Post Hoc, Ergo Ante Hoc

1

      “It began when the nations finally admitted to themselves that superluminal travel was impossible. We had found a planet believed to be habitable for outside the reaches of our solar system, beyond even the reaches of our fastest ships within a single lifetime. Rather than take the sensible route many a scientist suggested and send a robot (or a collection of them) out in a reaction-drive ship to this planet, the politicians opted to fund a program for a single generation ship. Funding also went into hopeful methods of cryogenic sleep, but all research turned up dead ends and suggested the impossibility of restoring any reasonable semblance of human consciousness after the brain had essentially shut down.
      “So the flagship generation ship was launched in the late twenty-second century, and, a midst the weekly light-delayed communications from the ship's crew, we resigned ourselves to a painfully slow exploration of the universe.

      “Imagine everyone's surprise when that same ship appeared a year later in orbit around Earth.

      “After days of communication attempts and political bicker, a team was finally sent to board the now-accepted-to-be-derelict vessel. Inside, the fried remains of both humans and machinery were all they found.

      “However, some new data was salvaged from the wreckage, mostly from the apparently new machinery that had been installed. That data revolutionized space travel forever.

      “See, it is indeed possible, as we now know, to travel faster than the speed of light. However, some very special circumstances must come into play, and there are even more dangers involved. While Einstein's equations still hold true, they make no provisions for what some simply call “tricky math,” that is, tweaking the numbers to what would seem more or less impossible to make superluminal speeds possible. The physicists generations down in that lone generation ship had figured out how to make one of these mathematical tricks a reality. But, as always, there were unforeseen consequences.
      “It is completely impossible to reasonably steer an FTL ship when engaged in superluminal speeds. This is both because it requires tremendous levels of energy, because space itself is trying its best to keep you in a straight path (relative to its own geodesic curvatures), and because the ship is moving so fast it would be nigh-impossible for even a weak AI to steer it, let alone a human being.
      “The other, more significant problem has to do with radiation.
      “The most appropriate analogy would have to do with when humans first broke the sound barrier. As one approaches the speed of sound in a medium such as air, sound waves begin to build up in front of the craft like a wall (hence the term “barrier”). When this wall is surpassed (and mach speeds are attained), it is broken up in a kind of sound explosion. This is commonly referred to as a sonic boom. FTL travel has a similar problem, but due to the nature of the mechanism, instead of this built up high-energy radiation exploding outward (which would be disastrous for anyone and anything nearby), it explodes inward from the craft shell (thus the essential Faraday cage-like structure of the spacecraft does nothing to protect the inhabitants or electronics). This is what killed the crew and destroyed all the working electronics on-board.
      “Within a decade, this drive had been reproduced. The problems still remain, of course, and while it is impossible to protect the navigation-essential and other structural electronic aspects of the ship, the implementation of the so-called “drive room,” a Faraday cage to house and protect some backup systems and the crew, allowed for relatively safe superluminal travel. The age of practical, manned exploration of the cosmos had finally arrived.”
      “Wait, wait, back up for a minute,” a student exclaimed, “how did the space ship get back to Earth after only a month?”
      “Ahh, a good question.” The speaker replied, pausing for a moment as if to gather his thoughts for what he was about to explain, “You see, the craft had indeed made it to its destination, and had been there for some time while modifications were made to it. The reason it arrived back so early has to do, again, with Einstein. Do you understand how time works?”
      The students nodded.
      “Time is a construct of your reference frame, where you currently are and how you're currently moving in space. If one of you raises your hand, it takes a immeasurably small amount of time for the light to travel the distance from your hand to my eyes, and, in that, carry the information of the event. I may respond with any sort of action, but I could not respond to it until I saw it happen. Now, if you were light-minutes away from me and raised your hand, then I would not see the change for minutes. To me, I would react instantly to the change, but in the time it took the light from my reaction to get back to you, more time would elapse.”
      He paused. Some students seemed slightly puzzled at this, and the speaker responded to the questioning looks by continuing.
      “What if I were to know that you had raised your hand instantly as you raised it? I would be able to react before the light from the event reached me. To any observer, it would seem the effect pre-dated the cause.”
      The speaker paused again, surveying the students for reactions. He realized that he had already lost a few of them, but elected to push forward with his point regardless.
      “When you send something faster than light, this is the exact sort of effect. In physics we have a term known as the light-cone. This cone describes the places light from an event has reached as time elapses. This is technically a sphere that expands outward with time, but we use only two-dimensional space with one time dimension to represent it visually, and...”
      The speaker trailed off, realizing he had lost all the students at this point. He had to work on that. Backtracking, he tried to move back toward his original point.
      “The point is, when you travel faster than light, you seemingly arrive at your new destination before you've ever left from their perspective. This seems to violate an old physics principle of causality. This means that an effect can happen before a cause, or in this case, a starship can arrive before it has ever departed.”
      A few of the students were struggling to get a firm grasp on this idea, the rest had resigned themselves to lack of understanding. One student spoke up:
      “But that doesn't make sense. If we worked out the technology within a decade, wouldn't we have sent one of these ships to that habitable planet?”
      The speaker nodded, in both affirmation and as a gesture for the student to continue his thought.
      “And, if we did, wouldn't the new—old—the generation settlers have simply learned from that?”
      The speaker nodded again.
      “So where did the idea actually come from? It doesn't make any sense!”
      The speaker smiled. “Ah, you've hit upon the crux of physicists and philosophers during that early period. The answer is as simple as it is completely non-intuitive and difficult to grasp: causality isn't a law of the universe. We observe things as proceeding from cause to effect, but that's due to our primitive brains trying desperately to comprehend the space we live in. The universe doesn't care why things happen, only that they happen. Causes can vanish, effects can change, effects can even become their own cause. Paradoxes don't seem to actually exist, they're more or a philosophical exercise. If you go back in time and shoot your own grandfather (more or less impossible), you'll find that your grandfather will be dead, and you'll never have existed. Who, then, shot your grandfather. Well, you did. Don't be ashamed if you don't get it. I don't even get it. But that just seems to be how the universe works. We just need to accept it.”
      The students didn't seem too happy about this answer. The same student as before raised his hand.
      “So is this going to be a physics or a history course?”
      The speaker sighed. He knew someone would ask this question; it didn't stop him from hoping they wouldn't. He rubbed his temples for a second, and then replied.
      “While the course will be heavy of physics ideas, it is primarily a history course. You will not be required to understand the physics ideas, only knowledge of the historical events will be necessary.”
      The students seemed satisfied at that answer. Of course, he told himself, what else would they have expected, taking a History of Space Travel? Don't try to force physics on these students just because you've been shunted from teaching any real physics. That's your problem, not theirs.
      Aloud, he spoke to the class, “I know we haven't filled up the whole time slot for today, but this is all I wanted to cover. Class dismissed, see you next time.”


      The speaker strode out of the room, and his posture visibly relaxed. This change was only momentary, as he tensed up again after nearly running into two men standing at strict military attention just outside his office.
      “Professor Julius Henthrow?” One of them inquired, never once relaxing his continence.
      “Ye-Yes, that's me.” Julius replied, both startled and slightly embarrassed.
      “ID?” The other inquired, equally stone-faced.
      “Oh!” He fumbled about in one of his inner pockets before producing a glossy card with a metallic backing.
      “No, personal ID. Not the antiquated system this institution insists on using.” The man glared at him stonily. With a slightly abashed look, the professor held out his hand and rolled up his sleeve. The guard swept a scanner over it, which let out a soft bing as it detected the chip in his arm.
      “Signature verification?”
      Julius pressed his thumb onto the open side of the scanner.
      “Thank you. You may enter.”
      It was only at that point that Julius recalled that the guards were standing outside his own office. What exactly is going on here?
      This question, of course, was answered the moment he stepped in, as the man facing the window turned around. He had similar military garb to the two outside the office, but Julius would have been able to tell even without that based on his posture alone. While n versed in military rank or garb, Julius could tell by his adornments that he was a higher-ranking officer than those he just encountered.
      “Professor Henthrow. I've been instructed to inform you that your presence has been requested on a... Scientific expedition.” The way the man paused seemed to indicate there was something more to be said. However, before Julius could interrupt, he continued. “The FTL ship Endeavor is parked in orbit and will be departing in three days. You should find an itinerary on your interface. We expect to see you there.” Then man strode past Julius and toward the exit to the office. As he reached the door, the professor managed to find his voice.
      “Wait, what's going on? Why me? I'm just a phys... a history professor.”
      “Professor Henthrow, your particular presence has been requested by those in charge of this... Expedition. Any more questions you have will be answered aboard the Endeavor. Good evening.”
      While the professor was still struggling to articulate a response, the man disappeared from his office, leaving more questions than Julius could ponder.