What is Cidri?

[Shaira]

Hi everyone,

I started playing The Fantasy Trip in 1980, and played the heck out of it for a couple of years, loving the game and its system. My young self, however, always had a bit of a problem accepting the description of Cidri - something didn't quite gel for me. Now I think it has.

I used to wonder about some of the physics of this almost infinitely large world. If it was a world of at least 48 continents, surely it must be much bigger than our Earth? And, if so, if the planet was the same density, then its gravity would be huge, far greater than ours. And, even if you handwaved the super-earth gravity with a boatload of magic and Mnoren tech (gravity engines in the planet's core?), then there were other problems: how could you have climatic variation in a reasonable distance? The poles would be much further from the equator than our own world, so any campaign area would be pretty much a mono-climate in terms of latitude. Sure, meteorology could affect that, and of course you could handwave with magic and tech again, but...

Finally, the horizon problem. If Cidri was a super-earth, then the horizon would be much further away. How much further? That depends on how big the world is. But it would affect everything: curvature of the earth, ships vanishing over the horizon, the visibility of distant mountain ranges, even spotting approaching armies.

I finally shelved the question and moved on to other things, but it's always been at the back of my mind: what is Cidri?

So now, reading the new Legacy Edition, my mind is turning so Cidri again. Here's a thought experiment I've been mulling over while reading and scribbling:

What if Cidri is a "multiworld"? Start of with a planet very like our Earth. Maybe it even is our Earth. We know Jen Mnoren made huge use of his gating ability, and that the subsequent Mnoren Empire held together by way of gates: what if these gates didn't just connect to other worlds, or other places on this world, but also connected to other versions of Jen Mnoren's world, too? What if these gates could be macro-scale structures where you could simply walk in a straight line from one parallel to another while crossing a plain, a forest, a river...? Maybe all those parallels are lined up on an east-west axis, as well as being accessible via gate - you could literally walk east forever, without ever circumnavigating the globe...

In other words: Cidri is a linked network of versions of the same planet existing in parallel universes. Some are near identical; others have different geography, peoples; on others the laws of physics, magic, what-have-you, work slightly differently.

In game terms, this means we're all gaming in Cidri, but our own Cidri-realities, the ways we interpret the rules, extrapolate Cidri geography, society, magic, can all coexist in this coherent but varying network of alternate world realities. Cidri as a physical planet can remain as logical as we like in "scientific" terms - horizon distance like our own world, same for gravity, air pressure, climatology, meteorology, etc, all without resorting to magical or technological handwavium.

It also means we can hop from one to another. There's no "Cidri Prime" - just this network of vast, possibly infinite, extent.

That would make Cidri the supreme Mnoren artifact - a magitech creation of super-ringworld or Dyson sphere scale. It also raises some tantalising questions as to where the Mnoren actually went...

What do you think?

Cheers,

Sarah

[Chris Rice]

I know there was considerable discussion about Cidri in the early days of the forum. I can't find all the entries but here is a link to one I started which had some interesting debate:

http://forums.sjgames.com/showthread.php?t=158278

[oldwolf]

Personally, I have never been keen on Cidri as it is described: an apparent giant planet built with a combination of high tech and magic. Of course, Cidri is a mostly low tech place as far as its inhabitants are concerned. It may well be that its description and explanation is as fallacious as most such found in the legends, mythologies and religions that humanity has believed in for all of history.

I certainly don't use Cidri in games that I run. I think the world the players explore should be one of mystery with possible amazing discoveries just over the nearest mountain range or across a few hundred miles of ocean. This is how our world was throughout most of history. Sadly that has been lost, probably not to be regained until our present civilization falls. Today, Google Earth lets me count the houses in the town of Mogana on the south bank of the Congo river. Every place is known. Even when we go to Mars it will already be fully mapped before we get there. We know other planets better than people a scant hundred years ago knew the surface of Earth.

For those reasons I avoid anything like Cidri in games I GM. My games usually involve a blend of books by: R E Howard, Zelazny, Dunsany, Chalker, Cherryh, Norton, LeGuin, McCaffrey, Cook and Abercrombie. Are there Mnoren? Probably not but Amberites and Markovians might be disguised here and there.

[larsdangly]

The beauty of Cidri is that you can reject it and create your own quasi-historical or totally fictional setting, and I can take your setting and put it somewhere in Cidri.

[larsdangly]

Re. the gravity problem: it isn't as severe as you might imagine. A Cidri with ~50 continents needs something like 10x the surface area of the Earth, which calls for ~3x the radius. The surface gravity of a body that size will be 1G if its density is about 1/3 that of the earth. The Earth has a metalic core with quite high density; we already know of 'super earths' that have densities something like half that of earth's (presumably because their initial constituents contained more ice and less metal, sort of like Neptune - though of course we need Cidri to have a solid surface). So, Cidri is loosely within the range of planetary bodies that exist in nature.

[warhorse11h]

What if Cidri is actually a Dyson sphere, designed to appear as a gigantic world to any who are looking at it from its exterior, which is where our heroes exist.
The Mnoren inhabit the interior, going about their business in anonymity, hidden from view by the elaborate camouflage of the exterior world.
Could that not provide a gigantic world with normal earth gravity at its surface?

Perhaps what is at the center of this Dyson sphere is not a star, but something else. An extra-dimensional prison.

Perhaps the Mnoren, having developed far beyond our current technology, split into two factions and fought a war among themselves. At the end of that war, one third of them, the losing faction, were confined in this prison. And the sphere was created to conceal it. The exterior of the sphere was transformed into a gigantic world, complete with varied lifeforms to further conceal and protect the interior.

Additionally, the Mnoren took steps to insure that the beings inhabiting the surface of the sphere would not develop technology to penetrate the sphere and disturb what was contained within.

Lastly, the imprisoned Mnoren, exposed to the environment of their prison, over the course of time, mutated into forms that the inhabitants of Cidri think of as Demons, who can temporarily be released from their prison by humans using magic. The magic frequently renders them insane and prone to destroy those who summoned them, who, after all, are the creations of those who defeated them.

Just a little food for thought.

[FireHorse]

Originally Posted by larsdangly

… A Cidri with ~50 continents needs something like 10x the surface area of the Earth, which calls for ~3x the radius. …

Except ITL says that Cidri is large enough to contain "thousands" of Earths — which could mean 108,612 Earths, or 57,915, or anything, but absolutely must mean at least 2000 times the surface area, bare minimum.

And that means a radius of over 177,000 miles (compared to Earth's ~3959).

Now, try to model a sphere that large, while maintaining not only the same surface gravity as Earth, but also the same rotational period (length of day) and the same orbital period (length of year), and without violating the Laws of Physics.

[larsdangly]

Originally Posted by FireHorse

Except ITL says that Cidri is large enough to contain "thousands" of Earths — which could mean 108,612 Earths, or 57,915, or anything, but absolutely must mean at least 2000 times the surface area, bare minimum.

And that means a radius of over 177,000 miles (compared to Earth's ~3959).

Now, try to model a sphere that large, while maintaining not only the same surface gravity as Earth, but also the same rotational period (length of day) and the same orbital period (length of year), and without violating the Laws of Physics.

I'm not sure what to make of the orbital period 'problem' because who's to say what the angular momentum of Cidri is. But the gravity problem is not as bad as it sounds. A psuedo earth with 50x the radius still has 1g so long as its bulk density is about 1-2g/cc (like Jupiter, Saturn, Neptune and Uranus). I'm not sure how you get a solid surface on such a body, but the point is surface gravity doesn't scale with planetary size in a way most people seem to assume

[warhorse11h]

Originally Posted by FireHorse

Except ITL says that Cidri is large enough to contain "thousands" of Earths — which could mean 108,612 Earths, or 57,915, or anything, but absolutely must mean at least 2000 times the surface area, bare minimum.

And that means a radius of over 177,000 miles (compared to Earth's ~3959).

Now, try to model a sphere that large, while maintaining not only the same surface gravity as Earth, but also the same rotational period (length of day) and the same orbital period (length of year), and without violating the Laws of Physics.

Well, we are talking about a world that is an artificial construct, where magic, dragons, demons, etc all exist, and that was constructed by a race advanced enough to develop a system of travel through differing dimensions and across space and possibly time as well. Who is to say what laws of physics operate in Cidri, or for that matter, fail to operate.

[FireHorse]

Originally Posted by larsdangly

I'm not sure what to make of the orbital period 'problem' because who's to say what the angular momentum of Cidri is.

Kepler…?

…the point is surface gravity doesn't scale with planetary size in a way most people seem to assume

I make no such assumption; I am familiar with the physics involved. The relevant numbers here are the total mass and the square of the radius (as measured from the surface). The density is irrelevant, at least with regard to calculating the surface gravity.