Monday, April 14, 2014

L is for the Limitations Imposed by Light Speed

According to the laws of physics, at least as we currently understand them, it is impossible to go faster than the speed of light.  That speed limit, in a cosmos as vast as ours, is problematic to say the least.

That speed limit, and whether or not it is obeyed within a science fiction story, determines the kind of story you can tell.

In Star Wars and Star Trek, we see ships moving at many times the speed of light.  Though Star Wars uses hyperspace and Star Trek uses warp, the effect is largely the same when it comes to storytelling.  The story isn’t inhibited by an inability to travel between the stars.  The protagonists in those stories are free to interact with a plethora of alien species, visit a multitude of worlds, and generally get into any kind of trouble the imagination can conceive.

Image courtesy of  Brad Wilson/
On the other hand, there are examples of sci-fi where the speed of light cannot be surpassed, yet humans still try to travel amongst the stars.  Barring the existence of a wormhole, which has often been used even in universes where faster-than-light travel is possible to get around the any limitations those technologies may have, humans have to travel the long and slow way.  In scenarios like this, we might see humans go into some kind of long-term sleep, which enables the human players within the story to still make it to their destinations within the allotted amount of time.

However, when there are no shortcuts to be had, and no way to sleep peacefully through the journey, we get generational ships.  These are ships where generations of people are born and die before the ship comes anywhere near its destination.  They never know a life outside the ship.

I’ve never written a story of this type (though it sounds tempting), but if I did give it a try, I know a few of the questions I’d like to explore.  Let’s say there are multiple ships, each heading to its own destination, and there is limited contact between them.  How long would it take for the people aboard each ship to develop their own distinctive cultural traditions?  How long before the languages changed so much between ships that it would no longer be possible for them to talk to one another?  Evolution would also continue on its course.  How long before the people between ships differed so much that they could no long breed with one another?  How long before they no longer recognized one another as members of the same species?

And, of course, after a group has lived on a spaceship for such an prolonged period of time, would it even be feasible for them to settle on a new world?


  1. Those are interesting thoughts to consider but probably the most realistic for now. Why would people be driven to go to that extreme though? That is also something that would need to be worked into the story. If they have to push themselves to such lengths, there must be a reason for it.

    LittleCely from LittleCely's Blog

  2. I love all the different ways sci-fi has come up with to get round the problem, in some cases just apparently ignoring it too :). I find the idea of subatomics incredibly interesting because all the rules break down, so maybe there are loopholes.
    Tasha's Thinkings - AtoZ (Vampires)
    FB3X - AtoZ (Erotic Drabbles)

  3. I like the end of 2001, when it seems the protagonist has transcended time and space altogether and reached the brink of a new and higher manifestation of human life. Rules were made to be broken, astrophysical rules at least.

  4. I like that Roddenberry imposed a limit on warp drive technology since it's too easy to ignore the laws of Physics. In the end it's all in good fun, but science always makes sci-fi better.

  5. Very interesting ideas. I would definitely read something like this.

    I don't believe in evolution, but even as I understand it, it would take a very long time for one group to change so much that they couldn't mingle with another group. Of course, the distance between stars could make it possible I guess, as it would take 100,000 years to go from one end the Milky Way to the other end—and that's if you travel in a straight line (galatically speaking). And if their destination was another galaxy, it would take even longer.

    Which brings up another question: why would a group of people do such a thing? Is the only other planet that far away? Or are they simply doing it for the "fun" of it?

    Also, speaking of evolution, as it began to happen, would the groups notice it? Probably not, but if they did some how, would there be anything they could do about it? Such as DNA manipulation or perhaps low tech like shuttling from one ship to another to keep the mingling active.

    A world of possibilities ... indeed.

  6. Oh wow, those questions are so thought provoking! I once read a children's story about a generational ship arriving at its destination. I never even wondered about any of those things. It would certainly be an interesting thing to write about.

  7. Good questions. Especially the last one. I assume that if a people lives aboard a generation ship with an enclosed ecosystem such as on a Bernal sphere, then living on the surface of a planet will be really alien. They're rather replenish their ship than settle, especially since by the time they get there, it will have been exceedingly hard to keep everyone aboard dedicated to the purpose of their long-dead ancestors back on Earth.