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I'm inspired by this question and was thinking that it is nigh impossible for sun, moon and star to exist in this world and even if they do, there is no way to sun and moon to orbit and create day-night cycles.

So i came upon a solution, how about a infinite tube world like this : Rendition of a tube world with alternating transparent and opaque sections

Here is my world :

  1. There is no end either side of the tube. It is infinite.

  2. Tube's surrounding walls are 6371 km thick and their geographical structure is just like earth.

If you started to dig at one point inside the tube first you will go through a solid crust, then a liquid mantle layer, then a solid outermost layer. if you go beyond this layer (beyond 6371 km) you will come out of the other side of the tube's wall travelling in reverse order of the layers.

  1. I have not decided the radius of the tube but it should be huge so that a large portion of the center remain empty like space and with negligible gravitation force.

  2. In this empty space are moon, stars, even planets, asteroid and lots of other stuff just floating around in either directions of the tube.

  3. When a star go supernova it destroy a large area of tube and hurled the debris in either direction. Some of these matter fall down on the surface again and rest create a debris cloud in the center.

  4. When this debris cloud gets enough matters either by other supernovas or some other ways they form stars and stuff.

  5. These stars and other material in the center space keeps running in either direction of the tube. (This can not be stationery otherwise they will just fall down to nearest surface of the tube due to gravity).

  6. These chaotic events could leads to a configuration of two binary stars revolving around one another with parallel to the tube.

  7. Thus above configuration can create a stable day night cycle on a small portion of the tube. When a sun comes near the surface it is day and whens it go away it is night until the other one comes around.

What are the possible flaws in this world if i wanted to follow real world physics (as close possibly) ? Could it work to create a possible earth like environment ?

Christopher King
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Deepak
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  • The tube world seems like a good solution until you modify it so that it's not a tube. You've made it so, once again, there can be no orbiting moon, no sun with day/night, and no stars. Why? – Samuel Dec 05 '15 at 19:10
  • @Samuel, Pardon me i don't understand. what you mean ? – Deepak Dec 05 '15 at 19:36
  • I think you may just be doing a coordinate system transform. You mention digging right through the core. What happens if, instead, you intentionally dig at an angle that misses the core. Where do you end up? – Cort Ammon Dec 05 '15 at 20:09
  • . . . I can't prove this, but I have to say, this sounds improbable. – HDE 226868 Dec 05 '15 at 22:04
  • So a circular cross section is a real projective plane? – Christopher King Dec 06 '15 at 00:04
  • This reminds me of The Way from Greg Bears Eon series. Basically a pocket dimension in the shape of a tube that extends to infinity inside of an asteroid. – AndyD273 Dec 06 '15 at 03:02
  • The current crowning champion of ultimate tensile strength belongs to carbon nanotubes at 63000MPa compare to iron at mere 3MPa, if you can work out the torsion/stress due to the force of your tube collapsing under its own weight as well as mechanical disturbances you will be lucky that carbon nanotubes still holds up! – user6760 Dec 06 '15 at 03:23
  • why would the tube walls be stratified in this manner? Where did the rock come from? – JDługosz Dec 06 '15 at 14:36
  • OK, with the edit it makes more sense. Another question: If you were digging from non-opposite points, but on the same circle (I hope it's clear what I mean), would you eventually get to the same point (similar to how you you get to the same center of earth no matter where on the surface you start digging)? – celtschk Dec 06 '15 at 15:04
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    @JDługosz. For the sake of convenience lets assume that an advance alien race or an omnipotence entity created this universe as it is. Right now i want to focus on the question if this universe is stable in it current form or not. – Deepak Dec 06 '15 at 15:22
  • @celtschk, sorry. It is not clear to me. – Deepak Dec 06 '15 at 15:25
  • Assume you make a cut through your tube-universe perpendicular through the axis. Then the surface would be a circle. Now you say if from one point on the circle you dig outwards, you end up coming out on the other side of the circle, with a tunnel now connecting both points. Now assume you start digging outwards ar some other point of the same circle (that is, neither the one you originally started digging, nor the one you came out again). Would you then hit the tunnel you have dug in the first step? On earth, you would, in the earth's center. – celtschk Dec 06 '15 at 15:38
  • No, you will not intersect. – Deepak Dec 06 '15 at 15:43
  • With the non-intersecting condition, I think the geometry will necessarily be non-orientable (that is, if you to dig through the cylinder wall, you'd come out at the other side as your own mirror image). At least I don't find a way how to do it without that property (of course it might just be a lack of imagination, though). So would you be OK with that, or would you prefer to have an orientable geometry, but with straight outwards tunnels meeting at a center? – celtschk Dec 06 '15 at 16:22
  • @celtschk picture the cross section as a surface of a sphere. Draw a circle and the inside is the air chamber. Geodesic lines connecting points on that bubble will go around the globe and will intersect, but not define a "center". Deepak, I think it should work that way (intersect). But if you make it a tourus like the video game screen the tunnels would not intersect. – JDługosz Dec 06 '15 at 17:05
  • @JDługosz: Yes, the sphere would be the intersecting solution. And the intersections of geodesics perpendicular to the "air chamber" walls (those outside the air chamber) would be the "center" of the filled part, as in, the single point with maximal and equal distance to all border points of that part (of course there's no center of the complete sphere). But I don't think you could meet all requirements with a torus. You'd get a non-uniform thickness of the walls. I think the only solution for non-intersection would be the (non-orientable) projective plane. – celtschk Dec 06 '15 at 17:26
  • I wonder what would happened in the tube was spinning rapidly around its axis? Centrifugal forces could allow people to stand on the inside of the tube. The outside of the tube would be held on with gravity (I don't think there would be gravitational force inside the tube inward, just centrifugal force outward). Would the tube be otherwise stable? Don't know. – user11599 Dec 07 '15 at 02:14
  • May be related: http://worldbuilding.stackexchange.com/questions/3653/how-would-warfare-be-different-in-a-world-made-up-of-two-infinitely-large-empire – Anixx Dec 09 '15 at 04:10
  • You need some illustration. At least two new answers are missing the idea of the tube being the whole universe with wrap-around connectivity. Or some readers might not understand the ramifications of this and treat it as a bolt-on teleporter rim with otherwise flat bounded space in the middle (which might be a suitable answer for you, actually), so you ought to link to pages describing compacted spaces like this. – JDługosz Dec 09 '15 at 22:29
  • I started a discussion thread at http://chat.stackexchange.com/rooms/32765/discussion-between-jdlugosz-and-pyrulez – JDługosz Dec 10 '15 at 00:05
  • Interestingly, each cross section is basically a projective plane. – Christopher King Jan 25 '18 at 00:55
  • I think the SF book Eon has something like this. Unfortunately, they don't really describe how it was created. It was an artifact humans stumbled upon and learn to use in a limited way. – Jim2B Feb 12 '18 at 20:00

7 Answers7

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It's not stable in its current form.

If you picture a cross section, it's a wrap-around video game screen and you can pan anywhere and make anything the center. The position of the hollow part and layers is arbitrary. That's interesting but not the point to follow.

There is no gravity holding it all together like the Earth's core. A hollow sphere will have no self-gravity felt inside it. So, digging out a rock it will not stick to the walls but float around.

So you describe a structure that's stratified in the manner caused by gravity with changing pressure and heat! But there's no pressure so your faux core will not have the right conditions, there is no mechanism to cause the stratification, so the material will get dug up and mix more uniformly over time.

JDługosz
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  • You are right. What if i abandon the idea of wraparound and make the tube outer layer fixed at a certain radius. An impregnable boundary with nothing outside of it. – Deepak Dec 06 '15 at 17:52
  • If you want to concentrate on the "inside" that makes sense. But boundaries cause problems. – JDługosz Dec 06 '15 at 20:10
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    Story-wise, having a "crystalline sphere" that's a tube can avoid the details of the hard border as something unknown to the characters. – JDługosz Dec 06 '15 at 20:13
  • @Deepak You could fill it with a fluid that provides pressure against it. That might work. – Christopher King Dec 06 '15 at 20:14
  • Note that this isn't a sphere, but a cylinder. The shell theorem does not apply. – Christopher King Dec 06 '15 at 21:38
  • Now, i'm thinking what if this wrap-around boundary have some charge or very minute gravity. Then all the matter can get accumulated on it thus creating the inner surface of tube. – Deepak Dec 06 '15 at 23:29
  • @pyrules so what would the gravity be if it doesn't cancel everywhere? – JDługosz Dec 07 '15 at 06:34
  • @JDługosz I looked it up and it goes torwards the center – Christopher King Dec 07 '15 at 15:10
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    Interesting, and exactly contrary to the matter arrangement that causes it. So it's unstable and the ground will fall up. – JDługosz Dec 07 '15 at 15:39
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    @PyRulez That only applies in a 3 dimensionally flat spacetime, the topology of the spacetime would make this all screwy. In order to figure out what is going on, you probably need to define a metric space too. – Lex Jan 25 '18 at 05:51
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I think you are going to end up with something sufficiently convoluted that you would be better off dropping "normal physics" entirely. There will be myriad problems... pretty much everything will stop working. Our physics is really not designed to handle infinite structures like you describe.

Let's talk diameter. You started with the suggestion of $6,371\;\text{km}$, the diameter of the Earth. In your edit, you clarified that you are not picky about the diameter, so let's fix it to something that works. You need supernovas right? A supernova emits $1.5\;\text{foe}$ ($=1.5 \cdot ( 10^{51}\;\text{erg}$ or $10^{44}\;\text{J})$) of energy. That's a lot of energy. Let's do a comparison. A supernova emits most of its radiation in about 1 second, so there's no time for cooling. We'll have to treat it as virtually instantaneous radiation energy. Let's see just how big the ring is if we want to see $100\;\frac{\text{W}}{\text{cm}^{2}}$ at the surface. With a little math we see the diameter of the tube needs to be about $7 \cdot 10^{18}\;\text{m}$ in diameter. That's right, not $6,371\;\text{km}$ in diameter, but $7,000,000,000,000,000\;\text{km}$ in diameter! So we don't have to write all those zeros, we'll call it $730\;\text{ly}$.

Why do I pick $100\;\frac{\text{W}}{\text{cm}^{2}}$? It wasn't an arbitrary number. As it turns out, that's right on par with the irradiance used by military lasers to shoot missiles out of the sky. That's right. If you were 730 light years away from the supernova, you'd feel like you were shot with a military anti-balistic missile defense laser!

Supernovae are bright!

Trang Oul
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Cort Ammon
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  • Thanx for the answer cort. 6371 is not diameter of the tube. It is the thickness of the tube. I have to edit my question and clarify it a little more. – Deepak Dec 05 '15 at 21:16
  • Ahh. I was making assumptions from the picture. However, does the idea of a tube thousands of light years in diameter cause you any grief for world building? Those sizes change a lot. For one thing, any 1m wide strip of land contains about 100 Jupiters worth of mass! – Cort Ammon Dec 05 '15 at 21:19
  • Not at all. I want it to be massive :D, go wild ! – Deepak Dec 05 '15 at 21:27
  • In that case, can you clarify my question on the original post: I'm trying to figure out the topology of your construction, especially when you don't dig at a perfectly right angle to the ground. – Cort Ammon Dec 05 '15 at 21:38
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    You are going to hit the core no matter at what angle you dig, because geographic layers like crust, mantle, and the core are concentric to the axis of tube like layer of onion.

    Ohh, I think you are again misunderstanding me due to the second image. That is not of the tube but of the earth.

     – Deepak Dec 05 '15 at 21:47
  • But i do come out the other side? I'm trying to figure out the connectivity of space for your world. You appear to want a manifold (at least everywhere except the central axis... not sure if you can get it there), but I don't known enough about how that works to figure out what happens. In particular, if you want gravity to work like normal, gravity is going to have an effect along those continutiiy lines. – Cort Ammon Dec 05 '15 at 22:01
  • Let us continue this discussion in chat. – Deepak Dec 05 '15 at 22:03
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As previously mentioned in both the comments and other answers, in our Universe this configuration is not stable and will collapse. However, if you're already world building, there's absolutely no reason you can't start with Universe Building.

I already answered a similar question to yours with this answer.

The results is something called a Khex Class Cosmos

enter image description here

It includes an energy source, energy sink, and materials in between the two.

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Jim2B
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  • Thanx for the answer jim2B but i don't want to use any magic. – Deepak Dec 07 '15 at 10:57
  • "Any sufficiently advanced technology is indistinguishable from magic." Arthur C. Clarke And the set up that you want is not possible in our Universe regardless of technology levels. Since humans are finite creatures, by definition they can not build a structure that is infinite in any dimension. – Jim2B Dec 07 '15 at 12:50
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    @Deepak magic? If this configuration is taken, it would be nature of the proposed universe. It would be as magical as quarks. – Theraot Aug 30 '16 at 09:23
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Actually, I think I see a way it might work. You'll want to ask on physics.se to make sure.

Make the tube rotating. Fast. The centrifugal force will both stabilize the tube against, uhm, itself (geometry is weird in this universe) and will keep the people from falling off of it.

Now, the tube's gravity is actually inward towards the center (an infinite cylinder has gravity pointing towards the center). Suns and such can simply orbit this axis, and even move along it at constant z-axis velocity. From the tube, the stars will look like they're rotating really fast, but really they will be orbiting the central axis quite slowly; it is the tube that is spinning fastest.

This will probably only work with Newtonian Physics, since you would get frame dragging from the tube.

Again, you will want to ask on Physics to make sure I didn't mess something up.

JDługosz
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Christopher King
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  • How can the tube rotate, as I noted on sdwawlcabdear's answer? – JDługosz Dec 09 '15 at 00:13
  • Could you explain the issue? If the entire tube is rotating, points opposite each other will stay opposite each other (so no rubbing). Basically, anything on the tube would be "attracted" to this outer circle, (if you hollowed a region around it, you could orbit it). – Christopher King Dec 09 '15 at 01:23
  • What's the distance from a point to the center of rotation? If you pass the point and keep going you reach it again! Go the other way, likewise. So what's the angular velocity and centripetal force? There is no self-consistent answer other than zero. – JDługosz Dec 09 '15 at 01:37
  • Imagine that you are on the world, and suddenly all the dirt disappears. You will continue moving towards the circle. When you hit the boundary, imagine that the entire circle is translated. You will be on the other side, aiming for another point on the circle. – Christopher King Dec 09 '15 at 01:40
  • What circle? What boundary are you referring to? – JDługosz Dec 09 '15 at 11:55
  • @JDługosz A cross section of the cylinder. – Christopher King Dec 09 '15 at 17:50
  • A cross section is not a bounded region and doesn't have an edge, as discussed on the OP and some early answers. You're still thinking of a tube in space, not what the OP postulated. – JDługosz Dec 09 '15 at 22:24
  • @JDługosz Although the circle is not a boundary, the circle still exists, just like any other circle. This circle has the property though that's its inside and outside are the same, making it unique for that reason. – Christopher King Dec 09 '15 at 23:04
  • Let us continue this discussion in chat. – JDługosz Dec 09 '15 at 23:58
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Okay, so all gravity is pointed at the center of cylinder, I think. Therefore, people can't live on it. They would fall into the center.

If I'm wrong, and gravity goes towards the tube, that means that the moons and stuff can't "float around". They would fall into tube immediately.

One way around this is if the tube is completely filled with fluid in which humans float (so they float towards the tube). The other way is if the tube is charged attracting either humans or repelling stars and planets.

Christopher King
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For day-night cycles : why not making your tube orbit and at a distance of it, place a wall of light, or just another infinite tube of light replacing the circle sun !

Aiman Vargas
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Make a wide Ring world.

See the book Ring World for a more full description. A very high strength outer shell is set spinning very quickly around a star, the centripetal force mimics gravity and keeps the shell taunt away from the sun, all pulls people along the inner surface toward the shell away from the sun. The shell must be mounted with thrusters to keep it centered. A cylinder is just an extended ring.

Some caveats a supper nova is huge and would obliterate the surface of the ring if it were close enough to receive sun light.

The ring world uses huge squares close to the sun to produce shadows and a day night cycle.

sdrawkcabdear
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  • But with the edges identified, what would the centripetal force end up doing? Is it even possible to rotate the walls or will it end up trying to go both directions at the same time? Remember this isn't a tube in space--it's a wrap-around closed dimension. – JDługosz Dec 08 '15 at 21:14
  • What do you mean an wrap-around closed dimension? How does having defined edges to the tube change what centripetal force does? – sdrawkcabdear Dec 08 '15 at 22:41
  • The position on the wall will be distance d from the axis, and also distance 2d+2w at the same time, and also -(d+2w) at the same time, etc. So how can it move with a velocity that depends on the distance from the axis? – JDługosz Dec 09 '15 at 00:10
  • What do I ean wrap-around? Reas the OP: if you dig through the wall you come out on the other side. Think classic video-game screen like Asteroids or PacMan. – JDługosz Dec 09 '15 at 00:11
  • please join at http://chat.stackexchange.com/rooms/32765/discussion-between-jdlugosz-and-pyrulez – JDługosz Dec 10 '15 at 00:04