...For when it's not enough for its own thread.

Someone who writes sci-fi might have to do a lot of research, and wind up with a lot of "little" questions about science—some which might not be significant enough to justify making a new thread. If this feels familiar to you, well, bring your questions here.

I'll start:

Something that's had me wondering: Is there a limit to how big terrestrial planets can be? For example, I mention in an early chapter of my book that the planet an alien colony is on has a gravity three times that of their home world (which is Earthlike in size and atmosphere), but this implies (to my understanding) a planet three times the size of Earth. The only planets that large that I know of are Jovian planets, which don't have solid surfaces. Help?

Not necessarily. Assuming a spherical body (and your garden-variety planet will probably be close enough), gravity is related to the density and radius of the primary (or so I learned in uni).

A quick consultation from Wikipedia says that your surface gravity, g, is equal to GM/r², where r is the radius of the planet, M is the mass, and G is a gravitational constant that's about 6.67 x 10^-13. If you have M in kilograms, r in meters, and G in m³/kg·s, then g will be in meters per second squared; divided by about 9.81 and you get how many gs it is (1 g is about 9.81 m/s², or one earth gravity).

An alternate formulation involving density may be useful. The symbol for density is ρ; setting it as mass over volume (kilograms and cubic meters here), you have g = 4πGρr/3. So you could play around with these values a bit and not get a planet that is three times whichever feature you use in defining the Earth's "size".

edited 20th Feb '13 9:23:44 PM by IuraCivium

Kepler 10b is a solid planet with a surface gravity over twice as heavy as ours. It's also 4.5 times our planet's mass.

This article should help you greatly because we're finding more and more of these with every year. (And other planets which are Earth-sized or smaller. The newest one is the size of our Moon.)

If you don't want to find a real planet to base your stuff off you can simply calculate/reverse calculate the surface gravity of a planet.

The math: (g = surface gravity constant in Earth gravity, m = mass in Earth masses, r = planetary radius in Earth radii)

• g = m/r^2

For example: (using my notes for when I designed the super-Earth Dreyorball in my works, based off the specs for Kepler 10b.)

m = 4.52
r = 1.42
g = 4.52 * (1.42^2)
Therefore:
g = 2.242
Convert to m/s^2:
g = 9.8 * 2.242
Therefore:
g = 22 m/s^2

You can reverse calculate a three times surface gravity in relation to Earth from that and tinker the numbers to fit your world building.

edited 20th Feb '13 10:11:43 PM by MajorTom

NOBODY SAID THERE WOULD BE MATH!

J/K. I'm grateful for the help. Just give me some time to get my head around that.

Dammit, this is bothering me.

I have some aliens that are tripods (three legs + humanoid upper body, similar to Species 8472◊), but the more I think about it, the more I realize that this isn't a very efficient form of locomotion and is thus unlikely to appear in nature. I watched a video about the creation of Species 8472, and the animators admitted the creature was rarely shown actually walking. My rationale was that my species, the Eileth, evolved from quadrupeds and the tail became the third leg of the species' tripod base, on account of the higher gravity and uneven terrain.

I imagined that such a creature might walk by moving one leg at a time, or moving the hind leg and one of the front legs together, or (somewhat goofily) by swinging the hind leg between the front two, like a person on crutches.

Also, I've been thinking very hard about designing functional feet for my aliens. That they have oddly-shaped hands or feet is a personal caveat when it comes to designing aliens that can broadly be considered humanlike. I toyed with the idea of giving the Celieuel (giant humanoids evolved from ungulates) hooves or something like hooves, but realized it's hard to morph a hand-like appendage from a single-toed, horselike hoof, and that hooves might not even work with a bipedal creature because they're inflexible. It works fine for quadrupeds, but for a biped, in order to move forward, you would have to lift your foot high off the ground with each step and you'd be unable to generate forward momentum by bending or "rolling" your feet.

Thoughts?

edited 22nd Feb '13 5:43:03 PM by Alma

Consider that the number of "fingers" and "toes" for this alien will impact it's culture. Most humans use a base 10 number system because we have ten fingers, it's obvious. An eight fingered alien would use octal (base 8) and six finger hex (base 6).

For your three legged alien, consider tri-lateral symmetry. Or have the third leg be smaller and used for balance. They don't need chairs because they just "sit" on leg #3.

I had a drider character in an RP who did this (okay she was a whip-scorpion from the waist down but I'll use the common term). For each scene, I stopped for a sec to consider how a person with 8 legs and a large lower body would move around. She was also an ice queen due to her curse/mutation.

So she would push chairs out of the way (since she couldn't use them). She'd "sit" on her legs to get on the same level as a person she was talking to if she was friendly. Or she'd lower her back legs and push up with her forelegs to tower over someone (and to make use of her steel grey eyes and goth look). She'd even use her forelegs like a second pair of hands if she was sitting, since her other legs could take the weight.

On the subject of feet: the human foot is made to take several tons of force from walking. Digitigrade is okay for an otherness, but lets get real. That's a lot of force to put on distal and intermediate phalanges. Apes had toes spread far apart for gripping branches and as a result of finger and toes spread far apart we developed tools over time. They could use one of their legs as a third hand when they are sitting or standing still. And remember Pronation. I twisted my ankle once, you miss the normal movement of your foot when it's gone believe me. Are your alien flat-footed or do they have arching soles?

It's not the direction of evolution, but it helped.

tl;dr - the takeaway would be to have the aliens with 3-legs have either:

• back leg with fused toes like a tail, they can sit on it like a chair, their spine and hind leg are in perfect alignment.

• their feet kinda-sort look like human feet from a distance, but only in that they were descendants of a primate-like critter.

• consider tri-lateral symmetry. Their body has three sides.

• remember the impact their body and anatomy has on their culture. Would a three-legged (and possible 3-sided) alien see us two-legs (2-sided) "huu-maans" as weird?

• Comparative foot morphology via the other wiki

edited 22nd Feb '13 7:22:32 PM by TairaMai

Thanks for the help. <3

The Cel (not the tripod aliens; these ones are biped and more humanoid) have ungiligrade legs: Like this◊, but without the keratin and with more digits (sort of like the early extinct equids), so that they can have humanlike hands. I was thinking that they would have prominent ankles, like a horse, to take most of their weight. They are also a very tall species—13+ feet. But they also have bones reinforced with a diamondlike substance, and their homeworld has a lower gravity and higher concentration of oxygen—I've done my best to account for the Square Cube Law.

Trying to come up with alternative biology tends to make one appreciate Rubber Forehead Aliens a little more.

edited 22nd Feb '13 8:43:09 PM by Alma

For three-legged aliens, look at how a cat or dog that has lost a hind leg walks.

I would like to add a character who is a Seer. However the setting leans toward hard on Mohs Scale of Science Fiction Hardness. Sf Debris points out the BS "quantum" of Star Trek.

I don't want a Story Breaker Power, it has rules. There are things he can't see no matter what for instance. It isn't limited to his species. It's just harder (and potentially lethal) for a human to acquire this "timesense".

So what should I consider and what tropes should I avoid?

edited 22nd Feb '13 10:09:02 PM by TairaMai

In a sci-fi setting, you could possibly explain telepathy/clairvoyancy with some form of inheritable nanotechnology—i.e. a person is injected with nanomachines which work some technological wizardry in the brain and are designed to roost in sperm/ova cells so the ability can then be passed on their children.

Just an idea.

edited 22nd Feb '13 10:20:50 PM by Alma

I have no idea what level of sci-fi I want.

The first thing that comes to mind is computer modeling, rather than some psychic sense.

Matues, once again you are awesome and I want to hug your avatar!

Thanks for the help!

I would also suggest invoking Sufficiently Advanced Aliens if you want future sight to be a thing in your universe. Say an advanced race bestows the ability of future sight on humans, for reasons unknown. Maybe they thought it would be funny.

Don't forget, 2001: A Space Odyssey did it, and it's considered one of the quintessential hard sci-fi works.

That, or make future sight the norm. Everyone has it. That way, you can just invoke advances in science or technology, or skimp on an explanation altogether. "One Big Lie" is still pretty far on the hard end on the Mohs Scale. If future sight is the norm, you might end up with a many-angled Scry vs Scry scenario, in which all the powerful seers are trying to manipulate events to make the future they desire come about—could be interesting. Maybe make the protagonist different or special somehow. Maybe his future sight is clearer, or he sees a certain event others can't—he sees the world ending, but nobody believes him because they're all predicting sunshine and rainbows in the future.

Also, how "the future" works can have an impact on future-telling abilities... Is there one future, where everything is predestined and fixed, or are there infinite, variable futures branching off from all possible events?

edited 23rd Feb '13 2:18:02 PM by Alma

Without giving spoiler info:

One race of aliens had an ethnic group that was "different" : they can see (almost) in 4-dimensions and perceive time (and model in almost like a computer). Other ethicn groups see them as either sacred seers or likes demons. Of course it's just one direction that the species could go, if their government didn't become an empire then a Nineteen Eighty-Four style police state. Cue the persecution! One of the villains had a mother who belonged to this group and he has the "sight" and shamelessly uses it to become an insane admiral.

Yes, he's a boomerang bigot and has to hide the secondary features his mother passed on to him.

The Scry vs Scry comes from a human getting into an accident with an invading alien's portal network. He's unstuck in time (a la Kurt Vonnagut) and now has mental timetravel of a sort. And these two characters can "see" each other. The lethal part comes from how the portal network functions: things go wrong and you get a gamma ray burst to the face.

edited 23rd Feb '13 4:22:33 PM by TairaMai

Yes, that was a serious question. I dunno what I wanna do.

Write an Xenofic from the POV of a newly born emergent AI.

A who from a what, now?

A story that takes place from the point of view of a newborn AI. Like writing from the POV of a newborn baby experiencing everything for the first time, only it has adult- or close to it -intelligence.

And if you still want to figure out your tech level, you could start by going to the Punk Punk page, go down to the 'By period' section of the examples, read up on each variety, and take notes on what you like and dislike about each. You're on a wiki of fiction. I've seen how much work you put into making it run; why not actually use it for once?

I don't know enough about any of them. I've tried sampling several sci-fi works before, but it just hasn't panned out. They all just went miles over my head. I even tried watching Firefly and had to quit 15 minutes in because I had literally zero idea what was going on even with a script in front of me.

What aspects of science fiction bewilder you?

Also: That suggestion was to help you understand more.

edited 23rd Feb '13 7:45:55 PM by Matues

Everything.

Uh.

Dear, you're going to have to narrow it down a touch if anyone's going to be able to help you.

Science Fiction is Fiction With A Scientific Bent.

It's looking at the far future, at technology and how it grows.

It's everything from Space Operas to Alien Invasions to Robot Wars to Clone Blues.

All I know is I want it to be on Earth. I've already established that it's a race of various furries, and has always been that way. But beyond "teh future!!!!!11!!1oneoneone!" I have no clue what I want.