decreases when moving faster than c.
An implication of this is the reversal of time dilation effects with regard to acceleration. In both STL and FTL, as one approaches c, one ages slower with regard to the larger universe. That is, the universe will age far faster than a spaceship barreling along at 99% of c. However, in FTL, approaching c means slowing down. If, instead, one speeds up, traveling at ever higher multiples of c, you would age faster and faster compared to the rest of the universe. This, of course, would be a major disadvantage of FTL travel if ships weren’t encased in a Markov Bubble when superluminal (more on this later).
As one can see in the graph, it is possible to have a velocity of 0 in subluminal space. What does this mean when motion is relative? That you are at rest with regard to whatever reference point you choose, whether that be an outside observer or the destination you wish to travel to. A velocity of 0 in subluminal space translates to around 1.7c in superluminal space. Fast, but still slower than the velocities of many FTL particles. Indeed, even low-end Markov Drives are capable of 51.1c. Nevertheless, if you need to reach a destination as quickly as possible, it can be worth the delta-v to bring your spaceship to a complete stop with regard to your destination before transitioning to FTL in order to get that extra 1.7c of velocity.
Were it possible to directly convert subluminal mass into superluminal mass, without a Markov Bubble, 1.7c would be the highest possible speed achievable, as there is no practical way to further accelerate the mass (i.e. further reduce the energy state of said mass) aside from chilling it. One can’t suck propellent into your tanks, for example. This would be the second major disadvantage of FTL travel, again, if not for the use of a Markov Bubble.
The third disadvantage would be the fact that matter in superluminal space behaves radically differently than in subluminal space, to the point where life as we know it would be impossible to sustain. This, again, is circumvented via a Markov Bubble.
The three different continua—the subluminal, the luminal, and superluminal—coexist within the same time and space, overlapping at every point in the universe. The luminal exists in a fluidic membrane that separates the subluminal from the superluminal, acting as an interference medium between them. The membrane is semi-permeable, and has a definite surface on both sides, upon which all EM forces exist.
The membrane itself, and thus the entirety of three-dimensional space, is made up of Transluminal Energy Quanta (TEQs), which are, quite simply, the most fundamental building block of reality. A quantized entity, TEQs possess Planck length of 1, Planck energy of 1, and a mass of 0. Their movements and interactions give rise to every other particle and field.
Figure 2: Simplified diagram of spacetime
Taken as a whole, TEQs—and spacetime itself—behave in a quasi-fluidic way. Like a fluid, the luminal membrane exhibits: