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Sidmen
2015-01-27, 01:33 AM
Hello Playground!

I'm beginning to design my own fantasy world and am slowly trying to fill in holes in my understanding to increase verisimilitude. It is called the Infinite World, and it is a Dyson Sphere encapsulating a yellow dwarf star at a distance of 1 AU.

Right now I'm wondering if you could see the interior rising up in all directions, or if the human eye would be incapable of seeing that distance. Assuming an atmosphere as thick and moisture-rich as earth's, and no night.

For those that are interested, and to collect my own thoughts:

There is no day-night cycle, the sun is always shining.
Powerful electromagnetic fields generated at the poles filter out much of the harmful radiation, venting it into space.
Time is judged based around the moons' moons. Gigantic geostationary space stations are visible over every major continent - appearing as moons of various shapes in the sky. Smaller satellites orbit these stations, taking roughly 24 hours to complete one rotation.
Seasons are based on weather patterns. There is the season of drowning - during which immense storms roll in off the oceans unleashing torrential downpours. The season of Growing - during which the skies are cloudy and people can go out to plant and grow crops. The season of Burning, during which the clouds depart and the sun beats down upon the land. The length of the seasons vary from year to year, depending on how long the weather patterns last - some years three crop rotations can be had, in others the rains don't stop until a few weeks before the Burning begins.
Massive solar collectors circle the sphere inside the moons, when they cast a shadow upon the land it becomes winter. Winters come once every five years on average, and depending on which collector is casting the shadow upon you - the winter could last anywhere from one month to a year or more. There are two 100-year cycles of winters. in the first, winters are quick, but in the second they can drag on for a LONG time.


More may come if there is any interest.

JNAProductions
2015-01-27, 01:38 AM
Could you see the Dyson Sphere itself? (I think that's what you're asking.)

Right, imagine if the sun was the size of your satellites. I'm going to assume each one is the size of Asia, just for overestimation. Now imagine it barely gives off light-maybe equivalent to, hey, Asia. Bright from an orbital perspective, but from an AU? Not so much.

Basically, one AU is mind-bogglingly far. Unless your satellites are comparable to planets, they won't be seen, and even then it won't be a constant thing. Just an occassional shadow across the sun (if between the sun and planet).

Also? Setting sounds cool.

Mastikator
2015-01-27, 01:52 AM
Unless the interior that is rising is the width of the Earth... no. At least not on the other side of the dyson sphere. You'd probably be more likely to see the atmospheric reflection. Consider that Venus is occasionally 1AU from us and is visible as a slightly bigger star.

I think something like this (http://ak2.picdn.net/shutterstock/videos/5339240/preview/stock-footage-hd-earth-the-dark-side-of-the-earth-with-city-lights-visible-loop.jpg)might be more appropriate. But rather than a glowing dot being a city, it's an moon-sized (or more) construct, or group of constructs.

I know it's not what you asked about, but if winters last for 100 years then people would move away from winter areas. 100 years is more than most people live.

Sidmen
2015-01-27, 01:52 AM
Thanks JNA,

That was my initial thought, that the curvature of the sphere over the vast distance would be so shallow that atmospheric vapor would make it impossible to see the continents immediately surrounding your own; and I knew you wouldn't be able to see all the way across the sphere. My only concern was the ability to see the nearest parts of the curve. But I think you're right - the distances involved would make that an impossibility - especially with an always illuminated atmosphere.

@Mastikator
Thanks,
The cycle of winters are trends, not actual winters. In the first of the 100 year cycles, winters are short - maybe 1-3 months long. In the second cycle they are long - from 3-12 months. They still occur at a frequency of once about every 5 years though. Its only each winter's duration that varies.

JNAProductions
2015-01-27, 01:57 AM
That being said...

What if you can see it? No one questions it. It's part of the sky, day and night, just a normal, everyday thing. What's that say about where they live, if anyone thinks hard enough about it?

I don't know if this setting is at all right for this kind of intrigue, but hey. Use it or not, the idea has been presented.

Edit: *facepalm* I totally whiffed. I thought it was a rock in orbit with they Dyson sphere seperate. Either way, you've got a valid answer, so all's well.

As a side note, this place has a positively ridiculous surface area. 2.81210^17 square kilometers. Compare that to Earth-5.110^8 square kilometers. This place is about 50,00,00,000 times bigger than Earth.

How many people live here?

BWR
2015-01-27, 01:59 AM
Have you read Larry Niven's Ringworld series? Not a full Dyson sphere but a 'small' ring around a sun. It might give you some ideas. I don't think the Ring was as much as 1 AU in radius but the inhabitants could see the Arch - the rest of the Ring arching above their heads.

gom jabbarwocky
2015-01-27, 02:03 AM
My thinking in regards to hollow world type settings in general is that unless the diameter is relatively short or there is no atmosphere (in a fantasy world, maybe instead of air and stuff there is invisible aether?) there would be a limit to visibility that would prevent you from seeing the earth wrap up around the sky. At 1 AU from the center of the sphere, that is definitely the case.

By that same toke, however, I always like to picture how to the inhabitants of a hollow planet, the horizon would always curve upwards, like they were in a shallow bowl - if an inhabitant were to stand at the top of a mountain, or in the center of a vary large field, it would look strange to us (as people who, you know, live on the surface of an oblate sphereoid and not in a concave basin). Although with a diameter of 2 AU, for the curvature would be so shallow as to be virtually imperceptible.

LooseCannoneer
2015-01-27, 02:11 AM
Have you read Larry Niven's Ringworld series? Not a full Dyson sphere but a 'small' ring around a sun. It might give you some ideas. I don't think the Ring was as much as 1 AU in radius but the inhabitants could see the Arch - the rest of the Ring arching above their heads.
The radius of the Ringworld is 1.02 AU.

Sidmen
2015-01-27, 02:13 AM
As a side note, this place has a positively ridiculous surface area. 2.81210^17 square kilometers. Compare that to Earth-5.110^8 square kilometers. This place is about 50,00,00,000 times bigger than Earth.

How many people live here?
Hehe, no worries.

But yes, a Dyson sphere is utterly massive - that's why I named it the Infinite world, because it is from the perspective of the people living there. My question was directed mostly because I'm filling a new sketchbook with this world's information, and am currently writing a preamble from the perspective from the Master of Maps at the archives of the Tower that Isn't. If you could see the curve, then he would point this out as proof of his claim that the world isn't actually infinite, just utterly huge.

Some trillions of people live on this world, but the vast majority aren't in contact with the others. It is a medieval fantasy setting that includes magic (since it's intended for use with D&D 5e, and everyone in that system has magic). So some of the answers can be "it's magic", but I want as few as possible of them to be.


My thinking in regards to hollow world type settings in general is that unless the diameter is relatively short or there is no atmosphere (in a fantasy world, maybe instead of air and stuff there is invisible aether?) there would be a limit to visibility that would prevent you from seeing the earth wrap up around the sky. At 1 AU from the center of the sphere, that is definitely the case.

Thanks, that's further reinforcement of my initial suspicion. There is air in my world, and it does have water vapor in it. I know the atmospheric interference on earth limits our sight to about a dozen or so miles, but I wanted to add some more brain power, or those with more knowledge to my thoughts.


EDIT: Oh, and I have unfortunately not read Ringworld.

JNAProductions
2015-01-27, 02:17 AM
What's Outside the Dyson Sphere? Speaking as a player who likes to push things, that's something you might want to give thought to.

In addition, just as a minor fluff detail, Star-Forged weapons, made from chunks of White Dwarf. No idea on the crunch, but could make a cool artifact.

LooseCannoneer
2015-01-27, 02:23 AM
Read it. The first few chapters on the ringworld will give you some truly mavelous ideas.

TheCountAlucard
2015-01-27, 08:00 AM
Another fantasy setting with a Dyson sphere is the Demon City in Exalted.

More specifically, the Demon City is a giant living structure of tarnished brass and black basalt bones centered around a hateful emerald star that casts no shadows. Due to the twisted nature of Malfeas, the green sun appears directly overhead from the viewpoint of any and every layer of the city simultaneously. Malfeas is insanely massive, yet still absolutely crowded with manic, braying demons, and his spiteful plate tectonics will grind two layers together at a time, killing untold thousands.

It's surrounded on all sides by an endless desert, which seals it away from the world it once ruled over; a wind runs through the Demon City whenever and wherever silence falls, killing everyone present; "lower" levels of the Demon City are flooded by a caustic sea filled with even more terrible monsters; buildings shatter in the wake of the Black Boar That Twists the Skies.

Also it's hella fun to play in. :smallamused:

Yora
2015-01-27, 08:14 AM
Not to spit into other peoples soup: But why?

So far, it seems like for people in this world everything is exactly the same as on a planet, except that the sun never sets. A few scientists might figure out that the infinite flat surface is actually not infinite but very slightly curved, but what effect does that have on anyone else?

Joe the Rat
2015-01-27, 10:37 AM
Ages of ages ago I'd read a story, part of which was set on a Jupiter-sized rocky planet with a breathable atmosphere. The author had suggested that so much air would refract the horizon upwards, giving you a concave horizon on a convex world. If that holds water (or rather, bends light), then you would definitely have a bowl horizon. If not... you still might get a bowl horizon. But consider that you are not looking at the outer surface of a 3900 mile radius spheroid. You are looking at the inner surface of a 93 million mile radius sphere. With a curvature roughly 25,000 times shallower, it may look pretty flat.

What is going to limit your horizon is distance and scatter. At some point, you will not be able to make out detail save at the largest scales, or with super-to-supernatural acuity. But at some point you will run into scatter from the atmosphere. Light bouncing off the air molecules and water vapor, shifting and fading color, washing out detail, and distortion from temperature variants will make everything disappear into a haze of distance. The horizon doesn't fall off so much as disappear into the ether. At first blush, this sounds like "fading into infinity" to me.

But let's play a game. set a tangent line ABC to a sphere, intersecting at B. Set another line (BD) at, oh say a 10 degree angle with the tangent line from B to where it intersects the sphere again at D. What's the distance between B and D? If I'm doing my math right, that's 16.14 million miles. 10 degrees up from a "flat" is looking at something 1.4 light minutes away, with light bouncing through two layers of atmosphere on one hell of an oblique. Best guess, you aren't seeing crap for detail. A moon-sized object at that distance will appear about 1/6 the size of our moon.

To the characters in the setting (assuming they're local), this is normal. What you do is set up the understanding of the world, and change one detail: Things don't disappear over the horizon, they disappear *into* the horizon.


What's Outside the Dyson Sphere? Speaking as a player who likes to push things, that's something you might want to give thought to.

In addition, just as a minor fluff detail, Star-Forged weapons, made from chunks of White Dwarf. No idea on the crunch, but could make a cool artifact.Outside? That's the Underdark.

Lord Torath
2015-01-27, 10:47 AM
What's Outside the Dyson Sphere? Speaking as a player who likes to push things, that's something you might want to give thought to.

In addition, just as a minor fluff detail, Star-Forged weapons, made from chunks of White Dwarf. No idea on the crunch, but could make a cool artifact."Chunks" of White Dwarf? The crunch is that there is no crunch. White dwarfs are stars, and as such, are made up of hydrogen and helium gas. Have to come up with another source of "star metal".

Segev
2015-01-27, 11:13 AM
Notably, the moons orbiting will be visible only to bands of the world that coincide in some way with their orbit. The orbit of the moons, if they are coplanar, will also define directions, but only for those regions which can see them.

Further away from the band in which the moons orbit, there will be no signs of such things.

Alternatively, there could be moons orbiting in many different planes, which would require them to also orbit at massively different distances. The ones closer to the sun would have to be bigger to remain visible on the surface of the sphere. Also, where moon paths cross, people would have different perspectives on their paths than where there is only one moon that passes into view, or where moons apparently travel similar paths.

Finally, moons would not "rise" and "set," but would instead approach and recede. They fly overhead more like an airplane seems to, appearing in year-long cycles as small specks in the horizon, growing and separating out to be overhead, then shrinking and receding into the opposite horizon.

Elvenoutrider
2015-01-27, 01:43 PM
The oceans on the planet would be unstable. Rendezvous with Rama by Arthur c Clark discussed this a bit. Because the surface of the ocean is heated and the outside of the Dyson sphere is not, it would cause ice to freeze at the bottom of it and rise to the surface. The massive quantities of ice fracturing and moving could cause massive waves and storms as well as massive fluctuations in water temperature. In ramas case, he crafts temperature rising as a whole caused a superstorm resembling a hurricane which threatened the safety if the exploration crew. I know Arthur c Clarke actually spoke with climatologists to come to this conclusion, and not being one I can't do it justice. Just keep in mind in this sort of environment, any storm has a harder time dissipating, and the fact that the ground is not heated from a central core as our planet is will cause problems.

Lord Torath
2015-01-27, 02:16 PM
Keep in mind, if the Dyson sphere is not rotating, there will be no Coriolis effect to cause storms to swirl. And even if it is rotating, the rotational speed will be so slow that most storms will be unaffected by it. So you'll be unlikely to get huge hurricane superstorms. You'll still get tornadoes and probably mesocyclones (http://www.slate.com/blogs/bad_astronomy/2014/10/04/stormscapes_mesocyclone_video.html), but there will be no jet streams or polar vortices.

How thick is your atmosphere? I think ours "ends" at about 100 km.

Segev
2015-01-27, 02:30 PM
Actually, that brings up another point: due to how fields work (in this case, gravitational fields), there is no gravity on the inner surface of the sphere. All the gravity pulls towards the star and other bodies orbiting within the sphere. (You would see a similar effect if you could sit at the center of the Earth.)

To get gravity, you'd need to rotate the sphere. This would, in effect, cause there to be a gentle-but-increasing slope as you moved away from the equator, with the equator being the "bottom" of the world, gravitationally-speaking. There would be some point where the gravitational pull towards the equator would balance its "out" force with the "in" force of the central star, which would cause the inner surface of the sphere to be sheer walls there. Go higher still, and the gravitational force felt would be strictly towards the sun, causing the inner surface here to feel like a ceiling as you get to the poles. A ceiling over an AU drop to a burning hot star.

You'd also have thinning atmosphere out that far, as, like any fluid, it would be pulled "down" towards the equator.

Also, go fast enough against the rotation of the sphere, even at the equator, and you will start to feel an upward force as you negate your centrifugal force.

Lentrax
2015-01-27, 02:47 PM
Well, as far as the gravity goes:

Where did the sphere originate? A species evolved enough to have created the sphere, to be able to completely encapsulate their own star, probably had sufficiently advanced gravity technology. Advanced enough to at least create a facsimile of Earth-norm gravity.

Lord Torath
2015-01-27, 02:56 PM
There does need to be a certain amount of "magic handwaving" for the concept of the dyson sphere to exist, as they are inherently unstable. A slight shift away from being perfectly centered on the star will quickly bring the whole thing to ruin, as the central star is pulled to the closer side of the sphere until it hits. Decide what you want to have "magically" working, and extrapolate from there.

gutza1
2015-01-27, 03:01 PM
Neat idea for a Hard High Science Fantasy setting (that's a term I coined just now. It means a setting that mixes high fantasy and hard science fiction. Like Lord of the Rings meets Interstellar). Let me offer my two cents:


The oceans on the planet would be unstable. Rendezvous with Rama by Arthur c Clark discussed this a bit. Because the surface of the ocean is heated and the outside of the Dyson sphere is not, it would cause ice to freeze at the bottom of it and rise to the surface. The massive quantities of ice fracturing and moving could cause massive waves and storms as well as massive fluctuations in water temperature. In ramas case, he crafts temperature rising as a whole caused a superstorm resembling a hurricane which threatened the safety if the exploration crew. I know Arthur c Clarke actually spoke with climatologists to come to this conclusion, and not being one I can't do it justice. Just keep in mind in this sort of environment, any storm has a harder time dissipating, and the fact that the ground is not heated from a central core as our planet is will cause problems.

There's a simple solution to this: The aliens who built the Dyson Sphere built heaters that generate upper mantle-like temperatures at the very edge of the sphere (the deepest areas underground to the inhabitants). The heaters would be powered by the immense amount of solar energy that the orbiting satellites and the Sphere itself generates. This solves the freezing ocean and allows for natural magma to form underground, creating natural volcanoes and giving dwarves a way to smelt stuff in an awesome way.


Outside? That's the Underdark.

Actually, the bottom of the world would likely be made of an extremely strong material. Considering the tech-requirements it would be a carbon-nanotube/buckyball alloy at the very least; I'd recommend neutron-degenerate matter. If, somehow, one were to breach the super-durable "skin" of the Sphere, they would be exposed to the vacuum of space. The breach would begin sucking out the atmosphere. However, the civilization that created the Sphere (I'm going to call them the Creators) would probably have foreseen that scenario and stationed repair drones/supplies on the "skin" to seal any holes in the Sphere. The drones would be powered by the incredible amount of energy produced by the Sphere, and with the Creators' super-science could last for billions of years (I think it is proper to use Clarke's Third Law here considering that the Creators had the capability to build a structure the size of a small solar system and planets to inhabit it).

Acutally, I have an idea. What if the Creators were a highly advanced version of humanity thousands of years in the future? They have started to Dysonize the galaxy (I'm going to assume that they have wormhole technology because without FTL travel and communication such an arduous construction project would be nearly impossible. Another assumption I am making is that future humanity has merged itself with the machines, and now is a seamless fusion of biology and technology. My last assumption is that future humanity does not use magic if magic is actually a supernatural force and not just supertech left behind by the Creators as I will elaborate later), and as an experiment, decided to recreate the fantasy worlds of their past fictional works by seeding one of those Dyson Spheres with life from Earth and leaving AIs to direct the evolution of creatures on the Sphere over billions of years so that a fantasy environment (metahuman subspecies, normal humans, etc.) would be created. If we take this even further, why not make magic just a product of godlike nanotechnology, and deities said AIs? Then this setting would have a good explanation for why magic exists in an otherwise scientifically-hard world. There would be ominous black towers dotted all over the landscape, made of nearly indestructible (to fantasy methods, anyway) materials, channeling "magic" or performing some other task unknown to such primitive inhabitants. The moons the elves worship are actually giant artificial planets harvesting ludicrous amounts of energy to be used by the Creators and the Sphere itself. And some of the God-AIs might have gone rogue over the billions of years that they were operational, and now seek to lead their created races out of the Sphere and into the depths of space.

Segev
2015-01-27, 03:03 PM
There does need to be a certain amount of "magic handwaving" for the concept of the dyson sphere to exist, as they are inherently unstable. A slight shift away from being perfectly centered on the star will quickly bring the whole thing to ruin, as the central star is pulled to the closer side of the sphere until it hits. Decide what you want to have "magically" working, and extrapolate from there.

Actually, this isn't quite true. Inside the sphere, the gravitational field of the sphere itself is flat. There is equal force in all directions, no matter where you are, due to its gravity.

All objects inside its center experience gravity as if the sphere were not there. This includes the central sun. So if it drifts, it does so only on its own momentum. No gravitic force will excacerbate the problem. That doesn't mean drifting wouldn't be a hazard; it would, unless corrected, still cause the sphere to impact the sun...eventually. Just due to momentum from whatever started the drifting.

Lord Torath
2015-01-27, 03:16 PM
Does this depend on the relative masses of the two bodies, sphere and star? As the sun "wanders," it will be closer to one side of the sphere, and will pull harder on that side than the other. But at the same time, there is now more mass on the other side of the sun, although it's farther away. So the two forces could continue to be equal and opposite, for no net effect. Hmm...

I suppose I could just go spend a few hours on Atomic Rockets if I really want to come down Stupidity Hill. :smallredface:

Fouredged Sword
2015-01-27, 03:29 PM
Thoughts on what you see when you look up.

Ok, so the horizon would look REALLY odd to someone used to a round world. The land curves UP, so you could see a LOT further than normal given a flat expanse. You could see ships DAYS before they got to shore. Navigation may be easier because landmasses could be seem weeks from landing. Climb a short mountain and you should be able to see as far as your eyes can make out detail.

The main constrain would be the size of the object you are looking for and the atmosphere. The air causes light to scatter. Blue light scatters much more than other light due to an odd interaction with air. It's why our sky is blue around the edges and gets whiter as you get closer to looking directly into the sun (the blue light hitting the edges of the atmosphere scatters in your direction. This is also why sunsets are red (blue light scatters elsewhere, leaving the sun reddish).

It would look like the horizon is cloaked in a fog after a point. You can clearly see the ground from 30,000 feet up, so you are likely looking at 10x that to get enough distance that scattering blocks your view. Even a short tower would be a crushing tactical advantage for a defender. Get up above the tree level and you can see anything not behind something else. moving more than a few men would be impossible to hide.

After looking up past about 2-5 degrees the sky would turn the expected blue color. The ability to see land would fade into a blue haze as the light scattered from the sun became more powerful than the light reflecting off the land behind it. It would not be a solid line, but a fading effect. Winter would reduce this significantly and allow you to see far further up the edge of the world.

Then you would look up and see the sun. Objects, like your moons, would have to be very large to be seen. The problem is that light is coming from behind them, this means very little light is coming off the surface pointing towards the land. Unless they eclipsed the sun they would appear as faint outlines in the sky.

An example using our moon during the day. Note the dark side is almost invisible.
http://www.google.com/url?sa=i&source=images&cd=&cad=rja&uact=8&ved=0CAgQjRw&url=http%3A%2F%2Fdebwegner.blogspot.com%2F2014%2F1 0%2Fhot-flashes-and-cool-weather.html&ei=OvLHVKWPBMnasATh24KwAg&psig=AFQjCNF2QGiobfcu3nH0hHkLYGa6ho_FsQ&ust=1422476218224532

Measured in AU, the moon is VERY close and VERY small. Something at .5 AU (half way between your sun and land) would have to be HUGE to be seen. Consider making them glow somehow, or very shiny. A large shiny object could be seen from the opposite side of the sun. It would have to be very shiny and very large though. Visible during the day is a large hurdle. (a mirror the size of a planet with perfect albedo of 1 though... maybe. Depends on the planet.). Think less visible object, more glowing star though, and faint as it is in a losing battle with the sun. They would be invisible when on the land side of the sun, only to suddenly appear in the sky when they turn 90 degrees to the sun, but disappear again when they pass too close to the sun and it's light blocks them out. They would reappear on the other side though, and disappear as they turn once more to face away from the land. The moons, well it would take a VERY large object to hold a visible moon.

Akodo Makama
2015-01-27, 03:57 PM
Thanks, that's further reinforcement of my initial suspicion. There is air in my world, and it does have water vapor in it. I know the atmospheric interference on earth limits our sight to about a dozen or so miles, but I wanted to add some more brain power, or those with more knowledge to my thoughts.

I am currently looking at a mountain over 200 miles away, it is barely visible, but there. Today it is quite cloudy and a bit foggy; On a clear day, the mountain is easily visible in great detail.

The planets are easily visible in our night sky. If you know where to look, you can even see many of them in the middle of the day, including Jupiter. The far side of the sphere would be closer than Jupiter ever is to the Earth, and is much larger. With clear skies, it should be easily visible.

This assumes that the atmosphere is a shell along the inside of the sphere with a depth similar to Earth's. If the entire sphere is filled with atmosphere, it would have enough mass to collapse into a black hole under it's own gravity. This would limit adventure possibilities.

Lord Torath
2015-01-27, 04:11 PM
The main constrain would be the size of the object you are looking for and the atmosphere. The air causes light to scatter. Blue light scatters much more than other light due to an odd interaction with air. It's why our sky is blue around the edges and gets whiter as you get closer to looking directly into the sun (the blue light hitting the edges of the atmosphere scatters in your direction. This is also why sunsets are red (blue light scatters elsewhere, leaving the sun reddish).Actually the sky looks darker, not lighter, the closer you get to looking straight up. Go outside and give it a look.

Also, you won't get quite as much advantage from height as you might think. The curve of the sphere is very gentle. If you had a 12" block, you could put a (perfectly straight, perfectly rigid) ruler on it that's 375 miles long before both ends would touch the sphere. You know, assuming there are no hills, buildings, trees, or other obstructions in the way. Yes, towers will help, but not much more than they do here on earth.

The planets are easily visible in our night sky. If you know where to look, you can even see many of them in the middle of the day, including Jupiter. The far side of the sphere would be closer than Jupiter ever is to the Earth, and is much larger. With clear skies, it should be easily visible.

This assumes that the atmosphere is a shell along the inside of the sphere with a depth similar to Earth's. If the entire sphere is filled with atmosphere, it would have enough mass to collapse into a black hole under it's own gravity. This would limit adventure possibilities.Keep in mind, there is no night. Venus is visible (barely) during the day at certain points in its orbit, so it's not impossible, but you're not going to be able to see anything within probably 30 degrees of the sun, unless you're having an eclipse from one of the "moons."

lightningcat
2015-01-27, 11:45 PM
@ Sidmen
Are you going for a "Hard High Science Fantasy" setting or just a high fantasy setting?
In the latter case, the god(s) created the world and ignore RL science. Just remember to apply the same rules every where that shouldn't have a specific exception. Down is towards the ground, up it towards the sun. Winters may or may not be predictable in occurrence or duration. Objects seem to fade off into the horizon, etc. Sometimes worrying to much about the science of a fantasy world keeps you from telling interesting stories within it.

Pryan, the world of fire in the Death Gate Cycle (http://en.wikipedia.org/wiki/The_Death_Gate_Cycle) is effectively a Dyson Sphere with 4 suns in the middle. There is some RL science in the backstory, but the entire universe operates on magical reasoning.

Rakaydos
2015-01-28, 12:16 AM
This is a ringworld:
http://upload.wikimedia.org/wikipedia/commons/4/40/Ringworld.jpg

Note the inner ring of shadow squares, casting night on the outer ring. This makes the view from the surface look like a heaveenly arch, like this:
http://www.withfriendship.com/images/i/40943/orion.jpg

A Culture Orbital (or for videogame fans, the more recent Halo ring) looks like this:
https://sp.yimg.com/ib/th?id=HN.608025605574099514&pid=15.1&P=0
With day and night being provided by the ring itself- it takes 1 day to make a full rotation, meaning the sun sets behind the ring and rises 12 hours later. From the surface, the ring is much more visible:
http://fc06.deviantart.net/fs70/f/2013/276/c/1/c10c4d947c16536b91377136745e1160-d6p4w50.jpg

A dyson sphere would be as visibe as that first arch... but covering the whole sky.

Sidmen
2015-01-28, 12:43 AM
Awesome discussion, guys. Really helps me in my own thoughts/answers questions I hadn't even thought to ask. So many things to reply to, so quotes would make it far too messy. Sorry if I miss anyone.

What's outside the sphere?
The sphere resides inside the Ephemeral Chaos, a point of solidity inside a sea of ever-changing reality. If you exit the sphere - somehow - you end up in a place where the laws of reality change based on the whims of the nearest fae creature.

Malfeas
I've long since given up on waiting for 3e Exalted to come out, and can't overlook 2e's problems. In a few years, when the Dragon-Blooded book comes out, I'll play in Creation again. So, yeah, that's a setting I'm defiantly using for inspiration.

But why a Dyson Sphere?
Simple, my friend. It's an excuse for me to employ my new sketch pad to detail theoretically limitless continents, archipelagos and nations. By setting up several conceits; these can all occupy the same world and be visited by my players.

Star Metal?
This does exist in my world, as debris that sometimes falls from the sky. Its essentially my version of Valyrian Steel or Adamantium - an incredibly rare and durable metal made using advanced metallurgy.

The Moons and their Eccentricities
The moons aren't actually moons, they orbit the sun at the same pace the sphere rotates, locked in geostationary orbits above each major continent on the sphere. They do glow with their own internal light, and aren't natural bodies - they're constructs.

Oceans freezing and causing storms
That's actually really cool and interesting. But I'm expecting the exterior of my sphere to be incredibly hot, not cold. As heat is drawn from the "surface" of the interior and stored in heat sinks between the shell and the land/water before being radiated through vents.

Gravity and rotation
I suspect this is one area where I will have to say "because magic". The exterior skin of the sphere is made from stardust (unapologetically stolen from the Star Force series), which is essentially Neutronium, so it does have the mass to generate it's own gravity, and the sphere will be slowly rotating, but those things probably won't cause the effects I want. So, as was suggested, some of the energy gathered by the collectors will be powering artificial gravity wells.

Where did the Sphere Originate?
In the most clinical way of telling it: a great power got tired of the ever-changing nature of chaos, so he built a shell around himself to keep them from bugging him. Bored, he started civilizations on the inside of his shell like a human may start up an ant colony. As a creature that likes order, he's built automated systems set in patterns to administer his colonies of living beings.

The Creators
A lot of gutza1's post is very similar to what I already had planned for my setting. The creator isn't a hyper-advanced human, but other than that... Magic comes from the various animating intelligences of the satellites and other monitoring spirits set to watch over the creator's pets. I hadn't considered using nanotechnology to be the means of the magics - but other than that: the AIs absolutely are the Deities and spirits that inhabit the lands, they do provide power for the casting of spells, and some of them absolutely have gone rogue to the creator's plan.

Looking at a mountain
Yeah, sorry. My 12-mile figure was to make out a human-sized object. Proportionally larger objects (like a mountain) can be seen at increasing distances.

Vindcara
2015-01-28, 12:53 AM
Bah! I was beat to the " no gravity In the sphere" thing! (Stupid phone not updating when posts are added:smalltongue:)

either way dwarves could have a legitimately founded fear of "falling up". If the magical gravity has a shorter than earth normal range from the surface of the sphere.

Psykenthrope
2015-01-28, 01:23 AM
"Chunks" of White Dwarf? The crunch is that there is no crunch. White dwarfs are stars, and as such, are made up of hydrogen and helium gas. Have to come up with another source of "star metal".

Neutron Stars?

Rakaydos
2015-01-28, 02:28 AM
Neutron Stars?

That's called a Sphere of Annihilation.

Lord Torath
2015-01-28, 08:44 AM
Neutron Stars?You really wouldn't want a hand weapon made of neutron star. One cubic centimeter taken from the crust of a neutron star has a mass of about 1 metric ton. A cubic centimeter from the core has a mass of 600,000,000 metric tons. If you must have star metal, metallic meteorites are your best bet. And there's no reason you couldn't have plenty of those inside the dyson sphere. More on neutron star material (http://io9.com/5805244/what-would-a-teaspoonful-of-neutron-star-do-to-you)

@vlad753:
You said the "moons" are in geostationary orbit over the continents, right? Geostationary in this case meaning they don't move in relation to the surface of the dyson sphere? So underneath them is permanent night? If this is what's intended, then that's going to require some magic as well. Geostationary orbits only work directly over the equator. It also requires the sphere to rotate at the same speed the "moons" are orbiting at, which is FAST. If the "moons" are orbiting at Venus' orbit (0.72 AU), they're moving at 126,065 km/hr. That means the sphere would need to be rotating at 174,300 km/hr, which would be one revolution every 225 days.

Segev
2015-01-28, 09:18 AM
Does this depend on the relative masses of the two bodies, sphere and star? As the sun "wanders," it will be closer to one side of the sphere, and will pull harder on that side than the other. But at the same time, there is now more mass on the other side of the sun, although it's farther away. So the two forces could continue to be equal and opposite, for no net effect. Hmm...
This is actually a non-intuitive thing with surface examination, but the way fields generated by spheroid objects works, if you are inside a sphere generating the field, you will, no matter where inside the hollow center, feel no effect. The field is "flat" inside the hollow part of the sphere.

You tend to learn this first in physics classes dealing with electromagnetism, because you do problems with distributed charges across solid objects and objects with hollow portions. But it holds true with gravity, as well.

What you might see as the sun drifted closer to the "walls" would be increased tidal (which are just gravitational) forces on the walls themselves, being pulled towards the sun. This could cause cracking and breaking and pulling those walls in, like a black hole sucks in nearby star-stuff. Those now-freed pieces would generate their own (miniscule, comparatively) gravitational force on the sun and (slightly) accelerate it towards the wall from which they broke off.



Gravity and rotation
I suspect this is one area where I will have to say "because magic". The exterior skin of the sphere is made from stardust (unapologetically stolen from the Star Force series), which is essentially Neutronium, so it does have the mass to generate it's own gravity, and the sphere will be slowly rotating, but those things probably won't cause the effects I want. So, as was suggested, some of the energy gathered by the collectors will be powering artificial gravity wells.

Its mass has nothing to do with the gravity one feels inside it. The nature of cavities in spheres is such that, anywhere inside the central cavity, the gravity of the sphere cancels out in all directions. You'll need rotation or magic. And "magic" does work as an explanation.

Fouredged Sword
2015-01-28, 09:37 AM
Rotation could be REALLY interesting, as "gravity" would not be even distributed. The sphear does not need to spin at the speed needed for a stable orbit, as it can self reinforce to hold itself up. Spin it slightly faster than needed to maintain a free orbit and you get "gravity" pointing away from the sun. This would make the equator "lower" than any other point, and climbing to the poles would be like climbing a massive mountain, tall enough to leave the gravity well. The tip would act like a shear face. The rotation would be pushing you sideways. It would be weak enough that one could theoretically climb it.

This also allows you to place your "moons stations" a close orbit. Because they are closer, their natural orbit velocity would be slightly faster than the surface natural orbit velocity. This means you could have bot moving at the same rotational velocity and be very close, but different enough to be unreachable.

Air would be thickest at the equator, and the spin would drag on the air into a constant wind in the direction opposed to rotation.

Also, constant day. Plant life would be WILD. You are talking about doubling the energy entering all biospheres. This means plants grow twice as fast and big things are far more practical for evolution. Last time we had that kind of energy coming through our atmosphere was the are of dinosaurs (we had less energy reflected by the atmosphere) you had dinosaur sized things. Fast growing plants are tough, so you need a big stomach to eat them. Thus herbivores grow big. Now you need bigger natural weapons to kill them, so your predators follow suit.

Also, I have to suggest a book to read. Rendezvous with Rama (http://en.wikipedia.org/wiki/Rendezvous_with_Rama) is a great reference for what it would look like to live in a closed object like this. Smaller in scale, but lots of interesting thoughts.

Another thing to keep in mind. A human eye can distinguish roughly .1mm at 25cm from the eye. This is the limit on angular differentiation of the human eye. You cannot see anything that occupies a smaller angular arc of your vision.

Double your distance, half your angular arc. A human is 180 some CM tall. A human becomes unable to be seen at less than 3 miles. They are just too small to make out. Practical considerations make this number even smaller. You can't see a human at 12 miles without a better optic than the naked eye.

Ceiling_Squid
2015-01-28, 12:10 PM
Keep in mind, there is no night. Venus is visible (barely) during the day at certain points in its orbit, so it's not impossible, but you're not going to be able to see anything within probably 30 degrees of the sun, unless you're having an eclipse from one of the "moons."

Oh, I like that.

Would make eclipses a bizarre sight. The appearance of a percievable "far side" during such an event might be afforded some mystical importance. Basically, crank the old eclipse-panic cliche in pseudo-medieval settings up to eleven. Seeing a strange and distant "phantom world" only during an eclipse?

That is, assuming those landmasses are so far away as to not be easily reached or even recognizeable to observers. Not sure how long until they realize that they can actually reach that place by traversing the inside of a sphere.

Fouredged Sword
2015-01-28, 12:23 PM
Oh, I like that.

Would make eclipses a bizarre sight. The appearance of a percievable "far side" during such an event might be afforded some mystical importance. Basically, crank the old eclipse-panic cliche in pseudo-medieval settings up to eleven. Seeing a strange and distant "phantom world" only during an eclipse?

That is, assuming those landmasses are so far away as to not be easily reached or even recognizeable to observers. Not sure how long until they realize that they can actually reach that place by traversing the inside of a sphere.

It would be visible, but I am not sure HOW visible. You still get scatter from the light in the air. The sky is still blue. You would perhaps see vague shapes and discolorations, but likely not landmasses and recognizable landmarks.

Ceiling_Squid
2015-01-28, 12:29 PM
It would be visible, but I am not sure HOW visible. You still get scatter from the light in the air. The sky is still blue. You would perhaps see vague shapes and discolorations, but likely not landmasses and recognizable landmarks.

Well, I suppose it could be handwaved a little bit. Perhaps a sage with a powerful enough apparatus might be able to describe the odd shapes in greater detail, or suggest the inconceivable to a mystified populace.

Anything for quest hooks, I suppose.



There's a simple solution to this: The aliens who built the Dyson Sphere built heaters that generate upper mantle-like temperatures at the very edge of the sphere (the deepest areas underground to the inhabitants). The heaters would be powered by the immense amount of solar energy that the orbiting satellites and the Sphere itself generates. This solves the freezing ocean and allows for natural magma to form underground, creating natural volcanoes and giving dwarves a way to smelt stuff in an awesome way.


I realize the thread creator has specified this as unnecessary (since the outside is not cold), but I am still amused by the thought that "going down to the basement to repair the water heater" is a rather succinct description for an epic quest. XD

illyahr
2015-01-28, 12:51 PM
Read the Death Gate Cycle books by Margeret Weis. Pryan, the world of fire, is basically a giant, magically-made, Dyson sphere. None of the natives realized this as no one could see that far and the entire world was covered in extremely dense (read: dwarves tunnel into the trees cuz no one can find the ground) jungles.

Time was given an arbitrary unit of measure based off of convenience rather than any solar body.

Akodo Makama
2015-01-28, 02:10 PM
Rotation could be REALLY interesting, as "gravity" would not be even distributed. The sphear does not need to spin at the speed needed for a stable orbit, as it can self reinforce to hold itself up. Spin it slightly faster than needed to maintain a free orbit and you get "gravity" pointing away from the sun. This would make the equator "lower" than any other point, and climbing to the poles would be like climbing a massive mountain, tall enough to leave the gravity well. The tip would act like a shear face. The rotation would be pushing you sideways. It would be weak enough that one could theoretically climb it.

Rotation period of 200 hours would generate 1.16g force at 1au, falling off at cos(lat) when approaching the poles (1g at 28 deg lat, .82 G at 45 deg lat).

Orbiting a Sun-like star at .67 AU would have period of 200 days.

Note: orbiting objects would either need to be all in the same plane, synchronized to avoid each other, or at different orbital altitudes. On Earth, we use a combination of synchronization and differing orbit heights (which leads to differing orbit periods) to avoid collision (sometimes more successfully than others).

To create eclipse, object at .67 AU would have to be 1/3 the size of the sun (angular). This would create a brief instant of full eclipse and several hours of partial. Larger satelites would produce longer full eclipses. 8-10 sattelites of proper size would create a pseudo day-night cycle. Additional satelites in inclined orbits would interfere with this cycle, creating 'winter' from time to time.

Proposal: let the obsucing 'satelites' orbit as necesary to avoid collision, in various inclined orbits of differing radii, creating nominal day/night cycles at the 'equator', but the closer you get to the puoles, the less predictable night would get. This system may have once been controlled by a central computer, but now is just a near-random mess. This would cause prediction of 'winter' to be difficult, but possible with enough observations. The man who knows when/where winter is coming would have a definitive advantage. Having adventurers gather observations from far off lands would increase the accuracy of the predictions = PLOT HOOK!

Lord Torath
2015-01-28, 02:27 PM
It would be visible, but I am not sure HOW visible. You still get scatter from the light in the air. The sky is still blue. You would perhaps see vague shapes and discolorations, but likely not landmasses and recognizable landmarks.Plus, those land masses would have to be HUGE to be visible. Venus appears as a point, and is roughly the same size as Earth. At a distance of 1.414 AU (distance to the surface of the sphere perpendicular to your own), you're not going to get a lot of detail. Hubble has nearly 5000x magnification, and you get resolution like this: Venus cloud tops (http://www.spacetelescope.org/static/archives/images/medium/opo9516g.jpg). You're not likely to see much more than bright points of light from other "moons", even with powerful (for the time, meaning 10-100x) telescopes.

gutza1
2015-01-28, 09:51 PM
Wait. I have an idea for the backstory. Here it is:

Thousands of years in the future, humanity has spread among the universe. We developed the technology to build gigantic superstructures, create AIs as smart as ourselves, and even travel through wormholes. However, man grew proud. They discovered the foundation for the laws of physics, and build a device that could change them. They called it Project Prometheus. Its completion would mark the day when man would have complete mastery over nature. Then came the fateful day when Prometheus was activated. The humans attempted to first increase the speed of light so that their energy generators would generate far more power. However, something had gone wrong with the machine. Something very wrong. The activation started to destroy reality itself. First went gravity, and all the suns in the cosmos exploded. Then went nuclear bonds, and all remaining matter dissolved into a soup of particles. Finally the fundamental laws of space and time itself were destroyed, and the universe descended into elemental chaos, where pure magic reigned free. However, not all was lost. The machine itself had somehow protected itself from the destruction, and one engineer had lived. He used the machine to create a bubble of stability, where the old laws of physics reigned free. He then built the Sphere in that bubble, seeded its surface with life, and hoped that someday the humanoids he created would progress to the point that they could help him restore physics to the rest of the universe. He created AIs to guide the humanoids modeled after the true human race. However, the stability bubble was imperfect, and smart people can use their brain activity to exploit weaknesses in the unstable physics. These weaknesses are the cause of magic. The engineer still lives outside the Sphere, waiting for the reborn human race to join him in saving the cosmos.