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Why don't Daysiders have dark skin?


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In Khriss' essay in Arcanum Unbounded it is said that the big sun is blue-white supergiant. Blue-white supergiants emit lots of UV light. The planet probably doesn't really have a UV filter, as the Darksiders have dark skin protecting them from UV light from their white dwarf. So why in the name od sands Daysiders are light-skinned? 

Edited by strumienpola
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Hm. There are a few possibilities.

  • Dayside's sun emits far less UV light than it would in our world for some reason
  • Bavadin has tinkered with Daysider and Darksider genomes to keep one light-skinned and the other dark-skinned (maybe she finds it aesthetically pleasing or something)
  • Dayside has not been inhabited by people for long enough for genetic changes to occur (though it's still odd that they only people we see with a tan are a half-Darksider and a guy who's been to Darkside very recently)

I have this feeling that there might be a WoB that explains it, but I can't remember if it actually exists and what it says.

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4 hours ago, strumienpola said:

In Khriss' essay in Arcanum Unbounded it is said that the big sun is blue-white supergiant. Blue-white supergiants emit lots of UV light. The planet probably doesn't really have a UV filter, as the Darksiders have dark skin protecting them from UV light from their white dwarf. So why in the name od sands Daysiders are light-skinned? 

I don't think getting a darker skin is the only possible evolutionary defense against UV-radiation. Since Bavadin has likely done some meddling in the humans on his/her/its(their?) planet it could quite possibly be she's built some other defense into their system.

Dark skin could have developed on darkside as a form of camouflage against predators. Darkside seems to be more advanced in technology than lightside (including firearms), which might mean they face some form of heightened hostility in their ecosystem.

Edited by randuir
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I have a theory on this. White skin is to increase UV light absorption to give enough vitamin d. Black skin is when you get too much UV and you need to absorb less. The blue-white supergiant gives off massive amounts of UV light. So yeah it makes no sense for daysiders to have skin that would increase absorption.

We know from AU that investiture is absorbed by microflora coating the sand, but not exactly how that happens.

Quote

For years we assumed that our Shard, Autonomy, had Invested only Dayside, through the sunlight itself. We know now it is not as simple as this, though the mechanism is best explained under those assumptions.

I suspect this relates to the atmosphere on Taldain filtering the light and converting it into investiture.

I also suspect that Autonomy either put the planet in the system (coz boy is it bizarre) or at least picked the system to populate with humans, because it is so bizarre and could be seen as something of an experiment.

So my theory is that the atmosphere, by design, actually traps the UV light from the supergiant, to turn it into investiture, and the dayside therefore doesn't actually get much UV light despite getting so much visible light. That's why daysiders have white skin, they actually need to reflect as much UV as possible because it's all being used up by the conversion.

It's not a theory with evidence behind it, and to be honest it's more a thought/wondering than a theory. I'd love to hear where it falls over. But at least it could explain the weirdness of white skin in a theoretically UV rich place.

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I quite like your idea @Extesian. But I just thought of another thing. Genetics. Kenton's mother was a Darksider and yet he's white and blonde. He should be mixed race, assuming genetics work somewhat like in the rest of cosmere. He's not. So I guess there must be some magic involved with his whiteness. Sigh. Is it because Autonomy supports separation that much? Lol, is Bavadin racist? :D

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4 minutes ago, strumienpola said:

Kenton's mother was a Darksider and yet he's white and blonde. He should be mixed race, assuming genetics work somewhat like in the rest of cosmere. He's not

He is. Kenton's skin is lighter than Darksider and darker than Daysider.

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7 hours ago, Oversleep said:

He is. Kenton's skin is lighter than Darksider and darker than Daysider.

Is it? I think I haven't seen it mention in the prose, but he does have a bit darker skin in to graphic novel I guess. 
Well, anyways, he's still blond and light-eyed, right? 

 

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15 hours ago, strumienpola said:

Is it? I think I haven't seen it mention in the prose, but he does have a bit darker skin in to graphic novel I guess. 
Well, anyways, he's still blond and light-eyed, right? 

 

His skin is noticeably darker than that of his fellow Daysiders, but he is still blonde and blue-eyed. This being said, we've seen on Roshar that genetics can work weirdly in the Cosmere (like blonde+brunette = two hair colours on a kid), so I guess that might be the same principle in action (which would suggest that Bavadin might've done some meddling in Taldainian genotype, perhaps to help Darksiders adapt to their star's light more easily).

Edited by Rasarr
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On 2/22/2017 at 4:04 PM, Extesian said:

I also suspect that Autonomy either put the planet in the system (coz boy is it bizarre) or at least picked the system to populate with humans, because it is so bizarre and could be seen as something of an experiment.

Not just that, Autonomy is actively keeping the planet stable. Since Taldain has a moon that orbits the twilight region of the planet, she has to apply a constant torque to keep the planet tidal locked. The explanation for this won't make much sense without a basic understanding of rotational physics, but it has to do with conservation of angular momentum. I can try to explain it if you want, but no promises that it will make sense.

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3 hours ago, Glamdring804 said:

Not just that, Autonomy is actively keeping the planet stable. Since Taldain has a moon that orbits the twilight region of the planet, she has to apply a constant torque to keep the planet tidal locked. The explanation for this won't make much sense without a basic understanding of rotational physics, but it has to do with conservation of angular momentum. I can try to explain it if you want, but no promises that it will make sense.

Even keeping in mind that the Physical Realm orbits of the Taldain system may not be perfectly circle, as Guyn's system charts would have us believe?  (Also, "Autonomy is actively keeping the system stable" would probably suffice as an explanation, but don't let me stop you)

EDIT: Wait a second, it doesn't matter whether the orbits are circular, ellipsoid, or egg-shaped - the sheer mass of the bodies involved means that it's really weird that Taldain's remained so stable for so long, even with that handwavy moon in there.  

Edited by Landis963
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13 hours ago, Landis963 said:

Even keeping in mind that the Physical Realm orbits of the Taldain system may not be perfectly circle, as Guyn's system charts would have us believe?  (Also, "Autonomy is actively keeping the system stable" would probably suffice as an explanation, but don't let me stop you)

The shape of Taldain's orbit has nothing to do with the orientation if its angular momentum. To explain how this works, I'm going to have to give everyone a brief lesson in rotational physics. If you already know rotational physics, great! If you don't, well, warning; Long and nerdy post follows.


Before we begin, we need to define some terms and conventions that physicists use to describe rotation. Clockwise and counter-clockwise won't work, because they are dependent on your perspective. Imagine you have a giant flywheel, oriented so it lies north to south. To someone on the west side of the flywheel, it might look like it's rotating counter-clockwise. However, to someone on the east side, that same rotation would look like it's clockwise. Two different viewers get two different results depending on where they are.

To rectify this, we use something called a right-hand-rule to define a single direction for any rotation. The way it works is like this: Take your right hand, and curl your fingers in the direction that the object is rotating. Your thumb now points in the direction of the object's rotation. If we use this rule to define the rotation of the flywheel, both observers will agree that the "direction" of its rotation is to the west. Don't believe me? Try it for yourself with a clock or something, and see what happens.

Okay, still with me? No? Try reading the Wikipedia page. They have a diagram.

Now that we understand rotational motion a little better, we can see how this applies to the Taldain system. I drew a picture to help everyone.

PGKqB13.png

This is what Taldain looks like as it orbits its sun. In order for the same side to stay facing the sun everywhere, the planet actually has to have a slight rotation relative to the rest of the universe. This means that Taldain, despite being tidal locked with its sun, has an angular momentum that "points" upwards, which is out of the page in this perspective. This momentum is constant in magnitude and direction. This doesn't violate conservation angular momentum, which states that without external torques, angular momentum stays constant.

Now wait a minute, you might say, what about the gravitational forces from Taldain's two suns? Couldn't those exert a torque? The short answer is: No.

In order for a force to cause a torque, that force has to have a lever-arm. It needs to be offset from the axis of the object's rotation by some arbitrary distance. Think about what happens when you open or close a door. If you use the handle, on the other side from the door's hinges, the door opens easily. If you try to push closer to the hinges, it gets a lot harder to rotate the door. You wouldn't be able to rotate the door at all if you pushed right on the hinges.

This is why the gravity forces between Taldain and its suns don't exert torque. Gravitational forces, by definition, are exerted on an object's center of mass. Since Taldain is a free rotating body, its axis of rotation always goes through its center of mass. Thus, the gravitational forces won't exert any torque on Taldain's rotation. So, under normal circumstances, the planet would just stay happily tidal-locked with its suns.

The problem comes from the moon.

JCZ7gxX.png

The moon of Taldain orbits around the twilight band of the planet, on the border between the day and night sides. This immediately causes some problems, since the moon also has angular momentum associated with it. If we apply our right-hand-rule again, this gives us a direction of rotation that is out of the page. However, this isn't the out of the page in the previous diagram, since we changed our perspective. This angular rotation actually points radially inward, towards the larger sun. You can see what I mean here:

QA3T6lR.png

Now this is unfortunate, since by putting the moon in, we essentially dumped the planet-moon system's rotational axis on its side. We can see that the direction of rotation is changing over time. At time 1, it points down, at time 2, int points to the right, and so on. This is a clear violation of conservation of angular momentum. When a planet is normally tipped on its side in it's orbit, the direction of rotation stays constant to an outside perspective. This means the planet would actually rotate very slowly as it went around is orbit. This is actually what happens with Uranus. One side of the planet experiences day for half the year, while the other experiences night for half the year. It's technically not rotating to an outside perspective, but more importantly, it's not tidally locked.

There fore, there has to be something that's not a celestial object that's forcing the Taldain-moon system to stay aligned with its star. The obvious, most natural explanation is Autonomy.

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3 hours ago, Glamdring804 said:

The shape of Taldain's orbit has nothing to do with the orientation if its angular momentum. To explain how this works, I'm going to have to give everyone a brief lesson in rotational physics. If you already know rotational physics, great! If you don't, well, warning; Long and nerdy post follows.


Before we begin, we need to define some terms and conventions that physicists use to describe rotation. Clockwise and counter-clockwise won't work, because they are dependent on your perspective. Imagine you have a giant flywheel, oriented so it lies north to south. To someone on the west side of the flywheel, it might look like it's rotating counter-clockwise. However, to someone on the east side, that same rotation would look like it's clockwise. Two different viewers get two different results depending on where they are.

To rectify this, we use something called a right-hand-rule to define a single direction for any rotation. The way it works is like this: Take your right hand, and curl your fingers in the direction that the object is rotating. Your thumb now points in the direction of the object's rotation. If we use this rule to define the rotation of the flywheel, both observers will agree that the "direction" of its rotation is to the west. Don't believe me? Try it for yourself with a clock or something, and see what happens.

Okay, still with me? No? Try reading the Wikipedia page. They have a diagram.

Now that we understand rotational motion a little better, we can see how this applies to the Taldain system. I drew a picture to help everyone.

 

  Reveal hidden contents

PGKqB13.png

 

This is what Taldain looks like as it orbits its sun. In order for the same side to stay facing the sun everywhere, the planet actually has to have a slight rotation relative to the rest of the universe. This means that Taldain, despite being tidal locked with its sun, has an angular momentum that "points" upwards, which is out of the page in this perspective. This momentum is constant in magnitude and direction. This doesn't violate conservation angular momentum, which states that without external torques, angular momentum stays constant.

Now wait a minute, you might say, what about the gravitational forces from Taldain's two suns? Couldn't those exert a torque? The short answer is: No.

In order for a force to cause a torque, that force has to have a lever-arm. It needs to be offset from the axis of the object's rotation by some arbitrary distance. Think about what happens when you open or close a door. If you use the handle, on the other side from the door's hinges, the door opens easily. If you try to push closer to the hinges, it gets a lot harder to rotate the door. You wouldn't be able to rotate the door at all if you pushed right on the hinges.

This is why the gravity forces between Taldain and its suns don't exert torque. Gravitational forces, by definition, are exerted on an object's center of mass. Since Taldain is a free rotating body, its axis of rotation always goes through its center of mass. Thus, the gravitational forces won't exert any torque on Taldain's rotation. So, under normal circumstances, the planet would just stay happily tidal-locked with its suns.

The problem comes from the moon.

 

  Reveal hidden contents

JCZ7gxX.png

 

The moon of Taldain orbits around the twilight band of the planet, on the border between the day and night sides. This immediately causes some problems, since the moon also has angular momentum associated with it. If we apply our right-hand-rule again, this gives us a direction of rotation that is out of the page. However, this isn't the out of the page in the previous diagram, since we changed our perspective. This angular rotation actually points radially inward, towards the larger sun. You can see what I mean here:

 

  Reveal hidden contents

QA3T6lR.png

 

Now this is unfortunate, since by putting the moon in, we essentially dumped the planet-moon system's rotational axis on its side. We can see that the direction of rotation is changing over time. At time 1, it points down, at time 2, int points to the right, and so on. This is a clear violation of conservation of angular momentum. When a planet is normally tipped on its side in it's orbit, the direction of rotation stays constant to an outside perspective. This means the planet would actually rotate very slowly as it went around is orbit. This is actually what happens with Uranus. One side of the planet experiences day for half the year, while the other experiences night for half the year. It's technically not rotating to an outside perspective, but more importantly, it's not tidally locked.

There fore, there has to be something that's not a celestial object that's forcing the Taldain-moon system to stay aligned with its star. The obvious, most natural explanation is Autonomy.

Sweet. My minimal amateur knowledge of physics and tidal locking and and so on made me strongly suspect such an orbit isn't really possible without some external force, hence my partly-formed theory, but I love that on here there's so many actual scienticians that I can hear physics applied to fantasy. This is a good explanation.

I still wonder why Autonomy would have chosen such a strange place but I figure it's because it's either naturally hard to get to, giving the planet it's own autonomy from others, or it gives each side of the planet autonomy from the other. Or both. And I still think it's the 'other' planet where humanity did not predate the arrival of the Shard.

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1 hour ago, Extesian said:

Sweet. My minimal amateur knowledge of physics and tidal locking and and so on made me strongly suspect such an orbit isn't really possible without some external force, hence my partly-formed theory, but I love that on here there's so many actual scienticians that I can hear physics applied to fantasy. This is a good explanation.

I still wonder why Autonomy would have chosen such a strange place but I figure it's because it's either naturally hard to get to, giving the planet it's own autonomy from others, or it gives each side of the planet autonomy from the other. Or both. And I still think it's the 'other' planet where humanity did not predate the arrival of the Shard.

Almost certainly. The odds of this system forming naturally are extremely low. With the Roshar system, it's unlikely, but not impossible. Autonomy needs to already do a lot to keep the planet habitable, otherwise the UV radiation from the blue-white sun would cook anything on the Dayside to a crisp. I wouldn't be surprised at all if she put the planet there herself, instead of finding an existing one.

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1 hour ago, Extesian said:

Sweet. My minimal amateur knowledge of physics and tidal locking and and so on made me strongly suspect such an orbit isn't really possible without some external force, hence my partly-formed theory, but I love that on here there's so many actual scienticians that I can hear physics applied to fantasy. This is a good explanation.

I still wonder why Autonomy would have chosen such a strange place but I figure it's because it's either naturally hard to get to, giving the planet it's own autonomy from others, or it gives each side of the planet autonomy from the other. Or both. And I still think it's the 'other' planet where humanity did not predate the arrival of the Shard.

 

21 minutes ago, Glamdring804 said:

Almost certainly. The odds of this system forming naturally are extremely low. With the Roshar system, it's unlikely, but not impossible. Autonomy needs to already do a lot to keep the planet habitable, otherwise the UV radiation from the blue-white sun would cook anything on the Dayside to a crisp. I wouldn't be surprised at all if she put the planet there herself, instead of finding an existing one.

I agree.  My impression is that Autonomy found the system interesting, but it wasn't in that configuration at the time, so she moved things around to make the unusual alignment of the system the way it is for a particular purpose (it may have been nothing more than an experiment or something artistic, instead of being directly connected to her Intent, especially if she did it soon after the Shattering).  The fact that she's obviously putting effort into maintaining it after all this time is interesting, too.  

Mistborn, Elantris, and Stormlight spoilers:

Spoiler

Preservation and Ruin weren't actively involved in keeping Scadrial stable as far as we can tell (if Ruin could have made the planet spiral into the sun, I suspect he would have), and Sel of course doesn't have any active control from the Shards since they're splintered and inaccessible, though they could have put something into place that is still working.  The moons of Roshar are implied to be unstable, though, so it's possible that Honor or Cultivation, or both, was and is maintaining their orbits, and that it could have future impacts.

I'd be curious as to how many systems in the Cosmere have active, ongoing efforts by their residing Shards to keep things working, vs them being set up by the Shards but then being stable on their own.

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3 hours ago, Jondesu said:

 

I agree.  My impression is that Autonomy found the system interesting, but it wasn't in that configuration at the time, so she moved things around to make the unusual alignment of the system the way it is for a particular purpose (it may have been nothing more than an experiment or something artistic, instead of being directly connected to her Intent, especially if she did it soon after the Shattering).  The fact that she's obviously putting effort into maintaining it after all this time is interesting, too.  

Mistborn, Elantris, and Stormlight spoilers:

  Hide contents

Preservation and Ruin weren't actively involved in keeping Scadrial stable as far as we can tell (if Ruin could have made the planet spiral into the sun, I suspect he would have), and Sel of course doesn't have any active control from the Shards since they're splintered and inaccessible, though they could have put something into place that is still working.  The moons of Roshar are implied to be unstable, though, so it's possible that Honor or Cultivation, or both, was and is maintaining their orbits, and that it could have future impacts.

I'd be curious as to how many systems in the Cosmere have active, ongoing efforts by their residing Shards to keep things working, vs them being set up by the Shards but then being stable on their own.

In terms of a stable orbit for Rosharan moons we have this brand new WoB

Quote

Q Roshar has three moons that orbit it, and I notice that these orbits somewhat collide. I was wondering if the moons have anything to do with...

A The moons are a little bit of a hint, but it’s not about what you’re thinking. They are not in a stable orbit on astronomical terms. They’ll last tens of thousands of years before they degrade. But it is a little bit of a hint of things. The fact that Roshar has three moons in a very specific orbit is a hint about things.

So it sounds like the Shards there were/are not keeping the moons stable, it's just a long time til the effects will kick in. I've briefly wondered if there's a connection between Shards in residence and the existence of moons themselves but that's for another thread.

But yeah I'm very interested in active Shardic influences on systems. It would just seem quite inefficient if there isn't a specific purpose. Taldain feels significant, with there being two distinct and unchanging sides of the world and accompanying peoples, two distinct stars influencing the system in completely different ways. Maybe I'll try a reread of White Sand prose with it in mind.

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On 2/25/2017 at 2:13 PM, Orion the Infinite said:

I think that this theory has merit, seeing as after sand has been used, it just requires a few hours of sunlight to recharge its investiture.

Actually I think it's the reverse. Naturally due to all the UV EVERYONE on the world should be dark skinned. But those living on Dayside get 'beached' out due to the Investiture leaking into them. Think of it as a weaker version of what Elantrins go through.

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  • 2 weeks later...

Someone asked Brandon this exact question at a signing today. The answer, to paraphrase, was roughly that while it would be better for the Daysiders to have dark skin, the pale skin genes became more prevalent in the Dayside population than the dark skin ones, randomly so.

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Its not just on Taldain I think.

 

Taking it from memory here since I dont got my books, but I seem to recall terris was on average darker skinned, and before Rashek altered the world, terris was the most northern part, wich should mean less uv. They should have been the palest if you look at it like that.

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3 minutes ago, dyring said:

Its not just on Taldain I think.

 

Taking it from memory here since I dont got my books, but I seem to recall terris was on average darker skinned, and before Rashek altered the world, terris was the most northern part, wich should mean less uv. They should have been the palest if you look at it like that.

Quote

INTERVIEW: Feb 22nd, 2016

QUESTION

What race is Sazed?

BRANDON SANDERSON

The Terris have intermixed to the point that they… Skin tone run the gamut, from being indistinguishable to being darker skinned. When I say darker-skinned I mean say, like as perhaps as a dark Indian, East Indian… But they can range in that skin tone

Also, Brandon kinda suggests that Terrisans were the first people of Scadrial so the fact that they live in mountains in the Final Empire does't mean that much. 

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