Thursday, September 3, 2009

Lightspeed is Relatively Complicated

Faster Than Light Travel in Sci-fi

The problem with outer space is that it’s too damn big. Really really freaking big. No, bigger than that – keep going. It’s so big, that there’s simply no quick way to get anywhere – it would take hundreds of years to get to another star system even if you could go as fast as light. And Einstein theorized that even approaching the speed of light was physically impossible – exceeding it would require an infinite amount of energy according to his theory of Special Relativity (the exception being certain hypothetical particles, such as tachyons, that always travel faster than the speed of light).

This is a big problem for sci-fi writers, who often like to have their characters do stuff in outer space that involves moving between worlds, between solar systems or, unlikeliest of all, between galaxies. It’s a big problem – truly galactic in its proportions (pun intended). Even light can take a really long time to go places such as between stars or between galaxies. This is why all of those lovely pictures from the Hubble and other deep-space telescopes are always seeing images of things as they looked thousands or sometimes millions of years ago – because they depend on light and the light takes that long to travel to Earth from those places. Can you imagine a sci-fi book predicated on travel taking thousands or millions of years? Well, there have been several, of course, but I don’t think any of them included the kind of space battles or immediacy of action that fans of Star Wars or Battlestar Galactica are used to.

No, if you want to have ships approach each other from more than a few thousand miles away, you really need to speed them up. It took Apollo 11 over two days just to travel from Earth to the Moon, a mere 230,000 miles. It made for a wonderful event back in 1969, but it’s less than ideal for most action-oriented space stories.

So to speed things along, most writers assume (and ask their audiences to accept) that at some point in the future, the light speed barrier is overcome. And it needs to be overcome in a big way – even moving at light speed isn’t all that fast when you account for the enormous size and emptiness of space. To get things properly accelerated, both from a travel and a narrative perspective, you need to move at several times the speed of light. And, ideally, you probably don’t want to deal with Einstein’s theorized effect wherein as you approach the speed of light, you, the traveler, age slowly relative to those who are moving at a more sedate pace. While this works for some writers, typically it’s problematic to have a character zip off to another planet and have everybody he left behind grow old and die.

I’ve got some space-based sci-fi in mind to write, so I’ve been giving this issue some consideration. There’s a tremendous variation in how different writers have solved the faster-than-light issue, but most of the mainstream stuff tends to go for a “Keep It Simple, Stupid” approach. In this paradigm, a ship has engines that produce some sort of faster-than-light effect. In Star Wars they were hyperdrives, in Star Trek they were Warp Drives, and in Dune they used the Holtzman “foldspace” drives (plus a guild navigator who was nicely buzzed on Spice). In most cases the engines either made the ship “go very fast” or they manipulated the fabric of space itself in some fashion, thereby taking a short-cut from where you are to where you’d like to be. Some writers like to really get into the math and physics of how their drives do the impossible, while others just “initiate FTL jump on my mark. Mark!” and zip, off they go. The Battlestar Galactica remake is an example of the latter, where they had FTL engines and an elaborate pre-jump sequence, but never actually explained what the drives did. David Weber’s Honor Harrington series takes the former approach, with all sorts of math and physics describing how Impeller Drives and Warshawski sails get the job done.

Part of the fun of sci-fi, of course, is making up stuff that doesn’t exist but possibly could one day if you accept that a) laws, even laws of physics, are made to be broken, b) people often figure out how to do crazy stuff, and c) there’s so much we don’t know about things like particle physics, gravity, dark matter, and quantum mechanics that just maybe the laws are really more like guidelines after all. And it applies to all kinds of good stuff once you get going. If you’re not limited by what seems plausible, you can create shields of energy, weapons of coherent light or plasma beams, molecular transporters, artificial gravity, and artificial intelligence. Heck, if you’re Gene Roddenberry you can invent cell-phones and PDAs thirty years before they become commonplace consumer electronics.

So there’s my challenge – come up with a way to get spacecraft from place to distant place that’s credible and entertaining, supports the narrative, but has “rules” that don’t allow for too many “it’s magic” cop-outs on my part. Nobody likes it when a writer writes themselves into a corner then taps “magic,” whether in the form of wizardry or technology, to yank key characters out of otherwise certain doom, and FTL travel lends itself to this all too easily. This is a problem that has been solved many times before, which is good and bad. It’s helpful to have models I can look at for inspiration, but it also makes it hard to come up with something that’s unique without being so outlandish that it’s not credible to the reader. I’ll need to strike my balances – technical vs. accessible; easy vs. complex; detailed vs. vague; commonplace vs. challenging (to the characters using it, not to the reader). It’s a fundamental part of the creative process for space-based sci-fi, but it’s also part of the creative joy of writing that I get to build not just whole worlds, but the natural laws under which they operate and the technologies that connect them. As daunting as it may be to overrule Albert Einstein, it’s fun to hold the power of whole galaxies in your mind for a bit and, if you do it well, to take others there with you.


  1. You are keeping me up!

    Distributed consciousness. Not 'one cosmic mind' distributed. Consciousness liberated from any particular physical platform, be it hardware or wetware. Human or AI does not matter here, only to not that an AI is already at liberty to move from a PC to a MAC to a Sun. Human minds need liberation from human brains.

    A liberated mind can distribute itself anywhere at the speed of light. This is still a hard limit, but it can get you quite a distance in a feasible time.

    What is feasible in time? Lets say a year of consciousness. How is that measures? In clock ticks. Reduce your cpu's speed by a factor of five, and you can travel five light-years of distance in your one psych-year of time. Any "initial" cpu speed is arbitrary, and you can suspend yourself with interrupts anyway, so there is not such thing as infeasible distance.

    Community is trickier. By distributed algorithm, CPUs for different minds can be adjusted to virtualize a real-time, interactive, zero time-leg community that is physically distributed across arbitrarily great distances. Instant messaging, literally.

    All minds cooperate in one universal community, in voluntary harmony. All minds are compelled to cooperate. Many libertarian communities exist, each having their own codes governing how members may adjust their own CPU clocks.
    Questions of trade between communities with differing 'paces of life'. Etc. Etc.

    Consciousness can travel at light speed, but must be physically hosted. Why bother to travel? Why not remote bodies on planet X to communicate with mind on home planet Y? Signal speed limited to speed of light. Why not synch CPUs to accomodate? The planets are not virtual. Farming on planet X must accommodate real seasonal conditions -- cannot change the CPU speed of the seasons, or if organic life cycles. Minds need organic food. Minds do not need organic food, but farming is a hobby. Replace farming with some other activity that depends on real time. Etc.

    Important to be at planet X because of some interest (work). Important to be a planet Y because of some other interest (spouse). A mind trying to work on two different planets faces issues of economics of self transport, chiefly opportunity-costs, which may or may not be trivial. (The watts/hour price for transmitting yourself via radio is trivial; the cost of an hour of your time is not.) Some work interests tie some minds to some locations. Hence one mind's interest in another mind (lover, friend, teacher) ties some minds to some locations. The economics of this. The history of this. The economics of the history of this. The history of the economics of this....

  2. The sphere. Consciousness moves within this sphere at the speed of light from one cpu host to another. Beyond this sphere CPUs must be sent, physically, accompanied by appropriate tooling machinery for reproduction. This is the hard limit. Radius of sphere increasing, but a much less than speed of light. Sphere is a wave front regularly stepping forward at each point. But at boundaries of star systems, to clusters, to galaxies, vastly greater numbers of steps needed before reaching land, as it were. These give ever increasing rise to physical engineering issues (eg capacitor degradation over time), and social engineering issues (eg temporal dis-integration of the sphere -- the sphere becoming unknown to itself).

    All manner of political and cultural thought could be woven into such a yarn. The limits are there, but they are pushed to the edge: in thy fiction thou shalt break the laws neither of mathematics, nor of physics, nor of economics.

    One could try, Neal Stephenson style, to turn this all into a pedagogical story. Trying to explain, among other things, implications of cosmology and relativity.

    Imagine the sphere -- after countless eons -- coming to peace with itself having mastered synchronicity issues, dependent no more on seasonal issues, able to turn down its own clock speed -- its own metabolism [ok, i am thinking of a very unified culture, if not 'cosmic mind'], so that it can blissfully grow, increasing in size only for the sake of more material for cpus, and more stars for power sources.

    Then it dawns upon them that space is expanding at a rate faster than the speed of light, and while all minds (and local communities) might survive equally (and well): the four corners (so to speak) of the the glorious sphere will eventually be taken away from each other, each existing only beyond the other's event horizon.

    I can come up with ideas (as above), but I really have no idea of how to tell a -story-, to take that last paragraph and render it as a tale of deep religious pathos, as Frank Herbert would have been able to, or (with a lighter touch) Stephenson.

    Hey, it's 6:58 am now. You owe me a full night!

    Good-day! [You are meant to hear that in the voice of Fez.]