Physicist: The Earth is really round. It’s not the roundest damn thing ever, but it’s up there. If the Earth were the size of a basketball our mountains and valleys would be substantially smaller than the bumps on the surface of that basketball. And there’s a good reason for that.
Rocks may seem solid, but on a planetary scale they’re squishier than soup. A hundred mile column of stone is freaking heavy, and the unfortunate rocks at the bottom are going to break in a hurry. Part of what keeps mountains short is erosion, but a bigger component is that the taller a mountain is the more it tends to sink under its own weight. So as a planet gets bigger, and gets more gravity, the weight of the material begins to overwhelm the strength of that material, and the planet is pulled into a sphere.
Phobos (left), a very small moon, isn't big enough to generate the gravity necessary to crush itself into a sphere. Unlike its host planet Mars (right).
So a tiny planet could be cube shaped (it’s not likely to form that way, but whatev’s). Something the size of the Earth, however, is doomed to be hella round.
This Cube-Earth is a lot more livable than it should be.
Life on a cubic Earth would be pretty different. Although gravity on the surface wouldn’t generally point toward the exact center of the Earth anymore (that’ a symptom of being a sphere), it will still point roughly in toward the center. So, the closer you are to an edge, the more gravity will make it feel as though you’re on a slope. So, although it won’t look like it, it will feel like each of the six sides forms a bowl. This has some very profound effects.
If you walk around the Earth's equator (left) your altitude says almost perfectly even. If you walk around the cube-Earth's equator, cutting four of the faces in half, you'd experience "altitudes" as high as 2,600km (Everest is 8.8km). The 8 corners of the cube would be 4,700km higher than the centers of each face.
The seas and atmosphere would flow to the lowest point they can find and as such would puddle in a small region in the center of each face, no more than a thousand miles or so across. However, both the seas and atmosphere would be several times deeper. Which doesn’t count for as much as you might think. Here on Earth (sphere-Earth), if you’re around 5km above sea level most of the air is below you.
The vast majority of the Earth would take the form of vast, barren expanses of rock, directly exposed to space. If you were standing on the edge of a face, and looked back toward the center, you’d be able to clearly see the round bubble of air and water extending above the flat surface. I strongly suspect that it would be pretty.
All life (land based life anyway) would be relegated to a thin ring around the shore of those bubble seas a couple dozen miles across.
Cross-section of a face: Gravity still points roughly toward the center of the cube-Earth. As a result the water (blue) and air (light blue) flows "downhill" and accumulates at the center of each face. The only land that could be inhabited is the land surounding the sea, where the air meets the ground (green lines). This picture is way out of scale. There is no where near this much air and water on our Earth.
Assuming that the cube was oriented in the way most people are probably imagining it right now, with the poles in the center of two of the faces, then two of those bubble seas would take the form of solid ice cap blocks.
What’s really cool is that the cube-Earth would have 6 completely isolated regions. There’s no good reason, beyond some kind of “local panspermia“, for the life on each face to be related to the life on each of the other faces. If the biospheres took different routes you could even have a nitrogen/oxygen atmosphere on some faces (like we have) and a hydrogen/nitrogen/carbon-dioxide atmosphere on others (like our old atmosphere 3 billion years ago).
The small area would also affect (end) large-scale air and water movement. You wouldn’t have to worry about hurricanes, but the cube-Earth would also have a really hard time equalizing temperature. If you’ve jumped into the Pacific Ocean on the west coast (of the United States) you’re familiar with the teeth-chattering horror of the Arctic currents, and if you’ve been in the Atlantic Ocean on the east coast (USA again) you’re no doubt familiar with the surprisingly pleasant equatorial currents. Point is: there’s a lot of thermal energy being carried around by the air and water. On cube-Earth you’d have to deal with huge seasonal temperature fluctuations.
If I had to guess; it’s unlikely that complex life would evolve on a cube Earth. However! If it did, then their space program would be as easy as a long walk, and their handsomest physicists would spend their time pondering what a round Earth would be like.
By the by, the cube earth photo is by “Altered Realities“.
Update: The dude over at Possibly Wrong went through a bunch of the math behind the gravity of cube earths, and filled in a lot of the details that this post left out. It’s clearly presented, and well worth a look: Possibly Wrong: If the Earth Were a Cube.
If cube-Earth is spinning, won’t there be weird shadow effects? And weird seasonal effects from any axial tilt?
The faces will experience the sun the same way the regions here on sphere-Earth at the same corresponding angle do.
So, the north and south faces would have 6 month days and nights, and the four “equatorial” faces would always have 12 hour days.
Like the equator, these faces will have two seasons: warmer near the equinoxes (equini?) and cooler near the solstices. However, since cube-Earth can’t exchange heat between the hemispheres (hemicubes?) I’d expect the seasons to be more extreme. Exactly how extreme is a “buy-time-on-a-supercomputer” kinda question.
As for shadow effects; I think the biggest one is that sunrise and sunset would be very sudden. None of this pleasant fade-in/fade-out we’re used to.
Pingback: TWSB: Well, it certainly would make the cartographer’s job easier… « Le Seul Mot Juste
If there are two electrons flying next to one another, do they attract each other, if the camera is flying along with them? (given that appurtenant velocity is zero) to parallel currents attract and two similar charges repel. In a stung gun the discharge is shaped like an onion due to low current but high voltage. In an arc welder the arc is thin because of the magnetic field making the arc come other and low voltage so the electrons don’t repel. So what would happen if you follow to parallel electrons at the same speed? Do they still attract each other?
Imagine a tilt such that one face has never been exposed to his star.
Why wouldn’t gravity point directly to the of the cube earth? Wouldn’t the centre of mass coincide with the geometric centre, and the gravitational attraction between you and this cube earth would act along a line joining to the two centres, would it not?
Gravity isn’t “smart” enough to know where the center of mass is.
For example; the center of mass for the Earth/Sun system is inside the Sun, But, we’re still pulled preferentially toward the nearby mass (Earth). Similarly (somewhat similarly) we’d be pulled roughly toward the center, but preferentially toward the mass nearer to us. The effect would be a “flattening of the bowls” (local gravity would be a bit closer to perpendicular).
Even here on (spherical) Earth we have slight irregularities in our gravity from place to place. Some of the earliest accurate maps of the topography of the ocean floor was done by carefully measuring sea level from orbit. The water “bunches up” over mountains, due to gravity swinging slightly toward the mountains.
Regarding Graham’s question, see http://i.imgur.com/dmgcw.png
If we consider the gravity due to these two sections separately, you can see that while the blue section pulls the green dot to the centre of the Earth, the red section does not (the gravity due to the nearby red section is much more significant than the others).
If by some magic, cube Earth came into existence, how long would it last before gravity squished it into a sphere?
@Managore
That is so much better than my explanation!
Should be almost immediate.
It would stay lumpy for a long while, but it would start to deform away from cubic as soon as possible.
Suggested that the atmosphere is also a cube would these abrupt altitudes still exist?
What about tidal effects? Would they be interesting/different in any way? If the poles were the vertices of the cube, would there be any notable differences from your cube Earth (other than no ice-cap sides)? What if the Earth was banana shaped? And that my liege, is my final question 😛
Tidal effects: not terribly different
Poles at the vertices: Every side would have the climate of our Earth at about 35° latitude, as oppose to regions of 90° and 0° latitude.
Banana shaped: the ocean and atmosphere would form a “napkin ring” around the center of the banana. And even more of the surface would be exposed to terrifying vacuum of space.
if there is a straight road from the sea to te edge of the atmosphere you could see all the plants and buildings leaning at increasing angle..
somewhat like pisa
First of all, if Earth were cubic, wouldn’t the rotation forces morph it into something more sphere-like?
I doubt that the cubic shape could stand long while the planet was rotating…
Sure!
A cubic Earth is completely unstable and totally unrealistic.
I would imagine a starfruit-shaped planet might have square or rectangular atmospheres. Does that seem right?
Five long troughs that end in points, if I had to guess.
Is star fruit any good? It seems like a novelty food.
Cubic world? Yes it is absolutely possible. See PIXEL ATTACK on YT:
Thanks for the responses. I did a bit more reading (yeah wikipedia). Turns out I needed to consider Gauss’ law for gravity rather than Newton’s http://en.wikipedia.org/wiki/Gauss%27_law_for_gravity
I did the integration myself and was surprised how far away from the centre of mass the gravitational force would act.
I am aware of fluctuations in local gravity due to topography and variable density across the planet, but I guess I always assumed that for uniform density, you could simplify the problem to two point masses.
raj: Gravity would pull it back into a sphere. The centripetal (or is it centrifugal, I can never remember) force from rotation actually squashes the sphere a bit along the axis of rotation, making it an “oblate spheroid” http://en.wikipedia.org/wiki/Oblate_spheroid.
NOTE: it is technically more accurate to say the the centripetal force “flings” some material outward around the equator than to say it “squashes” the sphere along the axis of rotation, but you get the idea.
Pingback: Morning Cup of Links: Renfaire Tortoise - Cine Sopaipleto » Cine Sopaipleto
Pingback: ¿Cómo sería la vida en una Tierra cúbica? | Maikelnai's blog
Pingback: Morning Cup of Links: Renfaire Tortoise - Sopaipleto » Sopaipleto
Pingback: ¿Cómo sería la vida en una Tierra cúbica? | ecoapuntes.com.ar
Clearly all the old Superman stories set on the Bizarro world are going to have to be rewritten:
Pingback: Geek Media Round-Up: August 30, 2011 – Grasping for the Wind
Would there be a measurable difference in the distance one could jump from the center of a face towards an edge vs jumping from the edge of a face towards the center? (I’m imagining in both cases jumping in the direction opposite rotation; but I’m guessing given planetary scale vs human scale my question is moot)
Another thought, if one vertex of the cube is a volcano, when it erupts; where does it’s ash/lava go? (assuming the direction of the eruption is radial through the vertex) (it wouldn’t reach escape velocity without the atmospheric drag, would it?)
This was great fun to read. So, can you do an article about the same using a “flat” earth like described in some mythologies?
Pingback: Link Latte 164 | Daily Cave
Pingback: World’s Strangest | Link Latte 164
Pingback: Hire Jim Essian - Friday Roundup: The “Are You Ready for Some FOOTBALL?” Edition
Pingback: If the Earth Were a Cube | Possibly Wrong
FWIW, I’m a dude :). Thanks for an interesting read, I learned something from this post, which I suppose is the point. I’ll definitely be back.
Pingback: Appelogen » Wat als de aarde een kubus was?
Is the effect measurable on small scales? E.g., a square table with raised edges, with a little water poured onto it, should show more or less spherical/rounded “humping” of the water at the center.
For a good sized (and perfectly flat) table the difference in the direction of gravity from one side to the other is about 0.00002 degrees, whereas in the post the difference was 90 degrees. The “bubbling” of the water due to surface tension alone would be a much larger effect.
But, yes, water tends (ever so slightly) to flow to the middle of perfectly flat and level tables.
Pingback: Appelogen » Wat als de aarde een kubus was?
Pingback: Awesome Artistic Rendering of a Cubed Planet Earth – The Blogs at HowStuffWorks
Pingback: Awesome Artistic Rendering of Planet Earth, Cubed! | wpgrabber
Pingback: Awesome Artistic Rendering of a Cubed Planet Earth | Tor.com
One thing that occurs to me is that noon would be noon over an entire face. No need for twenty-four time zones– cubic earth only has four (if you discard the uninhabitable polar regions). A perfect four-sided time cube!
By the same token, no tropical zone. Fall and Spring are the hot seasons for the entire planet.
What about centripetal effects? Confess I’m not sure what effect these have on a spherical earth, much less a cubical earth. Would higher angular velocity at the edges lead to further reduced perception of gravity?
A little bit. But next to the already weird gravity of a cube, it’s pretty low on the list of things you’d notice.
Pingback: ¿Cómo sería la vida en una Tierra cúbica? - LibreConocimiento.Com
This is an intriguing discussion. What’s the largest size possible for a cube-shaped planet before gravity crushes its hopes and dreams into a little ball? I image it’d be more of a cube-shaped asteroid rather than a planet.
This is pretty tricky to calculate. A solid stone cube probably couldn’t get more than a few hundred miles across before crushing itself.
Ballpark.
Buddhists claim that ALL animal life on this planet reincarnates either into the same form or a different form of life depending on one’s karma. It is estimated that there are 10 quintillian insects on the planet and 8 billion humans. Do not have a figure for the estimated population of all other animals. Question : If all populations in these categories continue to grow, then how is it possible for this reincarnation theory to work? Math is my worst subject but my common sense tells me this is total BS. If life started out as science tells us then this is totally impossible. If one believes Christian theory it is still impossible. Is there a way to prove mathematically that the Buddhists are full of it as well?
Kudos for this analysis of gravity on the flat surfaces of a cube.
I didn’t know anyone else had thought about this. Sorry to get in so late.
Twenty years ago I presented papers and published on this topic (see references below).
I did not use calculus but presented a geometric proof that gravity vectors changed direction along the “flat” surface of a cube. This disproved the contention from Aristotle to Asimov that gravity pulls perpendicular to a flat surface. They and contemporary textbooks neglect the “mass” below “flat” surfaces and continue to misunderstand the simple positions of “up and down”.
Perhaps textbooks will eventually recognize these flaws in (theoretical) flat earth models. Though mostly theoretical, there may be a practical application when vehicles land on large, irregular space objects like asteroids with large “flat surfaces.
Comments: If a rather solid cuoidal planet was found I see no reson to expect it to quickly deform anymore than the hundreds of millions of years it takes for mountains to erode. Of course if planatary formation begins with a liquid (magma) or tiny solids combining, the gravity would quickly shape this mallable mass into something fairly spherical.
Nate: It would not be noon everywhere at once. We measure noon when the sun is directly “up” from a “level” position, and this vaties on the same surface of a cube
For more information see: http://faculty.ccbcmd.edu/~dthornd1/EGSflatEarth.doc
Greifenkla : Yes, plants and would lean on slopes but buildings would be built on “level” bumps and seem normal and stable (though from a distance they might look like pisa)
http://gravityresearchfoundation.org/pdf/awarded/1991/thorndill.pdf
http://faculty.ccbcmd.edu/~dthornd1/publications.htm
http://faculty.ccbcmd.edu/~dthornd1/EGSflatEarth.doc
Published abstract of a poster paper presented at:
American Association for the Advancement of Science
Annual Meeting in Washington, D.C.
February 18, 1991
ancient flat earth gravity vectors corrected gravity on flat cube
A Reexamination and Correction of the Ancient Flat Earth-Round Earth Controversy
DAVID THORNDILL, (Essex Community College, Baltimore).
Aristotle, Ptolemy, and Copernicus gave several proofs for a spherical earth. They were so convincing that almost every educated person since the time of Aristotle has accepted these proofs. Yet most of these proofs for a spherical earth also fit many flat earth models. This paper will show how the following ancient observations which have been described as spherical earth “proofs” also fit cuboid flat earth models:
1. The pole star and the zenith appear to move as one travels north or south.
2. Stars disappear from the southern horizon as one travels north.
3. Ships sailing away appear to sink over the horizon.
4. Lunar eclipses have been recorded at earlier local time in western locations.
The earlier flat earth models assume the zenith, “up”, is perpendicular to the flat surface of the earth. Analysis of gravity vectors shows how “up” changes as one moves from the center to an edge of a flat earth (planetoid). A corrected flat earth model is presented.
P.S, See http://faculty.ccbcmd.edu/~dthornd1/EGSflatEarth.doc for graphics
Comments for: Managore says: August 27, 2011 at 9:51 pm
Regarding Graham’s question, see http://i.imgur.com/dmgcw.png
Your blue-red drawing analysis has to include gravitational attraction of the other three blue corners, but for a 3-D cube this would really mean the other seven corners of the cube. For a similar geometric arguement see: http://gravityresearchfoundation.org/pdf/awarded/1991/thorndill.pdf