Worldbuilding Wednesdays: Basic Consequences

Welcome to Worldbuilding Wednesdays!  Every Wednesday, we spend what is probably far too much time walking through our worldbuilding process.  In this week's post, we start what will become a recurring pattern:  determining the consequences of our choices, following them until we hit a snag, and then making a new choice and following those consequences.

What We Have So Far

Our world is one where fantasy and science blend in strange ways that make them indistinguishable from each other.  It is a world where physics (other than where we tweak it) works exactly the way our world's physics does.  It is a world ten times as large as Earth, ten times as massive, but with only 1/10 the gravity.

And... something about a basketball?

Hyper Inflation

Last week, we said that there was a problem with making a planet ten times bigger in every direction, but not (10x10x10) 1000 times more massive.  At the time, we were making it only 10 times as massive, which, due to the square-cube law, meant that overall there was 100 times less- well, stuff in this Super Earth.  There were two solutions, and the hint we gave for the most straightforward one was a picture of a basketball.

The solution we're talking about is simply making the Super Earth hollow.  Sure, it's 99% less massive than one would expect:  that's because instead of being solid, the entire planet consists of a relatively thin layer surrounding a whole lot of not much.

Now, this particular decision spurred a whole bunch of math.  We checked to see what it would take to maintain plate tectonics and volcanism.  We also checked to make sure that a world this size with a hollow core wouldn't collapse on itself.  Which led to an interesting discovery:  due to Newton's Shell Theorem, the inside of a hollow world won't experience gravity.  We discuss it quite a bit in our Random Rambling about Physics.  Long story short, as long as we don't ask how, exactly, the hollow Super Earth came to be in the first place, physics said it would work.

Sadly, dinosaurs inside the Hollow World would not.

Consequences, Part One

When you're building from the Outside In, one of the really neat things you can do as part of your worldbuilding is to effectively follow the ripples of your choices.  This is also possible, albeit more difficult, when you build from the Inside Out.  What it comes down to is the question you ask as the result of a worldbuilding choice you made, such as, say, deciding that your world is a massive Hollow Earth.

When you're building from the Inside Out, you'll ask yourself, "Why is this true?"  This is a good question to ask when you're expanding on your ideas.  It's not nearly as good a question to ask when you're zooming in from the outside, because the answer is never smaller than the question.

When you're building from the Outside In, you'll ask yourself, "What happens if this is true?"  This is a good question to ask when you're looking inward from the outside, since you are in a prime viewing location.  It isn't such a good question to ask when you're building outward, because you find the smaller details you've already put in place clashing with this new consequence.

So it is that we look at our Super Hollow Earth and, instead of asking, "Why is this true?" we simply accept that it is.  Instead, we ask, "What happens if you have a giant world with low gravity, but physics is otherwise the same?"

We ask this for two very good reasons.  First, exploring consequences is a wonderful way to find and add details to your worldbuilding that you never would have considered otherwise.  Second is that you can note where your decision making could lead to the accidental destruction of your worldbuilding.

For example, we now have a massive world with a radius 10 times larger than Earth's, but we're trying to keep the physical changes otherwise minimal.  So we think to ourselves, "Would it be possible for this world to have a normal, 24-hour day?"  And the answer, after some math, is, "Yes, but only if you're okay with everyone being flung into space."  It turns out that such a world would have to spin awfully fast in order to complete a rotation in 24 hours- more than fast enough to counteract the .1 g holding everyone down.

How can we fix this?  Well, any number of ways.  But before we do, we should nail down another preference that just got mentioned.

New Key Element Unlocked!

If you were just skimming, you might have missed it, but a couple of times, when we've thought about the real-world physics being the default, we have, in turn, made decisions that minimize the differences between the world we are creating and Earth.  This makes sense:  if we are going to use real-world physics as the default, the least amount of effort will come from making a world that reacts to physics the same way Earth does.  And that means making an Earth-like world.  Which in turn means that we're going to make decisions with the desire to keep the world Earth-like, if possible, in mind.  Because this impacts our design philosophy, it's a Key Element:

  Earth-Like Preference.  When in doubt about which way we should go in our worldbuilding, we'll tweak physics to make the world more Earth-like, rather than tweaking the world to match the physics.

You'll note that this new Key Element can clash with the Real-World Physics Key Element.  That's okay!  We're not robots (at least, those of us at Vagrant Dog Productions aren't robots; we can't speak for our audience), so we don't have to avoid conflict.  We can wade right in when it gets messy, make some questionable decisions, and explore the consequences.

So:  because of our new Key Element, we want this Super Hollow Earth to have a day that resembles Earth's in some way.  We can't have the day be exactly as long as Earth's because then Everyone Dies™.  What if we slow down the rotation until the spin is comparable to Earth's?  As it happens, Earth's spin causes a reduction in gravity of about 0.5% when you compare the poles and the equator.  If we set the Super Hollow Earth's spin to have the same effect, that would make the days on this planet... about 8 Earth days long.

Oog.

Consequences, Part Two

Just so you know, it is always okay to go back and undo a decision once you've made it.  For example, if a chain of decisions leads to a day that is long enough to wildly throw off things like the weather, circadian rhythms, and growth patterns, you can always backtrack.

Or, you could be like us cool kids and add more fuel to the fire.

You see, there are two different types of day.  There is the rotational period, which is the amount of time it takes for a planet to complete one full revolution.  And then there is the synodic period, which is the amount of time it takes for the local sun to appear at the same point in the sky.  In the real world, the difference between the two is slight but noticeable; ancient scholars used the difference between the two to figure out the length of a year to a respectable five significant digits.

However, we aren't in the real world.  So we have two options:  Let the real-world physics default stand, and explore a world with a week-plus long day; or change physics again until the world more closely matches what we're used to.

Well, how would we even change the synodic period, anyway?

...We could take a book out of the pages of those aforementioned ancient scholars, and say the sun revolves around the Super Hollow Earth, instead of the other way around.  Of course, if we did, some other things would have to change about the sun as well.  It would have to be closer (a lot closer), way smaller, and we would have to fiddle with its brightness to make sure our Super Hollow Earth was getting the same amount of sunlight as the regular Earth does.  But at that point, does it even count as the sun anymore?

Or is it something new?

A Note on Recursion

You may have noticed that our thought process when worldbuilding from the Outside In can be pretty quickly boiled down to the following steps:

1. Think of how to build the world in line with our Design Philosophy
2. Run into an issue (usually with the physics)
3. Change the physics to suit our Design Philosophy
4. Explore the consequences
5. Repeat as necessary

If you aren't focused on the end goal of having a fully-realized world at the end, you might wind up in a recursive loop.  You see, Step 5 is a little vague; we don't specify which steps you should be repeating as necessary.  If you find yourself repeating Steps 2 through 4 over and over again, you're caught in a loop.  Just working out the consequences isn't enough— you also have to think through what you need to build your world.

On the other hand, the more you work through the consequences, the more real your world feels.  When someone else asks a question about the world that lesser creators might not have delved into, they will find you in the depths, staring back at them.  It's a heady feeling.

So, how far should you go when it comes to pursuing consequences?  A good rule of thumb is never to go deeper than three levels.  That is, for example:

• You've decided that your world is going to be massive and hollow.  It should otherwise be similar to the normal world.
  • If the massive hollow world is similar to the normal world, you'll also want it to have a fairly normal day.
    • To give it a normal day, you're changing how the sun works.
      • Don't worry about anything further than this.  We're not going to worry about tweaking the physics a third time just to get the day perfect.  If the physics says things would differ from Earth-standard at this point, we'll either agree and move on... or simply say the physics happen to work the way we need and move on.

Why three levels?  Because that's about one more level than your typical audience will bother looking.  Question fatigue is a very real thing, and unless your audience is a bright and stubborn five-year-old, they will probably not ask "Why" more than twice on a given subject.  On the rare occasions that they do, you'll have the third level ready.  Anyone who asks a fourth time deserves to be ignored.

So, in our instance, we have the following discussion: 

Audience:  "What's your world like?"

Us:  "The world is huge, but otherwise similar to our own."

Audience:  "Cool!  ...Wait.  If it were huge, wouldn't it spin so fast that people would fly off?"

Us:  "Nope.  It takes about eight days to complete one rotation."

Regular Audience:  "Weird, but okay."

Curious Audience:  "But doesn't that do a whole lot of weird things to everyone on the planet?"

Us:  "Nah, it's got a different setup to make everything work out, like a little sun that orbits around it instead of it orbiting around a distant sun."

Audience:  "Oh, neat!"

Some random smartass:  "But how does the sun produce enough light if it's small enough to orbit your planet?"

Us:  "Look, buddy, we're already talking about a giant hollow planet with a day longer than a week and a sun smaller than the moon, and you want to know if we properly calculated the luminosity?  Come on, now."

Random smartass:  *Is suitably chastened*

Us:  *Wipes nervous sweat off brow*

Conclusion

To have a world where everything is bigger but isn't crushed under its own weight, we've made a Super Hollow Earth.  We've made sure that such a planet could physically exist using real-world physics, and we've tweaked our Design Philosophy to say that we would alter real-world physics whenever we needed to make this new world more Earth-like.

This new Key Element has far-reaching consequences, which we've started to explore.  Probably the biggest single consequence is that a world like the Super Hollow Earth couldn't just orbit the sun like Earth does.  It would need a much smaller, closer companion that still serves to light the darkness.  Instead of a sun, our new world has...

...A Lantern.

The sun (artist's rendering)

Next time, we'll create some orbiting bodies for our world, closing out the global changes we're making.  Until then, happy worldbuilding!