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The open secret that steelpushing makes no sense.


LazarusLong

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The physics of steelpushing and ironpulling are inconsistent and make absolutely no sense. And I'm not being a turbo nerd complaining about how magic doesn't exist in the real world so allomancy is nonsense. For steelpushing to work as described in the Mistborn Trilogy there must be some major fundamental differences between Scadrial and baseline reality.

The root of the problem is that the weight of the object you're steelpushing against shouldn't affect the force against you. Let's examine how steelpushing would work in baseline reality:

#1. You're a Coinshot standing on the ground and there's a metal coin beneath you. You steelpush on the coin with the same amount of force as you weigh (yes allomancers typically don't have the skill to be that precise with their force exerted, but let's assume you have more precision than Zane). That force will counteract the force of gravity and if you jump into the air or raise your legs you should begin to float over the coin.

#2. Now you're in the same situation as before, but you're standing at the edge of a massive cliff. You drop the coin off the cliff step over it and being steelpushing with the same amount of force. You will still begin to float! You won't even be able to tell when the coin stops falling and hits the bottom of the cliff. It'll all feel the same to you.

While the first situation plays out how it would in Scadrial you'll notice that #2 runs counter to every single described instance of its kind in the Mistborn Trilogy. You can flip to a random page in The Final Empire and you'll probably read a section where Vin is pushing against a coin but then suddenly thrown back/up/forward when the coin connects with a wall/floor. This is described as a natural consequence of the force of her push colliding with something that's pretty massive, but unless Sanderson means something unintuitive when he says the "force of her push" this is just an incorrect description.

I would like to state for the record that this doesn't affect my enjoyment of the series nor do I think it reflects poorly on Sanderson's writing. I do however think that Sanderson could forego the attempts to cling to baseline reality which in this case fall flat.

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We've gone turbo nerd to address this very same problem over here in this thread: 

To make a long story short, I view the force of a Steelpush as indirectly proportional to the relative velocity. Same way you can't push as hard on light objects, you also can't push as hard on fast objects. That reconciled all the screwy stuff, last I checked.

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On 8/17/2018 at 10:37 PM, LazarusLong said:

The root of the problem is that the weight of the object you're steelpushing against shouldn't affect the force against you. Let's examine how steelpushing would work in baseline reality:

#1. You're a Coinshot standing on the ground and there's a metal coin beneath you. You steelpush on the coin with the same amount of force as you weigh (yes allomancers typically don't have the skill to be that precise with their force exerted, but let's assume you have more precision than Zane). That force will counteract the force of gravity and if you jump into the air or raise your legs you should begin to float over the coin.

#2. Now you're in the same situation as before, but you're standing at the edge of a massive cliff. You drop the coin off the cliff step over it and being steelpushing with the same amount of force. You will still begin to float! You won't even be able to tell when the coin stops falling and hits the bottom of the cliff. It'll all feel the same to you.

I think you have a problem in your "baseline reality" (which is a pretty strange term to use when discussing magic).  It's pretty clear from the books that Allomantic force is dependent on distance.  So in your #2 scenario, it would only be identical to scenario #1 (floating) for the instant when the coin was at ground level.  However, as soon as the coin starts to get farther away from the Allomancer, the force will decrease because the objects are getting farther apart.  

There's tons of discussion about the mechanics of steelpushing (the thread Pagerunner linked is the main one, but there are others, including this cool one about someone coding up a video game), and nobody has come up with a perfect, intuitive explanation.  My mental picture is a combination of a Cognitively-linked, explosion-like conservation of momentum to determine the distribution and an inverse-square law determination of total energy input into the system.  

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Guy who's coding up the video game here. My idea was that pushing on a coin (or any metal, really) is in some ways similar physically pushing on the coin from a distance with a long pole. If you push on an anchored coin with a long pole, your force pushes on the pole, which pushes on the coin, which pushes on the ground. The coin doesn't enter the ground, meaning the ground must push back on the coin to counter the Push. This resistance pushes on the coin, which pushes back on the pole, which pushes back on you, giving you an extra boost to your Pushes on anchors.

If you pushed on a freely-falling coin, you don't experience the same resistance that you would from pushing on a coin on the ground. Picture yourself jabbing at the air beneath you with a pole, as opposed to solidly pushing on the ground.

Regardless of if that's true, we're very confident that pushes get weaker with distance, so pushing on an anchored coin that stays relatively close to you will always provide stronger pushes over time than a coin that shoots far away from you very quickly.

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1 hour ago, Artemos said:

My idea was that pushing on a coin (or any metal, really) is in some ways similar physically pushing on the coin from a distance with a long pole. If you push on an anchored coin with a long pole, your force pushes on the pole, which pushes on the coin, which pushes on the ground. The coin doesn't enter the ground, meaning the ground must push back on the coin to counter the Push. This resistance pushes on the coin, which pushes back on the pole, which pushes back on you, giving you an extra boost to your Pushes on anchors.

Considering the abrupt difference in force applied to the allomancer when a pushed object hits the ground (or anything else really) I don't see how it's possible for this to not be the case. 

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42 minutes ago, Fully_Invested said:

@Artemos that's exactly how I'd pictured it... Why then the confusion? Are we oversimplifying?

No, but there are other theories as to why anchored pushes are stronger. One is that the push gets weaker the faster your object is moving. At any given moment, if the metal is completely stationary, your push is strongest. If the target is instead flying away from you with a high speed, it'll be weaker. It's a valid theory, and the books never fully prove or disprove it. There's not as much "confusion" as there are multiple possible explanations.

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On 8/20/2018 at 10:06 AM, Artemos said:

Guy who's coding up the video game here. My idea was that pushing on a coin (or any metal, really) is in some ways similar physically pushing on the coin from a distance with a long pole. If you push on an anchored coin with a long pole, your force pushes on the pole, which pushes on the coin, which pushes on the ground. The coin doesn't enter the ground, meaning the ground must push back on the coin to counter the Push. This resistance pushes on the coin, which pushes back on the pole, which pushes back on you, giving you an extra boost to your Pushes on anchors.

If you pushed on a freely-falling coin, you don't experience the same resistance that you would from pushing on a coin on the ground. Picture yourself jabbing at the air beneath you with a pole, as opposed to solidly pushing on the ground.

Regardless of if that's true, we're very confident that pushes get weaker with distance, so pushing on an anchored coin that stays relatively close to you will always provide stronger pushes over time than a coin that shoots far away from you very quickly.

I think that your explanation is right on point. Our best evidence comes from the Bands of Mourning. Near the end I remember there is a scene where Wax Steel pushes himself into the sky using the Bands. What I remember is he describes that the effort required to balance himself so high without the Bands would have required more effort and multiple coins. This would mean that the OG MIsborn would have had stronger and longer "poles" to use when pushing on metals. The potency of their "pole" decreased as time went on through the generations. 

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On 8/17/2018 at 10:44 PM, Pagerunner said:

We've gone turbo nerd to address this very same problem over here in this thread: 

To make a long story short, I view the force of a Steelpush as indirectly proportional to the relative velocity. Same way you can't push as hard on light objects, you also can't push as hard on fast objects. That reconciled all the screwy stuff, last I checked.

My question has always been, say you have an Allomancer using clips to bound over an open field. They're arcing, right? When approaching the next clip, how come it never skids when they push on it? 

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Friction.

It's the same reason pushing on anything keeps it from moving. With a low enough angle, the clip would indeed start to skid, but friction keeps it in place otherwise. Taking your example of an open field, the clips would likely never move at all - they'd dig pretty into the ground from the initial push, like a nail or stake, depending on its orientation. It would take a lot to get a coin to skid across dirt and grass.

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1 hour ago, Artemos said:

Friction.

It's the same reason pushing on anything keeps it from moving. With a low enough angle, the clip would indeed start to skid, but friction keeps it in place otherwise. Taking your example of an open field, the clips would likely never move at all - they'd dig pretty into the ground from the initial push, like a nail or stake, depending on its orientation. It would take a lot to get a coin to skid across dirt and grass.

Fair point, but does that still hold considering everything is covered in ash? Cobblestone would be more dangerous, wouldn't it? Or would the friction again hold it in place?

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38 minutes ago, Naurock said:

Fair point, but does that still hold considering everything is covered in ash? Cobblestone would be more dangerous, wouldn't it? Or would the friction again hold it in place?

I don't imagine the ash would make the ground much more slippery. Rough stone still has pretty strong friction, and the coins could easily get caught in the cracks between the tiled cobbles - and if a coin's stuck against the cracks in the street, the ash won't make much of a difference.

Also, think about how much the allomancer is pushing down on the coin. To be flying upwards, they have to be pushing with a downward force at least greater than their weight, usually more. That's a lot of downwards force and a lot of friction.

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4 hours ago, Fully_Invested said:

@Artemos that's exactly how I'd pictured it... Why then the confusion? Are we oversimplifying?

I think we can all agree that steelpushes are supposed to be intuitive, like pushing with your arms but farther away. The trick comes in some very specific cases, where the differences between steelpushes and your body become more evident. If you physically grab a coin, push it through the air towards a wall, you won't move until you hit the wall and essentially push against the wall and can push harder. Right?

At least, that's what it seems like. But that's not exactly what happens. Try this experiment at home: stand with your back towards a wall, heels against the wall, shoulder blades lightly touching the wall. Put your hands right in front of your chest (you can hold a coin in each, for thematic reasons), and then throw your arms forward as fast as you can. (Kind of like a boxer throwing two punches at the same time.) As long as you're only using the muscles in your arms (don't put your back into it), you'll feel your shoulders push against the wall behind you - the force you're exerting on the coins is negligible compared to the force required to make your arms move, and that force moves your body. You just don't usually notice it, because your body is moving anyways to flail your arms around. Your body doesn't move a lot because your arms quickly reach full extension, and there's very little time to exert that force if it's just your hands moving.

If you push the coin against a wall, there's no discontinuity of force on your body. You're already exerting enough force to move your body just from moving your arms, but the force balance changes with the addition of the normal force of the wall, so your muscles can exert (the same) force on your body for a longer period of time. The wall doesn't let you push harder - it lets you push for a longer time. That may not be how it feels, especially when our bodies are doing subconscious adjustments all the time. (We don't think "arms, push with 15 lbs of force," the same way you don't focus on how to place your feet when you're walking.)

But that model is expressly opposite to what's described in steelpushing. Vin sets how hard she's pushing, and there is an abrupt discontinuity in force when the coin hits a wall. It's not Vin unconsciously modulating her push; it's something that happens due to physics, not unconscious response. That's why we're trying to develop a mechanism that can respond to that, which will by necessity depend on the velocity of the coin. Something that can be mathematically proscriptive with all the different scenarios we see in steelpushing.

2 hours ago, Naurock said:

My question has always been, say you have an Allomancer using clips to bound over an open field. They're arcing, right? When approaching the next clip, how come it never skids when they push on it? 

I can believe that would happen in some cases, but as stated already, it would depend on the terrain and how long the Allomancer kept their force applied. Do they keep pushing all the way until they drop their next coin, like how you always have one foot on the ground while you're walking? Or is it a quick burst to launch yourself into the air, like how you sometimes have no feet on the ground when you're running? The latter would minimize the time they're pushing at larger angles, so that could mitigate the effect

Are there any specific instances in the book that make you question the angles? (Aside from the time Wax pushed Marasi's notebook to the bottom of a table. Unless he was sitting real low on the table, I don't know how he was basically able to push that direction. From what it seems to me, he was pushing towards himself. So I can't help you out with that one.)

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