The Science of Worldbuilding

[Silverblade5]

In the Math and Science thread, we had an idea about expanding our services to the creation of believable worlds. Direct any questions about physics towards myself or @Glamdring804 and chemistry towards @Pagerunner.

[Glamdring804]

2 hours ago, StrikerEZ said:

Yeah, the other three are basically Earth equivalent in water coverage, though one of them may be a little less or more. I'm not quite sure about the exact amount of water coverage on that one, because for the map I drew of it, which is based off of Earth's map, I took away some land, so there'd be more water, but I also added more land as well. I want to say I added more water than I did land, but it's probably not enough to have any noticeable impact on how it appears.

I just want to say, what would it take for an Earth-like planet to have a sky that isn't blue, and what effect would that have on how it appears from one of the other three?

I don't really want them to appear all the same size though. I know, based on the current system, that two of them will always appear the same size, but I want the other one to appear a different size. The "smallest" of the three moons should appear slightly larger than our moon. I'm not sure if that makes the other two too big, but tell me what you think.

Also, should I move this discussion to the Creator's Corner thread?

Okay. So. There are a couple ways to get them to appear different sizes, but it gets messy. If you have them locked in a giant plus symbol, all the same distance from the center of mass, then two of them will be the same distance from the third, and hence the same size. The fourth will be a little smaller. There are two ways to get more variation.

1) Make the planets different sizes. I'm not sure how exactly like Earth they need to be, but you could make some slightly larger or smaller than each other. This would work well with one of them having a defunct geo-magnet, as a smaller planet's interior would cool faster, and its interior would solidify, leaving it without a magnetic field. This is what happened to Mars's magnetic field. Note that this would cause the planets to have slightly different gravity and surface areas. The gravity you could mitigate by varying their density a little, i.e. the small planet could have Earth-like gravity by having an extremely large metal core.

2) Put the planets at different distances from the center of mass. This would get very messy very fast. Moon-planet systems are stable because one mass is much larger than the other. In cases where the bodies are comparable in size (Earth & Moon, Pluto & Charon) there are only two bodies with significant mass. However, four planets orbiting a mutual center of mas at different rates wouldn't even be remotely stable. It would fall apart within a matter of days. You would get the planets to have different sizes in each other's skies, but they would grow and shrink as they got closer and further from each other. I wouldn't really recommend this option.

I don't know exactly how to make a planet's sky not blue without making it poisonous. You should probably have a chemist answer this question. I can tell you however, that without significantly increasing the cloud content of the atmosphere, you wouldn't significantly change it's appearance from space. The sea is blue because it sorta reflects blue light and absorbs everything else, not because it reflects the color of the sky. Again, you could in theory change the color of the sea with various chemicals, but I don't know how to do this without making it toxic to conventional life. Seriously, find a chemist if you want to pursue this line of reasoning.

[Silverblade5]

2 hours ago, Glamdring804 said:

I don't know exactly how to make a planet's sky not blue without making it poisonous. You should probably have a chemist answer this question. I can tell you however, that without significantly increasing the cloud content of the atmosphere, you wouldn't significantly change it's appearance from space. The sea is blue because it sorta reflects blue light and absorbs everything else, not because it reflects the color of the sky. Again, you could in theory change the color of the sea with various chemicals, but I don't know how to do this without making it toxic to conventional life. Seriously, find a chemist if you want to pursue this line of reasoning.

@Pagerunner

[StrikerEZ]

2 hours ago, Glamdring804 said:

Okay. So. There are a couple ways to get them to appear different sizes, but it gets messy. If you have them locked in a giant plus symbol, all the same distance from the center of mass, then two of them will be the same distance from the third, and hence the same size. The fourth will be a little smaller. There are two ways to get more variation.

1) Make the planets different sizes. I'm not sure how exactly like Earth they need to be, but you could make some slightly larger or smaller than each other. This would work well with one of them having a defunct geo-magnet, as a smaller planet's interior would cool faster, and its interior would solidify, leaving it without a magnetic field. This is what happened to Mars's magnetic field. Note that this would cause the planets to have slightly different gravity and surface areas. The gravity you could mitigate by varying their density a little, i.e. the small planet could have Earth-like gravity by having an extremely large metal core.

2) Put the planets at different distances from the center of mass. This would get very messy very fast. Moon-planet systems are stable because one mass is much larger than the other. In cases where the bodies are comparable in size (Earth & Moon, Pluto & Charon) there are only two bodies with significant mass. However, four planets orbiting a mutual center of mas at different rates wouldn't even be remotely stable. It would fall apart within a matter of days. You would get the planets to have different sizes in each other's skies, but they would grow and shrink as they got closer and further from each other. I wouldn't really recommend this option.

I don't know exactly how to make a planet's sky not blue without making it poisonous. You should probably have a chemist answer this question. I can tell you however, that without significantly increasing the cloud content of the atmosphere, you wouldn't significantly change it's appearance from space. The sea is blue because it sorta reflects blue light and absorbs everything else, not because it reflects the color of the sky. Again, you could in theory change the color of the sea with various chemicals, but I don't know how to do this without making it toxic to conventional life. Seriously, find a chemist if you want to pursue this line of reasoning.

I think I'm fine with two of them being the same size. Honestly, what's more important for these planets is that the have to be as close to being like Earth as possible, with th exception of the hotter one, while still meeting the requirements I've already mentioned. It's important for story reasons.

[Pagerunner]

54 minutes ago, Silverblade5 said:

@Pagerunner

Don't look at me. Light scattering is physics, not chemistry.

[+Extesian]

I'm no physicist, but isn't the sky blue because blue is a shorter wavelength and blue light gets scattered, making the sky around us blue (and it's less blue directly in the path of the sun because the blue is scattered away from the path of the white light)? And then the sea is blue on a sunny day because it reflects the blue light from the atmosphere. 

You can have a sky of a different color with a higher density of particles in the atmosphere, like we get at sunset. I think Venus has an orange sky? But them they've got crazy greenhouse gas effect so it's unliveable. How you can do it with a liveable planet I have no idea. 

[Erandeni]

Yes, the sky is blue due to Rayleight scattering, it depends on the wavelength, the shorter wavelength, the more intense is the light, and hence making the sky blue and purple, but purple light is absorb in the upper part of the atmosphere, and our eyes are more sensitive to blue(I am not sure about the eyes, but is what I've been told, Can someone confirm it?)

In the sun set the blue light get too scattered because the amount of atmosphere it has to pass through is higher, then the direct light of the sun is red/orange.

If you want a warmer color sky you can change the density of atmosphere or the angle at which light incide.

[Landis963]

19 hours ago, Idealistic Mistborn said:

Yes, the sky is blue due to Rayleight scattering, it depends on the wavelength, the shorter wavelength, the more intense is the light, and hence making the sky blue and purple, but purple light is absorb in the upper part of the atmosphere, and our eyes are more sensitive to blue(I am not sure about the eyes, but is what I've been told, Can someone confirm it?)

In the sun set the blue light get too scattered because the amount of atmosphere it has to pass through is higher, then the direct light of the sun is red/orange.

If you want a warmer color sky you can change the density of atmosphere or the angle at which light incide.

How dense does such an atmosphere need to be to affect a noticeable color change (e.g. from blue -> blue-green)?  I ask because, as I learned in my "world with a year-long day" thread, a thick atmosphere is one of the things I'd need to regulate planetary temperatures during the night.  EDIT: And how does that play with a dimmer sun than ours?  

Edited June 4, 2017 by Landis963

[Erandeni]

3 hours ago, Landis963 said:

How dense does such an atmosphere need to be to affect a noticeable color change (e.g. from blue -> blue-green)?  I ask because, as I learned in my "world with a year-long day" thread, a thick atmosphere is one of the things I'd need to regulate planetary temperatures during the night.  EDIT: And how does that play with a dimmer sun than ours?  

I don't have the numbers, I don't think it can be solved easily and I am really bad at computational science, but unless you want a red sky it should be just a litle bit more dense than ours, as I said in the sunset the light pass through more atmosphere so it'd be the equivalent to a "densier" atmosphere, for green it should be closer to ours.

With a red sun it has mainly orange-red light so I suppose the sky should be orange.

[Landis963]

On 6/4/2017 at 5:09 AM, Idealistic Mistborn said:

I don't have the numbers, I don't think it can be solved easily and I am really bad at computational science, but unless you want a red sky it should be just a litle bit more dense than ours, as I said in the sunset the light pass through more atmosphere so it'd be the equivalent to a "densier" atmosphere, for green it should be closer to ours.

With a red sun it has mainly orange-red light so I suppose the sky should be orange.

How about with an orange sun?  (As opposed to a yellow sun, like Earth's) It sounds like my sky will be green.  

[Erandeni]

26 minutes ago, Landis963 said:

How about with an orange sun?  (As opposed to a yellow sun, like Earth's) It sounds like my sky will be green.  

It's possible, assuming that the shift to cooler color is the same than ours(I don't think it is correct but should allow us to do some rough aproximation), a star with a temperature a bit less than 5000K should provide a green sky.

[Dragon314]

What would be the effects of orbiting a red dwarf?

[Glamdring804]

On 6/7/2017 at 11:26 AM, Dragon314 said:

What would be the effects of orbiting a red dwarf?

Well, for starters, the habitable zone of a red dwarf is going to be very close to the star, meaning that planets in the region will likely be tidal-locked. This of course means that one half of the world will be desert, the other will be covered in glaciers, and any habitability will be limited to a small band around the twilight region. You would bypass this two ways: having a thick atmosphere or significant ocean, to help regulate heat and expand the habitable zone, or to have the world be a moon of a gas giant.

Red dwarfs are also unstable. They can be covered by huge sunspots, significantly reducing sunlight emitted, or they can flare unpredictably. This would make environments and habitability very unstable.

As a result of the red coloration, any life that evolved on the world would have its visible spectrum shifted into infrared. They would be able to see higher wavelengths infrared radiation, and they would not likely be able to see greens or blues.

So, in a nutshell, things would be weird.

Edited June 11, 2017 by Glamdring804

[Eagle of the Forest Path]

I've got a (fantasy) story set on a water-world. It's over 90% ocean, all the land is in a single thin continent stretching north to south (uninhabitable because of the radiation from large handwavium deposits in the ground).

I'm having some trouble determining what the weather would be like on such a world. Due to the relative lack of topography, I'd image the weather to be pretty uniform.
In specific, the prevailing winds could become story-relevant. I think the winds would be opposite to the direction of spin (with some north or south added in, depending on the latitude) but I'm having some trouble remembering my high-school geography classes.

I also had the idea of a very rapid procession of equinoxes. They would come full circle in about 36/37 revolutions around the sun.
Can anyone tell me if that would have any adverse effects on my planet (apart from making navigating by the stars devilishly more difficult)?

[Oversleep]

I have absurdly strong character (think superhero strength) - you know, things like punching through walls, cracking sidewalk with jumping etc.

The question is: how do I make the strength feats consistent? (Without getting a degree in few fields) If punching through wall requires less strength than lifting a car and he can do the latter but not the former I have a pretty big flaw.

I hoped superhero fandoms would have such tables classifying various feats but apparently they categorise everything by how much a character can lift.

[Yuoaman]

I have a handful of questions concerning a magic system I'm working on. The magic system is, at its base level, the redirection and transformation of energy. A character could say, take the energy from a pot of boiling water and redirect that heat to set a log on fire or, with more skill, they could transform that heat into light and create a crude flashlight. Now, my questions are:

1. How difficult is it in real-world terms to transform one kind of energy into another? And, which forms of energy do this most readily?

2. What form of energy (or energies) could be applied to something to increase its physical resilience? I assume elastic energy would play a role, but otherwise am unsure.

(I may have future questions in the future, as well, but these ones are the most pressing.)

[Oversleep]

6 hours ago, Yuoaman said:

1. How difficult is it in real-world terms to transform one kind of energy into another? And, which forms of energy do this most readily?

Look up engines. Engine is a machine transforming one kind of energy into mechanical energy.

[+Extesian]

2 hours ago, Oversleep said:

Look up engines. Engine is a machine transforming one kind of energy into mechanical energy.

I love this. All my years of causal interest in science and I never realized nor heard that as the definition. One of those definitions that immediately makes sense when you hear it. 

[Yuoaman]

7 hours ago, Oversleep said:

Look up engines. Engine is a machine transforming one kind of energy into mechanical energy.

Interesting, this definitely gives me some things to consider.

[Glamdring804]

On 6/24/2017 at 10:21 PM, Yuoaman said:

2. What form of energy (or energies) could be applied to something to increase its physical resilience? I assume elastic energy would play a role, but otherwise am unsure.

Elastic energy wouldn't really effect how resilient something is. Elastic energy is a form of potential energy, i.e. energy stored in an object by deforming it. A compressed spring or a drawn bow is a good example of elastic energy.

To make something physically stronger, broadly, you would have to increase the strength of the bonds between the molecules of the substance. If you wanted to put this in terms of a form of energy, it would probably be binding energy.

I want to make a note about "energy" in general. A lot of authors in speculative fiction tend to treat energy as "stuff," a physical substance that you can hold in your hand if you concentrate hard enough. This is wrong. Energy is a property of an object, like its color or its texture. It's something that describes an object, not an object in itself. Specifically, energy is the ability of a system to do work, as my professor once put it, it's the potential of an object to do damage. A speeding bullet can do more damage than a lump of lead just sitting on your desk, which means it has more energy. A rock a hundred feet over your head can do a log more damage than a rock sitting next to your feet. This is something you should bear in mind as you write your magic system.

@Eagle of the Forest Path, @Oversleep, I'll try to answer your questions tomorrow. I'm sorry about not responding sooner, I've been kind of busy with my own writing.

[Yuoaman]

1 hour ago, Glamdring804 said:

Elastic energy wouldn't really effect how resilient something is. Elastic energy is a form of potential energy, i.e. energy stored in an object by deforming it. A compressed spring or a drawn bow is a good example of elastic energy.

To make something physically stronger, broadly, you would have to increase the strength of the bonds between the molecules of the substance. If you wanted to put this in terms of a form of energy, it would probably be binding energy.

I want to make a note about "energy" in general. A lot of authors in speculative fiction tend to treat energy as "stuff," a physical substance that you can hold in your hand if you concentrate hard enough. This is wrong. Energy is a property of an object, like its color or its texture. It's something that describes an object, not an object in itself. Specifically, energy is the ability of a system to do work, as my professor once put it, it's the potential of an object to do damage. A speeding bullet can do more damage than a lump of lead just sitting on your desk, which means it has more energy. A rock a hundred feet over your head can do a log more damage than a rock sitting next to your feet. This is something you should bear in mind as you write your magic system.

@Eagle of the Forest Path, @Oversleep, I'll try to answer your questions tomorrow. I'm sorry about not responding sooner, I've been kind of busy with my own writing.

Thanks for the food for thought! I definitely need to think about how I tackle it to avoid treating energy like "stuff" as you term it.

[Glamdring804]

On 6/11/2017 at 11:57 PM, Eagle of the Forest Path said:

I've got a (fantasy) story set on a water-world. It's over 90% ocean, all the land is in a single thin continent stretching north to south (uninhabitable because of the radiation from large handwavium deposits in the ground).

I'm having some trouble determining what the weather would be like on such a world. Due to the relative lack of topography, I'd image the weather to be pretty uniform.
In specific, the prevailing winds could become story-relevant. I think the winds would be opposite to the direction of spin (with some north or south added in, depending on the latitude) but I'm having some trouble remembering my high-school geography classes.

I also had the idea of a very rapid procession of equinoxes. They would come full circle in about 36/37 revolutions around the sun.
Can anyone tell me if that would have any adverse effects on my planet (apart from making navigating by the stars devilishly more difficult)?

The general weather would be generally what you find in the middle of large oceans on Earth. With very little land to break up storms, they could really get going though. I would imagine massive hurricanes thousands of miles across would be a regular occurrence, depending on the temperature of the world.

Temperatures would be fairly uniform. Water is a wonderful heat regulator, so extreme hot and extreme cold would be rare. I'm not even sure there would be ice caps. Again, that depends on the average temperature of the world. Prevailing winds actually follow a planet's rotation. Winds in middle latitudes move from west to east, while the sum moves from east to west. However, when you think about it, if you treat the sun as a stationary point, this means the any part of the planet is moving towards the east, just like the wind. Also, depending on how mountainous the continent is, it could have huge effects on the weather. If it has a lot of mountains, then they would force the clouds to drop all their moisture, making the western part of the continent very wet, and the eastern part rather dry. Also, any islands immediately downwind would be less lush as a result.

I'm not sure what you mean by rapid procession of equinoxes. Are you saying you want the planet to not have a stable axial tilt, and wobble back and forth several times in a single orbit?

On 6/24/2017 at 3:20 PM, Oversleep said:

I have absurdly strong character (think superhero strength) - you know, things like punching through walls, cracking sidewalk with jumping etc.

The question is: how do I make the strength feats consistent? (Without getting a degree in few fields) If punching through wall requires less strength than lifting a car and he can do the latter but not the former I have a pretty big flaw.

I hoped superhero fandoms would have such tables classifying various feats but apparently they categorise everything by how much a character can lift.

"Strength" is a messy way of looking at something like this. What a "super strength" hero can do depends an a variety of factors, including his bone strength, muscle strength, and the situation he's in. Lifting a car would require a much lesser impulse than punching through a wall, since the punch would be instantaneous, while lifting the car would (presumably) take several seconds. I'm not 100% sure, but I'm fairly confident that punching through a wall would take much more force than lifting a car. For a human fist to have enough momentum to break the wall, it would have to be going absurdly fast, and the tissue of the person's hand would have to be much stronger than normal human tissue.

[Eagle of the Forest Path]

4 hours ago, Glamdring804 said:

The general weather would be generally what you find in the middle of large oceans on Earth. With very little land to break up storms, they could really get going though. I would imagine massive hurricanes thousands of miles across would be a regular occurrence, depending on the temperature of the world.

Temperatures would be fairly uniform. Water is a wonderful heat regulator, so extreme hot and extreme cold would be rare. I'm not even sure there would be ice caps. Again, that depends on the average temperature of the world. Prevailing winds actually follow a planet's rotation. Winds in middle latitudes move from west to east, while the sum moves from east to west. However, when you think about it, if you treat the sun as a stationary point, this means the any part of the planet is moving towards the east, just like the wind. Also, depending on how mountainous the continent is, it could have huge effects on the weather. If it has a lot of mountains, then they would force the clouds to drop all their moisture, making the western part of the continent very wet, and the eastern part rather dry. Also, any islands immediately downwind would be less lush as a result.

I'm not sure what you mean by rapid procession of equinoxes. Are you saying you want the planet to not have a stable axial tilt, and wobble back and forth several times in a single orbit?

Thanks, Glamdring, that wind thing really helps. I'm wondering if you'd actually get storms on such a world though. As you say, water is awesome as a heat regulator, and as I understand it, you need masses of cold and hot air rubbing up against each other to make storms.

I think what you say is pretty much what I meant by precession of equinoxes (turns out it's pre-, not pro-, by the way). I looked up this wiki about it, the picture makes it pretty easy to understand the concept at least. On earth, the axis ("tilt direction") makes one full rotation in about 26-thousand years. On my fantasy world I'd have it happen in less than 40 years (and let's say year length is about the same).
This means that a four-season "cycle" from solstice to solstice would be noticeably shorter (or longer, depending on the direction of rotation) than an actual solar year.
Most I've worked out in consequences is that navigating by the stars is going to be a lot more difficult (and astrology has the possibility of being a lot more interesting) because each "cycle" you'd have the constellations in a different place.

[Glamdring804]

13 hours ago, Eagle of the Forest Path said:

Thanks, Glamdring, that wind thing really helps. I'm wondering if you'd actually get storms on such a world though. As you say, water is awesome as a heat regulator, and as I understand it, you need masses of cold and hot air rubbing up against each other to make storms.

I think what you say is pretty much what I meant by precession of equinoxes (turns out it's pre-, not pro-, by the way). I looked up this wiki about it, the picture makes it pretty easy to understand the concept at least. On earth, the axis ("tilt direction") makes one full rotation in about 26-thousand years. On my fantasy world I'd have it happen in less than 40 years (and let's say year length is about the same).
This means that a four-season "cycle" from solstice to solstice would be noticeably shorter (or longer, depending on the direction of rotation) than an actual solar year.
Most I've worked out in consequences is that navigating by the stars is going to be a lot more difficult (and astrology has the possibility of being a lot more interesting) because each "cycle" you'd have the constellations in a different place.

Hm, that's interesting. I'm not sure if such a precession would be possible. Your planet would probably need to lack any major moon. Even planets without moons like Mars have longer wobble periods. I'm not 100% sure on this though. It's possible, but highly unlikely to be natural. In any case, you could just rule of cool it away.

[Oversleep]

19 hours ago, Glamdring804 said:

"Strength" is a messy way of looking at something like this. What a "super strength" hero can do depends an a variety of factors, including his bone strength, muscle strength, and the situation he's in. Lifting a car would require a much lesser impulse than punching through a wall, since the punch would be instantaneous, while lifting the car would (presumably) take several seconds. I'm not 100% sure, but I'm fairly confident that punching through a wall would take much more force than lifting a car. For a human fist to have enough momentum to break the wall, it would have to be going absurdly fast, and the tissue of the person's hand would have to be much stronger than normal human tissue.

It basically works like... like pewter only enhanced flesh and he can sustain duralumin-level burn. Does it make sense? His power is over the flesh and he uses it on himself to strenghten his muscles. So I imagine he can enhance his muscles mutliple times and that's what I mean by "strenght".

Secondary power is strenghtening bones and provides regeneration when necessary.

The handwave is that his strength depends on how much power is he channeling at given moment, so if there are some not-too-big inconsistences it will be chalked up to "he's pushing his power".