Since the surface of the bubble acts as a perfect mirror, it is nearly impossible to shed waste heat from a spaceship during an FTL flight. This is why it becomes necessary to put crews and passengers into cryo prior to the trip.
Given that, it is impractical to run a fusion drive while in FTL. Thus, Markov Drives—which require a not-inconsiderable amount of power to generate and maintain a conditioned EM field of sufficient strength—rely upon stored antimatter to produce said power. This is more efficient and results in the least amount of waste heat.
Although a Markov Drive and the spaceship around it contain a large amount of compressed energy by FTL standards, the only energy that superluminal space sees is that which appears via the surface of the bubble. Thus, the more efficient a Markov Drive (i.e., the less energy it uses to generate the conditioned EM field) the faster you can travel.
Were one unfortunate enough to collide with a chunk of FTL mass, this would result in immediate disruption of the Markov Bubble and immediate return to STL space, with possible catastrophic consequences, depending on one’s location.
The less energy you use to generate a Markov Bubble, the increasingly delicate the bubble becomes. Large gravitational hills, such as those around stars and planets, are more than strong enough to disrupt the bubble and dump you back into normal, subluminal space. This is what is known as the Markov Limit. With adequate computational powers, the limit can be lowered, but it cannot be removed entirely. Currently, Markov Drives cannot be activated in a gravitational field stronger than 1/100,000 g. This is why, in Sol, spaceships have to fly out to a distance equivalent to the radius of Jupiter’s orbit before they are able to go FTL (although if you’re actually near Jupiter, you’ll have to fly out even farther still).
As annoying as the Markov Limit is—no one likes having to sit through several more days of travel after weeks or months in cryo—it has actually proven to be a good thing. Because of it, no one can drop an FTL asteroid directly onto a city, or worse. Were there no Markov Limit, every spaceship would be far more of a potential threat than they already are and defense against surprise attacks would be basically impossible.
We are also fortunate that the viscoelasticity of spacetime precludes superpositional bombs. If a ship in FTL space flies over a mass in STL space that produces less than 1/100,000 g, and the ship returns to subluminal space at that precise moment, the ship and the mass will push each other apart with equal force, preventing either object from intersecting. If they did intersect, the resulting explosion would be on par with an antimatter detonation.
Once a spaceship has entered superluminal space, straight-line flight is usually the most practical choice. However, a limited amount of maneuverability is possible by carefully increasing the energy density on one side or another of the bubble. This will cause that side of the spaceship to slow, and thus the vessel as a whole to turn. But it is a gradual process and only suitable for small course corrections over long distances. Otherwise you risk destabilizing the bubble. For more substantial changes, it is better to drop back into subluminal space, reorient, and try again.
Any changes in heading that occur in FTL will be reflected upon returning to STL. Likewise any changes to total momentum/speed, with the degree of change being inversely proportional.
Technically it is possible for two ships in FTL to dock, but the practical difficulties of matching exact velocities, as well as the mathematics of merging Markov Bubbles, means that while it has been done with drones, no one—to our knowledge—has been crazy enough to try it with crewed ships.
Although a ship within a Markov Bubble can never directly observe its FTL surroundings, some level of sensory information is possible. By pulsing the bubble at the appropriate frequencies, FTL particles can be created on the outer surface of the membrane, and these can be used both as a form of radar as well as a signaling mechanism. With careful measurement, we can detect the return of the particles when they impinge upon the bubble, and this allows us to interact with superluminal space, albeit in a crude manner.
This is the same method by which FTL comms and sensors work. Both may be used far closer to a star or planet than one can maintain a Markov Bubble, but as with the bubble, there is a point at which the associated gravity hills become too steep for all but the slowest, most energetic FTL signals to climb.
Due to the protection of the bubble, a ship retains the inertial frame of reference it had prior to FTL, which means it does not experience the extreme time dilation that an exposed superluminal particle would. Nor does it experience any relativistic effects at all (the twins of the famous twin paradox will age at the same rate if one of them takes an FTL flight from Sol to Alpha Centauri and back).
This, of course, leads us to the question of causality.
Why, one might ask, doesn’t FTL travel allow for time travel, as all the equations for special relativity seem to indicate? The answer is that it doesn’t, and we know this because … it doesn’t.
Although that may seem facetious, the truth is that the debate remained unsettled until Robinson and the crew of the Daedalus made the first FTL flights. It took empirical experimentation to answer the question of time travel for certain, and it was only after the fact that the supporting math and physics were fully developed.
What was found was this: no matter how fast a superluminal voyage—no matter how many multiples of c your spaceship travels—you will never be able to return to your origin point before you left. Nor for that matter can you use FTL signals to send information into the past. Some amount of time will always elapse between departure and return.
How is this possible? If one is at all familiar with light cones and Lorentz transformations, it should be blindingly obvious that exceeding the speed of light results in being able to visit the past and kill your own grandfather (or something equally absurd).
Yet we cannot.
The key to understanding this lies in the fact that all three luminal realms belong to the same universe. Despite their seeming separation (as it appears from our normal, subluminal point of view), the three are part of a larger, cohesive whole. And while local violations of physical laws may appear to occur in certain circumstances, on a global scale, those laws are upheld. Conservation of energy and momentum, for example, are always maintained across the three luminal realms.
Adding to that, there is a certain amount of crossover. Gravitational distortions on one side of the luminal barrier will have a mirrored effect on the other. Thus, an object moving in subluminal space will leave an STL gravitational distortion in the equivalent FTL space. Waves from the distortion will propagate outward at c no matter what, but the movement of the gravitational center will be less than c. And the reverse is true for a superluminal gravitational mass, which would leave an FTL track of spacetime ripples through normal, subluminal space. (Of course, no such FTL tracks were detected prior to the invention of the Markov Drive, but that was a result of—in most cases—their extreme weakness and the distance of most superluminal matter from the main body of the Milky Way.)
Note: it’s important to remember that just as anything moving faster than c in subluminal space could theoretically be used to arrange a causality violation, so too could anything moving slower than c in superluminal space. In FTL, c is the minimum speed of information. Above that, relativity and non-simultaneity are maintained, no matter how fast you might be going.
Even without the existence of a Markov Drive, we now have a situation where natural phenomena seem to be violating the light-speed barrier on both sides of the spacetime membrane, but again, without inducing any causality violations.
The question returns: Why is that?
The answer is twofold.
One: no particle of real mass ever breaks the light-speed barrier in either the sub- or superluminal realm. If one did, we would see all of the paradoxes and causality violations predicted by traditional physics.
Two: just as TEQs form the basis for every subluminal particle, t
hey also form the basis for every superluminal particle. As their name implies, TEQs are capable of existing in all three realms at once, and they are capable of moving as slow as the slowest STL particle and as fast as the fastest FTL particle—which is very fast indeed, limited only by the lower boundary of energy needed to maintain particle coherence, and even then, TEQs can move faster still given their Planck energy of 1.
Thus, with the discovery of TEQs, we have an object that is capable of conveying information far faster than the speed of light. Normally this only occurs in the superluminal realm, but any TEQ is capable of such speeds, and they often transfer from sub- to superluminal velocities as their position within the spacetime membrane changes. These changes are responsible for much of the quantum weirdness seen at small scales.
The light cone, as it were, of an observer using TEQs for informational gathering would be far, far wider than if they were only using photons (wider, but not complete; TEQs have a finite velocity). The wider light cone—or TEQ cone—expands the total set of events that can be regarded as simultaneous. Although non-simultaneity and relativity are maintained throughout all three luminal realms (when considered as a whole), the immense velocity of TEQs reduces the events that can be considered non-simultaneous to a far smaller number, and those that are lie outside the fastest speed of an FTL particle. And while, in theory, the universe remains fundamentally relative, in practice, the vast majority of events may be regarded as ordered and causal.
This means that when a ship goes FTL, it cannot induce any causality violations within superluminal space, as the Markov Bubble is a superluminal particle/object and behaves as such. And when a ship drops back to STL, no causality violations occur because travel times are always slower than the top speed of the TEQs (i.e., the speed of information).
Where a paradox would have occurred in subluminal space, events are found to have proceeded in a causal relationship, one after another, without any contradiction. From a distance, it may appear that one can send a piece of information back to its origin point before it was transmitted, but appears is the word to keep in mind. In actuality, no such thing is possible. If one tries, the return transmission will never arrive any sooner than one unit of TEQ Planck time (where TEQ Planck time is defined as the length of time for a TEQ at maximal speed to traverse one unit of Planck length).
As a result, whenever one sees the possibility for a causality violation in subluminal space, one is, in essence, seeing a mirage. And whenever one tries to exploit said possibility, one will fail.
This renders a large number of observations in our subluminal universe illusionary. Prior to the invention of the Markov Drive (or failing that, detection of FTL gravitational signals), none of this mattered. Relativity was maintained throughout because FTL travel and communications weren’t possible. Nor could we accelerate a spaceship to high enough relativistic speeds to really begin to investigate the issue. Only now, with access to both the sub- and superluminal realms, has the truth become clear.
As the light signatures of our modern-day FTL trips begin to reach the nearby stars, an observer positioned there with a powerful enough telescope would see a confusing series of images as ships and signals pop out of nowhere, seemingly out of order. However, by observing TEQs instead of photons, the true order of events may be established (or by physically traveling to the sources of the images).
The exact mechanism that prevents causality violations in STL space is the top velocity of the TEQs. As long as that isn’t broken (and no known mechanism would allow for this), FTL will never allow for time travel into the past. And for that we should be grateful. A non-causal universe would be sheer chaos.
* * *
With our overview finished, we will now examine the theoretical possibility of using conditioned EM fields to reduce inertial effects and to lessen or increase perceived gravity. Although as yet impractical with our current levels of antimatter production, in the future, this could be a means of—
APPENDIX II
SHIP-BASED COMBAT IN SPACE
Transcribed from Professor Chung’s Lecture at the UMC Naval Academy, Earth (2242)
Good afternoon, cadets. Be seated.
Over the next six weeks, you’ll receive the finest education the UMC can muster on the means and methods of ship-based combat. Fighting in space isn’t twice as hard as fighting in air or water. It isn’t three or four times as hard. It’s an entire order of magnitude more difficult.
Zero-g is a non-intuitive environment for the human brain. Even if you grew up on a ship or station, as some of you have, there are aspects of inertial maneuvering you will not understand without proper instruction. And no matter how sharp you might be when it comes to good old slower than light, FTL throws those rules out the airlock and stomps on them until they’re a bloody mess.
The maneuvering capabilities of your vessel and those you fight alongside will determine where you can fight, who you can fight, and—if needed—the requirements of retreat. Space, as has often been stated, is not only large, it’s larger than you can imagine. If you can’t close the distance between you and your target, they are invulnerable to your fire. This is why it is often advantageous to drop out of FTL with a high degree of relative motion. But not always. Circumstances vary, and as officers, you will be called upon to make those sorts of judgment calls.
You will learn the capabilities and the limitations of our fusion drives. You will learn why—despite what you may have seen in games or movies—the concept of personal combat space vessels is not only outdated, it never was a thing. A drone or missile is not only cheaper, it is far more effective. Machines can withstand far more g’s than any human. Yes, on occasion you get a radicalized miner or a local cartel member who uses a smaller spaceship for piracy or the like, but when confronted with a proper warship such as our new cruisers or battleships, they always lose.
When you do engage the enemy, combat will be a strategic interplay between the different systems of your ships. A chess game, where the goal is to inflict enough damage on the hostiles to disable or destroy them before they do the same to you.
Every weapon system we use has different advantages and disadvantages. Missiles are best for short- to medium-range attacks, but they’re too slow and carry too little fuel for longer-range engagements. And once you fire them, they’re gone. Point-defense lasers can stop incoming missiles, but only a certain number and only until the laser overheats. Casaba-Howitzers are also short- to medium-range weapons, but unlike missiles, lasers can’t stop them once they’re fired. In fact, nothing short of a solid wall of lead and tungsten ten or twenty meters thick is going to stop the radiation beam from a Casaba-Howitzer. The downside is their mass; you can only carry so many Casaba-Howitzers in your ship magazine. Also, at long range, the beam from a howitzer will widen, leaving it about as powerful as a wet fart in a blizzard. Medium to long range, you rely on your keel laser. But again, you have to worry about overheating, and your enemy can counter with chalk and chaff to disperse the incoming pulse. Mass drivers and nuke-powered penetrators can be used at any distance, as kinetic weapons have effectively infinite range in space, but they’re really only practical in close-range engagements where the enemy doesn’t have time to evade or long, long-range attacks where the enemy doesn’t know you’re shooting at them.
No matter which weapon or weapons you choose to employ, you will have to balance their use with your ship’s maximum thermal load. Do you fire your keel laser one more time or do you execute another evasion burn? Do you risk extending your radiators during a firefight in order to shed a few extra BTUs? How long can you risk cooling down before jumping to FTL if the enemy is chasing you?
Ship-to-surface combat has different requirements than ship-to-ship. Stationary installations such as orbital defense platforms, hab-rings, and converted asteroids all require unique strategies. If you choose to board an enemy vessel, how best to protect your troops as well as your own ship?
Along with physica
l combat, you will have to contend with electronic warfare. The hostiles will be trying to subvert your computer systems and turn them against you. Jamming may not protect you, as the hostiles could use a line-of-sight beam to initiate a system handshake.
All these things and more must be taken into account when engaging in space combat. The environment wants to kill you. The hostiles want to kill you. And your own instincts and lack of knowledge will kill you—and everyone around you—if you don’t master these fundamentals.
Now, some of you are thinking, “Won’t the ship mind or our pseudo-intelligences handle most of these things?” The answer is yes, they will. But not all the time. A ship mind doesn’t have hands. What they can move or fix is limited, and that goes double for pseudo-intelligences. In an emergency, some things can only be done by a human. And there have been numerous cases where the ship mind or the ship’s computer system has been disabled by enemy action. When that happens, these decisions will fall to you, the next generation of UMCN officers.
The next six weeks will be some of the hardest six weeks of your lives. That’s by design. The UMC doesn’t want anyone who is unqualified to step onto a spaceship where they can endanger not only their own lives but the lives of their fellow crew. Better that you wash out now and go back to being swabbies who only have to worry about keeping their boots polished and their jaws off the deck. If you don’t think you can handle this sort of responsibility, get up and leave. The door’s right there, and no one, not me, not your superiors, and not the UMC will think any less of you for walking out now.… No? Alright then. Over the next month and a half, my staff and I are going to put you through the wringer. You will wish you gave up. But if you do the hours, work hard, and learn from the mistakes of those who paid for their knowledge with blood and lives, then you have a good chance of wearing your officers’ pips—wearing them and doing justice to them.
To Sleep in a Sea of Stars Page 96