The last post in this series is here. You’ve decided to make up a name, but to be honest about how little you remember.
“I’m Sergeant Berschiss. Mind telling me your name, and what you know about what happened?”
After a moment’s hesitation, you reply, “Syndel. I don’t remember anything prior to looking over the cliff, so I don’t really know what happened.”
“Hmph,” is all the sergeant has to say at first. He stares at you for a moment, his one good eye narrowed with suspicion. Then he turns away, and waves at the younger man with him. “This is Corporal Dunscher.” Dunscher glances back from the horses to give you a broad smile that does not quite reach his eyes.
After the conversation stalls for a little bit, you ask, “Where are we going?”
“Venbrik,” the sergeant answers. “And we’re coming from the fort at Kleriv. We’re picking up some supplies.”
“There’s some sort of feast planned for this evening,” the corporal adds. “I’m not sure why, though. It’s not one of the regular holidays. But, the cook needs more stuff to make it happen. Also more beer.”
The remainder of the trip to Venbrik takes about two hours at the pace of the cart. The ride takes you south and down, running roughly parallel to the river. After the first hour, the trees thin out, the mist fades to nothing, and the sun shines on fields. A few farmers and their animals go back and forth across them, planting the spring wheat.
Sergeant Berschiss is mostly quiet along the way, adding only the occasional brief comment or grunt. He gives you the occasional glance from his one good eye, watching you for… something. You’re not sure what has made him suspicious.
Corporal Dunscher, on the other hand, is happy to chatter along about anything. He helpfully talks about whatever subject you bring up. He helpfully explains that you are currently near the eastern frontier of the Ishkaev Empire, ruled by Dleshan Kaev. The canyon you passed is a bit of an oddity, through which the river Layev passes. Between the mist in the canyon and the rapids further upstream, the river is not generally used for travel. The small town of Venbrik is the largest town nearby. It is primarily a farming community, with a few local craftsman as well. Dunscher has high praise for the beer, though he concedes that it is not as good as that which can be found in Alederik, the empire’s capitol. The fort of Kleriv is built on a small hill, overlooking the Layev. It serves as a base for the various expeditions that are currently exploring the frontier across the Layev. In all this discussion, the only name that stands out as being familiar is the name of the emperor.
It is only when Berschiss says that you are almost there that you realize you are almost out of time to interrogate the younger soldier. If you want to hear a bit more detail about something, now is the best time to ask before the two men go to do their business in town.
Option 16: Ask about Emperor Kaev.
Option 17: Ask for more details about Venbrik and the local geography.
Option 18: Ask for more details about Fort Kleriv and the frontier.
You may call parts of this fantasy rather than science fiction. Sorry for the blurry genre boundaries – Michael
People don’t like to die. That seems to be the basis of one of the oldest attested tropes: immortality, or at least far-longer-than-normal lifespans. Like The Hero With A Thousand Faces, this one shows up in very old cuneiform tablets from 2600 BCE or so. There may be some underlying neuro-psychological reason for this trope being common, but I cannot speak to that.
Instead, let’s talk about how immortality is presented in some more recent works and how those would play out if things were handled more consistently.
We mentioned Heinlein’s Methuselah’s Children before – it is the namer for The Masquerade. The Howard families there aren’t immortal, at least not at first. They are simply long-lived, due to genetic factors. But biotechnology develops to the point that the longest-lived Howards born in the early 1900s live effectively forever. Heinlein was born in 1907. I deduce Author Appeal.
To take a more extreme example, consider the Highlander franchise – the first movie only. Scattered around the world, born at various times over the last several thousand years, are a population of immortals. They appear like normal people until they “die” – or rather experience something that would kill a normal person. They then stop aging, which is convenient for explaining why some immortals are portrayed by old actors and some by younger ones. There aren’t any immortal children, so this must be a Puberty Superpower. The immortals are also nigh-indestructable, with nearly perfect memories for thousands of years of life, and only decapitation will kill them. Clearly, they have very unusual brains.
We’ve previously mentioned a common problem to both of these: why is there a masquerade? The Howards didn’t need to keep their life expectancies secret, and should have been discovered far sooner. The Highlander immortals run around having sword fights to the death for no adequately explained reason. Why didn’t one of them set up as a philosopher-king or an unkillable gladiator or a legendary drinker two thousand years ago? The real answer is meta-fictional: the authors didn’t want to consider alternate history, at least not for the past.
But what forms of immortality are more or less plausible in reality?
Extending human life expectancy, both for people alive now and in later generations, is obviously possible. After all, in many places, life expectancy is now about twice what it once was. There are genetic contributions to longevity, so a selective breeding program like that of the Howard’s isn’t implausible. But the program in Methuselah’s Children is implausibly rapid. The requirement for being inducted into the Howards is having had four centenarian grandparents. That’s not a strong enough selection criterion to increase life expectancy to 150 years over a half-dozen generations. Longevity is determined more by environment and luck than by genetics, so many people with good genes would not qualify and many with bad genes would. And longevity probably wouldn’t present as an overall slowing of normal aging. It would be more like “you are less likely to get rapidly-progressing fatal cancers” or “your hormonal balance is a bit different than normal and you probably won’t get osteoporosis”.
But massively increased human life expectancy could be plausible, provided it either developed over enough generations or from very sophisticated biotechnology. The limiting case might be “biological immortality” – a cell or larger organism can persist indefinitely without passing through a reproductive phase that would count as a new generation. For example, hydras, the jellyfish Turritopsis nutricula, and perhaps even lobsters appear to have an indefinite lifespan with no senescene. This is not “true” immortality, of course: the animals die by injury, disease, predation, or out-competition for resources.
Why isn’t biological immortality more common? One model is the Red Queen hypothesis, which says that a population of organisms needs constant changes in genetics and overall biochemistry to survive in an environment while competing against each other (this also gets invoked to explain the evolution of sex). A population of short-lived organisms that can adapt to take advantage of the environment and changes in it will often have an advantage over a longer-lived population that doesn’t adapt so quickly. So while biological immortality is possible, it is not likely to naturally appear in that many species, especially not in humans – none of our ancestors for the last several hundred million years have had that skill.
Technological immortality is another possibility. Should someone create strong/Turing-test-passing AI, it would be possible to just keep copying the AI program to new substrate – subject to all of the usual considerations when porting software to new hardware. But, to the great disappointment of people like Ray Kurzweil, human brains can’t be uploaded into computers with any approximation of continuity of consciousness.
Implausible and Impossible
The immortals in Highlander have problems, mystic “Quickening” superpowers aside. Connor MacLeod is thrown overboard and sinks to the bottom of a lake. He walks ashore, after spending a long time underwater. Brain damage aside (the water in the lake was relatively cold), where are his muscles getting the oxygen for that exercise? And when he is surviving being stabbed repeatedly or shot by a submachine gun, how is his body patching everything back together? He has to have some Wolverine-like healing factor. Which means Wolverine and the Highlander immortals have the same problem: food. It takes a lot of energy, protein, fat, and calcium phosphate to rebuilt an arm or a shattered rib cage. Why aren’t they constantly swallowing protein shakes and bone meal? And why isn’t there a huge temperature increase as all of that energy rapidly cascades down into heat?
A related question: McCloud dies if his head is cut off, but what if he loses a toe or an arm or a leg? A bunch of other works have explored possible answers to that one. And what happens if a disease appears that the healing factor doesn’t protect against? Etc., Etc. There is really no way to make a blanket healing factor like that plausible, at least not without imposing very steep associated costs.
Even more durable immortals, like Wolverine or vampires or some zombies, are right out – they aren’t completely consistent because there is no way to do so without immediately violating some of the laws of physics.
The last post in the sequence is here. Time to say hi to the soldier guys.
You wait a few minutes, hiding behind a tree, watching and listening to the two men.
“… and that,” the older man says, “Is Oblivion Canyon.” He waves towards the cliff you came from. “Or the closest this road gets to it, at any rate. Now, the exact region of danger varies a lot, so if you get stuck investigating it for some reason, the rule of thumb is that if you can’t remember what you ate for breakfast that morning, you’re too close.”
The younger man raises his eyebrows. “And what if I’m close enough to forget the rule of thumb?”
“Then you’re probably too far in for anybody to help you.”
“Great. Not only am I assigned to the Empire’s best backwater, it’s got a canyon full of soul-sucking magic.”
The older man chuckles, and points at his missing eye. “Believe me, next time there’s a war on, you’ll wish for the safe backwater again.”
Before the younger man can reply, you emerge from the brush, to the right from their perspective, and a little ahead of them on the road. “Hello! I could use a ride, if you don’t mind.”
The younger soldier pulls up on the reins, startled. The older one reaches for his sword, then relaxes slightly.
The older man looks at you up and down. “Chuthak, woman, what are you doing out here dressed like that?”
“I’m… not really sure,” is your best answer.
The older man squints at you with his one good eye. “What’s the last thing you remember?”
You don’t know much, so telling what little you do know probably won’t be too harmful. “Standing over there,” you say, pointing towards the edge, “and thinking about jumping in.”
He mutters a few more oaths, then stops. “Really. Hmph.” The younger soldier just looks back and forth between his superior and you, apparently confused. “Might as well give you a ride. Jump in the cart and we’ll be going.”
You hop the tail of the cart easily enough, and take a seat next to a couple of empty barrels. They must be going into town somewhere for supplies.
After getting the horses moving again, the young man speaks quietly to his companion. He probably thinks you can’t hear him, given that he says, “You know, if her memory’s that messed up, we could, heheh–”
“Not funny. Don’t even think that, unless you want a thorough flogging.” Then he turns around towards you, and says, more loudly, “I’m Sergeant Berschiss. Mind telling me your name, and what you know about what happened?”
Actually, you don’t remember your name. Or what happened. Hmm.
Option 12: Make up a name and some more plausible story than not remembering anything.
Option 13: Make up a name, but say you actually don’t remember anything.
Option 14: Shrug and indicate that you don’t have any answers, either.
Option 15: Change the subject.
“What if?” is a very popular question. It’s arguably the basic question for most works of fiction. But here we’ll talk about one variation: “what if something happened differently?”. As we talked about in the first half of this series, time travel jumps up and down the timeline of a story, causing closed loops and paradoxes. But what if the timeline breaks into two or more possibilities? Then you have alternate universes – where something in the past of a story is changed (the “point of divergence”) and everything afterwards is different.
This is popular for resolving time travel paradoxes, sometimes with a handwave misapplying the many-worlds interpretation of quantum mechanics. But it’s also popular in its own right, spawning long lists of related tropes and whole forums and wikis for discussion. There is both alternate history of reality, and alternate universe fic of other fictional stories. So what problems are there with such stories?
Butterflies & Butterfly Nets
The butterfly effect was originally named from discussions of weather forecasting. The basic idea is that while climate is relatively predictable, daily weather is a boundly-chaotic system. Even the slightest difference in initial conditions, like a butterfly flapping its wings, can dramatically change everything that follows. This is also known as “for want of a nail”.
For alternate universe fic and alternate histories, the butterfly effect is almost always not respected. That’s because it is hard to trace out causality in complex systems, even in retrospect. For example, if Star Trek: Voyager had cast a different actor as Seven-of-Nine, Barack Obama might not currently be president of the USA. The causality for that one goes like this: Jeri Ryan played Seven-of-Nine. She was then married to Jack Ryan. They eventually divorced, in part because of the stresses from frequent travel between Los Angeles and Chicago. Five years later, Jack Ryan was running against Obama for the Illinois seat in the US Senate. Jack Ryan was compelled to release the records of the divorce proceedings during the campaign. Various unflattering things about him in those documents led to him being compelled to resign from the race. Obama went on to win a landslide victory against Alan Keyes, who was brought on by the Republicans as a last-minute replacement.
It is hard to write an appropriately chaotic timeline, especially for something as complex as the history of a planet with more than seven billion people on it. And so authors invoke butterfly nets (or “in spite of a nail”), constraining their timelines to be artificially similar to each other. Thus we have good Spock and evil Spock; several dozen versions of Superman; and going back in time more than a hundred years changes the personality of a dictator but doesn’t erase every person currently in the world and replace them with different people.
The last deserves special mention. Part of the appeal of alternate universe fic (and a lot of alternate history) is “I have this cool character. What would they do in a different situation?” . In TV and film this also saves on casting. So butterfly nets are invoked to get the same set of characters, even when they should have been butterflied away entirely if the point-of-divergence was long before they were born.
One of the most notable offenders here is Star Trek. Despite 200 years or more of divergent history between the main Star Trek universe and the Mirror Universe, almost all of the characters exist in both – same names, same faces, same genomes, although far different personalities. This makes no sense. e.g. Ben Sisko was conceived by the Prophets/wormhole aliens to be their emissary. Since there is no emissary in the Mirror Universe, how is he there? And how did his father and mother and all ancestors back at least 8 generations exist, exchange gametes, and give the exact patterns of genes and environment that produced Sisko? The same argument applies to Spock, who only has the goatee so you can tell which one of him is evil.
In terms of total number of offending doppelgangers, comic books probably win. Consider the Crisis on Infinite Earths line, which was an attempt to clean up the various DC properties and all of the different alt universe versions of them – well over 100. And a bunch of new ones have been written since then. The Marvel comics have their own multiverse, with dozens of alternate universes in it. Comic book canon is very messy.
Economics of Parallel Worlds
Characters and butterfly nets aside, let’s consider the economics of alternate universes. First, there must be some way of getting from one world to another – be it a special communications device, a broken transporter, magic powers, or vaguely-described biological technology. As with time machines, the convention is usually to arrive at the same spot that you left from in a geocentric reference frame. This ignores length-of-day variations and perturbations to Earth’s orbit. Or you do some navigation and portal yourself anywhere you want. You may go “cross-time”, from one alternate universe to another, or also forward and backward in time.
I’ve written before about what you would want to do if alternate universes actually existed and were accessible. But this is rarely done. Charlie Stross’ Merchant Princes series is an example. In a European-Middle-Ages-like alternate North America, an extended family clan develops around carriers of a mutation that lets them walk themselves and a person-load of cargo between worlds a couple of times a day. This started in the 1800’s, and they established a credit base in our world by securely transporting bullion and on their side by rapid transit and limited technology imports. But the clan is not properly using their skills. Rather than going public and getting a load of money and bringing teachers and tech from our side to their side, they barely break even making money as cocaine mules. This holds even after some of them have been schooled in business, engineering, or medicine on our side. After a while, the whole plot kind of unravels. Rachel and I have considered a somewhat similar setting, based around the concept of world-walkers but done correctly. Things change very dramatically very quickly, as the walkers tie together a network of thousands of worlds by hauling petabytes of data back and forth until technology replicates their skill.
If there is time-travel as well as cross-time travel, you can engineer branches in the timeline (or you will can have). Subject to the limits of chaos and history before the point-of-divergence, you can build alternate universes to-order. Consider the ethics of that.
The idea goes back to A Connecticut Yankee In King Arthur’s Court, although Twain was writing satire. In some sense, it is the goal in the Terminator series: Skynet wants to engineer a timeline without humans, the humans want to engineer one without Skynet. But the most extreme case I know is a series by John Barnes, The Timeline Wars. Two large alliances of timelines are playing a massive game of Achron against each other, going back and creating alternate universes that support them (including some of the timelines that will provide the resources of the teams that went back in time to create those timelines). Their agents try to subvert the timelines that the other side has split off, either to ensure that the future turns out as it was going to or to split the line again and give an equal balance. The rival sides build massive generators to have sent agents further back in time, to gain an edge. Things end when a timeline that was spawned by agents going back to the Roman Republic and teching it up finally reveals itself and its Sufficiently Advanced Technology. The problem with this of course is the same as that with regular time travel: infinitely long time along one set of world-lines, looping through the time portal, leading to the heat death of the universe.
Good thing time travel is impossible.
Time travel is a popular theme in all three of our main categories here, so this will be a cross-category post. This time, we’re only discussing time travel that preserves a single timeline; the many-worlds interpretation version will be discussed in a later post.
In all currently-verified models of physics, backwards time travel is impossible. There are many reasons why this is true. Thanks to relativity, traveling backwards in time in any reference frame is equivalent to going faster than the speed of light, which is impossible for any particle with positive or zero mass. The laws of physics are also not time symmetric (although they are charge-parity-time symmetric). Time has a direction. And statistical mechanics lets us derive the second law of thermodynamics, which states that the overall entropy of the universe must increase monotonically with time in all reference frames.
That last point is important. If backwards time travel occurs at any point, then there are a set of world-lines that have infinite duration – closed loops looping back through the time travel device. But overall entropy has to increase monotonically with time along those paths, which is a contradiction since they are closed curves. The only way for this to work is for the universe to have already reached a state of maximum possible entropy. That’s called heat death – which means the universe has run down to thermodynamic equilibrium and time has lost all meaning because nothing can change, which means nobody exists to build time machines.
General and special relativity produce interesting effects on how fast time advances in difference reference frames, but there is no way to make time go backwards. But that hasn’t stopped people at various times from writing time-travel stories.
Closed Time Loops
Although they are already breaking the laws of physics, a lot of time travel stories make an effort to ensure that the time travel that does occur does not produce/has not produced/is not producing a causal paradox (yes, there will be tense trouble – I direct you to Streetmentioner’s book). This gets invoked to make prophecy work. In Babylon 5, the Minbari leadership know that the Babylon 4 station will be was their main starbase 1000 years ago, and so are the only ones unsurprised when it vanishes – with a momentary pause a few years in the future to drop off the human crew. It is sent back in time with one person, Jeffrey Sinclair, who received a letter he had will have written to himself 1000 years ago explaining everything that was going to have happen.
The problem is that it is very hard to make a closed loop consistent in terms of the characters. In Babylon 5, it takes a planet-sized machine several days of output to send a few-kilometer-long space station back 1000 years. But why couldn’t the Great Machine also have been used to send back equal or smaller masses back shorter times and win the Shadow War before it started or stop EarthGov from going sideways, or be used in the future for the same purpose? The in-universe answer is “nobody did that back then, so nobody can do that now”, but that doesn’t really make sense. The real reason is that closed-loop time travel makes some plots impossible to do consisently.
For another example: in Harry Potter, Hermione is given a Time Turner so that she can attend more classes than there are hours in the day (and be chronically sleep-deprived, subtracting from her expected subjective and external lifespan, and perpetually running into her past/future self). That is a relatively trivial use of a time machine, so they must be fairly common in the wizarding world and we see a vault full of them at the Ministry of Magic. But the Ministry isn’t using them for anything useful. Fans of the Potterverse have already dissected this from every possible angle, so I will just copy this photo:
When authors do think through all of the possibilities for closed-loop time travel, things get strange. Heinlein wrote a story called By His Bootstraps, where a 20th-century college student transports himself into a 20,000-year-or-so distant future. He is abducted by his subjective-future self, who sends him through the time machine’s portal to his subjective-further-future self. Further-future guy sends the guy back to pick up now-past guy and various other 20th century items. When he gets back from shopping, he tries to double-cross further-future guy by taking control of the time machine and sending himself back from 20,000 years in the future to 19,990 years in the future. But that only means that he spends ten years in the future until he becomes further-future guy.
Setting Right What Once Went Wrong
Since closed loops are hard to set up correctly, and pose annoying questions about freedom of action and if random events are truly random, many authors have the past be malleable and just conveniently ignore the paradoxes that that would imply.
Terminator starts out with an apparent closed loop, but in the second and later movies the future is specifically malleable. And even in the first movie, Skynet is trying to change the past by sending back its assassin (although it does not succeed). In the original Superman movie, Superman acquires new powers as the plot demands and flies faster than the speed of light, sending himself back in time to save Lois Lane. The Back to the Future movies took this sort of plot further, with multiple changes to the timeline from 1885 to 2015.
But there a lot of problems with this sort of plot. The first is the causal paradox again. Marty McFly goes back in time by accident, and spends a lot of time in 1955 ensuring that his parents actually do get together. Until he fixes it, he sees his siblings and himself slowly vanishing from a picture he brought back from 1985. But that doesn’t make sense – if the timeline had already been changed when the picture was taken, why does it take subjective time for it to change?
A second problem is ethics. In Schlock Mercenary, Kevyn Andreyasn goes back in time to save the entire Milky Way from being completely destroyed. Ethically, that’s pretty good. But consider Superman. He goes back in time and saves Lois Lane. But couldn’t he have gone back in time a little further and prevented the whole two-missiles-can’t-catch-them-both dilemma in the first place? And if he can go that fast, why didn’t he just do that in the first place and avoid the missile hitting New York at all? Back to the Future is even worse in that respect – all Marty changes is making his parents happier and more successful in life, making Biff less successful, and saving Doc Brown from getting shot. But there are more important things that could be changed. Even if Marty was unable to get things right on his first trip, he could go back again and relieve a huge amount of human suffering.
There is a countering ethical consideration, of course: history is complex and chaotic. Go back in time and step on a butterfly, and humanity may not exist anymore. You just killed everyone. Oops. But you can go back and fix it again, as long as there is any possible solution. If there isn’t, you go back and reset everything and it all reverts back to the prior timeline.
We’ll talk more about the complex nature of history in the next post. But for now, be grateful that backwards time travel is impossible.