Earth Vs. Discworld: liveable area.

[Staiduk]

OK; this is a pretty silly question but here goes.

My favourite fictional world is, of course, Terry Pratchett's Discworld. It's eccentric, witty and weird fantasy which pokes fun at modern culture, parodies old tales, gently criticizes Human nature, etc.

Geographically, the Discworld is a disc 10,000 miles across; resting on the shoulders of four giant elephants; who perch on the back of Great A'Tuin - the Star Turtle (and the only known member of the species Chelys Galactica.)

Only Terry Pratchett could get away with that.

I couldn't help but wonder - given the Disc's size; how much liveable land would it have in comparison with Earth?

The Disc is a 10,000 mile frisbee; the Earth is an 8,000 mile ball (or thereabouts.) Both appear to have a similar water-land ratio, both have a wide range of environments and climates; from the frigid mountains of the Ramtops to the deserts of Klatch. Of course, it's patently silly to try comparing a world run by natural rules with a world run by magic; but simply in geographic area - how much greater is Earth's liveable land area than that of the Disc? I'm assuming it's greater given the greater surface area of a sphere but I've no idea how to make even an educated guess.

Here's a map (or rather, mappe) of the Discworld:
http://www.fictionalworlds.com/ficwr...cworld-map.jpg

Knowing it's dimensions - 10,000 mile diameter - is it possible to guesstimate the liveable area?

Cheers!

[Wolverine]

Moved from BABBling to Small Media at Large (likely a more suitable home).

[Chris CII]

Earth is (roughly) a sphere some 6 400 km in radius and the Discworld is a disc roughly 8 045 km in radius (5 000 miles).

From these we can apply simple formulas to get their surface :

Sphere : 4*Pi*r^2 = 515 10^6 km^2 (in fact 510,1 10^6 km^2)
Disc : Pi*r^2 = 203 10^6 km^2 (39,8% of Earth surface)

With 29,29 % of dry land Earth has 149,4 10^6 km^2 of dry land

A quick photoshopping of your mappe gives that (very roughly) 41377 pixels of the 88541 are dry land which amounts to 46,7% so using a 45% estimate we have 91,5 10^6 km^2 of dry land (61,2% of Earth's dry land)

After that we wander into climatic considerations on which I can't answer, but people with geo-science backgrounds will be able to go on from there... ;-)

Hope this helps at least a little.

[Staiduk]

That's great Chris, thanks!

Your 'simple' formulae went zipping so far over my head I got whiplash trying to see them.

However, your figure of 61% makes total sense to me - it's a number at least I understand.

As for climatic/geological considerations, I think its reasonably safe to conclude that other than the Hub; where magical concentration is so high that it precludes sustained Human life (that is, human life that doesn't want to wake up in the morning transformed into something with entirely too many legs), the climate of a given region would be more or less the same as its Roundworld equivalent. Hence, Lancre would be chilly, windy and rainy; like any mountain province, Djelibeybi (spell it out) would be hot and dry with frequent floods like it's equivalent, Egypt. Xxxx is an analogue of Australia, etc. so wherever humans would live on the Disc; they'd more or less find the same conditions as Earth.

Except Uberwald, of course.

Sorry; this was just a fun question for me - unreal as it is; little questions like this add a bit of reality to the fantasy.

Cheers!

[Gillianren]

Just a hint--Americans don't generally get the "Djelibeybi" reference, which is of course why he created Hersheba. (For us Americans--I understand a jelly baby is something like a jelly bean, only not quite.)

[Roy Batty]

Just a hint--Americans don't generally get the "Djelibeybi" reference, which is of course why he created Hersheba. (For us Americans--I understand a jelly baby is something like a jelly bean, only not quite.)

Yep! I have some in my kitchen right now. It's always tough to decide whether to bite their feet or heads off 1st though...

[Alasdhair]

Jelly Babies



Jelly Beans

[Chris CII]

That's great Chris, thanks!

Your 'simple' formulae went zipping so far over my head I got whiplash trying to see them.

However, your figure of 61% makes total sense to me - it's a number at least I understand.

As for climatic/geological considerations, I think its reasonably safe to conclude that other than the Hub; where magical concentration is so high that it precludes sustained Human life (that is, human life that doesn't want to wake up in the morning transformed into something with entirely too many legs), the climate of a given region would be more or less the same as its Roundworld equivalent. Hence, Lancre would be chilly, windy and rainy; like any mountain province, Djelibeybi (spell it out) would be hot and dry with frequent floods like it's equivalent, Egypt. Xxxx is an analogue of Australia, etc. so wherever humans would live on the Disc; they'd more or less find the same conditions as Earth.

Except Uberwald, of course.

Sorry; this was just a fun question for me - unreal as it is; little questions like this add a bit of reality to the fantasy.

Cheers!

That's just why I couldn't go into those considerations, on Earth we have quite a few conditions which preclude sustained human life :
- High latitudes = Ice caps
- High altitudes (mountains)
- Deserts
- Marshes and other wetlands...

I don't know what proportion of earth drylands are considered inhabitable, and by what criterion. But if someone more knowledgeable could answer I'd be grateful.

And then I haven't even read a single Discworld novel so I can't even imagine what proportion of discworld dryland is inhabitable...

[Gillianren]

There's a couple of deserts mentioned--the Great Nef and most of the continent (well, all of the continent) of XXXX. As mentioned, you can't live too close to the Hub on account of the magic. There's swamps near Genua. People live in the Ramtops, but they're pretty steep in places . . . but then, the dwarves live under the land; wouldn't that affect calculations? Or are we just talking where humans can/do live?

[Roy Batty]

I'd count most of Ankh-Morpork uninhabitable... well The Shades & anywhere within 50 ft of the 'river' anyway

[Staiduk]

Actually no; it's the healthiest place in the city - it even kills the germs!

[Lianachan]

Are there not supposed to be areas of the surface that are uninhabitable due to the magical residue of an ancient war against the gods too? That rings a vague bell, but I haven't read any Pratchett for years and may be wildly off the mark.

[darkhunter]

Depending on your definition of habitable....

If you don't mind waking up a different shape every day, then it's all habitable.

Also, Djelibili spent quite a bit of time not taking up any of the disk's area--there could be more aeras like that that would increase the habitable area by an unknown amount.

"!!!!!"

edit--spelling

[Mellow]

There is also the habitable space on the circumfence.

BTW - I would highly reccommend reading the 3 "Science of Discworld" books. They don't explain how Discworld works, but rather how our galaxy works and uses the Wizards from UU as observers. The books contain very good quality science.

[Gillianren]

I think they should be used as teaching books wherever possible. They're certainly a heck of a lot more interesting that textbooks.

[Mellow]

I should coco, Ian Stewart and thinggy Cohen are really interesting writers. have you read "Evolving the alien" ?

[HenrikOlsen]

Geographically, the Discworld is a disc 10,000 miles across; resting on the shoulders of four giant elephants; who perch on the back of Great A'Tuin - the Star Turtle (and the only known member of the species Chelys Galactica.)

The part I always find funny is that all illustrations I've seen have the elephants facing outwards, which begs the immediate question of how they prevent chafing from the rotation of the Disc and the answer given is always "it's magic, don't ask", while from the first time I read the desciption of the disc, I pictured the elephants head to tail, ponderously walking around in a circle at about 3 miles/hour, completing a circuit every 400 days.

[Mellow]

Perhaps Discworld is like a really really big "Lazy Susan"