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 Post subject: The physics of Teledahn
PostPosted: Wed Aug 01, 2012 10:02 am 
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Shorah,

I took a while,but here it is.The answer to the question.
Why does Teledahn have such an odd rotating sun?

Well,basicly because the planet rotates on its side,not like Earth at all.
That rotation axis is also tilted.If it was pointing straight at the sun Teledahn would not move the way it does.But since it does not,two forces are working against each-other at an angle.The momentum of its spin would force Teledahn to remain
rotating along the same path indefinatly,resisting a shift in any other direction.
But,it is orbiting a sun,The gravitational pull of that sun never stops,and is strong enough to keep turning the rotation axis away from the course it would otherwise have held.The effect is called gyroscopic-precession.
http://www.youtube.com/watch?v=st7Us-DHclY

Because of this effect the path the sun makes in relation to Teledahn's surface can be plotted on a map.Sun at zenith.The map in the Baron's office shows the current solar-track on the left side.

That leaves the conundrum of the map showing not one but two solar-tracks.What is that all about?

The only force strong enough to rock Teledahn in another gyroscopic-precession-balance likely to occur is again gravity.A large moon would have effect on the precession but not strong enough to shift the balance so much.The passing or collision
with another object could.

There are basicly two options:
Asteroid or planet.

The passing of an asteroid with enough mass,could rock Teledahn in another balance,It would be a one-of occurrence.If that was the case the right-side solar-track is showing the original path,before this occurrence.It must have happened rela-
tively recent or it would not show up on this map.

The other option is more likely in my opinion.

Another planet.The balance-shift happenes regularly every time the two planets are at there closest distance.A bit like a collossel switch.Since this is happening regularly,the two paths where both known by the D'ni guild of carthographers and due to the cyclic nature of the event both paths are included.

Now there is ofcourse no definitive answer to this.We will have to wait for the next shift to know for certain that the sun's path will return to the other track or not.

tommyap

(edit)
Hmm, on second thought it is even more likely that due to the fact that the orbits of the two planets rotation does not change,that the next switch will force a new balance to the left as seen on the map.We will see.
(second ediot)
Nope that was silly of me. :lol:
(edit three)
When you morph the map so the solar-tracks are circular.Taking the middle of the map as Rotation-Pole draw a circle that
touches the center of both solar-track's,the next shift will cause the center of the next solar track somewhere along that circle at least.For CERTAIN.
(edit four)changed thread name for being stupid.


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PostPosted: Wed Aug 01, 2012 11:52 pm 
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Oh,and i am thinking about naming the star MERRY.


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PostPosted: Thu Aug 02, 2012 1:08 pm 
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I am going to prove that there is no realistic astrophysics involved in Teledahn :-)

First, let's establish the facts we may assume.
  1. By observation, the sun's height above the horizon does not change. It is clear if you look at it through the "solar telescope".
  2. The period of the sun is about 66.7 seconds.
  3. The gravitation at the site seems to be at least roughly similar to Earth's


Realistically, we should assume that the planet orbits the sun, like it is everywhere else in the universe :-) The sun should be of giant proportions, reasonable density and we are reasonably far away from it, so the day cycle is caused by the planet's rotation (I will return to these later). The fact that the sun's height on the sky does not change, has only one explanation: we are situated on a pole. Let's prove this. In the planetary reference frame (non-rotating), let's formulate the "zenith vector" as a unit vector pointing upwards to zenith. We place the planet's rotation axis on the Z-axis. Therefore, we have the zenith pointing in the direction specified by coordinates (X,Y,Z):

Image

T is the period and Θ is latitude. The sun has a fixed position relative to our reference frame, given by an angle relative to the planetary rotation axis, which has the Z-direction. Without loss of generality, we can place the sun on X-Z plane.

Image

Now the relative angle of these two must be constant, which means that the sun does not change its angle relative to our zenith (and horizon). If we calculate the dot product, we obtain only one term which is time-dependent. Its coefficient must be therefore zero:

Image

This provides us with two options. The second cosine could be zero, which would mean that the planet's rotation axis points directly at the sun. In that case, the sun would stay at one point in the sky no matter where we are on the planet. So we are left with the other cosine, which tells us that our geographical position is at one of the poles. Given this, we can calculate the planet's tilt relative to the sun by measuring how far above the horizon the sun is. We cannot do that precisely, but we can see that the planet's rotation axis is almost perpendicular to the orbital plane.

Now, this is all marvelous, because if we are on the pole, we feel no centrifugal force. And if the planet is roughly spherical, we should examine its maximum radius, which means that at the equator, the centrifugal force should be smaller than gravity. Or else everything would fall in the sky there :-) If we calculate this, given that there is earthly gravitation on the pole and there is 66.7 s period, we arrive at maximum radius of 1.1 kilometers, which is clearly nonsense. The planet simply cannot be turning that fast. Not even if we assume very elliptical shape of the planet.

Another possibility is sun orbiting the planet. We would still have to be on a pole and the sun has constant velocity, therefore circular orbit. We don't know the planet's mass, but in order to preserve Earth's gravity, we must increase the planet's radius with the increasing mass. Simultaneously, we have to keep the sun in orbit, so depending on the planet's mass, not only can we calculate the planet's radius, but the sun's distance from the planet's center as well. For non-believers, spherical objects have the same gravitational pull as if the mass would be concentrated in their center. Clearly, the sun's orbit radius cannot be smaller than the actual radius of the planet :-) Also, the sun's mass is much smaller than the planet's or else there would be problems about different centrifugal pulls around the planet. Here's a plot:

Image

The blue line is planet's radius and the orange line is the sun's distance from the planet's core. Horizontal axis represents planetary mass in kg, vertical represents radius in meters. Clearly, if we'd have a planet only like a kilometer wide, the sun (or light) would be about 100 m above the surface. This is clearly nonsense.

A third and last possibility is that the daily cycle would be caused by the planet's orbit. The planet would not rotate at all, just revolve around the sun. In order for this to work, the planet would have to be very far from the sun, which would mean that the sun would have to have enormous mass and therefore unrealistic density.

In conclusion, I don't think we should analyse fictional worlds which were created by graphic designers in order to be fun and pretty, not realistic.


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PostPosted: Thu Aug 02, 2012 1:24 pm 
Thankyou for proving what we knew all along. That thing in the isn't a sun. Now, next theory please...


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PostPosted: Thu Aug 02, 2012 1:42 pm 
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I didn't prove that it isn't a sun, I proved it can't exist and behave this way without violating physics, whatever it is. Also if it would radiate so much energy to propel the whole machine, the planet would look more like fiery abyss :-)


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PostPosted: Thu Aug 02, 2012 2:02 pm 
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Ragupki wrote:
I didn't prove that it isn't a sun, I proved it can't exist and behave this way without violating physics, whatever it is.


Just in general.. it can't operate within known physics of OUR reality. What's coming next will MOSTLY be Star Trek-esque technobabble:

As I understand the Art, it is loosely based on Einstein's ideas of quantum physics, and how they apply to MWI theory-- in a nutshell: there are an infinite number of universes that allow ALL potentialities & possibilities to take place.

When someone uses the Art to 'create' an Age-- they aren't actually creating the 'universe' in which that age exists-- for at least the early part of creating an age, they are 'honing in' on a place that already exists, albeit in an alternate reality. Difficult steps have to be taken to insure the described Age is 'stable' --- meaning it works on valid principles of physics, matter and energy, etc, so it doesn't collapse soon after you link to it.

However, it is possible that the laws of physics are applied differently, in different realities. As I understand it, the speed of light, 'Placnk's constant' and the gravitational constant are specific values that determine how the laws of physics 'behave' in our reality. If those constants were different in another Age, then the laws of physics might be different there, as well.

So there IS a case to be made, for Teledahn to exist in a stable Age where the laws of physics are slightly different. BUT a more educated person than ME would have to look more specifically at that.

Frankly, I think that IS the sun!

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PostPosted: Thu Aug 02, 2012 3:10 pm 
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Location: Hanging around with mermaids. And still looking for the elusive Funky Bahro.
"Any sufficiently advanced technology is indistinguishable from magic."
Arthur C. Clarke

"There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy."
William Shakespeare
Hamlet Act 1, scene 5, 159–167

In other words, we may not so much be dealing with different laws of physics, but rather an advanced technology that has somehow overcome the (known) laws of physics. (Anti-gravity, perhaps?) Didn't we already establish that object as some kind of artificial spinning solar disk? We've only seen a small fraction of this Age. Even Douglas Sharper told us there was a lot more to see on Teledahn. If projects such as MO:RE ever get off the ground, I think we're in for a lot of surprises!

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Murinna (the mermaid) 2484723
Mallina (the other mermaid) 3015052

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 Post subject: teledahn
PostPosted: Thu Aug 02, 2012 5:09 pm 
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Shorah,nice to see you guys. :D

In this universe Teledahn exists.

The movement of the sun is perfectly in agreement with the planet having its rotation axis turned to that star.It could not move otherwise.The laws of physics are opheld in that arrangement.
We may not be familiar with that arrangement,but this is how it looks.
Nothing out of the ordinary so far.

We expect a planet to behave in a certain way because Earth does.Teledahn does not,it is of the other type.So we tend to ignore the visible evidence before our very eyes or "reason" the problem away.
There is nothing unusual in that.

For Teledahn to have a mild climate it needs to be farther from its sun,or else the bay eould boil.
Which...incidentaly...makes it a lot more likely that the next planet out is a jovian,which...incidentaly...is what i predicted with my "switch" hypothesis.So that would fit quite well.

We do not know what is driving the machinery other than it comes from the sun.We do not know on what principles it operates.We do not know the purpose of the floats either.For all we know it could be a photon-deflector,to make a wild guess.The apparrant power of that energy not effecting us at all.

Because Teledahn apparantly rotates FAST it is save to asume its shape will be more like a disc than a globe,or some-where in between.The gravitation at the pole would not be the same as at the equator,not more but less.A considerel part of that force applied at an angle rather than linear.While at the equator it would for the most part be linear.This would throw Ragupki's calculations right out of the window,and there may be something else wrong with it too.(Not that i would know.)

If calculations do not fit all the other evidence it is usualy due to some error in the calculations.It may not be easy to find, and i would be the last to attempt it in this case.At some point in time,science proofed that Earth was flat,until someone proofed that science was not applied quite as it should have.

So i repeat:
In this universe Teledahn exist.
A set of calculatens proofing it does not...hmm...must be something wrong with them.

I am thinking on naming the jovian ARCHIMEDES,for having a lever long enough.


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PostPosted: Thu Aug 02, 2012 5:45 pm 
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Of course, this universe is one where spirits and floating rocks are a reality. :wink: Who knows what wacky laws of physics are king in Teledahn? Maybe the planet is flat. Maybe the stars are yellow balloons floating in the air. Maybe Pi is exactly 3.

The point is, we can't necessarily apply Earth physics to a parallel universe, as Serenia shows. It might be highly advanced science or just plain magic, but in any case it's there, and it does something. Anything beyond this observational standpoint is pure speculation. Though it's always fun to speculate. 8)

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PostPosted: Thu Aug 02, 2012 5:48 pm 
Actually, Ragupki, you did, even though it wasn't your aim. What you did was disprove the assumtion that Teledahn orbits/is orbited by that disk, by reducto ad absurdum. So, the disk isn't the sun. Q.E.D. Next suitable hypothesis is that the sun is just out of sight all the time, so the D'ni constructed a device to channel light to the area. Considering their other known technology, their unknown technology could literally be anything. See the floating statues in Eder Tsogahl and Delin.


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PostPosted: Thu Aug 02, 2012 7:26 pm 
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Yes, of course, the gravitation could work a lot differently, there could be entirely new force interactions and so on, but then there is no point in trying to analyse it, because we simply don't have enough information to go on. And we have to keep many physical laws intact, because our bodies, molecular structure, fluids, all is intact. I was trying to demonstrate that there is no point in trying to analyse artistic creations, because there is no point for their designers to worry about physics. There is nothing hidden out there :-) Also, you usually arrive at unrealistic conclusions. And you can't simply scratch some parts of physics, like they do in science fiction, and "choose" which parts to keep, it typically leads to paradoxes. And not only physics, chemistry, biology, the whole thing. Linking itself is perpetuum mobile :-) And if we assume that by linking, we can cover great distances without time slowing down for us significantly, we arrive at breaking causality itself. It's just not proper to try to make it proper :-)


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PostPosted: Thu Aug 02, 2012 8:03 pm 
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Uhmm...DLT,If the sun is out of sight all the time,there can be no other conclusion than one of it's poles is facing the sun.In which case Teledahn will move the way i said it does.So we seem to agree on that.
Can you come up with an explanation why the D'ni would create a liveable area AS FAR AWAY AS POSSIBLE from the sunny side?
They had the technology to go anywhere in the universe,d'niverse and pluriverse right at their fingertips.
Doesn't sound right to me somehow.

@Ragupki,you are right.But in that case i would need no explanation for any thesis at all.I would rather go the other way. Find out how,instead of can't be,on the premisses it might actually work,if only i could solve this riddle.
I think i am making progress on deciphering the map by going about it the way i do.


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PostPosted: Thu Aug 02, 2012 10:00 pm 
@Ragupki: It is no far cry to assume that every Writable Age follows the same laws of physics.It would make more sense than the alternative. Even Katran's 'dream' Age did, despite Atrus claiming that it was impossible. Things cannot be labelled as impossible purely because you can't see how it would work, but by careful cosideration and thought, and then a logical reason. Oh, and you can't link within an Age. And Ages are usually labelled as parallel universes. So, no causality violation.

@Tommyap: And I quote Sirrus: 'Father never could explain how Emmit and Branch just "appeared" [in Stoneship]. He said the Art was always surprising him.' And Atrus, in BoA: 'Birds? I didn't Write birds!' Things can be very different to how they are imagined. However, I never said that the sun couldn't ever rise, just that it doesn't in the short amount of time we could ever spend there. The regions up to 23.5º around the Terran poles spend six months with no sun. Wouldn't that warrant a device such as we see in Teledahn?
Oh, and your reasoning is wrong. Take the Terra-Luna system, for example. Just under half of Luna never sees the Earth, yet it has an upright axis.


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 Post subject: to clear some things up
PostPosted: Fri Aug 03, 2012 10:16 am 
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A note of some import:

I think i have not been clear enough about the rules here.We start with the basic assumption that Teledahn is real and what we see in the sky is its sun (ignoring glitches as we do elsewhere in the game) In other words an IC point of view.I can not prevent this thread to touch on spoilers (we are trying to solve a puzzle here) or switch from IC to OOC on occasion.So i thought it best to put it here.

I do not want this thread to end up the same way most on this topic did.They are best left gathering stray electrons,in the bottom drawer of a forgotten cabinet,somewhere in a dark corner of the intermess...uh net's attic.
If i have to change the name of the topic to make things a bit more obvious,like adding "may contain nuts" or something, pm me,i am open to suggestions.

From an IC point of view a theory that does not support the evidence is out of the window even when it would stand from an OOC perspective.If we can not make the physics work,it simply means we must find a longer lever,we have not been clever
enough yet,or move on.It is very difficult to find the physics behind growing grass,but we do not go about saying that it doesn't grow,for no better reason than pride.
NO.You admit that you do not know and get on with your life.Someone somewhere may yet solve it,but in this case it probably won't be you,right.

There may be a bit of a problem with Teledahn rotating so fast.But apparantly it is not a big problem.We would not be able to go there if it was.Teledahn has solved that problem and it does not even have a brain.The forces must balance somehow,
even when we can not find that balance yet.

Let us go explore wide and deep in to the mystories...
Not of that booooooring oversized kitty-litter with those nasty pits you stumble into,for having dust in your eyes,while looking for your ball,and end up with a bit of bone up your nostril.

NO

We are going into the mystory of all mystories:(insert drumbeat here)

----< TELEDAHN >----

The world that defies logic...or does it.

tommyap


@DLT:I am not sure,but was there not a thread on the "rotating-searchlight-on-a-tall-tower-mounted-on-a-vehicle-of-some-sorts-driving-at-supersonic-speed-thread"somewhere? You may want to go there,or start it.The basic asumption here is that
what we see is what we get.That thing in the sky is the sun,if you like the idea or not.Assuming otherwise would be off-topic.


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PostPosted: Fri Aug 03, 2012 10:23 am 
Your entire post is flawed by assuming, even when the evidence points against it, that the disk is the sun. If it is the sun, Teledahn cannot be rotating as fast as it is. The g-forces would rip the planet apart, unless it is tiny. Which it isn't. I am very sorry, but you must back up your statements with evidence, otherwise they are 'out of the window'. The only assumtions we can make from our IC PoV is that Teledahn is a real Age, it has the same laws of physics that we know, and that it has sufficient mass to approximate a gravity of 1G. All this we can observe. If you like, I can take you through the stages of deducing everything we are able to about the Age. With evidence.


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