Gensokyo Physics: Youkai of Systems goes insane.

[Delfigamer]

I sure ZUN have some principles standing behind all kinds of magic in Gensokyo. At least he should determine how they must interact.

[Imosa]

I sure ZUN have some principles standing behind all kinds of magic in Gensokyo. At least he should determine how they must interact.

I rather think he does not.

[Imosa]

Ok, so here's one to think about, Komachi. All kinds of nice stuff here. She can change the distances between things and uses this power to make trips across the Senzu river reflect the crimes of whoever she is ferrying.
First of all, how does this power manifest. I see a few possobilities. If you are holding a 12 inch ruler and you are space dialated twice as long by Komachi, how long will the ruler be?
The first possobility is that you wouldn't see the ruler because once the building blocks of creation are seperated by twice the distance that they normally are, you became a whole new kind of dead, along with the ruler. This is pretty boring so lets try a diffrent answer.
12 inches. This is because when space stretches those building blocks of creation are also stretched and so everything built on those blocks, is streated. This includes the ruler, along with your head, eye, and light traveling from the ruler to your eye. I'll be focusing on this scenario.
So everything within the dialation looks the same but what about outside the dialation. One possobility is that everything looks the same because as you or anything else (light) passes from normal space to the dialated space, it too becomes dialated (being within space, and all). So doesn't this render Komachi's power useless? To an extent, yes. Unless Komachi has some mechanism by which to ignore spacial dialations. With such an ability her powers become very useful. She can compress space in front of her and them walk into it and appear to grow in size.
This leads us to our final part of the scenario. Consider the ruler, now held by Komachi. After dialating space by 2 she leaves her dialated space while ignoring space dialations, causing her and the ruler to grow. The ruler is now 24 inches long. However, note that the situation could be worked out to the same effect if Komachi had just dialated the universe by 1/2 causing everything else to shrink in comparison to the constantly sized Komachi.

Now lets move onto Komachi, when doing her job. Komachi sees her target, a distance away from her. She dialates space between her sand her target she perpares to ignore space dialations and raises her weapon. Now lets for a second believe that Komachi uses a Naginata instead of a scyth. She swings her Naginata through dialated space and her target's head is removed by what appears to him to be a very long blade (not that he has much time to care). A fine kill but Komachi does not use a Naginata. As many of you might know, the possition of a scythe's blade makes a bad weapon but Komachi his it a little diffrent. Consider that when Komachi swings her scythe, because she ignores space dialations her blade goes around her victim even though he is a distance away. When the blade is in front of him and Komachi, she can pull the blade toward herself through dialated space. The blade travels the distance between the reach of her weapon and her body in a certain time. However, while the pole is in undialated space, the blade travels through undialated space and both have to reach body at the same time so the blade travels many times faster through dialated space, amassing much more momentum when finally hitting her target. The conclusion is that Komachi's attacks are more deadly at long range.
One last thing to consider. What if Komachi just let her blade sit in front of her. Instead of pulling the blade, why not undialate the space? Now her targets neck will try to expand into an area occupied by her blade unless it moves out of the way. While this may increase the cutting power of her blade, because we have no idea on how fast she can dialate or undialate space, we can not predict how much more effective this would be. However, it does mean that Komachi can effectively kill, without moveing her weapon and instead just dialating space around it.

Some problems are that I feel like I'm missing something in my idea here. Something about Komachi reaching around enemies with her scyth doesn't seem quite right. I'm sure there might also be some issues with the blade speeding up through the dialated space and then not comming out the side a the same time. For one thing, if the blade gains momentum in the space, does it still have that momentum when it comes out? Would that momentum break the pole and send the blade flying into Komachi's face? Maybe?

[Delfigamer]

Ok, so here's one to think about, Komachi. All kinds of nice stuff here. She can change the distances between things and uses this power to make trips across the Senzu river reflect the crimes of whoever she is ferrying.
First of all, how does this power manifest.

http://en.wikipedia.org/wiki/Special_relativity#Consequences_derived_from_the_Lorentz_transformation
Time dilation.
Length contraction.
ZUN is a clever guy, isn't he?

[Imosa]

http://en.wikipedia.org/wiki/Special_relativity#Consequences_derived_from_the_Lorentz_transformation
Time dilation.
Length contraction.
ZUN is a clever guy, isn't he?

What are you addressing here. I might be missing something but approaching the speed of light, is not going to make crossing the river any longer. Yes I'm sure relativity comes into play here somewhere but I don't know enough to say how (which is why I didn't touch on it in my post).

[Delfigamer]

What are you addressing here. I might be missing something but approaching the speed of light, is not going to make crossing the river any longer. Yes I'm sure relativity comes into play here somewhere but I don't know enough to say how (which is why I didn't touch on it in my post).

I don't know if Komachi actually uses relativity for making trips longer, but its equations can give you an idea of what is going in the distorted space.

However, there's also another explanation for it - human's perception. Komachi just makes a dead to feel like they was floating for long period.

[Starxsword]

However, there's also another explanation for it - human's perception. Komachi just makes a dead to feel like they was floating for long period.

I am pretty sure it is not just perception. You can see Komachi teleport herself and her opponent in the fighting games. You can also see how she can put up a field that causes you to not be able to move out of there that easily.

Would that momentum break the pole and send the blade flying into Komachi's face? Maybe?

Why would the blade even hit her if her ability is distance manipulation. She could just make the blade fly elsewhere.

[Drake]

An extra spatial dimension would be my thing. It doesn't take her (or anything else in normal space, really) any extra effort to do anything through the stretched space, the space can be stretched and unstretched without any artifacts that might occur from other "explanations", and it does directly tie in to reality so it isn't just a perception trick. The speed of light would restrict the propagation of movement regardless, but if the movement/bending is manipulated through another spatial dimension then a movement/space bend may seem as though it were done imperceptibly quickly. It might account for apparent warping in Soku. The length of the Sanzu would also have to asymptotically approach an equivalent crossing at light speed. And junk.

I sure ZUN have some principles standing behind all kinds of magic in Gensokyo. At least he should determine how they must interact.

ZUN has incredibly detailed explanations for some things and essentially no explanation for others. If things need to interact in a significant way then it can be explored further but isn't necessarily the case. It suffices to just say "it's magic dwi"; there does not need to be an explanation for anything. Having what we do have is pretty great in itself. He has said that many inner workings of Gensokyo are in his head and generally they won't be revealed, so perhaps he has more explanations than you may think, and there are definite sorts of principles and standards that he uses when defining new characters and locations and whatnot. But in no way does he have to determine how they interact besides maybe a "this happens just because". He isn't required to satisfy any random fan's demand for an in-universe explanation for some event that he never thought of writing about in the first place. He's probably been asked these sorts of questions in interviews and just makes it up on the spot.

[Imosa]

I don't know if Komachi actually uses relativity for making trips longer, but its equations can give you an idea of what is going in the distorted space.

However, there's also another explanation for it - human's perception. Komachi just makes a dead to feel like they was floating for long period.

I'm not sure they're relevant at all since those equations can't allow space to expand.
Also if it is a perception thing then I'll be disappointed.

I am pretty sure it is not just perception. You can see Komachi teleport herself and her opponent in the fighting games. You can also see how she can put up a field that causes you to not be able to move out of there that easily.

Why would the blade even hit her if her ability is distance manipulation. She could just make the blade fly elsewhere.

Well, I don't know if she can make stuff turn but you're right she can just give the blade space to slow down.
That is a good question though. If there is wall with a thin tunnel that turns on it's way to the other side, can she still get through the tunnel?

[Raikaria]

Here's something I theorycrafted somewhere else, about Aya's speed:


Theory has it that if Aya is faster than Youmu, and Youmu can do 100 Yojuna in one slash, then Aya's top speed is at least 1/4 light speed.

299,792,458 m/s = speed of light
/4 = 74,948,114.5 m/s *Theoretical MINIMUM top speed*, also known as Mach 220,247


 That's multiple times re-entry and escape velocity. To put into perspective, if for some reason Aya was on the Sun, she could escape it's gravity with ease. Let's ignore the fact she's be KFTengu.

Put simply, Aya is pretty much incomprehensibly fast. She also very, very rarely goes at top speed... simply because at those sorts of speeds... she's cause utter devastation. Not to mention she wouldn't be able to keep those speeds up for long without burning herself to a crisp from air friction


Aya probably can't go anywhere near Mach 10 without harming herself, regardless of how well adapted she is, and Mach 20+ would carry the severe risk of... catching fire, since that's re-entry speed. Her top speed may well be the highest, but that dosen't mean she can achieve it without becoming a fireball. [Or being in space, but that has it's own problems]

[KFCbbQ]

Perhaps Aya's ability to manipulate wind can be used to negate air friction, allowing her to fly at higher speed also preventing her from catching on fire. Of course she'll need to have superhuman reflexes if she doesn't want to bump into every tree in her way..

[Hanzo K.]

It's assumed she flies above the trees though.

[KFCbbQ]

You're still gonna run into things when going that fast.

[Delfigamer]

I'm sure Aya's brain is fast enough to maintain that speed.

Raikaria, what time did you got for the slash?

[Imosa]

Raikaria, what time did you got for the slash?

I'd like to know this too. First of all, the spell card is called "200 Yojana in 1 Slash" so maybe your figure needs doubling. The wikia mentions your same answer and sites a doujin, Touhou Kaidan Seven #3, as it's source. Unfortunately I can't find a translated copy of it. The wikia also mentions the speed Mach 70 but with similarly poor work.
One thing that kind of confuses me about the whole premise of "200 Yojana in 1 Slash" is what is being slashed. Surely you're not slashing something in front of you, not if it's 1200 to 3000 kilometers away. It would only make sense to me if you approach for that distance and then actually slash at the last moment. I guess the idea is that she's so fast she can just hold the sword next to her and cut things in passing.
If someone wants to try and find the time it takes for a samurai to slash then we could figure this whole thing out for ourselves.

[Drake]

"In one slash" probably refers to Youmu's instant movement from one side of the screen to the other, rather than slashing something far away. In this case, what's being slashed doesn't matter, it's her being able to move that far in the time it takes for her to slash once.

Also, 200 yojana in one slash. The actual length of one yojana is pretty vague, but a smaller measure would be 10km. The important part however is how fast the sword slash is, since this can vary pretty wildly and would drastically affect the speed. Assuming one slash takes 1/3 of a second, this is 10000*3*200 m/s = 6000000m/s = 1/50 the speed of light. If the slash takes something more like 1/30 of a second it changes it to 1/5 the speed of light. It's pretty much some arbitrary fraction of the speed of light dependent on how fast you assume Youmu is, which itself makes the exercise redundant because you've already determined how fast she is.

[Starxsword]

Well, I don't know if she can make stuff turn but you're right she can just give the blade space to slow down.

Her ability is distance manipulation. If she can manipulate distance, there is no reason to believe she can only manipulate that distance in what I guess is would be the X plane(the object going towards you and away from you) from the blade to her, instead of being able to manipulate the distance in all 3 planes, X(towards and away), Y(upwards and downwards), and Z(sideways). What I mean is there is no reason to believe that she can only manipulate distance from point A to point B in a straight line. Who is to say she can't manipulate Point B upwards and towards, in addition to forwards and backwards or sideways?

Not to mention she wouldn't be able to keep those speeds up for long without burning herself to a crisp from air friction

Aya's a youkai... Her physical nature is different from a humans. Whether she burns or not can be contested.

Theory has it that if Aya is faster than Youmu, and Youmu can do 100 Yojuna in one slash, then Aya's top speed is at least 1/4 light speed.

Aya and Remilia are likely faster than Youmu. The prior, because her boast and it was uncontested by anyone. The latter, because of Youmu's comments that against a fast opponent Yuyuko says one must close one's eyes. Youmu, unfortunately, did not understand the reasoning behind closing one's eyes. Youmu only makes this comment to Remilia in vs mode.

Also, 200 yojana in one slash.

How come her spell card isn't translated to 200 Yojana in a Flash?

[Drake]

Because 一閃 is a (more or less anime-used) term used denoting a quick sword slash, usually also done in iaido-esque fashion. Saying that it could be "in a flash" is nearly the same thing as my pointing out that "in one slash" means a length of time and nothing more.

[_cf]

When I read Suika "breaking the heavens" interview, I understood that she interfered with the density of the atmosphere over Gensokyo. When you change the density of a medium, you change how light refracts through it, as in this classical phenomenon:



Now picture this being made chaotically all over the sky. The result is that the form of the moon seems to "break". She probably can't say exactly what she's doing (Suika and Aya don't look exactly scientifically minded) so she says what she knows, that she somehow "broke the heaven".

[Imosa]

Her ability is distance manipulation. If she can manipulate distance, there is no reason to believe she can only manipulate that distance in what I guess is would be the X plane(the object going towards you and away from you) from the blade to her, instead of being able to manipulate the distance in all 3 planes, X(towards and away), Y(upwards and downwards), and Z(sideways). What I mean is there is no reason to believe that she can only manipulate distance from point A to point B in a straight line. Who is to say she can't manipulate Point B upwards and towards, in addition to forwards and backwards or sideways?

I guess.

How come her spell card isn't translated to 200 Yojana in a Flash?

Ask the wiki I guess. Spell Card 74 in PCB.

When I read Suika "breaking the heavens" interview, I understood that she interfered with the density of the atmosphere over Gensokyo. When you change the density of a medium, you change how light refracts through it, as in this classical phenomenon:



Now picture this being made chaotically all over the sky. The result is that the form of the moon seems to "break". She probably can't say exactly what she's doing (Suika and Aya don't look exactly scientifically minded) so she says what she knows, that she somehow "broke the heaven".

Very cool idea. I should point out that density is only only generally associated with the index of refraction so who knows but it's still pretty clever.

[Delfigamer]

The actual length of one yojana is pretty vague, but a smaller measure would be 10km.

Merry says about 7km.

"And 'yojana' is a measure of distance?"
"Yes, it's a unit of length from ancient India. One yojana is about seven kilometers, so forty thousand yojana would be about two hundred eighty thousand kilometers. <...>"

[Drake]

In that case it's a better reference of what ZUN uses than simply guessing. Of course, in-story Mary wouldn't really know whether it was 7km or 15km either, but if ZUN uses 7km in one case it's better off to use that for others. Of course, what I noted about sword slash speed still holds; the difference between 10km and 7km is on the same order rather than an order of tens or hundreds.

[Starxsword]

Now picture this being made chaotically all over the sky. The result is that the form of the moon seems to "break". She probably can't say exactly what she's doing (Suika and Aya don't look exactly scientifically minded) so she says what she knows, that she somehow "broke the heaven".

I don't think that would be accurate. Suika mentions that she shattered the heavens, so that she can break the moon. It isn't like the result of shattering the heavens is the moon looking like it is being broken, which is what this explanation would imply.

Because 一閃 is a (more or less anime-used) term used denoting a quick sword slash, usually also done in iaido-esque fashion. Saying that it could be "in a flash" is nearly the same thing as my pointing out that "in one slash" means a length of time and nothing more.

I see, so that is why it is translated to that.

[Imosa]

I don't think that would be accurate. Suika mentions that she shattered the heavens, so that she can break the moon. It isn't like the result of shattering the heavens is the moon looking like it is being broken, which is what this explanation would imply.

So one reason I havn't thought about this is because it makes no sense. What is the result of  "shattering the heavens".

[_cf]

I don't think that would be accurate. Suika mentions that she shattered the heavens, so that she can break the moon. It isn't like the result of shattering the heavens is the moon looking like it is being broken, which is what this explanation would imply.

You can only see the Moon when it's reflected in things. And the things it reflects in, like water or glass, can all be broken, right? Since the moon you see in the sky is just being reflected in the heavens, if you tear open the heavens it's easy to break it~

Whatever Suika did, it was an atmospheric phenomenon. The actual Moon is full of super-powerful humans and gods that probably can do something against their world being shattered against their will.

While Oni can't lie, they can surely boast or simply misunderstand the physics of what they did. Suika used an incorrect analogy there. She compared the sky with a lake's surface. If the water is calm the moon's reflection appears perfect. But if you cause waves, the reflection "breaks".

Now there's also the possibility that the sky on touhouverse works exactly as a lake's surface and "reflects" the moon, but whenever possible, I like to think physics there work as here, and magic works by interfering with the actual physics laws. So Suika messed with refraction, not reflection. Her analogy, while not perfect, was good enough for Aya's article. The oni messed with the medium through which moonlight arrives on Gensokyo and as the result the moon's image broke.

[Starxsword]

Whatever Suika did, it was an atmospheric phenomenon. The actual Moon is full of super-powerful humans and gods that probably can do something against their world being shattered against their will.

No, you misunderstand. The point I was making is that Suika mentions it as a two step process. If it were actually an atmospheric phenomenon, it would simply be a 1 step process and shattering the heavens would result in breaking the moon. But that is not the case here.

In the first place, it isn't their moon that is being shattered. Their moon is kind of like Gensokyo, protected by a barrier, so it is in a sense in a different dimension. The moon that Suika shattered would be the moon in the real world.

So one reason I havn't thought about this is because it makes no sense. What is the result of  "shattering the heavens".

Have you seen One Piece? Did you see what White Beard did to the air? I presume what Suika did was similar to that. She applied overwhelming force to split the heavens in half. So, instead of "air" there, it results in "nothing" in between the moon and her location. Then, breaking it would be easy, or so she says.

[Maiden Synnae ミ☆]

I'm gonna try contributing to the thread with something.

Not sure if someone said something similar already...... but it's about Cirno's StB Freeze Sign "Minus K"

I suppose the letter K stands for "Kelvin", which is a temperature measurement unit. For this Scale, Absolute Zero (the theoretical lowest possible temperature) is achieved at 0K, or "Zero Kelvin"

I think Zun was trying to make Cirno look badass by going even lower than absolute zero with this spell. Said temperature itself being unable to be achieved (and technically impossible to be achieved by any means) even by the Boomerang Nebula, which is the coldest place in the universe, with a temperature of −272 ?C, which is only 1 ?C warmer than absolute zero (The equivalent of 1K in Kelvin terms). However... since Kelvin is an absolute, thermodynamic temperature scale system, a truly negative temperature with said scale is hotter than any other system with a positive temperature. (i.e... Celsius, Fahrenheit... etc)

So..... would that mean that Cirno can increase temperature and make the surroundings hotter as well...?

.........I really don't think so. Because Zun explicitly stated "FREEZE sign" so... she is still freezing things, right...? In that case, that was just a slip from his part, I guess.

For more details: Negative Temperature

[Szayelaporro Granz]

So..... would that mean that Cirno can increase temperature and make the surroundings hotter as well...?

.........I really don't think so. Because Zun explicitly stated "FREEZE sign" so... she is still freezing things, right...? In that case, that was just a slip from his part, I guess.

For more details: Negative Temperature

I assume you're right, Cirno's ability is manipulation of chill after all stated by PMiSS.

[Imosa]

Did you see what White Beard did to the air?

I think that can also be explained by the whole index of refraction thing. White Beard creates pressure waves which would change the index of refraction of the air, which might create a shattered effect. As for the whole two step process... I dunno...

I'm gonna try contributing to the thread with something.

Not sure if someone said something similar already...... but it's about Cirno's StB Freeze Sign "Minus K"

I suppose the letter K stands for "Kelvin", which is a temperature measurement unit. For this Scale, Absolute Zero (the theoretical lowest possible temperature) is achieved at 0K, or "Zero Kelvin"

I think Zun was trying to make Cirno look badass by going even lower than absolute zero with this spell. Said temperature itself being unable to be achieved (and technically impossible to be achieved by any means) even by the Boomerang Nebula, which is the coldest place in the universe, with a temperature of −272 ?C, which is only 1 ?C warmer than absolute zero (The equivalent of 1K in Kelvin terms). However... since Kelvin is an absolute, thermodynamic temperature scale system, a truly negative temperature with said scale is hotter than any other system with a positive temperature. (i.e... Celsius, Fahrenheit... etc)

So..... would that mean that Cirno can increase temperature and make the surroundings hotter as well...?

.........I really don't think so. Because Zun explicitly stated "FREEZE sign" so... she is still freezing things, right...? In that case, that was just a slip from his part, I guess.

For more details: Negative Temperature

Calling ZUN a liar is dangerous territory. In my opinion it's much more likely that Cirno lied about the name of her card, rather then the god of all creation being wrong about something.

[Maiden Synnae ミ☆]

Calling ZUN a liar is dangerous territory. In my opinion it's much more likely that Cirno lied about the name of her card, rather then the god of all creation being wrong about something.

Nobody is perfect.

And besides, when did I call Zun a liar? I said it was a "slip" everyone commits slips every now and then, and this is fact. There's no such a thing as "perfection" anywhere. It doesn't matter who you are.

Like any other series, Touhou can also have some flaws/holes. It's not really a negative point. Rather, it's a natural thing.