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How to create a black hole using Feruchemy


Thmrgnd

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EDIT: There are NO spoilers ahead for any book.

So i have an idea: is it possible to create a black hole using the Feruchemical ability to store weight?

First of all i am no physicist, and all my calculation my be incorrect, so feedback is appreciated.

storing weight in iron is something a feruchemist do all the time and it's said that it changes his density when tapping the iron - not his strength though it affects it.
and what is a black hole if not a really REALLY dense point in space?
Could a skimmer store enough weight to use it all in one second and make himself so dense that even the light can't escape his gravitational force?


there are standards to black holes - according to wikipedia - some are huge, some are even micro.
Assuming a skimmer who is 1.80 meters and 80kg, is storing 99% of his weight, we could, after a bit more than a whopping quadrillion years (1,000,000,000,000,000) use all that weight in a second to make himself dense as a large black hole.
But we don't really need a whole second isn't it? we can do it in half a second' or a tenth, or a planck second: the shortest time possible in the universe.
This actually shortens the storing time to less than a second!
That's not even considering compounding...

Sanderson once said that increasing weight affects the Higgs field, which is essentially gravity.
The only problem I see is that they will need to empty the reserves in the shortest time possible according to science,
and by what i have read i don't see any indication to the speed of which you can tap into a metalmind.

In conclusion, any skimmer can destroy Scadrial without breaking a sweat.
If you want more calculations, or see something wrong please say so.
Thank you for coming to my ted talk.

TLDR; skimmer OP must nerf quick.

 

Edited by Thmrgnd
explained that there are no spoilers
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You are ignoring that Metal Minds have a waste of energy as you increase the amount of the attribute you use at one time. In addition to that, Composition would require you to burn more and more metal and faster.
I don't see this happening with a human, you would probably need a mechanical form of Compouding and a source of Alomatic Investiture that does not need to be consumed internally. Something like White Mists in abundance.
And I doubt that this is nerfed. It is something really interesting to allow mini black holes to be created technologically for some applications as a weapon or source of energy.

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Definitely not any Skimmer, since they have the normal limitations on how much they can store at any given time, and limited lifespans, etc.  A true Twinborn Iron Compounder might have a better shot, especially if they team up with a Nicroburst. There are still quantifiable limitations to how much can be stored in a given sample of metal for both Feruchemy and Hemalurgy, so I dont know where the numbers would actually fall out, or how close to the full Black-hole critical mass a human body could reach before it dies and cant perform the magic anymore, dissipating the effect.   

By Era4 I wouldnt be surprised to see that somebody will have tried to pull something like it off with the more Mechanical Allomancy we're supposed to get.  

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I don't see a reason why this wouldn't work. Like you said, if they tap it as in a very short amount of time, they would not need to have much "weight" stored to achieve this. However, having a black hole exist for only a Planck time isn't going to do very much. There will also be very odd effects, as Brandon has said that tapping iron increases your strength just enough that your weight doesn't crush you. The amount your strength would have to increase at the levels you are suggesting is massive though, and that is an understatement. It would be like trying to keep something from falling into a black hole... while inside the event horizon. In order to figure out how effective this is, we would have to figure out how long someone could make a black hole last for given a lot of iron, a lot of time to store, and compounding.

Really this hinges on whether the things in Feruchemy that are said to have no limit really do have a limit. If your mass has to increase gradually, and if your strength doesn't really go up enough to keep you alive at those levels, that could solve the problem.

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Thanks for the answers!

3 hours ago, Raphaborn said:

You are ignoring that Metal Minds have a waste of energy as you increase the amount of the attribute you use at one time. In addition to that, Composition would require you to burn more and more metal and faster.
I don't see this happening with a human, you would probably need a mechanical form of Compouding and a source of Alomatic Investiture that does not need to be consumed internally. Something like White Mists in abundance.
And I doubt that this is nerfed. It is something really interesting to allow mini black holes to be created technologically for some applications as a weapon or source of energy.

I didn't know that metal minds have a limitation or waste of energy cuz of all the end-positive deal but nevertheless i hope this will turn up one way or another.

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4 hours ago, Thmrgnd said:

Thanks for the answers!

I didn't know that metal minds have a limitation or waste of energy cuz of all the end-positive deal but nevertheless i hope this will turn up one way or another.

Sporkify

This is more towards the whole physics stuff, but is Feruchemy really balanced? If it gives diminishing returns, wouldn't this end up as a net loss of power?

Brandon Sanderson

It doesn't diminish. Or, well, it does—but only if you compound it. You get 1 for 1 back, but compounding the power requires an expenditure of the power itself. For instance, if you are weak for one hour, you can gain the lost strength for one hour. But that's not really that much strength. After all, you probably weren't as weak as zero people during that time. So if you want to be as strong as two men, you couldn't do it for a full hour. You'd have to spend some energy to compound, then spend the compounded energy itself.

In more mathematical terms, let's say you spend one hour at 50% strength. You could then spend one hour at 150% strength, or perhaps 25 min at 200% strength, or maybe 10min at 250% strength. Each increment is harder, and therefore 'strains' you more and burns your energy more quickly. And since most Feruchemists don't store at 50% strength, but instead at something like 80% strength (it feels like much more when they do it, but you can't really push the body to that much forced weakness without risking death) you can burn through a few day's strength in a very short time if you aren't careful.

Footnote: This question was asked when fueling Feruchemy with Allomancy had only been seen in Rashek. As such, the term compounding is used purely to reference tapping at a higher rate than can be stored.
Hero of Ages Q&A - Time Waster's Guide (Oct. 15, 2008)
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@Thmrgnd sorry to burst everyone's bubble, but that's not how F-iron works. Wax specifically notes how it doesn't make him denser (no more bullet resistant). The language on the coppermind is contradictory, but I'd go with the actual book.

Frankly, I'm not sure Brandon even solid on how it works.

Quote

Seonid

I noticed that you-- Was that a retcon on the way iron Feruchemy works?

Brandon Sanderson

What do you mean?

Seonid

There's a researcher who talks to Wax, asking him about whether he's changing his mass of whether he's changing whether the planet perceives him-- affecting his gravity.

Brandon Sanderson

Right. It's more a re-- Defining something I didn't pin down strongly enough. I wouldn't call it a retcon because it's something that nobody really did until Wax, really, in the series. The only one really capable of doing that in the original trilogy would have been the Lord Ruler, maybe some of the Inquisitors, but we don't have viewpoints from them. So I wouldn't call it a retcon I would just say it’s something that didn't come up in the first series that now I have to make sure is clear.

Seonid

So is it Higgs field stuff going on?

Brandon Sanderson

Yeah. Mmhmm.

Seonid

My idea was right.

Brandon Sanderson

Mmhmm.

Bands of Mourning release party (Jan. 25, 2016)

 

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5 hours ago, Raphaborn said:

Sporkify

This is more towards the whole physics stuff, but is Feruchemy really balanced? If it gives diminishing returns, wouldn't this end up as a net loss of power?

Brandon Sanderson

It doesn't diminish. Or, well, it does—but only if you compound it. You get 1 for 1 back, but compounding the power requires an expenditure of the power itself. For instance, if you are weak for one hour, you can gain the lost strength for one hour. But that's not really that much strength. After all, you probably weren't as weak as zero people during that time. So if you want to be as strong as two men, you couldn't do it for a full hour. You'd have to spend some energy to compound, then spend the compounded energy itself.

In more mathematical terms, let's say you spend one hour at 50% strength. You could then spend one hour at 150% strength, or perhaps 25 min at 200% strength, or maybe 10min at 250% strength. Each increment is harder, and therefore 'strains' you more and burns your energy more quickly. And since most Feruchemists don't store at 50% strength, but instead at something like 80% strength (it feels like much more when they do it, but you can't really push the body to that much forced weakness without risking death) you can burn through a few day's strength in a very short time if you aren't careful.

Footnote: This question was asked when fueling Feruchemy with Allomancy had only been seen in Rashek. As such, the term compounding is used purely to reference tapping at a higher rate than can be stored.
Hero of Ages Q&A - Time Waster's Guide (Oct. 15, 2008)

I did calculate that - the poor feruchemist would have to spend time as 1% of his weight. And a planck second is so short that you can potentially become really dense.

4 hours ago, Elsecaller_17.5 said:

@Thmrgnd sorry to burst everyone's bubble, but that's not how F-iron works. Wax specifically notes how it doesn't make him denser (no more bullet resistant). The language on the coppermind is contradictory, but I'd go with the actual book.

Frankly, I'm not sure Brandon even solid on how it works.

 

Yeah thats exactly the quote i read that convinced me it was possible. After the superaonic boom Marasi created accidentally and that woman who asked Wax about momentum and redshift my hopes got up... Guess we will see it some day....and maybe FTL travel will be possible using the same method with compounding :)

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14 hours ago, Thmrgnd said:

So i have an idea: is it possible to create a black hole using the Feruchemical ability to store weight?

First of all, from steel pushings we are pretty sure it is mass, not weight. So they are not manipulating gravity acting on them. Not that anybody vocally disagreed, but sometimes you need to establish the basics.

Quote

Could a skimmer store enough weight to use it all in one second and make himself so dense that even the light can't escape his gravitational force?

Provided his gravity changes at all. There is no evidence for or against that.

Quote


there are standards to black holes - according to wikipedia - some are huge, some are even micro.
Assuming a skimmer who is 1.80 meters and 80kg, is storing 99% of his weight, we could, after a bit more than a whopping quadrillion years (1,000,000,000,000,000) use all that weight in a second to make himself dense as a large black hole.

I really doubt that they get denser. You'd suffer an instant lethal hard attack if you got much denser. The cube/square law would strike and your heart would be unable to move your blood. Iron feruchemy seems to split up mass. You have a mass with respect to the external world in terms of acceleration and another mass with respect to yourself and for other effects.

 

Edited by Oltux72
typo
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I would agree, but I found this, so now I only mostly agree:

Quote

Argent

We know that you can't Lash people in Shardplate, but can you Lash the person inside the Plate? If they had their helm off, for example. At that point Plate should be just dead weight, right? 

Brandon Sanderson

There's a bit of an interference envelope. Wearing plate, the person has this big ball of investiture around them, and so pushing any through it--even by touching a person without a helm--is going to be tough. Easier than with the helm on though, I suppose.

Investiture acts (roughly) like a saturated solution in these cases. Sticking more power into something like a Feruchemical storage or a hyper-invested object like Plate is increasingly hard. The other part is that Investiture tends to interfere with other Investiture, unless there's a familiar resonance. (This is part of what philosophers call Identity.) Slapping your hand through a sand master's stream of sand will cause interference, and make them start to drop. It's not that the sand is supporting them, it's that the investiture holding them up gets scrambled for a moment because of your own investiture.

Investiture pushed toward someone inside a hyper-invested (supersaturated) system like a person in Shardplate is going to get hard push-back.

This is similar to the reason that it's harder to Push on invested coins. Depends on how invested they are, in that case. It's generally not as hard as doing something like Lashing a person in plate. (This is more about the interference than the saturation of investiture.) But the two principles are what I use to guide the physics in these areas.

quietandproud

Can we take that as a hint that the Investiture in the Plates and the Investiture that the Surge of [Adhesion] uses come from different Shards? Or do they interfere because they "belong" to different spren?

Brandon Sanderson

You know, I should have realized this one would bring out the follow up questions. Let's leave it at what I posted for now. This is a deep, deep rabbit hole, and I do need to try to get some more writing done tonight. So...RAFO. (Sorry.)

Stormlight Three Update #4 (Nov. 2, 2016)

So you can't fill one metalmind enough to become a black hole, but filling tons... Do we know if you can empty multiple of the same metalmind at the same time? I think we do, but can someone confirm? (haven't read mistborn in a while)

So if you put weight into multiple metalminds at once, and took all of the weight from the tons of metalminds, then, theoretically, you could become a black hole

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8 minutes ago, GoWibble said:

I would agree, but I found this, so now I only mostly agree:

So you can't fill one metalmind enough to become a black hole, but filling tons... Do we know if you can empty multiple of the same metalmind at the same time? I think we do, but can someone confirm? (haven't read mistborn in a while)

So if you put weight into multiple metalminds at once, and took all of the weight from the tons of metalminds, then, theoretically, you could become a black hole

See, you are missing my last calculation: if you can use 100% of your body weight in a planck second (which is 1.911X10^-43), you can get a density of a normal, existing black hole.

If you use it in a whole second you will need to store billions and billions of tons - not very practical. Will this black hole survive more? Idk thats more of a physics issue.

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Just now, Thmrgnd said:

See, you are missing my last calculation: if you can use 100% of your body weight in a planck second (which is 1.911X10^-43), you can get a density of a normal, existing black hole.

If you use it in a whole second you will need to store billions and billions of tons - not very practical. Will this black hole survive more? Idk thats more of a physics issue.

No, I see what you said, just to do it, you are going to need to fill and drain a whole ton of metalminds to do that. It is more of a scenario problem than a physics one because you have to be connected enough to all of the metalminds to drain them all. 

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18 hours ago, Elsecaller_17.5 said:

@Thmrgnd sorry to burst everyone's bubble, but that's not how F-iron works. Wax specifically notes how it doesn't make him denser (no more bullet resistant). The language on the coppermind is contradictory, but I'd go with the actual book.

When Wax says this, he presumably means that it doesn't increase how much matter he is made up of, which goes along with how Brandon says that it just changes interactions with the Higgs field. Going at close to light speed works the same way. The amount of matter packed into each unit volume doesn't change, but your mass--and therefore density--does change. The idea that density has to do with how much matter is packed into something often works, but does not at relativistic speeds or for f-iron. Wax was making a common mistake in using the word "density" that way.

13 hours ago, Oltux72 said:

Provided his gravity changes at all. There is no evidence for or against that.

The evidence is that that is the way mass works. Everything has a gravitational field, and things with more mass have stronger gravity. If the force of gravity on a skimmer didn't change, their gravitational acceleration would change, but Wax specifically notes that he falls at the same "speed." Since things with more mass have greater inertia, they take more force to accelerate the same amount as a smaller thing. It is a common misconception that the force of gravity is the same for different objects; gravitational acceleration doesn't depend on mass, but the force of gravity does. If Wax's gravity stayed the same, he would accelerate less while tapping his metalmind.

13 hours ago, Oltux72 said:

I really doubt that they get denser. You'd suffer an instant lethal hard attack if you got much denser.

They do get denser, but the amount of matter they are made up of does not increase. It can be kind of complicated, but if you want to know more on how that works, research a little about the Higgs field. You don't need to get into any of the more complex parts of it, but the general idea behind it is good to know.

13 hours ago, Oltux72 said:

The cube/square law would strike

The cube/square law has to do more with large things, not things with a lot of mass. 

Edited by ChickenLiberty
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16 minutes ago, Elsecaller_17.5 said:

Explain this like I'm stupid, please (physics is not my thing).

When you go close to the speed of light you get more massive(sort of) and your volume also decreases(sort of) but you don't really get more dense the way physisists talk about density. 

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11 hours ago, ChickenLiberty said:

When Wax says this, he presumably means that it doesn't increase how much matter he is made up of, which goes along with how Brandon says that it just changes interactions with the Higgs field. Going at close to light speed works the same way. The amount of matter packed into each unit volume doesn't change, but your mass--and therefore density--does change.

No. The density does specifically not change. That would have observable effects. In particular it would make them bullet proof. That they would notice. Any object entering your body needs to move aside the part of your body that is within its path. The energy needed to do that is proportional to the mass, hence in a given volume density, of the part of the object that is entered.

11 hours ago, ChickenLiberty said:

The idea that density has to do with how much matter is packed into something often works, but does not at relativistic speeds or for f-iron. Wax was making a common mistake in using the word "density" that way.

The evidence is that that is the way mass works.

That is the way mass works while not under the influence of feruchemy. It cannot be used to conclude that it behaves the same way under altered circumstances. That would be circular reasoning. You need to do it the way Khriss does. You look for observable differences.

11 hours ago, ChickenLiberty said:

Everything has a gravitational field, and things with more mass have stronger gravity. If the force of gravity on a skimmer didn't change, their gravitational acceleration would change, but Wax specifically notes that he falls at the same "speed."

If he really were more massive he would fall faster. Normally that effect is tiny. But we are talking about a black hole here.

11 hours ago, ChickenLiberty said:

Since things with more mass have greater inertia, they take more force to accelerate the same amount as a smaller thing.

Well, here things get complicated. Wax is in free fall. He does show an effect while allomantic acceleration acts upon him. Hence the forces behave differently depending on their source.

11 hours ago, ChickenLiberty said:

It is a common misconception that the force of gravity is the same for different objects; gravitational acceleration doesn't depend on mass, but the force of gravity does. If Wax's gravity stayed the same, he would accelerate less while tapping his metalmind.

That depends on whether you define gravity as an acceleration or a force. Usually these are equivalent descriptions. No longer with feruchemy becoming active.

11 hours ago, ChickenLiberty said:

They do get denser, but the amount of matter they are made up of does not increase. It can be kind of complicated, but if you want to know more on how that works, research a little about the Higgs field. You don't need to get into any of the more complex parts of it, but the general idea behind it is good to know.

I am afraid it won't explain everything, in particular why your heart can still pump much denser blood, why your bones don't splinter, but you still cannot punch through concrete walls.

11 hours ago, ChickenLiberty said:

The cube/square law has to do more with large things, not things with a lot of mass. 

Not really. You need to counter increased mass, while volume increases much slower. In case of feruchemy it does not increase at all, while mass does increase. Your heart should stop.
 

Now, which experiments can we run? We could observe radioactive decay in a feruchemist. In particular beta+  - decay. Where is the annihilation line?

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@oltux72 @ChickenLiberty 

So i have read about the higgs field and gravitation forces in general, and apparently almost all of any particle mass comes from the energy of the bond between the quarks - the strong nuclear force...

This got me thinking that maybe tapping an iron metalmind doesn't make you magically more dense (pun intended), it makes the bond stronger - more energy and therefore more mass, all thanks to e=mc^2.

Too good to be true?

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12 minutes ago, Thmrgnd said:

@oltux72 @ChickenLiberty 

So i have read about the higgs field and gravitation forces in general, and apparently almost all of any particle mass comes from the energy of the bond between the quarks - the strong nuclear force...

This got me thinking that maybe tapping an iron metalmind doesn't make you magically more dense (pun intended), it makes the bond stronger - more energy and therefore more mass, all thanks to e=mc^2.

Too good to be true?

The problem is that it would produce side effects that would be immediately observable (death of the feruchemist), hence they would need to be worked around.

So you can become denser by adding more atoms or by making each atom heavier. So far so good. Mechanically on a macro level the difference is unobservable. The most obvious example is that your blood would become x times denser if you become x times heavier. Your heart needs to become x times stronger. But then why does your blood pressure not go up x times and you start bleeding into your lungs? And so on.

Hence it looks to me like some weird relativity like stuff is going on. You get heavier to an external observer but not to yourself. But even that is not the full truth. A Feruchemist feels lighter when storing. Wax should have broken most of his bones when he tapped the metal mind to break through the floor. So tapping and storing must be different. It is not sufficient for you to simply get stronger muscles. At some point your skin will rip free.

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5 hours ago, Oltux72 said:

That is the way mass works while not under the influence of feruchemy. It cannot be used to conclude that it behaves the same way under altered circumstances. That would be circular reasoning. You need to do it the way Khriss does. You look for observable differences.

If he really were more massive he would fall faster. Normally that effect is tiny. But we are talking about a black hole here.

Well, here things get complicated. Wax is in free fall. He does show an effect while allomantic acceleration acts upon him. Hence the forces behave differently depending on their source.

That depends on whether you define gravity as an acceleration or a force. Usually these are equivalent descriptions. No longer with feruchemy becoming active.

Acceleration and force due to gravity are completely different. The force of gravity is directly proportional to the mass of either object. That is what weight is. If you have two objects on a planet, and one is twice as massive as the other, that one will be twice as heavy, as the force of gravity between it and the planet would be twice as large. For the acceleration however, it is different. "F=ma" can be rewritten as "a=F/m." If the force stayed the same, but the mass increased, acceleration would decrease. Wax is shown to fall with the same acceleration, regardless of his mass, barring the effects of drag. For Wax's acceleration to stay the same, the force of gravity between him and the planet would have to change with his mass. Since his gravitational acceleration is observed to stay the same, we can conclude that his feruchemical mass is still subject to the increase in gravitational force. The claim that more massive things fall faster is incorrect in free fall. With air involved, the greater inertia of a massive object allows it to fall faster, as the air pushing on it cannot affect it as much, but in true free fall, the mass of the falling object doesn't matter at all for gravitational acceleration. It is not that the effect is "tiny." There is no effect.  A black hole would still have the same acceleration.

5 hours ago, Oltux72 said:

I am afraid it won't explain everything, in particular why your heart can still pump much denser blood, why your bones don't splinter, but you still cannot punch through concrete walls.

This would be correct, but Brandon has said that the feruchemy will increase your strength just enough to keep you alive, which doesn't nessecarily mean just your muscle strength. It is accounting for those things as well.

5 hours ago, Oltux72 said:

No. The density does specifically not change. That would have observable effects. In particular it would make them bullet proof. That they would notice. Any object entering your body needs to move aside the part of your body that is within its path. The energy needed to do that is proportional to the mass, hence in a given volume density, of the part of the object that is entered.

This is where we get into the weirdness of feruchemical iron, as this would normally be true, but we know that his mass is changing due to what I explained above and because of the increase in velocity Wax experiences when decreasing his feruchemical "weight." In order for these things to happen, either density or volume would have to increase. Since Wax does not double in size when he doubles his "weight," his density must be increasing. The fact that bullets are not affected by Wax's increased mass is a known problem with iron feruchemy, and I do not have a explanation for it. We can only assume that it has to do with realmatic effects. It is likely something Brandon put in just to make it less powerful, like how there is no redshift from speed bubbles.

Edit: I may have been unclear when explaining how the acceleration does not change for more massive objects. To clarify: the more massive object's acceleration would be the same, but the planet's acceleration would be greater. 

I also have a possible realmatic explanation for the bullet penetration. It could be that once a bullet enters Wax's view of "himself," its mass also increases. This explanation does have the issue of how the bullet would decrease in velocity, and thus kinetic energy, which would affect the penetration. The realmatic effect that allows this to happen is probably similar to, but not exactly what I described because of that issue.

Edited by ChickenLiberty
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1 hour ago, Oltux72 said:

So you can become denser by adding more atoms or by making each atom heavier. So far so good. Mechanically on a macro level the difference is unobservable. The most obvious example is that your blood would become x times denser if you become x times heavier. Your heart needs to become x times stronger. But then why does your blood pressure not go up x times and you start bleeding into your lungs? And so on.

We already know that tapping iron doesn't make Wax denser because bullets still kill him, so adding more atoms can't be the solution.

 

1 hour ago, Oltux72 said:

Wax should have broken most of his bones when he tapped the metal mind to break through the floor

Why? Its not like he ran into a wall, he was standing on a spot that couldn't take his weight.

 

I don't see the problem in my comment about the steong nuclear force, but an alternative can be that he is vibrating extremly fast, and speed= mass in the really high numbers (this one im half guessing cause im really no physicist). Vibrating won't make him bulletproof, but i dont see how stoping the vibration mid air will make him go faster.

Actually i don't really know how dropping mass mid air will make you go faster so if anyone can explain in simple terms i will thank him...

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4 minutes ago, Thmrgnd said:

Actually i don't really know how dropping mass mid air will make you go faster so if anyone can explain in simple terms i will thank him...

Momentum is mass*velocity. If there are no losses due to heat or similar things, momentum in a system is conserved, staying the same. If your mass is halved, in order for your momentum to stay the same, your velocity would have to double. This only works if the mass that is "dropped" is removed from the system. If the mass was literally dropped, the same effect would not happen, since the total mass of the entire system would still be the same.

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3 hours ago, ChickenLiberty said:

Acceleration and force due to gravity are completely different. The force of gravity is directly proportional to the mass of either object. That is what weight is.

Well, weight needs an object to rest again. Hence you are weightless while in orbit. You can add centrifugal force, if you wish.

3 hours ago, ChickenLiberty said:

 

If you have two objects on a planet, and one is twice as massive as the other, that one will be twice as heavy, as the force of gravity between it and the planet would be twice as large. For the acceleration however, it is different. "F=ma" can be rewritten as "a=F/m." If the force stayed the same, but the mass increased, acceleration would decrease. Wax is shown to fall with the same acceleration, regardless of his mass, barring the effects of drag. For Wax's acceleration to stay the same, the force of gravity between him and the planet would have to change with his mass.

 

F = G * (m1 + m2)/ r^2
Usually we neglect m2. In case of a macroscopic black hole, that is no longer a valid approximation.

3 hours ago, ChickenLiberty said:

This would be correct, but Brandon has said that the feruchemy will increase your strength just enough to keep you alive, which doesn't nessecarily mean just your muscle strength. It is accounting for those things as well.

Then he would turn deaf. His altered eardrums would need to be stronger not to rupture under their own weight. Yet if they are that massive and that strong, the now ultrathin air will not make them vibrate. This is just one of the many contradictions we could come up with.

A feruchemist tapping iron is truly two things at once. Heavy to the outside world, unchanged to himself.

1 hour ago, Thmrgnd said:

Why? Its not like he ran into a wall, he was standing on a spot that couldn't take his weight.

A spot that could carry a piano, a safe or many other kinds of furniture. If that breaks, so will human leg bones. Conclusion:  his mass with respect to the floor is not the same as with respect to himself.

1 hour ago, ChickenLiberty said:

Momentum is mass*velocity. If there are no losses due to heat or similar things, momentum in a system is conserved, staying the same. If your mass is halved, in order for your momentum to stay the same, your velocity would have to double.

Velocity with respect to what? That is the problem with all these conclusions. Himself? Scadrial? Scadrial's sun? A galactic core?

 

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10 minutes ago, Oltux72 said:

Well, weight needs an object to rest again. Hence you are weightless while in orbit. You can add centrifugal force, if you wish.

Weight is the force of gravity. You still have weight in orbit, you just can't perceive it, as in free fall you do not have a normal force acting on you, where on the ground, you can feel weight because it and the ground are squeezing you.

15 minutes ago, Oltux72 said:

F = G * (m1 + m2)/ r^2

This is incorrect, and it is also not acceleration. The equation that you are referring to is "F = G*m1*m2/ r^2."

21 minutes ago, Oltux72 said:

Usually we neglect m2. In case of a macroscopic black hole, that is no longer a valid approximation.

m2 does not get neglected. If you neglected m2, that would mean that everything on Earth would be pulled by gravity with the same force. If that was true, everything would weigh the same, and massive objects would fall slowly, as they have more inertia. This is not the case. Something twice as massive is pulled on twice as much by gravity, but it accelerates the same amount.

Picture this scenario (with everything having arbitrary units):

There are two objects, one with mass 1000, one with mass 1. The force of gravity between the two is 1000. Both objects will be accelerating towards the center of mass. The larger object has an acceleration of 1, and the smaller object has an acceleration of 1000.

If instead, the smaller object had a mass of 2, the force of gravity between the objects would be 2000. Both objects will be accelerating towards the center of mass. The larger object has an acceleration of 2, and the smaller object has an acceleration of 1000.

The acceleration of the object that changed mass stayed the same, but the force of gravity between both is twice as much.

48 minutes ago, Oltux72 said:

A feruchemist tapping iron is truly two things at once. Heavy to the outside world, unchanged to himself.

That is a possible realmatic explanation for some things, such as the problem with bullet penetration. Only, we do know for sure that his strength changes in some way to counteract the extra weight.

24 minutes ago, Oltux72 said:

Velocity with respect to what? That is the problem with all these conclusions. Himself? Scadrial? Scadrial's sun? A galactic core?

I assume the reference frame in this case works the same as the reference frame for speed bubbles.

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The black hole that will be created will be gone in a blink. Because black holes can be so small, they will just move between the particles in the planet, and because of hawking radiation it would die out very quickly. They'd need to actually make a black hole of some size in order for it to do anything, and as noted in the post, that will take unrealistic amounts of time and metal.

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8 hours ago, Gderu said:

The black hole that will be created will be gone in a blink. Because black holes can be so small, they will just move between the particles in the planet, and because of hawking radiation it would die out very quickly. They'd need to actually make a black hole of some size in order for it to do anything, and as noted in the post, that will take unrealistic amounts of time and metal.

Well, if you go by such considerations ...
The feruchemist is made mostly from carbon, oxygen, hydrogen and nitrogen. These elements can all release energy by fusion. Long before the feruchemist is dense enough to form an event horizon, the atoms of his body will be attracted to each other strongly enough to overcome electrostatic barriers. He will turn into a thermonuclear bomb.

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