Space: the Really Big Frontier

Doctor Who fans know "it's bigger on the inside," but science fiction writers often fail to apply the same idea to the vastness of space. Just look at our own solar system. Sure we've had to adjust our models recently; after all, Pluto's not a true planet anymore (thanks again, Neil deGrasse Tyson). Just this week scientists announced the discovery of another dwarf planet hugging the edge even past that demoted orb, which they're affectionately calling (I kid you not) "Biden."

But we're all familiar with how the eight larger planets fit together in a tight little group, like they do on placemats and bulletin boards around the country. What those models are missing is actual space, as in lots and lots of empty space between each point. I'll let Bill Nye the Science Guy explain:

Need another demonstration? Josh Worth, a web designer, has developed a website called "If the Moon Were Only 1 Pixel: a Tediously Accurate Scale Model of the Solar System." Worth used horizontal scrolling, measured to scale in pixels, to simulate the actual size of our solar system. A visitor starts with an explanation of the scale and the sun, then starts scrolling toward Mercury. After a second or two of blackness a little sign appears alerting the user of the 10 million kilometer mark past the Sun. The user hasn't reached any actual planets yet, just a place past the sun that is approximately 900 times longer than the flight distance between New York City and Beijing. At about 28,991,993 kilometers Worth adds a marker simply stating: "Pretty empty out here." Mercury isn't reached until the user has scrolled another 30 million kilometers or so.

Fortunately Worth provides a top menu that allows users to click a planet icon and get whisked along to the next stop rather than sitting for minutes and simply holding down the space bar. A user even gets the sense of traveling faster by the little messages he placed along the way wiping by too quickly to read. Even with more speed, though, it still takes time to cross that amount of space. The planets don't magically become closer.

Science fiction writers have used in number of plot devices to get around this issue, from ships that can travel faster than light to actual tunnels through space. That's perfectly understandable: after all, you don't want your heroes arriving at another planet forty years later. There's debate over whether faster-than-light travel could ever be achieved, considering that's supposed to be the universal speed limit in our current understanding of physics. But at one point binary star systems were deemed entirely fictional creations: today we have proof of their existence. To paraphrase Shakespeare, there are more things in planets and molecules than are dreamt of in our current philosophy. So long as a writer has a good story, I'm willing to suspend belief to go along on the ride.

Even with acceptance of these superfast ships, though, I've seen complaints that science fiction planets are incredibly easy to get to. Remember how far apart our own planets are? Now picture traveling beyond our solar system to another one, say the Alpha Centauri system, which encompasses three stars: a binary pair, Centauri A and Centauri B, and a red dwarf, Proxima. That last star is currently the closest one to our own Sun, and it's still 4.24 lightyears away. Even if a ship that could travel twice as fast as light, none of the original passengers or their children would survive such a trip. By the time any of the descendants returned home for a visit whole generations would have come and gone.

There have been authors who explore the mechanics of time in space travel, such as Joe Haldeman's The Forever War. In that book a group of space fighters travels faster than light to get to a distant world, but due to quantum physics and relativity, exponentially more time passes back on Earth than when they are away in combat. An early science fiction story called Starman's Quest explores the same theory but with twins, where one ages faster on a planet while another ages slowly in space.

But here's a concept I haven't seen anyone explore, either in print or film: unlike on Earth, destinations in space move.

Remember all those measurements we looked at earlier? Even those incredibly long journeys are all based around approximations. In reality, everything in space is constantly moving, whether its moons around planets, planets around stars, stars around centers of gravity in the galaxy. The distance between our Earth and other planets in the solar system changes based on where the planets are in orbit around the sun. They don't all orbit at the same speed and time. Imagine a trip to Mars when its on the opposite sides of the solar system from Earth! That'd be a significantly longer flight than when the two planets are nearer each other. Now push that idea beyond to planets with even wider orbits, such as Neptune or Saturn, or beyond to another solar system, which might be on the other side of the galaxy now but in a couple thousand years be comparatively closer.

NASA and other contemporary space agencies deal with this phenomena all the time when planing launch windows for probes and satellites. Without proper scheduling a probe could be launched into completely empty space, no planets in sight. A space pilot for a manned voyage wouldn't just need to be aware of where the planets are now, but where they're likely to be in the future, plus how to avoid obstacles like comets.

Science fiction usually covers this issue with star charts and advanced computer calculations to plot a ship's course. But beyond a story where it takes more than a day or two to reach a planet, I'd like to see one where the characters actually had to plan their trip in advance, and deal with the emptiness of space travel.

Always remember: it's a great big universe out there.