# Possible weaknesses of a vector manipulator

In this world everyone has superhuman abilities and multiple abilities are a thing although it's rare to see more than 2. Some abilities are also more common than others like creating fire or ice is more common than summoning spirits. Knowing that, our main character has a rather unique ability. He can manipulate vectors to a certain extent.

When he comes into contact with an object he can steal the object's vectors and store them, and he can also visualize all vectors associated with that object and steal those as well. He can then use this stored energy to apply vectors on objects in any direction and any velocity (limited by the energy he has stored).

Example He can stand in front of a moving train and by touching it he can immediately stop the train and every person and object inside it (negating inertia) and storing all the energy from the vectors (he would also have to kill the engine but you get the point)

There's also pretty interesting things he can do with his ability like negating a bit of gravity and storing energy passively while making him lighter, or negating more so he can jump high.

Now my problem with this ability is that I can't find a lot of weaknesses apart from isolating him in vacuum so the question is, what other weaknesses would this ability have?

Note This ability only steals vectors related to movement. If you want to, you can think of it as stealing kinetic energy. It's just that it wouldn't go well with his visualization.

• The use of 'vector' here was sufficiently strange to make me question whether I understood the term at all, so I looked it up again and realized that a 'vector' is a description of (for example) motion. So, if the vector is stolen, do we simply lose the ability to describe the object's motion, but it keeps moving? Because otherwise he's just changing the object's vector by making its magnitude zero. – Frostfyre Feb 9 '17 at 17:37
• @Frostfyre This anime character was probably the inspiration. Maybe this helps in clarifying things. – Sec SE - clear Monica's name Feb 9 '17 at 17:42
• "steal the objects vectors"?! Vector is just a set of three* numbers, what's there to steal? Could you clarify, rewrite it using real world names of things instead of names used in your world? Velocity, speed, momentum, things like that? – Mołot Feb 9 '17 at 20:47
• "stealing an object's vectors and storing them" is precisely as meaningful as "stealing an object's numbers and storing them". – user253751 Feb 9 '17 at 23:23
• It looks like Mr Vector can manipulate & store kinetic & potential energy (the train & gravity respectively). Suggest editing your question to say something like that, there will be less confusion. – a4android Feb 10 '17 at 0:35

### Gas him, drown him, electrocute him, set him on fire.

You're thinking in terms of applied violence which is his strength. Use things that aren't his strengths against him.

• Wire his doorknob to the mains
• Drop a toaster in the bath
• Barricade his front door, pour petrol through the letterbox and set it on fire
• Sabotage his boiler so he dies of carbon monoxide poisoning in the night
• Tie his shoelaces together
• Mock him until he runs away crying
• Put laxatives in his tea

If you confront him in the street to have a fist fight, you're not going to win, but he's apparently otherwise still an ordinary mortal.

Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life. - Jingo, Terry Pratchett

• "Put laxatives in his tea?" My god, you're an animal!!! :) – CaM Feb 10 '17 at 14:44
• theoretically, vector manipulation could overcome electricity, by manipulating its vectors. – Ryan Feb 10 '17 at 16:26
• @Ryan, true yes, but generally one doesn't know one has a mains powered doorknob until it's too late for such considerations – Separatrix Feb 10 '17 at 16:52

A few potential weaknesses that come to mind:

Battery capacity He has a finite capacity to store this kinetic energy. What happens if he has to stop something that overloads that capacity? Does it injure him, or explode outward in random ways or other sorts of potentially bad backlash? What if the battery is empty? Does he feel that as a something like hypoglycemia, where he has trouble focusing or acting until he's absorbed some energy?

Heat 1.0 In the real world, temperature is a measure of kinetic energy at an atomic level, IIRC from high school science classes. Therefore, the more kinetic energy your mage takes from an object, the colder that object becomes. Flash-freezing a train full of people will not win friends and influence people. Therefore, he'd have to be careful how he used his powers around living things. Perhaps this issue only triggers if the delta between starting vector and final vector is above some arbitrary amount, so stopping a slow-moving train cools the interior a bit and maybe fogs the glass, but stopping a bullet train at full speed is more like a quick dip in liquid CO2 or worse, liquid N2. The reverse would be true for adding vector energy: more energy means more heat.

Heat 2.0 Or maybe all that temperature delta gets transferred to the mage instead of the object. So if he takes on too much motion, he gets a fever. So there's the limit to his battery: he could stop a bullet train at full speed, but that much energy would literally cook his brain. Releasing the energy would also cool him off, so speeding that bullet train from dead stop to full speed might cause deadly hypothermia.

Concentration You say he's aware of all the vectors. How much concentration does that take? Can he easily concentrate on slowing a stroller rolling down the hill? Is it harder to mentally juggle all the vectors involved in stopping that train and all the people and cargo on board? Maybe that's his weakness at larger scales: he simply can't "do the math" fast enough for something that big. Or maybe he tries to stop that train, but fails to stop that one person asleep in the back who is now going to ram into a completely immovable seat with a great deal of force. Or do more complex sets of vectors take longer to manipulate safely? Maybe he has to start stopping the train with the last car, then work his way forward so each car helps brake the others forward of it, otherwise the whole train will pancake into a messy pile of scrap iron and people-goo?

Micro Control Does he have highly refined control of this power? If not, he might accidentally steal biological vectors. This could induce blood clots or interrupt their breathing, or halt the various enzymes and other molecules moving around inside a living being that, well, are life. Or halt the air flowing into a person...

Macro control if he forgets in a moment of panic, he could accidentally (or perhaps not so accidentally) negate the vectors imparted at a macro level. Suddenly your victim is not moving. But the Earth still is. At the equator, that's over 1,000 mph. Imagine Bob standing on the street you stop him, and quite literally the world smacks into him at that speed -- a building, a parked car, a tree... at these speeds, it doesn't much matter). Or worse, the earth orbits the sun at about 67,000 mph. So now Bob is either ripped off the earth in a blur of motion, or pancaked into a micro-thin puddle as the earth tears into or away from Bob. Or at an even worse scale, the solar system moves through the galaxy at about 515,000 mph. (speeds from space.com) Taking away THOSE vectors would be... bad.

• Wouldn't stopping a train actually make it hotter instead of colder? As in converting the kinetic energy into heat? – Eleshar Feb 9 '17 at 21:12
• I suggested colder because all of that movement is gone; movement generates friction which translates to heat. (you slow down molecules, they get colder). But yes, the opposite effect could easily be explained, too, as a conversion from kinetic to heat. – CaM Feb 9 '17 at 21:18
• There would be a limit to how much he can store but he wouldn't suffer from it. The energy would just disappear if he couldn't store it. Also I would say stopping a train full of people would be the limit of his concentration. – user31746 Feb 10 '17 at 9:57

To Aru Majutsu no Index is an anime series that has a character who has that ability, nicknamed Accelerator. Conveniently, thanks to some training, he also had a computer like brain ability so he could passively deflect even sniper rifle bullets to the back, and once even reprogrammed a computer virus.

He however had 3 weaknesses (4 if you count the main protagonists power to negate any and all supernatural phenomenon) They are revealed throughout the series and/or in the Light novel.

1) While he could reflect punches when they hit him, he was weak to the One inch punch style of attack after it hit him. The fist gently landing on his body meant it would not deflect, but would otherwise be a soft touch. Then the attacker would punch after contact had been made, resulting in a lot of force. He was so skilled he could punch, pull the punch, softly touch Accelerator, and then resume the punch, in what appeared like a regular punch, and Accelerator would take the hit like a regular punch.

2) He was unable to manipulate vectors of material and matter that did not work like regular matter. Another person with the superpower to control dark matter could use it to conventionally attack, and its naturally abnormal physics made its vectors nearly impossible to manipulate. He may have been able to figure it out eventually, but I do not know that. Regardless, since the material did not work like he would have expected it to, he was unable to calculate is vectors and manipulate them.

3) The power was only activated through conscious effect. Even the Sniper bullet to the back was consciously reflected, by a passive reflex he had trained. He had a limited capacity to calculate, but it was generally significantly more than enough computational power. However, when he was reprogramming the computer virus in someones brain, he used all of his power to do so, and was unable to use his power for anything else, completely vulnerable to any normal attack during the time. Indeed, he was shot in the head, and the bullet went partly through his brain before he finished and reflected the bullet. He suffered brain damage, and was severely weakened. With their "my phone is more powerful than your supercomputer" (an actual quote in the series, reworded a bit) level technology, they had a way to work around this brain damage, but when the device ran out of battery, he was unable to even speak, let alone use his superpower.

• He had another weakness, suffocation, changing vectors doesn't help if their is not oxygen in the air around you. – John Feb 9 '17 at 19:21
• @John Agreed, though that is true of pretty much everyone, and only specific powers that allow you to not need to breathe, or generate oxygen are the only ways around that, so its kind of a given. He could probably at least somewhat counter a Vacuum and prevent it from sucking his air away though. so you would be hard pressed to get him in such an enviroment – Ryan Feb 9 '17 at 19:24
• If he needs contact then he can only affect the very small number of molecules on the area, so he can hold the air in his lungs which is just like holding your breath, a burning building would be just as deadly to him as anyone else, the oxygen hasn't moved it has been consumed. he would have similar problems with airborne gases. fill the air with halon or serin he can push all the air away from his lungs and suffocate or keep breathing the invisible unknown gas. – John Feb 9 '17 at 19:59
• @John If your going to keep on spouting weaknesses, just make your own answer. You dont need to bog down the comment section with your ideas which are unrelated to my answer. – Ryan Feb 9 '17 at 20:18

As far as I can see he has a lot of weaknesses:

• His only strengths are against big bulky slow attacks like hitting him with a steam-roller and then he has to be prepared.
• He can only change the vector whilst he is in contact with the object so has to have very quick reflexes to stop anything moving fast.
• Shooting him would be easy unless he can spot the bullet, know exactly when it will hit him and time it just right to activate his power.

If you want to give him super reflexes:

• Hit him in the dark.
• Hit him when he's asleep.
• Sleeping gas, then hit him.
• Whilst he is under the effects of sleeping gas you could tie him up.
• Tying him up will mean he has no vector to negate unless he wants the rope to pass through his body....sound rather messy.
• Burn him (he can't stop all the molecules at once)
• Freeze him.
• Acid.
• Poison gas.

The lists go on but unless you're giving him super reflexes he only has limited actual uses for his power.

## A point to consider with his limits: Storing energy increases your mass

The stock physics equation sci-fi turns to is: $E=mc^{2}$, or rather, in this case $m=E/c^{2}$. So you'll probably realise $c^{2}$ is pretty big ($9\times 10^{16}$) and so he can take rather a lot of energy before he starts to feel it ($9 \times 10^{16}J$ before he gains a kilogram). This limit, therefore, only comes into play if we're considering large amounts of energy.

Now you're probably thinking: "Pft, no problem, my guy can just counter the effects of that gravity so his bones won't get crushed" Sure...and store that energy in himself? This results in a vicious cycle of constantly gaining more mass to resist gravity and then needing to store more energy.

• Your TeX is messed up: x is a variable not the multiplication sign. – JDługosz Feb 10 '17 at 7:14

There’s a limitation due to a complication that people are avoiding noticing. Kinetic energy and momentum are two different things. The OP talks about vectors and setting the length to zero, but the “energy” (kinetic energy) is a scalar value, not a vector value at all. The linear momentum, on the other hand, is a vector quantity.

Consider the example of two billard balls colliding. As a model of perfect collisions there is a unique solution to how the balls roll, because only that maintain (the total of) both quantities. It is limited in the sense that one ball can’t just convey an arbitrary amount of kinetic energy to the other.

Second, momentum vectors can combine from different directions to cancel out. The idea of storing and then calling up does not work as you suppose. Let’s say he pulls out 50 units of momentum pointing North. If he had near 0 to start with, then now he has 50 units pointing South left over. So really he can conjur up any momentum at any time and what’s left in his internal account is just for satisfying the physicists that momentum is globally conserved, and has no observational purpose otherwise.

If you want otherwise, then you need to impose a limit on what he can store. But note again how vector subtraction works: It is a limit only if he wants to produce momentum in the direction opposite his current store, and he can reset that by producing momentum in another direction.

In other words, his ability to not show any recoil will be limited. If he wants to keep throwing stuff “that way” then he needs to balance it out with throwing stuff in the opposite direction too. Or just wait 12 hours in the case of due east or west!

Now his internal kinetic energy store can behave in a more straigtforward manner, since it’s a scalar and not a vector. He needs a positive stored value to draw down, to make his power work, and it’s depleted when it dropps to zero. In this account, direction does not matter.

So how does he recharge that? Shouldn’t stopping an object consume kinetic energy from his store too, rather than replenishing it (like regenerative breaking)?.

Now that you understand the need for two separate accounts of stored physical properties (one vector, one scalar), we come to the real, interesting, limitation.

To manipulate objects of various masses, he needs to use both values in a controlled manner. First, you might consider limitations of his control or of the underlying ability to transfer the values. This happens in real life when a hammer bounces back rather than delivering all its momentum and energy with the blow. If his power works “like a hammer” at the point on the object he decides, it may bounce back some of the momentum. This limits how fast he can affect the object, based on its composition and physical properties. It might also, like with using a hammer, hurt and tire him.

So, a large mass covered with padding may be impossible to push rapidly enough to change the situation in his favor.

Using the hammer analogy and confining application to the surface, it is easy to explain difficulties and limitations in manipulating objects.

Second, the momentum and kenetic energy accounts are separately limited in what he can store. This means that objects that exceed one or the other would be a problem. A small, fast object will exceed his kinetic energy store, and he’ll have to shed it by throwing other objects away, until he runs out of other close-at-hand objects or runs out of time.

A huge slow object will overwhelm his momentum store, which he’ll have to shed by throwing something else in the same direction. But it’s providing far less kinetic energy, in proportion, so he’ll not have energy enough to shed the momentum by throwing small items. He will be crushed.

Finally, back to the hammer analogy. If he delivers the dose of energy and momentum off center, it will impart a rotation to the object being controlled. And angular momentum is not among his powers. So he will feel a torque recoil from this, and set himself spinning.

What happens if you bounce a spinning ball? If the transfer is not instantaneous and behaves in a similar way, the adversary could throw spinning objects his way, and applying his power to them will cause the change to be other than what he intended — and as discussed earlier, this will hurt and tire him. And, he will be unable to help getting some of the spinning transferred to himself during the moment he applies his power.

With the specifics in mind, other problems can be thought of. Can he stop water? No, because a hammer blow at the surface would not transfer to the bulk. Likewise, could he affect a pile of loose sand or stop millions of separate small grains from moving towards him?

• This is exactly the kind of answer I intended to start writing. I would add some things or phrase them differently: physics laws still apply. Momentum and energy cannot disappear. So (1) any energy he 'dissipates' has to go somewhere. Suppose he radiates it away as heat, just assume (as in the real world) that he cannot do so instantaneosuly and would thus overheat if he overuses his powers. Continued... – user3106 Feb 10 '17 at 13:53
• And (2) any momentum (lineair or angular) he 'dissipates' will have to go somewhere - either by exactly balancing out magnitude and direction of several impulses he absorbs, or by letting his body move. Even if he had the magical power to 'store' momentum temporarily, he has to 'vent it off'. Again, there is no circumventing laws of nature. – user3106 Feb 10 '17 at 13:54

Let's call your hero Vector Thief.

You need another superhero with the ability to steal mountain climbers. He sneaks up on the climbers and makes them disappear, teleported to another mountain. This other hero just needs to walk around Vector Thief... Vector Thief will be forever trapped inside that circle. Why? Because Vector Thief can never cross Scalar Thief!

• Well, this is more of a comment than an answer... – PatJ Feb 10 '17 at 7:18
• More of a comment, but I appreciate the terrible maths pun. – Joe Bloggs Feb 10 '17 at 7:39

He seems to store this energy which in turn needs to have a storage limit. Otherwise he can walk around and stop everything moving store it up and send some massive mass fast enough that he could pretty much blow up the core of the planet. Maybe there is a limit to how much of this absorption his body can take and reached a limit that made his body turn into pure energy and burst.

Maybe his weakness is someone else's ability. Since his power has the ability to steal motion and then make objects move, why not have a character that... influences space-time or someone who influences gravity? If he can steal velocity, then someone who can use gravity can add gravitational force to the object thus deadening the vector applied. If he wants to get rid of the gravity vector applied, he would have to steal the vector which would cause the object to stop on a dime as well and the 2 would cancel each other out until fatigue and or help came.

With Space-time, you can alter the time and space around him. if he tries to steal energy, you can revert his being back 10 seconds to before he stole the energy but only effecting himself so that anything he stopped stays stopped and thus not allowing him to steal any vector energy.

I'll discard the notion of a storage limit. For energy conservation sake we could say he store the energy by turning it into radiation that is send via wormhole to another existence realm / pocket dimension / similar. I'll just not bother with it.

I'll also discard the notion of visualization, because reasons.

Power Interpretation

Only in contact

So, there is a flux limit for his power. He can only take vectors from thing he is contact with, so his body is a bottle neck for how much he can take simultaneously.

When stopping a large solid object such a car or the aforementioned train, he is taking the vectors of the material with which he is contact with, since the train keeps pushing he keeps taking... this could put the train to stop in his tracks, but it is not stopping the engine, and any object in the train (which are beyond his touch) will still be affected by inertia.

When stopping a liquid, remember that he is only taking from what he is touching... so he could - for example - calm water by touching it, but it will only be a growing volume in his immediacy. He will not calm the ocean... immediately, that may take ages.

Relativity

I'm taking that he can only take vector relative to himself. So, he will not stop the planet, for example, because he is moving with the planet.

Flying Speedster

He can store a fraction of gravity, and we can assume he is doing this all the time. This causes gravity to affect him less, making him lighter... this does not only means that it takes less energy to propel him forward (allowing him to reach higher speeds) but also that he can use that energy to gain a huge acceleration.

He could even use his power to absorb the damage of the sudden acceleration, and to absorb the movement of air around him reducing air resistance and negating air friction.

There is no reason why he can't use similar techniques to apply anti-gravity.

Super-strength and durability

He can use his power to apply speed vectors to objects, throwing them away as if he were super strong. Also hitting him won't help because he can absorb that too.

In fact, since he can absorb gravity partially, he will be able to reduce a strong gravitational field to a normal one; in fact, by the same principia he could survive spaghettification.

Defeating him

Note on healing: For practical purposes, his healing is normal. Under the assumption that he doesn't have the fine control to repair tissues, he won't be using his powers to heal. So damage done, is damage done... you need to do damage by non-mechanical ways, so think about chemicals and drugs. Of course the problem is to get those into his body.

Note on freezing: On the idea of freezing him (which admittedly is a common power), this will put him in a situation where there is little to absorb... sadly he has been absorbing gravity, and he can use that energy to break the ice.

Note on putting him on a vacuum: How do you create the vacuum anyway? He can stop air from going away. Also, he can fly. The only variant of this that is viable is to throw him to outer space… but you can’t throw him.

He has one big weak point: His mind. In particular if his power requires concentration. Also heightened reflexes are not part of his power... if his power is at least partially voluntary, you can take him down when he is not aware, for example when he sleeps. You may also try sneak attacks or deprive his senses. Furthermore if there are psychic powers that's game over.

Alternatively, there could be powers that use forces outside his reach. Any non-corporeal power could be effective. For instance... can you touch spirits? If no, then perhaps summoning spirits to attack him is viable (I don't know how that works).

Finally, nothing has been said about massless particles. Could he stop light? I believe this is beyond the reach of his power, so attacks based on light could be effective. This means that light / shadow based powers should be able to do damage.

Does anybody have laser cannon? If it can't burn him, it can at least make him blind.

I will borrow from your kinetic energy note, as using vector in this case would allow for confusion with regards to the nature of vectors also including direction (which affects the addition/multiplication of vectors).

Kinetic Energy is defined in physics as being equal to 1/2 the product of the mass (kg) and the square of the speed (m/s) and is given in units of joules. Your character must store this energy, which means his actions are limited by A) Amount of energy currently stored and B) The Mass of objects available to impart this energy to.

For example, assuming his current store is 0 J and he robs a .357 bullet of its kinetic energy, he will now have approximately 780 J of energy in store. If he wishes, he could simply impart this energy on the same bullet for a similar affect as if it were fired from a gun. If, however, he only had a more massive object to use such as bowling ball, the result would be much different. Assuming the bowling has a mass of roughly 6 kg, the velocity of this ball once imparted with 780 J would be 16.12 m/s or 36.5 mph. This is merely twice the average speed of a bowling ball rolling down a lane, and while it would hurt, it would also not be nearly as deadly as a bullet with the same energy. Similarly, a 4-door sedan being about 1500kg imparted with such energy would only be moving at 1.02 m/s or 2.28 mph.

What I am getting at is that ensuring the power user only has access to large objects which require large amounts of energy to move at any meaningful speed does two things for an opponent: 1) Drains the user's stored energy at an increasing rate and, 2) Render the power to be essentially infective from an energy-out-to-damage standpoint.

Granted, this is a high situational design, but could be used to create some interesting situations.

On a physiological level, the user's ability to actively manipulate objects moving at high speed is reliant on his mental power to even discern these objects and then react to them. For the bullet example, he would need to be aware of the shot in order to activate the power in time, and that's assuming his body is covered by the effect, so to speak. If he needs to touch the bullet with one of his hands or something like that, he would not only need to see the bullet coming but also be able to intercept its path with his hand, which requires very above-human reflexes and physical speed.

That example boils down to attacking at extremely high speed at great range, or under the cover of darkness/surprise/smoke/etc.

A final consideration would be this character's storage capacity. If it were possible to disable the power by simply overloading his ability to store or manage the influx of raw energy, then an opponent need simply able to rapidly dose out large amounts of kinetic energy at a rate greater than the user can manage.

Picking up some of the earlier comments and building on @Tmartin.

KE = mv.v/2. Note that this contains vector and scalar terms. Note also that KE is relative to the coordinate frame of the observer. If my velocity vector is the same as the object's velocity vector it has no KE relative to me (free fall). mv is the momentum term (velocity x mass) it is a scaled vector with magnitude and direction. Changing the direction component changes the KE relative to the chosen reference frame. So, what is our superhero changing (and what is the field of action)? The possibilities are:

• The mass. Probably Not.

• The magnitude of the velocity vector

• The direction of the velocity vector

Classical physics achieves this by applying applying a force F = ma (a is a vector quantity) over a time (roughly - integrate ma over time and 1/2 m v.v is the result). If this is the mechanism of action, as already discussed, it leads to considerations about where the energy required comes from / goes to (and what is the conduit). Also if the time is short the accelerations are large.

One solution might be that our hero has the ability to change the object's reference frame. ie the reference frame of the bullet speeding toward me (that I share) is exchanged for one in motion relative to me that is opposite to that of the bullet. The bullet still moves toward me but it's reference frame is moving away from me. The bullet appears to stop. How. There are more than the 3 dimensions we experience, the remainer (number under dispute by physics) are tightly curled at a microscopic scale. If our hero has the ability - insert handwaving - to cause movement along one or more of these with a small expenditure of energy then reference changed without flipping brain out of ears. What is the area of effect? I don't feel it could be contact. If it is contact what happens to the back half of the bullet when the tip in contact stops? Eventually the bullet is a flattened disc of monatomic bullet material surrounding the hero that immediately oxidises (bursts into flame). Hmm, potential for humorous training scenario. Also where does the energy of deformation come from? If it is an area effect then power development can come from increase in control of:

• Affected area ( larger volume of effect)

• Larger objects (more atoms affected)

• Finer control (ability to affect single atoms)

The power would also give our hero the ability to move very fast. Exchange the hero's local reference with that of the centre of the Andromeda Galaxy and all of a sudden moving at an appreciable fraction of c. Solve the friction problem by having any atom in contact experience a similar reference frame change (or what happens to clothes - again, humorous training scenario). However the surface of the field will be a ball of hot plasma in-atmo.

This could also prevent our hero being gassed / asphyxiated. Cause the dangerous gas to rush out of the space and or cause all the oxygen molecules to rush in.

Weaknesses would be related to scale / fineness of control, awareness and reaction time.

• Kinetic strike from orbit at just under orbital velocity is hypersonic and transits the troposphere in ~3 sec. Gotta know it's coming in order to stop it unless there is some kind of shield in place. But you'd need to stop the whole projectile or the hero is standing beside a ball of superheated plasma.

• Slow poison (but with fine control could tissue be repaired)

• Directed energy weapons. Unless the hero can control photons. Does the hero have the reaction time to move a shield in place. Not in time to block a first shot.