Jupiter-sized Earth

This ain’t going in GQ because it’s off in hypothetical bizzaroland…

Let’s say that our planet is the size of Jupiter. We have to set this up correctly, so:

  • laws of physics are suspended and it’s not a gas giant with crushing gravity. Any other prohibitive reasons I’ve not thought of are also suspended.
  • It remains a blue-green rocky, watery planet with an equable climate, and the inhabitants feel a gravitational pull of 1 G.
  • Continents, other land masses, and oceans are not proportionately larger. They are still just Europe or America sized, and the oceans likewise. There are simply more of them. Instead of there being seven or so continents, they are numbered in the hundreds or thousands.

Now, the questions.

Assuming our Earth was like this, and there was a long-ago “cradle of humanity” at a random geographical point from which we spread out, how would history have developed, and where would we be now? Would we still be in the grand age of exploration? Would there be uninhabited continents? Would we still coexist with neanderthals? Would commercial transport be global? Weeks or months in a 747 with hundreds of refueling stops? Or would we simply say, “Stuff it, it’s too hard” and be content for distant lands to have nothing to do with one another? Would the concept of the nation state (or EU-style confederations) remain the top level political unit, or would there be federations of federations of federations? A UN? Would there be fewer wars because we’d not be living on top of one another and competing for land or fighting over religious shrines?

Just to help frame the discussion: Jupiter’s diameter is about 10 times that of Earth, giving your Jupiter-sized alternate Earth — “Jupitearth”? — 100 times the surface area. There would therefore be about 100 times the amount land to settle, assuming the same ratio of ocean area to land area.

I’ll say yes. If we take our Age of Exploration be the interval from 1500 to 1800, then the Jupitearth Age of Exploration wouldn’t end until about the year 31500 — 30,000 years after it started, instead of 300.

Hmmmm. Let’s take the amount of time it took us to people the Earth, multiply it by 100, and have a guess.

I’m not quite sure when the first ocean-sailing society arose. The Australian Aborigines are thought to have crossed over from wherever they came from about 40,000 years ago, maybe. (No one really knows for sure; they are a mysterious bunch, and they’re not sayin’.) That’s the earliest such figure I’ve heard about. And, the Earth’s continents, except Antarctica, were all inhabited as of 15,000 years ago, perhaps earlier. Roughly 25,000 years then from start to finish, with strong emphasis on “roughly”.

My best guess then is that settlement of all desirable land masses would take well over 2 million years.

However, on a planet so much larger, there’s a statistically greater chance that some land masses will be even more isolated that ours — perhaps “10 times” more isolated, since that’s the ratio of travel distance. Consider New Zealand as an example, which is thousands of kilometers away from the next sizable chunk of land. On your Jupitearth, there would be even more such isolated lands, and in even greater isolation. So quite possibly, there’d be an entire Australia-sized continent or two that would have never seen a human before modern times.

If they died out in our history, I don’t know why they wouldn’t die out in the alternate history just as well.

“Stuff it” would certainly be my reaction to taking a month-long plane trip. But presumably global communications would keep the world wired together, culturally and financially, if not always physically.

These are political science questions on which I’m entirely disqualified to speculate. Not that a little thing like would normally stop me. Dinnertime does however.

It actually is possible for such a planet to exist.

With 4 caveats.
[li]It is a do-it-yourselfer[/li][li]You have to turn it inside-out.[/li][li]You need to build your own mini-star[/li][li]You call it a Dyson Sphere.[/li][/ol]

What is a Dyson Sphere? Click here to find out.

I predict that republics & democracies would not exist.

Every time a tyrant got to be too intolerable, people would merely flee into unknown lands. Effectively speaking, something similar happened on a small scale in North America prior to the revolution.

The book The World Is Round by Tony Rothman takes place on such a planet, Patra-Bannk. The planet is a hollow shell, and has a mini-black-hole inside to provide appropriate gravity. People live on the outside as normal; but because of axial tilt and huge continents, the weather gets… interesting. :slight_smile:

Except that doesn’t figure in technological shifts. It’s a heck of a lot easier to go exploring nowadays than it was in the 1500s. So I don’t think you can just multiply everything by ten. That said, I do think we would still be in the Age of Exploration right now, but it would probably be winding down and just about finished.

Again, you can’t do that because technology and population don’t increase in a linear fashion, they do it exponentially. So would the rate of settlement.

Highly doubtful. I’d be surprised if it even took 100,000. Again, linear vs. exponential.

Agreed. As near as I can tell, Neanderthals weren’t a big seafaring people. And since continents are the same size, they would have been overtaken by homo sapiens at the same rate. Now, if you made the continents 10 times larger then maybe, as they would likely have more time to develop before encountering modern man.

On to the OP’s questions:

I don’t see why the nation-state wouldn’t develop. Remember that we’ve got the same size continents, just more of them. Man likely still starts up in one “cradle” location, say Jupiter Africa. Well, political development still likely follows a similar course. You’ll run into the same issues as you did on earth. Having more land mass wouldn’t make much of a difference at first, just like having another huge landmass floating out there didn’t stop wars and political developments from occurring in, say, Eurasia. So I think you’d see a similar development curve, and then an explosion of colonization, imperialism and destruction of more primitive native cultures. Except there would likely be more native cultures around. And maybe a few more advanced ones.

But no, wars would still be the norm because until that huge shock of exploration hits, most people are really going to be confined to that initial continent and kingdoms are still going to fight each other.

If you assume that the entire planet has a climate where human existence is reasonable, I see no reason why early homo sapiens would not spread over the entire surface rather quickly. To cover a distance of 125,000 miles in 10,000 years is only 12.5 miles per year. Hunter-gatherer socieities can easily move that far in a day. Let’s face it. Wherever there is a ready food source, there will be rapid population growth, which in turn motivates bands to split off and head for unoccupied territory. Most researchers think that when Native Americans first crossed the land bridge to the Americas, it took them only one or two thousand years to spread all the way down to South America.

Doubtful. We’ve got all sorts of remote sensing equipment, such as satellites. I reckon we would have explored the entire surface of “Juipitearth” by now.

Put another way, we already have fairly accurate maps of several of the other planets, including fairly accurate pics of the clouds and features (red spot, rings) of Jupiter’s atmosphere.

Technology accelerates the ability to explore. For example, look how fast, once they were motivated, the Europeans advanced their ship technology, and were able to explore the Americas.

Actually I think once the initial exploration was done, the rate of colonization would be more dependent on resources and climate than anything. Continents with lots of resources for the taking, in more temperate zones would be settled quickly. Witness the California vs. Alaska gold rush, there was something valuable to motivate in both cases, but California was easier to colonize, hence more people went there.

I understand this planet has One-point-zip normal gravity. Still, would orbital flight over such a large planet be practical?

I am not a rocket scientist, but I guess that it would take a boatload more energy to get to orbit in such a world.

Another question. Would be still have dinosaurs? Or to say it another way, might we presume some obscure continents might have wildly different flora and fauna?

Escape velocity is escape velocity is escape velocity, so getting to orbit wouldn’t be any harder; individual orbits would simply take longer to complete. Jupitearth would probably accelerate the development of something like orbital spaceplanes for world travel once a technological civilization boostrapped itself up that way–more reward for the investment, as opposed to just Earthearth, where, sure, a suborbital plane could get to the other side of the globe in a couple hours, but why in the world spend that much money developing such a thing when a regular old jumbo jet doesn’t take an inordinately longer amount of time?

But before spaceplanes, we’d have giant airship caravans. You gotta love giant airship caravans.

More distinct ethnicities would probably develop in the long stretch of non-technological times–much more isolation of population groups and genetic drifting in various areas. This holds especially true if Jupitearth would have the same rough percentage of areas that are technically habitable, but so unpleasantly so that they’d remain natural barriers anyway–deserts, particularly high mountain chains, etc. The same rough percentage would translate to lots more of them, and bigger barriers to foot-and-hoof-and-watercraft means of getting around. So census forms would be even longer.

Classroom globes would be bigger, or require tiny tiny print. Flat mercator-style maps would introduce truly absurd amounts of distortion at the edges.

It would take longer, most likely, for the technological leap of nailing down the problem of determining longitude and making global circumnavigation much easier to occur.


With Dyson Spheres, you live on the inside. Hollow ball, & all. Artificial star in the middle. A teeny one. White dwarf.

Slightly simpler in execution :smiley: is the “Niven Ring” a la “Ringworld” (Larry Niven). Six hundred million miles of U-section track one million miles in width with thousand-mile-high sidewalls (so it’s a very flat U!!) bent into a circle with a Sun-type star at the middle. You spin the ring to provide artificial gravity by centrifugal force, and this enables it to hold air and water. Then you terraform the inside.

“Ringworld”, for the one in a hundred Dopers who may not have read the book, is set long after the fall of the civilization that built it, but they built it as a no-maintenance proposition and the more-or-less barbaric cultures inhabiting it don’t need to worry about the world malfunctioning (until “Ringworld Engineers”), nor are even aware of its true nature. There is room for a practically indefinite number of different almost-human cultures on the Ringworld; it has a population of 3*10^13 or thereabouts and is sparsely populated at that.

Apparently Niven was contacted by Freeman Dyson himself, who had some very complimentary things to say about the Ring idea.

The recent computer game Halo is set on a Ringworld.

How long would a day be on such a planet?

If it was the same length, then the planet would be spinning pretty fast, and could inhabitants take advantage of this to aid journey time to the “other side” of Jupitearth?

By my reckoning, there would be many different species of Jupitearthman, so while not living next to neanderthals as such, maybe a different version of us has developed in a far off land, just to the south west of Jupitafrica, and North East of Jupitantartica called Neo-man

Once discovered by the original explorers, Neo-man is totally wiped out, once it is found that they are in fact more intelligent than them, but not yet advanced enough, as they only started evolving half the time ago…or something.

Good point (made by both you and Urban Ranger). Modern technology would arrive and accelerate exploration of whatever mysterious places were left. However, much of the world would still likely be unsettled, even after you’d launched your first satellite. (More below.)

I don’t agree, though my linear approximation was admittedly crude.

First, population growth rates over our history have been anything but uniformly exponential. Not to mention that societies aren’t always intent on colonizing every bit of land they can sail to. But more importantly, even if both these things were consistently true, the world’s “saturation” function is still dominantly linear over the main growth phase.

If you model the spread of humanity like that of a virus — perhaps an uncomfortably apt comparison — then the growth rate changes from a short initial exponential phase, through an approximately linear phase, until the population approaches total saturation, when growth slows to a crawl as it approaches the asymptote. As an illustration of this behavior, I refer to the first plot on this page of a research paper on virus growth.

So, I maintain that the time of total settlement of Jupitearth’s land masses will be roughly, very roughly, proportional to their number — and so about a hundred times longer for them than it was for us. (Settlement of a land mass once you’ve found it goes much faster of course, as ITR champion points out. The question I’m considering here is how long it takes to discover all the land by ship.)

Taking 25,000 years as the duration of our Age of Settlement might have been a gross overestimate on my part. On further (and I hope better) thought, the Polynesians might be a more telling example, since they sailed the ocean and colonized its lands more persistently than most other folk. But someone will need to tell me how long it took them to achieve this. At the moment I’m too lazy to go look it up. But if it took them, say, even just a thousand years, then Jupitearth’s Age of Settlement would still be about 100,000 years. And that assumes they keep up the spirit of exploration consistently for all that time; more likely they’ll give up long before that, or proceed in fits and starts.

Tentative conclusion: on Jupitearth, the Industrial Age would arrive long before all land mass had been discovered and settled, unlike the case for Earth.

No, because any inhabitants of Jupitearth would be rotating along with the planet, whether on the ground or in the air.

Technology would probably advance more slowly on the giant Earth, because of the relative lack of metals.

A Jupiter-size planet with Earth-normal gravity would be considerably less dense than Earth, which almost certainly means that iron and other dense elements make up a smaller percentage of its substance. Without easy access to the metals which have provided the backbone of our technological development, the inhabitants of Giant Earth would lag far behind us in mechanical technology, and probably in electrical technology.

This would probably severely hinder exploration, since they would be mostly limited to sailing ships for water travel, and probably to blimp-type aircraft. Communications would be limited, because all of our own high-speed communication is dependant on electricity, which is essentially dependant on a ready supply of conductive metals.

As a result, large political and commercial organizations with inter-continental reach would be far harder to establish and maintain, so individual states would be less likely to merge into large empires, and local cultures would be more likely to remain basically unaltered for longer spans of time.

The Giant Earth people might, however, be far ahead of us in chemical or biological technologies, since their creativity has to go somewhere.

Upside: We wouldn’t have to ever listen to that sickeningly sweet “Its a Small World” song.

Downside: Just that many more French!

Hmm, there would be many moons orbiting Jupiterearth (or Jearth), which might affect the tides and possibly sea travel. Having multiple moons could spark more interest in Astronomy, theoretically propelling space exploration sooner, assuming technology and infrastructure were sufficiently developed.

It strikes me that it’s quite likely that Jupitearth will feature a few exceptionally large oceans/tall mountain ranges/vast deserts which will result in some human populations being completely reproductively isolated for a sufficient length of time that multiple species of language using human-like beings might arise.

It also strikes me that here on earth, as soon as a high enough level of education and standard of living are reached, birth rates drop dramatically. It seems quite possible to me that on Jupitearth one might see a pocket (say, the size of 3-6 earth-type continents) of highly advanced civilization which reaches a point where even though it now has the technology to explore and expand rapidly over the entire globe, it doesn’t have expansionist social dynamic that drove, for example, the European colonization of the Americas. And meanwhile, the spread of primitive hunter-gatherers would continue on distant frontiers. And then some far off pocket of humanity might independently make technological leaps forward, and another advanced pocket would develop, quite possibly with radically different features. And numerous such areas could coexist, even after the advance of sub-orbital hypersonic planes and the like, since the transportation costs involved in moving such vast differences would outweigh any commercial benefits to extensive intercourse between the pockets.

Or perhaps the “barbarian” peoples living on the fringes of such pockets would seize on the opportunities made possible by the technology of the advanced groups, and go on expansionist frenzies of their own, resulting in a sort of ripple effect over the entire globe.

Interesting possibilities.

Er, Bosda, I was referring to the world in the OP, not a Dyson Sphere. :slight_smile: