I suppose I shall have to mention that the current train of though amongst my colleagues and me is that the disk's purpose has nothing to do with solar energy. Rather, it produces a certain kind of particle, which, if you wished to distinguish it from background radiation, would require a precisely aligned emmiter and collector. It also wouldn't matter if anything got in the way of these particles. The rest I shal leave to you to deduce. The purpose of these is still being discussed and pondered upon.

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KI: 17967159

Last edited by DLordofTime on Wed Aug 22, 2012 8:30 am; edited 1 time in total

Some reactions to earlier posts:

@ HarveyMidnight:
Uhm, i have tried very hard to show that there is actualy no problem with regards to Teledahn's rotation speed. There is a lot of scientific material available to describe how planets come to be. And what the real consequences of the rotation of
the cloud of debris (asteroids) are to the form of the planet formed from it.
I have provided several links in earlier posts containig all the evidence you will ever need. Teledahn is not unstable because of it. The star is not affected by Teledahn's rotation around its axis.
We are not used to this arrangement. Earth rotates at a sedate pace. The flattening of Earth due to its rotation is measurable but slight. Leaving us with the ilusion that Earth is a perfect sphere, leading to the believe that this is the
"normal" shape of a planet.
It is not. Every planet and every star in the universe sits somewhere between a perfect sphere and a disc with the thickness of a single atom. If ever a planet or star is found that appears to be a perfect sphere it would raise eyebrows all over the scientific community.
The gyroscopic-precession of Earth is extremely slow but discovered anyway.
There is nothing particilarly special about Teledahn as far as astronomy is concerned.
Teledahn obeys the laws of physics.


@ Seraku:
Interesting point. I always wondered where Atrus found the time, tools, material and the energy to build all that. Remarkable man.

If the original sun of Teledahn had "died" it would have sterilized Teledahn. Stars "die" very violently. So that can be ruled out.

But yes it seems the option that something artificial can be written into an age could be viable. And there is no obvious requirement for the writer to be aware of it. The lack of research in the matter could suggest that D'ni scientist were in
agreement the sun was natural. On the other hand .. they might not have been particularly interested or we have not found the records yet.


@ HarveyMidnight:
About the star not rotating the planet:
Absolutely, A planet orbits a star, not the other way round.


@ Guybrush Threepwood:
Hi , nice to see you here.
OOc: Nah those guys in Spokane did not make an error, someone else did.
IC: I love Teledahn, very interesting place.

tommyap wrote:

@ HarveyMidnight:
Uhm, i have tried very hard to show that there is actualy no problem with regards to Teledahn's rotation speed. There is a

Hmmm... well, being fairly ignorant of the specifics of physics and astronomy, I certainly can't suggest you're wrong, and honestly I didn't intend to. I was engaging in a different type of debate, than you were.

I was mainly trying to advocate the general principle of being "in-character", and how much weight you give to onscreen 'clues' versus 'real science', when one feels they are apparently at odds.

Teledahn's rotation may be possible or not... that's for smarter people than me, to decide.. MY point was-- if it IS impossible, that doesn't matter when you're trying to be in-character. REAL science takes a back-seat to story canon when one is discussing a fictional world. And if it's pretty clear, within the logic of trying to solve the Teledahn puzzle, that that disc is supposed to be a sun.. well, the logic of that, as a story element, outweighs ANY scientific principles.

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Ah , yes, i agree on that. by rhe way i prefer In Cavern over In Character

Resigning this thread to the junk heap, as you all have heads with the thickness of a supercluster, and the density of a black hole. Have really bad days.

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KI: 17967159

Tommyap, you miss the point. It is not about whether Teledahn is a sphere, ellipsoid, disc or a banana. Whatever shape it has, it cannot be spinning that fast, because if you wander 1 km from the axis, the centrifugal force becomes as big as Earth gravity. Look at oceans on Earth and how they are affected by tiny tidal forces, it is not physically feasible. I have said that in my first post, but of course, no one listens to the physicist, let's shoot Wikipedia articles instead!

I'm finding this whole discussion quite fascinating, but I'm confused about the use of the term centrifugal force. I was taught that it doesn't exist, and that what appears to be centrifugal force is simply an objects inertia trying to move the object in a straight line while a centripetal force pushes or pulls the object back toward the center of rotation which causes it to move in a circular path. If someone could explain centrifugal force in the context it's being used in this thread, I'd greatly appreciate it.

Ragupki wrote:

Tommyap, you miss the point. It is not about whether Teledahn is a sphere, ellipsoid, disc or a banana. Whatever shape it has, it cannot be spinning that fast, because if you wander 1 km from the axis, the centrifugal force becomes as big as Earth gravity. Look at oceans on Earth and how they are affected by tiny tidal forces, it is not physically feasible. I have said that in my first post, but of course, no one listens to the physicist, let's shoot Wikipedia articles instead!

We are not talking about tidal-forces. As far as we know Teledahn has no moons.
Due to the hydrostatic-equilibrium that EVERY planet has (it would not even be a planet otherwise) the centrifugal-force is less than the gravitation-force anywhere on the planet. The acceleration you are so worried about is already overcome by the shape the planet asumed on its creation.
ANYWHERE on the surface the centrifugal-force is LESS than the centripetal-force, The shape of the planet is not the result of tidal-forces. I strongly advice you to read this article:
http://en.wikipedia.org/wiki/User:Iridia/J_2
Pay special attention to this quote:
quote: ... the planet will deform under the centrifugal force, developing an equatorial bulge. This redistribution of mass alters the shape of the gravitational potential around the planet ... end quote
I also advice you to check the origin of that article, to determine its scientific relevance.
In asuming the shape of a planet is irrelevant to its gravitational potential you are making a fundamental error.

First, centrifugal force is "special", because it is considered in non-inertial (accelerating) frame of reference. Newton's laws of motion apply to inertial systems only. And they DEFINE force. So in a sense, it's not real. Just as the whole world spinning aroud you when you sit on a carousel is not real, because there would have to be some force to maintain it spinning. The difference needs to be known in order to clarify the sense of all those physical laws and how to use them. But everyone somehow "knows" what a centrifugal force is, because you get pulled off that carousel. Yes, it is just your perception of reaction to the centripetal force, but since force is just disguised acceleration, it is in no way "improper" to use the term centrifugal force (provided you have the mechanics sorted out). Physics is not really about arguing which way of looking at things is correct, it is about asking or disagreeing if it is unclear or gives wrong predictions. And I think the concept of centrifugal force is intuitive. I prefer it, because it is more understandable to everyone and less "sciencey".

tommyap: The tidal forces were meant as illustration of how much can a tiny force influence a body of water. Having a >1 km planet rotate at Teledahn's rate is by no means a tiny force at all. The hydrostatic equilibrium is very nice, but it only guarantees the planet can have some shape at all. It does not guarantee that there will be stable oceans and atmosphere on it. And even though the shape of the planet DOES influence the gravitational potential, I dare say that it will have little effect on "fixing" the massive irregularities created by the centrifugal pull. In other words, if you have a rubber ball full of water and spin it, it assumes elliptical, even disc shape, but that does not mean water drops won't fly off its surface. If you don't believe me, tak the extreme cases - a sphere, a disc, and a pole with roughly the same diameter and mass and try to calculate the differences in gravitation. Regarding another argument by someone, the fact that the centrifugal force gets so big cannot be fixed by altering the physics, like setting a different gravitation constant, because they arise solely from Newton's laws, which are still correct. If they weren't, everything in the Age would behave very differently, and I mean visually.

Generally, you should read more carefully, because some things I have not said nor implied at all, and the argument of planet shape or precession is really irrelevant. Even if the panet was teapot-shaped, it does not change a thing about the size of the centrifugal force.

Well , that is where you are wrong.
On the north pole the centrifugal-force you are subjected to is zero.
When you move away from the pole, your distance to Earths rotation-axis grows. The centrifugal-force grows with it. BUT, so does the radius of Earth, and as a result of that the gravitation-force grows just as fast, pulling in exactly the opposite
direction. You do not loose weight if you move from Reykjavik to Equador. In your calculations you would.
The forces Teledahn is subjected to now, have always existed. Due to these forces Teledahn has asumed a shape in balance to these forces INCLUDING its centrifugal force.
When you move away from the pole on Teledahn, yes the centrifugal force will grow with it. But, just as on Earth, so does the radious of the planet etcetera.
Usualy this is ignored, we even name the net-acceleration on Earth its g-force while in reality it is not. If we go scientific about it, you have to calculate BOTH the acceleration growth caused by the rotation AND the acceleration growth in the opposite direction caused by the larger radious. You can not pick and choose what force to calculate in and completely forget about the other.
Not the shape of the planet is irrelevant, its rotation is. It can be ignored. The same way we do on Earth, for the very same reason.

Sorry to come back to you, but did I just see Tommyap imply that gravity increases with distance from the centre of the object?

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KI: 17967159

Nope , better read the article. Scroll up a bit.

tommyap wrote:

When you move away from the pole, your distance to Earths rotation-axis grows. The centrifugal-force grows with it. BUT, so does the radius of Earth, and as a result of that the gravitation-force grows just as fast, pulling in exactly the opposite direction.

Lol, I did.

And another thing...

tommyap wrote:

You do not lose weight if you move from Reykjavik to Equador

Technically, you do, provided you remain at the same altitude, due to the 27(?) mile bulge at the equator. But it is imperceptible, so most people, except die-hard physicists, think you weigh the same everywhere. My little card of physics for reference states g to be c. 9.81N. However, it also says that that is in the UK, implying that it is different elsewhere.

Oh, and can you not work out what sort of particle I was talking about earlier?

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KI: 17967159

It is obvious your weight will not be exactly the same wherever you go. There are factors to take into account such as altitude and the density of the strata below your feet. These small differences are neglectible in comparison to the differences i was refering to. I think you are mistakiing net-acceleration with G-force here.

Your comment about some particle you may have mentioned somewhere eludes me.
Please direct me to the post you are refering to.

Some things i could have written in my last post, but forgot to put in:

First of all: elevation is measured from average sea-level not the distance to the very centre of the planet. And as you should know, the sea-level follows the shape of Earth. This is a bit of an archaic system and likely to be abandoned at some point, but is has not happened yet.

Secondly: does it not strike you as a bit uhm peculiar that the centrifugal-force that you appear to experience at the speed of 1674km/h at a radious of 6378km, has less effect on you than what you experience standing on a merry-go-round designed for todlers, while you prevent your beaming baby niece from falling out of the fire-truck for she has suddenly decided it would be even more fun riding the ghastly pink and badly flaking unicorn right in front of her?

spend a moment contamplating this oddity.