Apologies for the triple post. An equal-scale slice with more detail
we have the technology 
Now THAT pic is excellent, because it shows exactly what I would expect, that the chopped off sphere pieces that are the oceans would look like parts of the same sphere if the world wasn’t in the way.
I note that the vertices don’t seem to have much affect on the shape of the oceans. Are we then saying that the relative effect of a cubical mass rather than a spherical mass is not much different?
And I was thinking about this while trying to imagine the drawing of a line of equig, that is, the connected points on the Cubearth that all have a gravity equal to g[sub]Earth**. My first thought was that it would be a circle, but then I got to thinking that a circle doesn’t represent the points on the face that are equidistant from the center of the cube. It would be a curved shape modified by some trigonometric factor, to account for the greater distance from the cubic center as you travel towards the diagonal of a face. The Ocean, I would imagine, would have to take that into account, too.
Indeed, and my first image includes that effect. (The “circle” of blue in the middle isn’t an exact circle. It’s ever so slightly squared off. The effect is tiny since the extent of the ocean is small.)
As far as inhabitants getting over the edge: I calculate that it would take the energy equivalent of 200 kL of gasoline to get something as heavy as a Boeing 747 (fully loaded) from the center to the edge, considering only overcoming gravity. The fuel capacity of a 747 is just shy of 200 kL, so things are definitely in range for not-too-difficult travel. (Of course, an airplane wouldn’t be the vehicle since there’s no air up there.)
Glad to see that my guess about the size of the oceans was a bit scanty. Still, it is a much different percentage of the planet covered by water. Since weather is not going to happen in anything like the manner it does on Earth[sup]o[/sup], and the tropopause will reach all the way to the ground somewhere within a hundreds, or perhaps scores of miles of the “seashore” the inhabitable part of the Earth[sup]3[/sup] is going to be a real limiting factor. There can’t be much in the way of meandering for rivers, since they are perhaps a hundred miles long, and down is always in the same direction, leading directly to the Ocean. No flat tidal marshes, just straight out into the center, and moving very fast. Of course, they can’t cut any sort of channel in the material, if it’s obdurate enough to not just collapse. Fresh water is at a real premium.
Now, about rotation, and sunshine.
Corner rotation is a nightmare to model, but I think the northern ring of each north hemicubeal face becomes ice bound, and the southern side of the ocean becomes a near steam generator. Does the axis tilt? How much?
In the axis through the center of a face version, you get very short days, six hours of light followed by 18 hours of darkness, and the tilt only changes the intensity of the light, not the length of the day. North and south faces get absolute darkness or low intensity constant sunlight for six months each. I think you get hard freeze and very little melt that way, without circulation from the equatorial faces. Basically, the entire face gets the amount of sun that the arctic circle gets on Earth[sup]o[/sup], but shared over a vast area. Very high albedo, once the pack ice covers the center. I don’t see how it could ever melt, once it froze.
Tris
Damn. I just realized that entire sun thing was wrong.
The amount of sun is equal for the entire face, whatever angle it is at. No latitude. North is not colder than equatorial! When the sun is straight overhead, the trivial angular difference between the east and west pole compared to the sun is not going to matter. No longitude, either.
Tris
What I don’t understand is that if everybody at the moment is at 1g then why would that increase if Gods thumbs and forefingers came down and squashed that putty into a cube. Wouldn’t the diagonals of the cube have the same or less mass underneath them that the Earth has at present?
The very short version is that the perceived force of gravity depends on the quantity of mass of the Earth (which we assume is NOT changing), and its physical distribution (which we most defnitely ARE changing).
The real value of discussions like this is get people to notice hidden assumptions in their knowledge. Unless you’re a physicist by trade, every time you’ve ever heard or read about gravity, there’s been an implicit assumption that the source is a sphere. Now it isn’t.
Whatever level of sophistication your knowledge of gravity is, talking about cube-earth requires you to add this extra factor. This may go strongly against your intuition, which is really to say your heretofore-unnoticed assumptions.
Or, to answer your question more succinctly, the reason that we experience gravity on Earth as a force pulling us toward the center of the planet, no matter where we are, is that, when you add up all the gravity forces from every bit of matter in a sphere under your feet, the result is the same as if all the mass was pulling from the center of the planet. That won’t be true of a cube; depending upon where you are, there will be mass exerting gravitational force on you in one direction that won’t be cancelled out by mass exerting gravitational force upon you in a complementary dircetion (or degree).
getting from one face to another would be as simple as an elevator/counter weight set up. just having a pair at each side would do the trick, ride the elevator up while the weight falls, switch to the elevator on the other side and ride it down. the hard part would be getting your neighbors on the other side to help with construction…think “contact” only with a message in a bottle shot over the edge instead of radio from space.
this is definitly a strange ass thread but interesting as hell.
Let’s compare a cubic world to a sphere of about Earth’s size.
The radius of the Earth is about 4000 miles. This gives us a volume of V = [sup]4[/sup]/[sub]3[/sub]πr[sup]3[/sup]=268 billion cubic miles.
A cube of this volume would have sides of 6448 miles.
The distance from the center of the cube to the middle of a side would be r=3224 miles.
The distance from the center of the cube to the middle of one of the edges would be sqrt(r[sup]2[/sup]+r[sup]2[/sup])=4559 miles.
The distance from the center of the cube to a corner would be sqrt(r[sup]2[/sup]+r[sup]2[/sup]+r[sup]2[/sup])=5584 miles.
So, standing in the middle of a face, you would see four mountains at 90[sup]o[/sup] from each other, each appearing to be 2360 miles high.
Each mountain would be connected to two others by a ridge that would 1335 miles high at the lowest point.
The consider that the space shuttle orbits at just a couple of hundred miles, it is most likely that those mountains and ridges would extend into a vacuum.
(The Earth, as an oblong sphere, is actually more round than a highly polished cue ball. The highest mountain is only 5.5 miles above sea level, at the top of which unaided breathing is extremely difficult.)
Just wanted to add that this thread has reminded me of a great series of small posters distributed by Litton Industries in the early 70s. There were about two dozen 8.5x11 posters all titled, “What If The Earth Were…Cubical” or “…Tetrahedral” or …“Toroidal” and so on, all showing the Earth in space, shaped as specified in the caption. IIRC they didn’t go into any details about what the geophysical implications would be, but the pictures were sure great.
Apparently you couldn’t buy these any place, and Litton didn’t hand them out to individuals, but I was a kid when I called them up on the phone, and must have sounded so ingratiating, or so disappointed, that the woman I talked to promised to send me a set. And they graced my bedroom wall for quite some time after that.
How rigid would this cubic earth have to be? Are we talking diamond, carbon fibre honeycomb, any other man-made material? or only Unobtainium would do? What force is it that makes this impossible? Compression at the aristas? Flexing on the faces?
Since this is only a thought experiment, I’d say it would only have to be rigid enough to meet the design requirements (=“if the earth was a cube”), and the substance is not important for now.
Although Saponium might be good.
**Saponium ** turns gaseous in the presence of burritos and curry. Not a good material to start a civilization on.
Oh, God! <ROFL>
PLEASE purchase a full membership!!! 
Is anyone able to tell me how steep a gradient it would feel like walking towards one of the edges? I’d assumed it would increase towards 45 degress, gradient increasing faster and faster as you move away from the centre.
But somebody reckoned that when near an edge the pull of gravity wouldn’t actually be directly towards the centre of the cube so how much less than 45 degrees would that make it feel? Negligible?
Anybody got the skills and interest to draw what a cross section through the surface would look/feel like? To be clear i know it would actually be a flat line but it would feel like it should look like a curve right? What would it look like if it looked like it feels if you see what i mean?
It would be a shallower curve going towards the corners rather than the shortest route to the edge but unless the centre of mass thing mentioned above is significant they’d both ultimately be ~45 degrees at the peak right?
Am i way off here? If not bar the lack of atmosphere it seems that crossing an edge wouldn’t be that difficult.
Don’t flame me if i’m way off, i’m way out of my depth here but having great fun flailing around. Cool thread!
Fun thread. On a lark, went hunting. Finally found a site with all twelve Litton Earthshapes, including cubical.
Very cool. When we get bored of the cube i vote we do donut shaped next!