Guild of Astronomers

Marein · **Posted:** Tue Mar 02, 2010 3:12 pm

Apparently my membership of the old forum got approved, so I just went through it and grabbed the interesting topics for archivation

Good to have this information stored.

Calam · **Posted:** Tue Mar 02, 2010 9:55 pm

Quote:

My theory is that of the first one: Teledahn rotating on it's size. But it's not the same size as Earth. It's a LOT smaller, but is mostly made up of very dense materials, so it's mass is increased. Due to it's smaller size, that mass would still work out to be the same as Earths, but the distance of rotation would be a LOT smaller, there for the velocity of rotation is a lot less.

I like this theory the best. The whole, "wait, what if this Age is FAKE!?!" routine just doesn't cut it. Technically, physically plausible? Sure, but then again, any Age can be explained as being "fake", because they are fake, and their flaws are going to show, and if you point them out it ruins everything.

It makes the most sense that Teledahn is simply very dense. And in fact, if you look out of Sharper's office window, I seem to remember seeing the horizon's curvature-- this probably wasn't intentional on Cyan's part, but it does still explain the size of the planet.

Also, keep in mind that the planet doesn't necessarily have to be dense and tiny-- it could be only somewhat smaller than Earth and significantly more dense, thus compensating for the escape velocity. This would crush humans, wouldn't it? Not if the rotation of the planet and the speed of the escape velocity are compensating for the intense gravity. Perhaps the rotation of the planet is allowing for only half the planet's escape velocity. Wouldn't this then reduce the impact of the gravitational force?

Or am I mistaken here?

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

forgive me if i suggested that we simple call it fake, my comment about it maybe being flat was merely a joke.

actually, your point about having a balance of the rotational speed and the extreme gravity got me to look at the problem again. and it think we made a mistake. the axis of the planet is right beneath us, yes? as though we are standing above the rotational axis of spinning top. our calculations for the escape velocity were for the speed of rotation around the equator. but for any other location we would have to work out the angular velocity, from where we are however, i would think the angular velocity would be zero, or near zero. unfortunately i dont think this helps us, we still cant have an earth like planet spinning at that speed since it would tear itself apart. and we cant have a planet of greater density to compensate for that spinning, because we, on the top of said planet, would not experience that speed. please correct me if i have made a mistake, i am very tired at the moment : )

andylegate · **Posted:** Wed Mar 03, 2010 1:37 pm

1helios1 wrote:

forgive me if i suggested that we simple call it fake, my comment about it maybe being flat was merely a joke.

actually, your point about having a balance of the rotational speed and the extreme gravity got me to look at the problem again. and it think we made a mistake. the axis of the planet is right beneath us, yes? as though we are standing above the rotational axis of spinning top. our calculations for the escape velocity were for the speed of rotation around the equator. but for any other location we would have to work out the angular velocity, from where we are however, i would think the angular velocity would be zero, or near zero. unfortunately i dont think this helps us, we still cant have an earth like planet spinning at that speed since it would tear itself apart. and we cant have a planet of greater density to compensate for that spinning, because we, on the top of said planet, would not experience that speed. please correct me if i have made a mistake, i am very tired at the moment : )

On the surface of the planet, the speed of rotation would not be felt by us as here on earth, we are moving at 1,000 mph, but as in a car, train, or Jet, we only feel changes in velocity (Delta V), when we accelerate the car or jet, or when we brake, etc.
The speed of rotation will not affect the effect of gravity upon anyone on a planet, as it's the planet's mass that "causes" gravity. If you weigh 180 pounds right now, but then the earth were to suddenly stop rotating, you would still weigh 180 pounds. "Artificial Gravity" on a space station that is spinning, is not the same as the gravity you feel here on earth (or any other planet for that matter). That's centrifuge force that works for a spinning space station.

That's what makes Gravity so neat to me. To have it, you simply need to have mass. To have more gravity, you simply need more mass.

Size maters only when we're talking about what the mass is made of. You can test this yourself. get a piece of wood, and then get some lead fishing weights. Gather enough lead weights so they are about the same size as the piece of wood. You'll notice that the lead feels heavier than the piece of wood. To make the wood feel as heavy as the lead, you'd have to get a much bigger piece of wood. This is because the wood is less dense than the lead.

This works out with planets too: The Earth, Mars, and the Moon are all made out of rocky material (they are not exactly the same, but close enough for what we're talking about). You will find that you weigh less on Mars and the Moon because they are much smaller in size (but of the same material), so they have less mass than Earth. Less mass means less gravitational force is acting upon you.

The main reason we're concerned about Teledahn being earth sized, yet spinning as fast as it would have to, is as 1helios1 said: At what speed can a planet spin, yet still hold itself together? There has to be an upper limit, as too fast and the planet will do some while things: hurricane force winds that are over 1,000 mph (yes, the earth's rotation does affect the weather, as does heating and cooling, and many other things), the tensile strength of the rocky crust, would it be too much for it (spin too fast and the planet will flatten at the poles, take a look at Saturn at is' rotation speed, it has an effect on the planet's shape).

Anyway......where was I? hehehe, got to running off on a tangent, Ha!

I've got to get to work, see you guys later.

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

but the net force would be less. remember the centrifugal force is directed outward, and our gravitational force inward. the speed of rotation does not change, but remember velocity is a vector, its the constant change in direction of that speed that gives us the acceleration. the earth did start to spin faster, someone standing on the equator should be lighter, the gravitational force has not changed though, only the net force.
but as i say it would not help us given our location. and as andy pointed out, it would likely deform the planet

wait.....

*pauses to do some reading*

so, apparently earth does experience this already. objects around earths equator do experience less net force, and in fact our planet is not a perfect sphere, but is slightly deformed, and bulges a little around the equator.

i am afraid that still does not get us anywhere though. with the kind of rotation and size we are talking about, teledahn would be more disk than sphere, and from our location on its axis, we would get the full effects of its gravity. no, the planet would have to be small.

Hobbes · **Joined:** Fri Nov 10, 2006 4:57 pm **Posts:** 8

If you want to join the guild on the game, you have to give me your KI after adding me, so that I can answer to you. (It happened

)

kaelisebonrai · **Joined:** Sun Jan 20, 2008 2:14 pm **Posts:** 902

It gets even harder to explain it, when you realise what we see of the age is, infact, only a *tiny* part of teledahn. I can't remember where I've seen the map, but someone has, at some stage, compared the part of teledahn we see, with a map found either in teledahn itself, or in the Baron's Office in Ae'gura. And found that there is a part that matches. That part is only a small part of the map, too. so, Teledahn is a much bigger age. The trouble is.. that sun gets even harder to explain, then... :<

Ahlehn · **Posted:** Fri Mar 19, 2010 10:42 pm

Oooo, I love the idea! This is something that has always fascinated me... Just imagine how blown my mind was when I linked to Todelmer...

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

hm, i shall have to get a look at that map you mention, if its detailed (and drawn accurately, which is a big assumption) then we might be able to get a better idea of the size of the planet.

when i did my calculations for the size, i did so with the idea that the planet would have an equatorial spin the same as earths (merely for convenience sake) but given that everything we encounter in the age is on top of the axis, we dont need to limit the spin quite so much, in fact, there is probably a fair bit of tolerance in those figures. the planet could likely be a bit larger than my original estimates....still, i have the feeling that the problem has a much simpler explanation.......

heimdall · **Joined:** Thu Feb 25, 2010 8:32 am **Posts:** 45

The way I think about it is if Atrus can write an Age like Spire with impossible rules of physics, it lends precedence for the D'ni to write an age with a sun that rapidly revolves around a rotating planet.

Or... what if the rapidly moving sun isn't a sun at all, but rather a perpetually moving lamp just outside a dome. That would make Teledahn a bubble resting on a giant stage.

Or... how close would Teledahn have to be to a sun in order for such a wonderful climate to be in a planet's Arctic or Anarctic zone? Given the wonderful climate experienced by the explorers, what kinds of climate zones would be required in the lower latitudes?

I'm probably thinking about this wayyyy to much.

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

how exactly does spire defy the laws of physics? is there something i have forgotten?

as to your climate point, its likely that the planet is very cold at lower latitudes, save for the warm current descending from our location in it. i would not know enough to be able to say more...........

heimdall · **Joined:** Thu Feb 25, 2010 8:32 am **Posts:** 45

In Myst 4,
[spoiler]Sirrus explains in his journals:

Quote:

For the past few weeks, I have been watching storms move through the second cloud layer. They appear as flashes of light inside the strata. The violence of these storms does not reach me in the garden. I encounter no rain. Barely feel the wind. I am completely safe here, nestled between layers.

I do not know how this is possible. How could Father have created a world which exhibits so many scientific impossibilities?

Then there is the matter of the the magnetic rocks and the crystals. I can't remember the last time I McGuyvered a hand crank that could either charge a crystal so that it glows or transfer that energy to a magnetic stone so that it floats.

[/spoiler]

As far as the climate is concerned, it is expected for the temperature to increase as you decrease in latitude. How would it be possible for the temperature to decrease as you approach the planet's equator?

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

perhaps i am being terribly foolish, but i am not understanding how the peculiarities of spire are impossible, perhaps improbable... for the time being i am going to assume there is something i dont understand, and perhaps you might explain it too me.

as to the climate, my statement was in error, as you decrease latitude the sunlight will become more direct, but also more intermittent, it would imagine it would reach its highest intensity above the equator however, below which it should get more indirect again and increasingly intermittent.

heimdall · **Joined:** Thu Feb 25, 2010 8:32 am **Posts:** 45

When is the last time you saw levitating crystals, or rocks that changed their levitation based on their static electric charge? If you see no physical pecularity to this, I challenge you to attach a car battery -- or an electrical socket -- to a rock or magnet to see if it rises. Short story: it won't happen. The most dramatic effect is that you shatter the rock and/or fry out your electrical source, provided you don't kill yourself first. Or what about the elevator ride? If this doesn't scream physical impossibility, I don't know what does.

Then consider the fact that the habitable rocks are _floating_ above a gaseous planet without any sun in sight. The fact that Sirrus didn't go insane or get brittle bones from Vitamin D deficiency is another thing altogether.

As for the climate, consider this: many nations have jumped on the bandwagon of Global Climate Change. Scientists show great concern at the thought of the global average temperature rising only a few degrees. In order for the polar zones of Teledahn to be what looks like a nice 60 or 70 deg. F, the equitorial regions might have to be in the 140s or higher (that's just an estimate). The fact that the seasons never change indicates that Teledahn might have stable weather patterns, meaning that hot zones stay hot and cold zones stay cold. In order for weather patterns to shift, you not only need a change of seaons, but also things like a global conveyor belt in the oceans.

Just looking at aTeledahn makes me appreciate how intricate our own Earth systems are, with far more moving parts than an expensive Swiss watch.

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

well, i cannot speak to any specifics, we dont know the metal content of the rocks, nor his method. but we do know that we can achieve levitation through the application of electric fields, in fact, his set up, is fairly familiar looking. two electro magnets, one above, and one below, after that it is a simple matter of balancing the currents to fight against the natural forces at work. which, if i recall correctly, is what you actually have to do. i can think of a few methods for levitating an object, and so have a good many other people, as such devices can be purchased. i imagine your issue with spire must be a more specific event that i am forgetting.

as for the elevators, i dont remember them at all.....

as to the health issue, there is clearly light in spire, the source of the light will make no difference. i dont know enough about vitamin d deficiency to say how much exposure is needed.

remember, the earth is tilted, that is why we have seasons, on earth the equator gets the highest intensity of sunlight, varies with seasons of course, but it is always roughly around the equator. teledahn is not like earth in either of these respects. teledahn is not tilted, and will not have seasons. teledahn will also experience the highest intensity sunlight at higher latitudes than on earth.

edit: anyway, the point is to take what we see, and explain it with the knowledge we have. so you will forgive me, i would rather discuss why a particular theory does not explain the phenomenon, and not why the phenomenon could not occur, as the latter is not nearly as interesting.

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