[QUOTE=Musicat]
For those of you who are talking about “no air at the edges,” the OP didn’t specify the thickness of the atmosphere… I see no reason why it couldn’t be thick enough all around to have some air at the edges.
[/QUOTE]
Since the OP specified that we’re dealing with the Earth, it seems reasonable to work with a volume of air approximately that of the Earth’s. This would be far less than what’s necessary for any meaningful amount of air to be found at the edges.
[QUOTE=Musicat]
The OP didn’t say each side would be flat. There is no reason why mountains couldn’t exist on any face, just as they exist on a sphere. They would be mountains relative to the nominal surface just like Earth’s mountains are relative to sea level (or some other surface average).
[/QUOTE]
That is very true. How flat is flat would depend on how this cube was formed. Any minimal imperfection would give us some topography.
If we follow the no air at the edges thing, though, there should be no weathering and no erosion, though which would limit the types of formations that would be there.
As for the internal mechanics of our cubic planet, well, your guess is as good as mine. I would suggest that for a planet to remain cubic and not be crushed into a sphere, it would have to be very solid and very rigid. That means no plate tectonics, which would mean no mountains. Unless, of course, our cubic god decided otherwise to trick the inhabitants of it
So I am going for a flat surface with the appropriate canyons and river valleys around the oceans.
[QUOTE=Musicat]
For those of you who are talking about “no air at the edges,” the OP didn’t specify the thickness of the atmosphere. Certainly it would be thinner nearer the edges and therefore have lower atmospheric pressure, but I see no reason why it couldn’t be thick enough all around to have some air at the edges.
A pressure of “1 atmosphere”, normally thought of as sea level on a globe, would have to be defined as 1 atmosphere at the center of a side.
[/QUOTE]
I think the presumption is that with a mass similar to Earth’s, the volume of the atmosphere would be about the same. In that case, I don’t think there would not be enough to cover the entire planet. Just a flattened lens of atmosphere and water at the center of each side
Can anyone work out the size of these lenses?
It also seems to me that if there was enough atmosphere for there to be breathable air at the corners, the pressure down in the center of the face would be very high. Many atmospheres.
If there were mountains on this surface, it would be very strange. Since you’re already feeling like you’re at close to a 45 degree angle near the edges, a mountain that had a slope of more than 45 degrees would appear to be hanging right over top of you like a ceiling… Utterly impossible to climb.
I thought this was beginning to sound a bit familiar…
A dome of air in the center of a square would have a very steep density change compared to the Earth. Earth[sup]3[/sup] must have its own set of physics laws, but if optics are the same, a convex lens of air will make the edges, and corners look “up” with respect to an observer near the center of the ocean.
However there is no reason that the air cannot be the same density and general composition as the Earth at all points on the surface. In fact, gravity might well be perpendicular to the planes, not toward the center. Cubic planet sized objects are not composed of materials in any way similar to the Earth. They are rigid on an order of magnitude greater than any known physical material. Gravity obviously cannot work in the same way. Pretending that physics applies here, but not there, or works this way now, and some other way later is just an exercise in guessing. Physics as we know it on our Earth does not apply on Earth[sup]3[/sup]. What it is like is entirely up to the spell caster who created it. Perhaps his magic has limits, but we have no way of knowing them.
Geometry can still describe some aspects of the world presented, but even so fundamental a thing as geometry might not apply. The step over the corner could be undetectable, or impossible, according to the desire of the designer. The corners might be highly pitched, or apparently flat. If it was Newtonian gravity, and Euclidian geometry, it would not exist, so, given that it exists, some other systems exist as well. Since it is imaginary, each creator may imagine as he will. Put in the subway to the “other side” if you want. The center can be molten, solid, or filled with galleries, or demons, or burrowing thingies beyond description.
Every single application of ordinary physics to the description is just a choice, and the creator must tell his magical minions “Make it look like this” and they comply, being magical minions and having no choice in the matter. They might well mutter among themselves about particular choices, but if Maxwell’s Demon is summoned, he spends his time violating the Second Law of Thermodynamics, just like Maxwell said.
How does it work? Well, as a magician I remember used to reply to that question, “Just fine, thank you.”
Tris
Triskadecamus, you might be right is most of what you just said but I think the point here is how far can you go to make this work changing as little as possible. Every time we hit a wall, we drop one more law of physics and carry on. This ceases to make sense and be interesting to different people at different times. It appears to have happened to you already but some are still having fun so there is no need to jump skip to the very end and let the imps loose.
We have decided, so far, that gravity does point towards the center just as in nature because there has been no need to change it. Based on that, we are speculating about the rest and how it responds to this type of gravity.
That this type of gravity would crush the planet, we had to go magical on that and assume some super rigid material. In the spirit of changing as little as possible, I am assuming that this should make the planet solid (which I am guessuming is the solution that would require a less super rigid material).
Different things will continue to change until we get to the point of ridiculously ridiculous (we are only at just plain ridiculous, right now) and we will move on the next what-if thread.
[QUOTE=Sapo]
Different things will continue to change until we get to the point of ridiculously ridiculous (we are only at just plain ridiculous, right now) and we will move on the next what-if thread.
[/QUOTE]
Are you kidding? I was thinking we should copyright this thread before Larry Niven came along and found it. 
[QUOTE=Triskadecamus]
<snip>…Earth[sup]3[/sup]…<snip>
[/QUOTE]
Clever, very clever.
[QUOTE=OneCentStamp]
Are you kidding? I was thinking we should copyright this thread before Larry Niven came along and found it.
[/QUOTE]
That would certainly put a Jinx on the game, wouldn’t it?
[QUOTE=OneCentStamp]
Not too strange: the end of the state religion of ancient Greece (Zeus, Athena & co.) was hastened by people succeeding in climbing Mount Olympus.
[/QUOTE]
Really? I’m very interested in the end of Classical Paganism, so if you have a cite for this I’d be interested to see it. I know that Paganism was outlawed by the Roman Emperor – who probably thought to himself, “there, see how you like it”–around 380, but I would be very surprised that it all immediately ended at that point.
[QUOTE=Triskadecamus]
Earth[sup]3[/sup] must have its own set of physics laws…
…there is no reason that the air cannot be the same density and general composition as the Earth at all points on the surface. In fact, gravity might well be perpendicular to the planes, not toward the center. Cubic planet sized objects are not composed of materials in any way similar to the Earth. They are rigid on an order of magnitude greater than any known physical material. Gravity obviously cannot work in the same way. Pretending that physics applies here, but not there, or works this way now, and some other way later is just an exercise in guessing. Physics as we know it on our Earth does not apply on Earth[sup]3[/sup]. What it is like is entirely up to the spell caster who created it. Perhaps his magic has limits, but we have no way of knowing them.
Geometry can still describe some aspects of the world presented, but even so fundamental a thing as geometry might not apply. The step over the corner could be undetectable, or impossible, according to the desire of the designer. The corners might be highly pitched, or apparently flat. If it was Newtonian gravity, and Euclidian geometry, it would not exist, so, given that it exists, some other systems exist as well. Since it is imaginary, each creator may imagine as he will. Put in the subway to the “other side” if you want. The center can be molten, solid, or filled with galleries, or demons, or burrowing thingies beyond description.
[/QUOTE]
I must respectfully disagree with you here, Tris. While these hypotheticals are certainly fantastic, I prefer to treat the system as if all other physical laws did apply.
Yes, a cubic planet of this size couldn’t exist and we can’t imagine from where it would spring if normal physics applied.
If normal gravity applies, our atmosphere (following normal fluid rules) would form a sphere centered on each face. The atmosphere on each face would be isolated from all others by the edges. If we were to add enough air to connect these lenses the pressure at face centers would be unbearable.
A ball dropped anywhere on one of the faces would roll to the center of the face. Walking away from the face center would feel like walking uphill, though g would decrease rapidly. By extension erosional fragments from the edges and vertices would move inexorably toward the face centers, rapidly turning our nice Earth[sup]3[/sup] (thanks for that, by the way) into a more familiar sphere.
But for me, part of the whole point of mulling this stuff over, with the help of the rest of the group (in fact with most of the work done by the rest of the group), is to think about how these physical laws, which we mostly take for granted, actually work. For me it’s always an enlightening exercize, one which would collapse if I just assumed that changing the initial conditions means that I am now in a different universe with different rules.
of course I meant to type “exercise.” :smack:
[QUOTE=Spectre of Pithecanthropus]
Really? I’m very interested in the end of Classical Paganism, so if you have a cite for this I’d be interested to see it. I know that Paganism was outlawed by the Roman Emperor – who probably thought to himself, “there, see how you like it”–around 380, but I would be very surprised that it all immediately ended at that point.
[/QUOTE]
I don’t have a cite for this, unfortunately, as it was something I picked up in a lecture in college. The professor’s assertion was that by the time Greek/Roman paganism was outlawed, it had already been badly undermined by cynicism (one of the problems with assigning your gods to a physical location rather than heaven or hell).
[QUOTE=Sapo]
We have decided, so far, that gravity does point towards the center just as in nature because there has been no need to change it. Based on that, we are speculating about the rest and how it responds to this type of gravity.
[/QUOTE]
The gravity would only point to the center if you were in the center of a face, the center of a vertice, or a corner. From other locations, it would seem to point slightly towards the nearest vertice and/or corner. It would still be pretty close to the center, though.
[QUOTE=snailboy]
The gravity would only point to the center if you were in the center of a face, the center of a vertice, or a corner. From other locations, it would seem to point slightly towards the nearest vertice and/or corner. It would still be pretty close to the center, though.
[/QUOTE]
how would that happen? Are you talking about a perception thing? No matter where you are, it should point to the center of mass of the cube, right?
[QUOTE=Sapo]
how would that happen? Are you talking about a perception thing? No matter where you are, it should point to the center of mass of the cube, right?
[/QUOTE]
No. Remember that the closer matter is to you, the more pull it has on you. The dirt under your feet right now exerts a hell of a lot more gravity on you than an equal amount of dirt in China. On Earth, all the matter’s pull averages out so you are pulled to the center, or really damn close. On this cube planet, if you were say halfway between the center of a face and a corner, that corner would exert more pull than the other corners and gravity would be just slightly off-center. I’m tempted to try to write a program that would calculate it, but I know it would be more than a 15 minute process.
[QUOTE=snailboy]
The dirt under your feet right now exerts a hell of a lot more gravity on you than an equal amount of dirt in China.
[/QUOTE]
I say that with the assumption that you’re in the western hemisphere. If you aren’t, change it to the United States, or whatever country is across the world from you.
Someone already had a stab at calculating the pull of gravity. Are you saying that gravity in the vicinity of a corner would be lower than in the center of a face but also pointing a bit towards that corner? Would that cancel the “walking uphill” sensation we had discussed before?.
[QUOTE=jlrepka]
Well a first shot…
Again, assuming mass and volume are the same as for spherical Earth:
Standing at the center of a face, you are 5135 km from the center of mass. If gravity were simple here, gcube would be about 1.54*** gsphere (about 15 m/s^2). It will actually be less than that since there’s significant mass in the four nearest edges and vertices that cancels out (are the core and mantle cubes as well?).
Standing at the middle of an edge, you are 7262 km from the COM. Ignoring the fact that the gravitational attraction of the two adjacent vertices will cancel each other, I get gcube would be about 0.77*** gsphere (about 7.6 m/s^2).
Standing on a vertice (peak), you are 8894 km from COM. gcube here is 0.51*** gsphere (about 5 m/s^2).
[/QUOTE]
[QUOTE=jlrepka]
I must respectfully disagree with you here, Tris.
[/quote]
Thanks, that a nice way to disagree.
Well, I am not entirely unwilling to play the game, I just reach the magic/physics barrier a bit sooner.
But the atmosphere, and the hydrosphere both want the same territory! The only reason our oceans cover seventy percent of the surface is that the surface is almost perfectly round, and very smooth. The water alone would only form a sphere 840 miles in diameter. Divide the sphere into six, and let it reach equilibrium on each face, and you have a lens of water less than a thousand miles in diameter on each face. (No, I didn’t do the trig, I just guessed.) The air forms a shell over that, probably the troposphere reaching a bit higher than currently, but still only measured in hundreds of miles. You got progressively rarified air for another couple of hundred miles, and then, 1300 miles of bare vacuum reaching to the near edges.
If this stuff can erode, you get one hell of a landslide, pretty damned quick. Imagine a scree slope a thousand miles wide, and surrounding the entire livable region!
Yeah, I know. But you really hit the wall fast on some things. Rotating on an axis passing through a pair of vertices was mentioned. The eccentricity of that dynamic adds yet another level of stress that this material must withstand, now including torsion, as well as compression. It canna take it, Cap’n! It’s gonna tear itself apart!
“It should be possible to explain the laws of physics to a barmaid.” ~ Albert Einstein ~
“You should see the place where Einstein used to drink!” ~ Triskadecamus ~
[QUOTE=Triskadecamus]
Rotating on an axis passing through a pair of vertices was mentioned. The eccentricity of that dynamic adds yet another level of stress that this material must withstand, now including torsion, as well as compression. It canna take it, Cap’n! It’s gonna tear itself apart!
[/QUOTE]
Clearly, you underestimate the tensile strength of unobtainium. :dubious: