• 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.