Could you send a small metal object into orbit using A-iron?

[Stormlightsong]

A-iron allows you to pull metal to you, so if you accelerated it to orbital velocity based on how much you’re pulling it, compensating for of the earths gravity, could you send it into orbit around yourself?

Of course, you would probably need some other thing like F-zinc to calculate all this, but could it be done?

[alder24]

14 hours ago, Stormlightsong said:

A-iron allows you to pull metal to you, so if you accelerated it to orbital velocity based on how much you’re pulling it, compensating for of the earths gravity, could you send it into orbit around yourself?

Of course, you would probably need some other thing like F-zinc to calculate all this, but could it be done?

No. Your body has almost no gravitational force, Earth massively overshadows it. A-iron also pulls in a straight line, you would not be able to pull it in such a way to curve it without moving, nor your gravity is strong enough to do that for you.

Not to mention A-iron is weak. For objects to stay in Earth's orbit they need to move tens of thousands of m/s. Faaaar too much for Allomancy to produce. Vin in TFE when she was  pushing herself for the first time up to the wall, did it in a few seconds. It took her a few seconds to get to the top of a 10 or so meter high wall (or higher I don't know if there is a number). Later she became better, but the speed she was able to produce was still small. But that's compared to Earth's orbits.

For objects to be in orbit you need 2 things - a force pulling it towards you, and a perpendicular velocity, making it "miss" you. You have a force pulling it towards you, A-iron, but no perpendicular velocity and now way of making it. Plus air drag will be constantly slowing it down, so there is no way for you to create a force perpendicular to A-iron pull, to give that object orbital velocity.

It's like having a ball tied to the end of the string, start spinning that string and it will make a circle, but you need to constantly apply force to uphold that speed, otherwise a ball will fall. You don't have that sideways force, you only have a "string" with A-iron.

[Quantus]

16 hours ago, Stormlightsong said:

A-iron allows you to pull metal to you, so if you accelerated it to orbital velocity based on how much you’re pulling it, compensating for of the earths gravity, could you send it into orbit around yourself?

Of course, you would probably need some other thing like F-zinc to calculate all this, but could it be done?

Allomancy has no way to let you do this, you cannot apply a force in any direction other than directly toward or away from you.  To achieve an orbital effect around yourself, you'd need three different forces at 90° of each other: One Pushing upward to counter gravity, one Pulling horizontally toward you to mimic a gravitational field, and a third (stronger) one pushing tangent to the plane of rotation so that the object keeps trying to fall toward you and missing. Those last two forces would need a delicate balance to maintain the orbit and not sling it inward or out after a couple orbits.  

At best you might be able to make it orbit in a small circle in front of you and between your hands, if you are good enough to Push and Pull toward them and not just your center of mass (like Marsh). 

[LimeJack]

TLDR; The layman can for a few seconds, and a skilled enough lurcher could keep it up indefinitely.

 

2 hours ago, alder24 said:

It's like having a ball tied to the end of the string, start spinning that string and it will make a circle, but you need to constantly apply force to uphold that speed, otherwise a ball will fall. You don't have that sideways force, you only have a "string" with A-iron.

This ball metaphor matches up exactly to this scenario. Yes air resistance will slow the ball and make it fall, but if you stop spinning the string the ball won't fall immediately. So pulling from your center of mass, and with a friend throwing it perpendicular to you, you could get a few revolutions. BUT you don't actually have to pull from your center of mass. You could, with experience, practice, and probably luck pull from an orbiting node around your center of mass, just ahead of the ball. This provides the forward force you need, and if you get it exact you can perfectly negate air resistance.

[alder24]

32 minutes ago, LimeJack said:

TLDR; The layman can for a few seconds, and a skilled enough lurcher could keep it up indefinitely.

 

This ball metaphor matches up exactly to this scenario. Yes air resistance will slow the ball and make it fall, but if you stop spinning the string the ball won't fall immediately. So pulling from your center of mass, and with a friend throwing it perpendicular to you, you could get a few revolutions. BUT you don't actually have to pull from your center of mass. You could, with experience, practice, and probably luck pull from an orbiting node around your center of mass, just ahead of the ball. This provides the forward force you need, and if you get it exact you can perfectly negate air resistance.

No, you can't pull a metal to the place where you're not there. A-iron pulls to the center of self, not even the center of your mass, so gravity and mass do not matter. You can't pull to the place outside of your body, only a very skilled Lurcher would be able to pull towards a hand for example.

A very experienced Lurcher could extend his hand and pull the metal towards it while spinning. That's the closest you can get to orbit. But being constantly in a spin would be very unpleasant, to put it mildly.

Spoiler

Questioner

I have a theory. Because the center of gravity for a female is naturally lower, but when Vin burns iron or steel, the blue lines come from her chest, does that come from her center of self, rather than the center of gravity?

Brandon Sanderson

Yeah. That's probably a more accurate way to put it. 

Questioner

Would it be possible for that to change, then? 

Brandon Sanderson

Yes, that is possible. I should say it like that, because it's not going to actually be... Because center of gravity, where you would actually put it, is not where I'm having those lines come from. You came in costume. You can just make that canon now and we will put that on all of the lists that that is what it is.

Starsight Release Party (Nov. 26, 2019)

 

[Stormlightsong]

4 hours ago, alder24 said:

For objects to be in orbit you need 2 things - a force pulling it towards you, and a perpendicular velocity, making it "miss" you. You have a force pulling it towards you, A-iron, but no perpendicular velocity and now way of making it. Plus air drag will be constantly slowing it down, so there is no way for you to create a force perpendicular to A-iron pull, to give that object orbital velocity.

Sorry for not clarifying this. I was thinking the A-Iron would act as a gravitational force, but you would push it into orbit by slinging it with your fingers or something. You could also probably keep it in orbit by lessening your pull on it when it comes close and then strengthening it when it goes farther. To my knowledge this should cause an elliptical orbit.

And you mentioned it would be impossible to reach the speed needed to enter earths orbit, but all you need is the speed necessary to enter orbit with the force exerted on it. I’m pretty sure orbital velocity goes down when the gravitational force goes down.

[alder24]

3 minutes ago, Stormlightsong said:

Sorry for not clarifying this. I was thinking the A-Iron would act as a gravitational force, but you would push it into orbit by slinging it with your fingers or something. You could also probably keep it in orbit by lessening your pull on it when it comes close and then strengthening it when it goes farther. To my knowledge this should cause an elliptical orbit.

No it won't work. Iron pulls go straight towards you, not next to you. Just pushing that object with your finger won't do that, as you need a constant horizontal force acting in the perpendicular direction from the pull of A-iron - because of the atmosphere and gravity. That would require quite fast speeds, not Earth's orbits fast, but too fast to push it with a finger or be safe for you. 

An object pulled from a far away would gain a lot of speed, too much for you to push it with a finger, and lessening the pull would not lessen its velocity. An object in motion will stay in motion unless a force acts on it. It would kill you, and rip off your finger on the way.

7 minutes ago, Stormlightsong said:

And you mentioned it would be impossible to reach the speed needed to enter earths orbit, but all you need is the speed necessary to enter orbit with the force exerted on it. I’m pretty sure orbital velocity goes down when the gravitational force goes down.

Yes, it depends on the mass and distance: v = sqrt(GM/R) and v=2piR/T . But on Earth you have gravity always pulling it down, which, as Quantus said, needs to be counteracted, air drag slowing it down, which means you need not a perpendicular velocity like in space, but constant horizontal perpendicular force, acceleration to combat that air drag. And third one is the pull towards you, which has to be very precise, not too strong, not too weak. You can only create the last force. You have no way of combating the gravity, no way of combating the air drag, and no way of applying constant perpendicular acceleration.

Pushing it with your finger would rip your finger off and won't do anything as that's only a singular push. You would have to first hold the metal in your hand, pull it with iron, spin around and constantly push it with your extended hand. But gravity still remains, and spinning is painful and useless.

[LimeJack]

2 hours ago, alder24 said:

No, you can't pull a metal to the place where you're not there. A-iron pulls to the center of self, not even the center of your mass, so gravity and mass do not matter. You can't pull to the place outside of your body, only a very skilled Lurcher would be able to pull towards a hand for example

I was refering specifically to rotating the point you are pulling from inside your body. We know for a fact that you can do this with marsh and the gun. If you have the point you are pulling from be a few inches from your center of mass and you pull you get a vector that breaks down into the perpendicular and pulling that you wanted. If this point, within your body rotates at the same speed as the object you have both components you need. The anti gravity component can be canceled as well if the object is orbiting below your center of mass, so your pulling vector gets all 3 components. See really bad picture below.

left side is top down view, right is from the side. I have drawn both the force vectors and the decomposed ones with dashed lines.

 

Edit: image did not seem to work

Edited June 2, 2023 by LimeJack

[Stormlightsong]

1 hour ago, alder24 said:

An object pulled from a far away would gain a lot of speed, too much for you to push it with a finger, and lessening the pull would not lessen its velocity. An object in motion will stay in motion unless a force acts on it. It would kill you, and rip off your finger on the way.

I’m not saying you would use your finger to keep the momentum. You would just use it to start the speed.
 

I still think you’re right that the finger push would not give it enough speed to start an orbit, but if you had some sort of contraption, like a rail gun, that could give it the speed to complete several revolutions, you could get it into a pretty consistent orbit.

[NameIess]

21 hours ago, Stormlightsong said:

A-iron allows you to pull metal to you, so if you accelerated it to orbital velocity based on how much you’re pulling it, compensating for of the earths gravity, could you send it into orbit around yourself?

Of course, you would probably need some other thing like F-zinc to calculate all this, but could it be done?

I'm a bit confused by the question. Are you asking if a lurcher could spin a piece of metal around themselves using A-iron? Because I can definitely see that working. For example, a very skilled Lurcher could probably spin a bullet around themselves a few times before air resistance slowed it or keep a lower speed orbit going by pulling metal towards themselves then moving out of the way.

[alder24]

1 hour ago, LimeJack said:

I was refering specifically to rotating the point you are pulling from inside your body. We know for a fact that you can do this with marsh and the gun. If you have the point you are pulling from be a few inches from your center of mass and you pull you get a vector that breaks down into the perpendicular and pulling that you wanted. If this point, within your body rotates at the same speed as the object you have both components you need. The anti gravity component can be canceled as well if the object is orbiting below your center of mass, so your pulling vector gets all 3 components. See really bad picture below.

left side is top down view, right is from the side. I have drawn both the force vectors and the decomposed ones with dashed lines.

 

Edit: image did not seem to work

No you don't. That doesn't work. The pulling is happening in a straight line between your center of self and the pulled object, rotating the center of self doesn't change the direction of the pull, it changes nothing. It still pulls the object to the same point in your body. Just like the rotation of the Earth doesn't change the point to which a satellite is attracted gravitationally.

Even if your center of self is making circles inside your body, it is still pulling the object straight towards it. You won't ever create a vector that would point outside of your body with this method. no matter where you place your center of self. You won't create a side force constantly acting on the object by changing where your center of self is located.

1 hour ago, Stormlightsong said:

I’m not saying you would use your finger to keep the momentum. You would just use it to start the speed.
 

I still think you’re right that the finger push would not give it enough speed to start an orbit, but if you had some sort of contraption, like a rail gun, that could give it the speed to complete several revolutions, you could get it into a pretty consistent orbit.

Yyyy, rail gun? Maybe. But why? 

1 hour ago, Nameless* said:

I'm a bit confused by the question. Are you asking if a lurcher could spin a piece of metal around themselves using A-iron? Because I can definitely see that working. For example, a very skilled Lurcher could probably spin a bullet around themselves a few times before air resistance slowed it or keep a lower speed orbit going by pulling metal towards themselves then moving out of the way.

Yes, by moving in circles and pulling in the right moment it could work. But that isn't really an orbit. 

[NameIess]

1 hour ago, alder24 said:

Yes, by moving in circles and pulling in the right moment it could work. But that isn't really an orbit. 

You could get it roughly circular, and orbit isn’t really anything other than falling in such a way that you miss whatever you’re circling anyways.

[Jn819]

Let's try to find some points of agreement.

If the Lurcher was already in orbit (or further) around the planet (in a space suit), we all agree that he could get something (that had the right velocity for the strength of his Ironpull) to orbit him, right?

Also, we have seen A-Iron used to start something moving and then release and step out of the way. I think that we all agree just doing that over and over does not count as an orbit, right? But it could be a method of imparting the necessary initial velocity (though you'd probably need to use a weaker constant Pull to maintain the orbit).

Also, we have all seen somebody swinging (something on) a rope around themselves, right? A lasso, a grappling hook, a yo-yo, or something. Look up a video of someone playing with a lasso if you don't know what I mean. I think something like this is what you were picturing when you said this, right?

18 hours ago, LimeJack said:

I was refering specifically to rotating the point you are pulling from inside your body. We know for a fact that you can do this with marsh and the gun. If you have the point you are pulling from be a few inches from your center of mass and you pull you get a vector that breaks down into the perpendicular and pulling that you wanted. If this point, within your body rotates at the same speed as the object you have both components you need. The anti gravity component can be canceled as well if the object is orbiting below your center of mass, so your pulling vector gets all 3 components.

The object being pulled (whether a lasso or the hypothetical metal target of the Lurcher's power) would hang below the point it's being pulled from due to gravity, and that point would have to revolve (not rotate) itself to maintain the velocity despite air resistance (the same way a cowboy's hand moves when swinging a lasso around).

Since the revolution of the pulling point can be much smaller in radius than the revolution of the target (or to put it another way, the subject does not move as far as the object), a Lurcher could definitely take sort of a wide spearman's stance and shift his weight (or do lunges) to keep something spinning around him.

I will say, even if you could pull from somewhere other than your center of self/Identity as Marsh seems to (though it's possible using his hands was more about showmanship than actually directing his powers), it would probably be easier to physically move whatever body part you're Pulling from than to constantly change which part of your body you Pull from.

It's a matter of semantics whether this would actually count as an "orbit" though.

Side note:

19 hours ago, Stormlightsong said:

You could also probably keep it in orbit by lessening your pull on it when it comes close and then strengthening it when it goes farther. To my knowledge this should cause an elliptical orbit.

Actually, an elliptical orbit involves exactly the opposite. It's just that the object is going slowest when it's furthest away and goes increasingly fast until its closest pass (aphelion, if I'm remembering the term correctly Edit: nope, perihelion). The closer it is to the object it's orbiting, the stronger the force of gravity will be.

Edited June 3, 2023 by Jn819
English error correction

[alder24]

14 hours ago, Nameless* said:

You could get it roughly circular, and orbit isn’t really anything other than falling in such a way that you miss whatever you’re circling anyways.

Circular, yes. But it's not orbiting you as you run in a circle (question is can you run in a circle fast enough to make that work). And the pull isn't applied constantly. Even without running (which now I think is what you meant), he waits for an object to get close to him, while it passes by pulls shortly on it, making it go behind him, pulls again, making it turn, and pulls to make it go in front of him. Basically pulling only when the object is making a turn. That's like a square with curvy tips. The force isn't applied consistently, it can't be because the distance between the lurcher and the object will keep getting shorter, and therefore that's not an orbit. 

3 minutes ago, Jn819 said:

If the Lurcher was already in orbit (or further) around the planet (in a space suit), we all agree that he could get something (that had the right velocity for the strength of his Ironpull) to orbit him, right?

No. He can't create a sideways velocity fast enough to make an orbit around him. And Earth's gravity will mess things up. And he can't move in space that easily. He can only pull things towards himself, nothing more.

5 minutes ago, Jn819 said:

Also, we have seen A-Iron used to start something moving and then release and step out of the way. I think that we all agree just doing that over and over does not count as an orbit, right? But it could be a method of imparting the necessary initial velocity (though you'd probably need to use a weaker constant Pull to maintain the orbit).

Right, kind of? Hard to say.

9 minutes ago, Jn819 said:

The object being pulled (whether a lasso or the hypothetical metal target of the Lurcher's power) would hang below the point it's being pulled from due to gravity, and that point would have to revolve (not rotate) itself to maintain the velocity despite air resistance (the same way a cowboy's hand moves when swinging a lasso around).

That's not the same. The center of self even if revolving won't make the force of A-pull change directions, while a cowboy's hand IS forcing the change of direction to the rope, by pointing always away from the center. Look how his hand is moving when making the circle, it leads the rope into a specific direction. Center of self won't be able to create that force in that direction as it always makes the force on the shortest route - it would just make the force vector turn a bit left or right, not resolving around you.

14 minutes ago, Jn819 said:

I will say, even if you could pull from somewhere other than your center of self/Identity as Marsh seems to (though it's possible using his hands was more about showmanship than actually directing his powers), it would probably be easier to physically move whatever body part you're Pulling from than to constantly change which part of your body you Pull from.

That's too short of a distance to make a difference like that. Changing your pull from your extended left hand to right hand will only create a mess of the path for the object that will constantly slow it down, and eventually make it go straight through your body, but unable to do so as it's too slow now. You would need to spin your whole body, extend your hand and pull the object towards your hand. But that's not an orbit, you're only creating one vector, you're just leading the object behind your hand in circles around you, while you spin.

 

 

To be fair, what is the point of it? The best thing a Lurcher can do is to step back and pull it stronger as it passes next to him, for it to make a half-circle and go straight back to the person that launched that object towards the Lurcher. Good for dealing with a gun fire. But that's it. He can't even pull some static object towards himself, make it gain enough speed to go around him and be launched into some distant opponent, as that object's greatest speed is in the moment just before he starts to curve it. That object would just drop short of the target (unless the target is far closer than the initial position of that static lurched object). But there is literally no point in making something orbit around the Lurcher, it’s only making him focus just on that and lose attention to the surroundings. 

[cometaryorbit]

I'd say ... probably not technically 100% impossible, but would require very precise initial conditions + exceptional skill.

An orbit is based on gravity pulling an initial perpendicular motion into a circle. You could use A-Iron to replace gravity - both are forces pulling directly toward the center of the planet/Allomancer ... but the object still needs the initial velocity.

For example, an arrow flying by, but not directly at, the Lurcher could be Pulled into a circle around the Lurcher in the same way an object flying by a planet could be pulled by gravity into an orbit.

However, this would take a pretty specific Pull strength, and precisely modifying Push/Pull strength is hard.

Also, actual gravity is still going to be pulling the arrow down. So you'd only get a few "orbits" unless the arrow is at exactly the right height that the angle upward of the Pull to the Lurcher's center counteracts the downward force of gravity (which would probably be something bizarre like an arrow at calf level).

It'd be easier, I think, if you had both Steel and Iron. Vin's horseshoe-flight trick is kind of similar to this. But Vin is also the only person ever who figured out that trick, in a thousand years of Mistborn, and Elend couldn't manage it even with Vin trying to teach it to him. Vin has exceptional intuition with Allomancy, probably due to her Connection to Preservation.

To do it with Iron alone... I don't think it's technically impossible, especially for a savant-level Lurcher who can move the center of Pulling around their body, but it'd take both ridiculous skill and very precise initial conditions - to the point that it'll probably never happen in practice.

Edited June 3, 2023 by cometaryorbit

[NameIess]

36 minutes ago, alder24 said:

Circular, yes. But it's not orbiting you as you run in a circle (question is can you run in a circle fast enough to make that work). And the pull isn't applied constantly. Even without running (which now I think is what you meant), he waits for an object to get close to him, while it passes by pulls shortly on it, making it go behind him, pulls again, making it turn, and pulls to make it go in front of him. Basically pulling only when the object is making a turn. That's like a square with curvy tips. The force isn't applied consistently, it can't be because the distance between the lurcher and the object will keep getting shorter, and therefore that's not an orbit. 

Whether or not it’s an orbit by the technical definition, it’s still possible to spin metal around oneself with A-iron.

Also, A-iron doesn’t have to pull towards center of self. Marsh pushed from his hands, so it’s safe to assume that a sufficiently skilled Lurcher should be able to pull from different parts of their body.

[Jn819]

38 minutes ago, alder24 said:

No. He can't create a sideways velocity fast enough to make an orbit around him.

What I said (in parentheses) could be rephrased as "assuming something had the right relative velocity somehow" and therefore this statement of yours qualifies as completely missing the point. My point is that we all agree Ironpulls are consistent enough that the force could hypothetically create an orbit. Right?

38 minutes ago, alder24 said:

And Earth's gravity will mess things up.

No, it wouldn't. Have you never seen video recorded on the International Space Station? If you're in the same orbit as another object (as everything inside the ISS is), Earth's gravity is no obstacle to making things move relative to you however you want. Yes, there would be some effect, but it would be negligible, insignificant, not an obstacle except in the very long term.

38 minutes ago, alder24 said:

And he can't move in space that easily.

You do have an imagination, right? Hypotheticals are about assuming certain things don't factor in so that you can better understand the influence of another factor. Maybe he has a jetpack. Maybe there's another, larger piece of metal nearby that he can Pull on. The point of such hypotheticals is that you are focused only on one factor and imagine there is a means to account for any others.

38 minutes ago, alder24 said:

That's not the same. The center of self even if revolving won't make the force of A-pull change directions, while a cowboy's hand IS forcing the change of direction to the rope, by pointing always away from the center. Look how his hand is moving when making the circle, it leads the rope into a specific direction. Center of self won't be able to create that force in that direction as it always makes the force on the shortest route - it would just make the force vector turn a bit left or right, not resolving around you.

That is not how it works. Grab a string, maybe tie something on the end of it, and try it yourself. (Heck, hold some wired earbuds in your hand and swing them around.) If anything, the force on the rope is making his hand change directions, not the other way around. You can hold your wrist and hand rigid and still make it work, it's just a waste of effort. The elbow and shoulder movements are what actually keep everything spinning.

38 minutes ago, alder24 said:

That's too short of a distance to make a difference like that. Changing your pull from your extended left hand to right hand will only create a mess of the path for the object that will constantly slow it down, and eventually make it go straight through your body, but unable to do so as it's too slow now. You would need to spin your whole body, extend your hand and pull the object towards your hand. But that's not an orbit, you're only creating one vector, you're just leading the object behind your hand in circles around you, while you spin.

Does a cowboy have to spin himself while swinging a lasso? No. Can Ironpulls be modulated such that the strength of the Pull is the same as the force of the rope on the object at its end? Yes. So if you could Pull from your hand, you could move your hand exactly the same way a cowboy does and make something spin around you exactly the way a lasso does. You do not seem to understand physics. Swing things around more until you do.

38 minutes ago, alder24 said:

To be fair, what is the point of it? The best thing a Lurcher can do is to step back and pull it stronger as it passes next to him, for it to make a half-circle and go straight back to the person that launched that object towards the Lurcher. Good for dealing with a gun fire. But that's it. He can't even pull some static object towards himself, make it gain enough speed to go around him and be launched into some distant opponent, as that object's greatest speed is in the moment just before he starts to curve it. That object would just drop short of the target (unless the target is far closer than the initial position of that static lurched object). But there is literally no point in making something orbit around the Lurcher, it’s only making him focus just on that and lose attention to the surroundings. 

Have you heard of a slingshot orbit? Nevermind, just consider a standard sling weapon. You use string and a pouch to accelerate a rock better than throwing it with your hand. A Lurcher might be able to achieve a similar increase in effectiveness by using a tactic that spins their metal around them.

45 minutes ago, cometaryorbit said:

I'd say ... probably not technically 100% impossible, but would require very precise initial conditions + exceptional skill.

An orbit is based on gravity pulling an initial perpendicular motion into a circle. You could use A-Iron to replace gravity - both are forces pulling directly toward the center of the planet/Allomancer ... but the object still needs the initial velocity.

For example, an arrow flying by, but not directly at, the Lurcher could be Pulled into a circle around the Lurcher in the same way an object flying by a planet could be pulled by gravity into an orbit.

However, this would take a pretty specific Pull strength, and precisely modifying Push/Pull strength is hard.

Also, actual gravity is still going to be pulling the arrow down. So you'd only get a few "orbits" unless the arrow is at exactly the right height that the angle upward of the Pull to the Lurcher's center counteracts the downward force of gravity (which would probably be something bizarre like an arrow at calf level).

It'd be easier, I think, if you had both Steel and Iron. Vin's horseshoe-flight trick is kind of similar to this. But Vin is also the only person ever who figured out that trick, in a thousand years of Mistborn, and Elend couldn't manage it even with Vin trying to teach it to him. Vin has exceptional intuition with Allomancy, probably due to her Connection to Preservation.

To do it with Iron alone... I don't think it's technically impossible, especially for a savant-level Lurcher who can move the center of Pulling around their body, but it'd take both ridiculous skill and very precise initial conditions - to the point that it'll probably never happen in practice.

It would definitely take lots of practice yes, but so does throwing a lasso or using a sling. I think it could make sense to have a Lurcher who has trained to do this, though it would probably be easier from a story perspective to just use a Coinshot to achieve similar results.

13 minutes ago, Nameless* said:

Whether or not it’s an orbit by the technical definition, it’s still possible to spin metal around oneself with A-iron.

Also, A-iron doesn’t have to pull towards center of self. Marsh pushed from his hands, so it’s safe to assume that a sufficiently skilled Lurcher should be able to pull from different parts of their body.

I think we agree, but I'm not confident that Marsh was actually using his hands to direct his powers. I think that might have just been showmanship and he Pulled the far end while Pushing the close end. Brandon is very fond of having unreliable narrators leave him enough wiggle room to decide on the exact mechanics later. More importantly, it might be about body parts having somewhat of a distinct Cognitive Identity. Kind of like how when Wax focuses on Entrone's safe, he can distinguish the different parts. The Lurcher in question might have to pull from his right shoulder blade, then his left shoulder blade, then his third rib, etc. as opposed to just picking a point somewhere within his body with nothing particular to distinguish that point. I think that even if that was possible, it might be easier to just move your body around the way a cowboy's hand moves while swinging a lasso.

[therunner]

1 hour ago, Jn819 said:

Does a cowboy have to spin himself while swinging a lasso? No. Can Ironpulls be modulated such that the strength of the Pull is the same as the force of the rope on the object at its end? Yes. So if you could Pull from your hand, you could move your hand exactly the same way a cowboy does and make something spin around you exactly the way a lasso does. You do not seem to understand physics. Swing things around more until you do.

That would not work at all.

Lasso works because there are two forces involved, one is the centripetal of the rotating object (counteracting the centrifugal force) and also tangential force accelerating the object along the 'orbit'. Both of these are transmitted through the rope.

However, A-Iron only pulls towards you, e.g. it can only replicate centrifugal force, not the tangential force.
Hence, A-Iron alone cannot help you force object to accelerate.

Edit: Better analogy is planet rotating around sun, in that case there is also only centripetal force. However, there the original velocity of the objects was already present when solar system formed.

Hence, at best if you were in vaccuum, the object already had some speed, you knew exactly what the speed is, and what distance you are, and you could modulate your Pulls with precision bordering on impossible, then yeah, you could do it.

But that is just 'catching' something into orbit, not putting it there using A-Iron.

And you can forget about doing it on the ground, there the object would simply fall, because A-iron could not counteract that. (Again, the rope does a lot of work).

1 hour ago, Jn819 said:

 You do not seem to understand physics. Swing things around more until you do.

You should consider physics a bit more before making statements like this.

Edited June 3, 2023 by therunner

[Jn819]

2 hours ago, therunner said:

That would not work at all.

Lasso works because there are two forces involved, one is the centripetal of the rotating object (counteracting the centrifugal force) and also tangential force accelerating the object along the 'orbit'. Both of these are transmitted through the rope.

However, A-Iron only pulls towards you, e.g. it can only replicate centrifugal force, not the tangential force.
Hence, A-Iron alone cannot help you force object to accelerate.

Edit: Better analogy is planet rotating around sun, in that case there is also only centripetal force. However, there the original velocity of the objects was already present when solar system formed.

Hence, at best if you were in vaccuum, the object already had some speed, you knew exactly what the speed is, and what distance you are, and you could modulate your Pulls with precision bordering on impossible, then yeah, you could do it.

But that is just 'catching' something into orbit, not putting it there using A-Iron.

And you can forget about doing it on the ground, there the object would simply fall, because A-iron could not counteract that. (Again, the rope does a lot of work).

You should consider physics a bit more before making statements like this.

You can't push something via a rope, they're only good for pulling. You create that tangential force by pulling the rope in a similar "orbit" (with a smaller radius) ahead of the end. You could do the same by moving your hand in a circular motion while pulling from it. Or, if you can't Pull from distinct body parts, you could do something like the motion of using a hula hoop to achieve the same effect.

You should consider how your chosen example works before you say it can't be imitated by swapping one piece out. A rope can only pull. A-Iron can only pull.

Edit: picture for clarity

Edited June 3, 2023 by Jn819
added picture

[therunner]

2 hours ago, Jn819 said:

You can't push something via a rope, they're only good for pulling. You create that tangential force by pulling the rope in a similar "orbit" (with a smaller radius) ahead of the end.

Yes, as you said, you create tangential force by pulling the rope and the rope then pulls the object at the end.
And neither of these are possible with A-Iron, since the Connection is only spiritual, not physical.

Quote

You could do the same by moving your hand in a circular motion while pulling from it. Or, if you can't Pull from distinct body parts, you could do something like the motion of using a hula hoop to achieve the same effect.

No.
The reason rope works is because the force is transferred along it, so the tangential motion can happen.
But there is no such analog in A-Iron.

If you motion with your hand, or move the pull to distinct body parts you are minutely changing the body part to which it is drawn, but there is no appreciable tangential acceleration to speak of.

Since you like ropes, it would be like if you would argue you can get object to orbit you when all you can do is drag the rope towards yourself. Because that is what A-Iron does.

2 hours ago, Jn819 said:

You should consider how your chosen example works before you say it can't be imitated by swapping one piece out. A rope can only pull. A-Iron can only pull.

I think it is you who should consider the chosen example actually works, instead of drawing on imprecise analogies.

Rope can create orbit because it can pull in the tangential direction. The rope does the pulling.

A-Iron cannot create orbit, because there is no metaphysical rope that could create pulling in tangential direction, only Misting themselves.

Edited June 3, 2023 by therunner

[Jn819]

2 minutes ago, therunner said:

Yes, as you said, you create tangential force by pulling the rope and the rope then pulls the object at the end.

And neither of these are possible with A-Iron, since the Connection is only spiritual, not physical.

I think it is you who should consider the chosen example actually works, instead of drawing on imprecise analogies.

Rope can create orbit because it can pull in the tangential direction. The rope does the pulling.

A-Iron cannot create orbit, because there is no metaphysical rope that could create pulling in tangential direction, only Misting themselves.

It's not a matter of whether there's a rope or a Spiritual Connection. It's a matter of how the source of the pull (or Pull) is moving relative to the object being pulled. You are acting as if Lurchers are statues incapable of moving while they burn their metal. Look at the diagram above. Imagine instead of having a hand holding the end of the rope on that inner circle, you have a Lurcher who's pulling an object on the outer circle. If the Lurcher moves the way the hand moves (as in, along that smaller circle), and Pulls with the strength the rope pulls, the force of their Pull can similarly be broken down into component vectors of centripetal force towards the center around which the Lurcher moves and tangential force perpendicular to that center. In fact, something like this (bigger in scale, though shorter in duration) happens in the books. Well of Ascension, Vin's fight against the koloss as she returns to Luthadel:

Spoiler

The skaa at the back of the square began to chant. It was a bizarre sound to hear in the middle of a battle. Sazed sat up, ignoring his pains and exhaustion as Vin jumped. The city gate suddenly lurched, its hinges twisting. The koloss had already beaten on it so hard....

The massive wooden portal burst free from the wall, Pulled by Vin. Such power, Sazed thought numbly. She must be Pulling on something behind herself--but, that would mean that poor Vin is being yanked between two weights as heavy as that gate.

And yet, she did it, lifting the gate door with a heave, Pulling it toward herself. The huge hardwood gate crashed through the koloss ranks, scattering bodies. Vin twisted expertly in the air, Pulling herself to the side, swinging the gate to the side as if it were tethered to her by a chain.

Is that enough to convince you?

[therunner]

16 minutes ago, Jn819 said:

In fact, something like this (bigger in scale, though shorter in duration) happens in the books. Well of Ascension, Vin's fight against the koloss as she returns to Luthadel:

  Reveal hidden contents

The skaa at the back of the square began to chant. It was a bizarre sound to hear in the middle of a battle. Sazed sat up, ignoring his pains and exhaustion as Vin jumped. The city gate suddenly lurched, its hinges twisting. The koloss had already beaten on it so hard....

The massive wooden portal burst free from the wall, Pulled by Vin. Such power, Sazed thought numbly. She must be Pulling on something behind herself--but, that would mean that poor Vin is being yanked between two weights as heavy as that gate.

And yet, she did it, lifting the gate door with a heave, Pulling it toward herself. The huge hardwood gate crashed through the koloss ranks, scattering bodies. Vin twisted expertly in the air, Pulling herself to the side, swinging the gate to the side as if it were tethered to her by a chain.

Is that enough to convince you?

No, because you are wrong.
All Vin did in that scene was Pull on gate, and Pull herself to the side (most likely dropping the Pull on gate at some point in the maneuvere) to dodge the gate that was hurtling at her.
Very different from getting object to orbit you.

16 minutes ago, Jn819 said:

It's not a matter of whether there's a rope or a Spiritual Connection.

Yes it quite literally is.
Again, A-Iron cannot generate tangential Force, nor can it transfer it. It is literally not what it does.
So from the start, rope is incredibly bad analogy.

16 minutes ago, Jn819 said:

 It's a matter of how the source of the pull (or Pull) is moving relative to the object being pulled.
 You are acting as if Lurchers are statues incapable of moving while they burn their metal.

Yes, I can move to the side, to get Pulled object to bank.
But I have to move about as fast as the object to get it to bank and not hit me.

16 minutes ago, Jn819 said:

Look at the diagram above. Imagine instead of having a hand holding the end of the rope on that inner circle, you have a Lurcher who's pulling an object on the outer circle. If the Lurcher moves the way the hand moves (as in, along that smaller circle), and Pulls with the strength the rope pulls, the force of their Pull can similarly be broken down into component vectors of centripetal force towards the center around which the Lurcher moves and tangential force perpendicular to that center.

Again no.
Your rope analogy is flawed at the core, so the diagram won't work as you imagine it to be. The only situation where it would make sense, is if the object was already moving, which I already said.

If the object is at rest, then it will simply fly towards you, because the centripetal force will be far larger, and the object has no centrifugal force that would be counteracting it (since it has no orbital momentum), no matter how you move your hands around.
 

Edited June 3, 2023 by therunner

[Jn819]

Just now, therunner said:

All Vin did in that scene was Pull on gate, and Pull herself to the side (most likely dropping the Pull on gate at some point in the maneuvere) to dodge the gate that was hurtling at her.

What part of "as if it was tethered to her by a chain" sounds like she stopped Pulling it as soon as it was moving?

2 minutes ago, therunner said:

Yes it quite literally is.
Again, A-Iron cannot generate tangential Force, nor can it transfer it. It is literally not what it does.
So from the start, rope is incredibly bad analogy.

Tangential force is not real. It's the component of the actual force being exerted on the object being swung. Any vector can be broken down into component vectors at right angles to each other; that's what the "centripetal force" and "tangential force" are, the vectors that add up to the total SINGLE real force being exerted. Do you think a rope transfers tangential force by being so stiff you can use it like a lever?! No! You just change where it's pulling from--exactly the way the hypothetical Lurcher either moves their hand (if they can Pull from just their hand, or themselves if not) around while Pulling on the object in question.

9 minutes ago, therunner said:

Yes, I can move to the side, to get Pulled object to bank.
But I have to move about as fast as the object to get it to bank and not hit me.

If your masses and the radii of your turns are similar, yes. If the ratio of the radii is more in line with the picture I posted a couple comments ago (presumably because you're Pulling with much more weight than it has), yes you still need to have the same period of revolution, but the radius is smaller, so your actual Cartesian velocity (not rotational speed) is much lower.

14 minutes ago, therunner said:

Again no.
Your rope analogy is flawed at the core, so the diagram won't work as you imagine it to be. The only situation where it would make sense, is if the object was already moving, which I already said.

I'm tired of your repeated failure to understand how well the analogy works, so if you respond with anything like this again, I will ignore it.

16 minutes ago, therunner said:

If the object is at rest, then it will simply fly towards you, because the centripetal force will be far larger, and the object has no centrifugal force that would be counteracting it (since it has no orbital momentum).

And then you move to the side while still pulling it and while its acceleration is always directly towards you, its velocity remains mostly tangential to the point you are moving around. This is how you bring something up to speed when you start swinging it around on some kind of tether. It begins moving towards your hand, you continue moving your hand ahead of it in a circle, it continues chasing your hand, your hand keeps going around the circle...

[therunner]

11 hours ago, Jn819 said:

What part of "as if it was tethered to her by a chain" sounds like she stopped Pulling it as soon as it was moving?

The part where it is told from external perspective, where we have no idea what she is pulling (or Pushing!) off of.
If someone described what Kelsier was doing in his last fight, people who argue that Mistborn are basically Magneto, but we had his internal monologues to see just how it was to pull it off, and required use of both steel and iron.

And that is why I think Vin was using both metals in that scene.

11 hours ago, Jn819 said:

Tangential force is not real. It's the component of the actual force being exerted on the object being swung. Any vector can be broken down into component vectors at right angles to each other; that's what the "centripetal force" and "tangential force" are, the vectors that add up to the total SINGLE real force being exerted.

What the hell are you talking about?

Like yes, any force can be broken down into components, but that does not mean tangential forces are not real?

Quote

Do you think a rope transfers tangential force by being so stiff you can use it like a lever?! No! You just change where it's pulling from--exactly the way the hypothetical Lurcher either moves their hand (if they can Pull from just their hand, or themselves if not) around while Pulling on the object in question.

Why do you think rope is taut once in air?  It is because the tension of the rope makes it serve as sort of lever.
I mean, when you are starting to rotate the rope, the objects is being dragged by the rope. You can literally try it at home.

You don't seem to understand physics very well.

Forget about rope for a second and look at gravity, which is much better analogue. There we have a central force (like in A-Iron) and it is quite well known that you cannot use such force to induce torque.

11 hours ago, Jn819 said:

If your masses and the radii of your turns are similar, yes. If the ratio of the radii is more in line with the picture I posted a couple comments ago (presumably because you're Pulling with much more weight than it has), yes you still need to have the same period of revolution, but the radius is smaller, so your actual Cartesian velocity (not rotational speed) is much lower.

That only works if the object is already moving, you simply cannot get it to start orbit you that way.
Additionally, your image implies that the object is being continuously accelerated, which is well, not the case.

11 hours ago, Jn819 said:

I'm tired of your repeated failure to understand how well the analogy works, so if you respond with anything like this again, I will ignore it.

Feel free, does not make you any more right.

11 hours ago, Jn819 said:

And then you move to the side while still pulling it and while its acceleration is always directly towards you, its velocity remains mostly tangential to the point you are moving around. This is how you bring something up to speed when you start swinging it around on some kind of tether. It begins moving towards your hand, you continue moving your hand ahead of it in a circle, it continues chasing your hand, your hand keeps going around the circle...

But there is no tether! How many times do I have to say it?
When you have tether you are never dragging the object close, which is exactly what you do with A-Iron. It simply does not work like you are saying.

I will try for the last time to explain why it won't work, using your image if you don't mind.

Alright, lets take you image then and analyze it then.
Assuming the circle in the middle represents hand span of grown human we can take it at about ~1 meter in radius. Then the trajectory has radius of circa 6 meters. So at any point in the trajectory, the tangential force will be 6x smaller than the force pulling the object towards the center.
If you just start a pull at ~10 Newtons, nothing too fancy, the object will hit you in ~1.1 seconds, and no amount of moving your hands about is going to change. So you have to move to the side. Why am I not considering the centrifugal force? Because it is too small to do anything, even after 1.1 seconds, the speed generated in the tangential direction is tiny. The centrifugal force generated through the movement would be only 0.2, far smaller than the attractive force you are using to drag the object towards yourself. Even taking it into consideration immediately, it would mean still you have to move at ~5 m/s or something like that.

So you have to move, specifically, you have to move in such a way that you maintain the distance to object as constant (or nearly so). So that immediately means you can get object to orbit you only if you are pulling at less than 20 Newtons (in plane) or so, because at that point you have to move yourself faster than humans can move (on their own).

In our scenario, you have to be moving at ~5.45 meters per second. The issue of course is that when you move, it will change what is the centrifugal and what is tangential, in ideal scenario you moved in such a way that the original centrifugal direction is now tangential. You also have to modulate your pulls somehow, but lets not get into that.

Now, how fast would the object have to be moving for the image to work?
Well, we know that v^2/r = F. So if you are pulling at measly 10 Newtons, the object has to be moving at ~7.8 meters per second.

Which is my entire point, you can use A-Iron to sort of catch an object that is already moving and capture it for orbit. But you cannot induce an orbit.

And all of the above still neglects gravity, which would complicate things further (again, the rope does a lot of work). Since we are assuming that the Misting has hands apart to get as much tangential force as possible (for some reason, since as I outlined that part is basically negligible), that means they are ~1.5 meters above ground level. (for simplicity)
Part of the pull force has to be counteracting gravity, so right off the bat, Misting must pull more forcibly than 10 Newtons, because 10 Newtons is force of gravity alone.
Assuming the object will be orbiting at ground level, and  keeping  the 6 meter distance, we get that Misting must be pulling at ~24 Newtons only to overcome gravity, leaving 14 Newtons in plane for all the other stuff. You can make the plane force smaller, by bringing the object closer, but then you are losing on the already small tangential acceleration.

So, the way you suggested simply won't work, moving hands around is not enough, you have to be basically running/sprinting to get it to the orbit.
Of course, the issue is that compared to my simplified approach, the A-Iron force always points towards you, so to get enough tangential acceleration, you have to be moving even faster.

Edit:

To summarize (TL;DR):

You have 2 problems, how to overcome gravity and how to accelerate the object tangentially to yourself.
Overcoming gravity requires pull of minimum of ~20 Newtons, when the object is at certain distance from you, and you must always pull from a point higher then the plane of orbit. The closer the distance between the plane and the point of pull, the greater the pull force must be.

The second issue is more problematic, because unless the object is very close (i.e. closer than circa 1 meter), then the tangential component will be always far smaller than the gravitational component and the centrifugal component. Hence you can achieve it only when the object is close. However, there you run into the issue that because of the gravity, the force of pull is quite large, and so the tangential speed is going to be faster than you can react most likely. And if it is that close, you would have to rotate your entire body to achieve the desired effect, rotating as fast as the object you are trying to pull like this (which @alder24 already pointed out).

So no, rope analogy does not work, because rope is actively dragging the object (that is what is accelerating the object). You cannot create such effect with A-Iron, due to the fact there is only one central force being applied (whereas in the rope case there are two independent forces, the tension of the rope creating centripetal effect and the force generated by movement of the hand which creates the rotational component, A-Iron mimics only the first part not the second).

You could in principle create tangential component large enough by extending your hands, and having the object very close (sub 1 meter), and the rotating yourself at equal speed. However, due to the fact that the pull has certain minimal strength due to needing to overcome gravity as well, you would have to be rotating at quite large speeds, which makes it problematic.

For distances greater than 1 meter, the forces will be roughly F_grav > F_centri > F_tan, so the tangential component will always be smaller (and usually much smaller). For distance smaller than 1 meter it will be F_grav > F_tan > F_centri, however due to geometry of the situation the only way you get orbit is if the Misting starts spinning with outstretched hands, just as fast as the orbit is. You also have to balance tangential component against the centripetal component such that the object is accelerated only to the speeds which can be counteracted by the centripetal force, which is now quite small.

Edited June 4, 2023 by therunner

[cometaryorbit]

Yeah, the object has to already be moving for some reason other than F-Iron.

But once it is, the analogy to gravity capturing an object in initially linear motion (say, a rocket firing horizontally above the atmosphere) into an orbit works perfectly. Both gravity and an Ironpull are forces that pull toward the center of the relevant object (planet/Lurcher).

If the Lurcher is on Scadrial's surface rather than in open space far from planets, though, the planet's own gravity will make this tricky enough that it requires both very precise & unusual initial conditions + exceptional (possibly savant level) skill.

Vin was able to use her own motion to get an effect sort of like this because she had both Steel and Iron, but even then, it took exceptional ability.