33 KiB
[Q][D] Rational definition of "object"
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Author: u/eaglejarl *
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URL: https://www.reddit.com/r/rational/comments/3rqd2y/qd_rational_definition_of_object/
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Score: 3
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Created: 2015-11-06T06:01:36
Post:
Any story that uses magic eventually needs to answer the question 'what is an object?' As in, 'Shatter destroys an object' and 'Transfiguration turns one object into another'.
I'm running into it a lot in my novel, and I'm tired of trying to patch an answer, so I thought I'd attempt to crowdsource it. Hopefully, other authors can benefit from the discussion.
Let's start by dealing with the core issue: yes, the concept of 'object' is an illusion of our perception because quantum mechanics and atoms and physics. We're looking for a definition that will work to keep story magic consistent, not necessarily one that satisfies Newton, Einstein, and Planck.
Here's some use cases and how I would like them to turn out; can we come up with a definition that works? If not, which of the cases would need to change?
Example objects:
- An empty cardboard box
- A freestanding wooden door
- A gun
- Some water, cupped in your hand when your hand is in free space
- Anything that you are holding in your hand that is not in contact with anything else
Example not-objects:
- One board in a door
- A door that is mounted in its frame
- Yet another brick in a wall
- Some water, cupped in your hand when your hand is underwater (to the extent that the water is 'in your hand', it's part of the ocean instead of being a discrete object)
The definition I've been using isn't perfect, but it covers most of these cases:
Imagine an infinitely thin sheet of shrinkwrap. If you want to check whether X is an object, can the shrinkwrap go completely around X without tearing or penetrating matter?
If you found the above easy, try the bonus question: define 'wearing'.
Comments:
u/alexanderwales [+14] Time flies like an arrow (an hour later)
Object-oriented magic needs a definition of object, but not all magic systems are object-oriented. If you're looking for a magic system that stands up to heavy scrutiny, I'd suggest staying away from anything object-oriented.
With that out of the way, here are a few of the solutions I've used for the "object problem".
- Objects are defined by what people think constitutes an object. This implies that someone sufficiently psychotic would be capable of affecting different things.
- Objects are defined by group consensus. If you have the ability to affect "cats", the definition of a cat depends on what everyone in the world would call a cat. Not subject to the lone psychotic problem.
- Objects are defined by the magic system itself. I've used this for systems where the world itself is an object-oriented simulation; if you break a chair apart into pieces, each piece becomes its own object, but if you go too small they become particle effects instead.
- Objects are defined by some external agent. Every time you want to check objectness, the external agent takes a look at what you're trying to do and says "yea" or "nay". Indistinguishable from authorial fiat, so isn't great under scrutiny.
u/sir_pirriplin [+5] (5 hours later)
Objects are defined by group consensus. If you have the ability to affect "cats", the definition of a cat depends on what everyone in the world would call a cat. Not subject to the lone psychotic problem.
Even better is to make it so that the definition depends on what everyone in the world called a cat at some well-defined point in the past. For example, when a demi-god a thousand years ago first "tamed" magic and made it suitable for human use or something like that.
This way, magic works as expected even in the event of massive psychosis or near-extinction of sentient beings.
u/Chosen_Pun [+3] The Chosen Ones (7 hours later)
I mean, not that there's anything inherently wrong with a plot that, at some point, involves a widespread plague of madness and/or an extinction event that, incidentally, affects how magic works in ways that are hard for the survivors to predict. Could be interesting.
u/None [+5] (9 hours later)
Elantris, by Brandon Sanderson.
u/gabbalis [+2] (11 hours later)
Encode subconscious magi-memetic virus.
Infect Everyone.
Farm Bitcoins.Bend all magic to your whim.
u/Jiro_T [+2] (13 hours later)
Then someone invents TVs, cars, or can openers, and "object-affecting spells" don't work on can openers because they didn't exist when the demigod tamed magic.
u/derefr [+3] (23 hours later)
You don't have to encode a complete taxonomy into "consensus-based" magic OOP semantics. Just grab all the human brains around at the time, and extract a template neurotypical human from it; and then, when you want to do an OOP identification, simulate a human-instance that was born in that time period and had average learning experiences, and ask that simulated human to create an Interactive Fiction-like object model of the current "scene."
One of the fun things about this mechanic is that if everyone in some time period believes in the "atomicity" of something like "blood", then you can't ask magic to select out parts of it; but once the compound nature of a thing becomes common knowledge, then magic suddenly gets more scientifically-minded as well.
An interesting question is how to "pick between" the several multi-level models that co-exist within the human mind: thinking of blood as a liquid, as cells, as proteins, as molecules, as atoms, etc. My suggestion: don't. Instead, presuming the magic system has a "cost" for a spell, present the most "intuitive" model-level of a given phenomenon as the least-costly one to use, and have cost rise exponentially the less intuitive the model-level becomes.
Also, note that this breaks if transhumans try to use human-derived magic, because they no longer follow the human-template the magic system is using. That's an interesting plot-point. :)
u/sir_pirriplin [+1] (13 hours later)
Maybe the language of the gods is one of those that rely on a few simple words and lots of composite words (polysynthetic language).
In any case, even when new things are invented that have names that can't be addressed by magic, the definition of "object" itself will still make sense, so you can affect them with any spell that targets a generic object.
u/Jiro_T [+1] (13 hours later)
You don't need a psychotic. You just need someone who is willing to think of arbitrary targets as objects. Once he manages to think that, it becomes self-fulfilling because the fact that the spell works reinforces the idea in his mind, making such spells continue to work.
Mind you, I'm not convinced that even for ordinary people, there is a consistent "what people think constitutes an object". If you ask people whether a specific number of sand grains is a heap, there will be a small size that is not a heap, a large size that is, and an intermediate size where people say it is or is not a heap depending on their mood. There will be intermediate "objects" as well.
u/GaBeRockKing [+1] Horizon Breach: http://archiveofourown.org/works/6785857 (14 hours later)
magic doesn't have to have binary states- almost heaps or barely-heaps could have heap-affecting spells only affect them to a certain degree. As the heap becomes more heap-like the behavior of heap-affecting spells approaches 100% effectiveness, but never quite reaches it.
u/notmy2ndopinion [+4] Concent of Saunt Edhar (5 hours later)
You're getting too theoretical with the definition of "object". Think about the intuitive, physical sense of the word, and it is about MANIPULATION. We primarily manipulate objects with our HANDS, so naturally, what we consider objects can be easily manipulated with one or both hands. Thus, a car is an object (we could potentially roll it by pushing really hard when it is in neutral) but a building is not an object (unless you're superman.)
If we alter our method of manipulation from hands to say... multi-tools, or large robot claws, or octopus body-parts, etc. we get at the core issue, in my opinion.
Screws in a door are objects if you have a screwdriver. A brick in a wall is an object if you have a solvent that dissolves the mortar or a vibratory robot claw. Water underwater is an object if you suck it into your ink pouch and squirt it at your enemy.
Object-oriented Magic should initially starts off at the "gross motor" level of development in fiction, like a baby able to rake something towards themselves, and then toss it across the room. Then, it can progress to fine motor, like opening up a can of food and shaking it around to make a mess. Then, it can go even further to precision motor skills, like lock-picking or surgery. Or go bigger with progressively heavier object manipulation like weights, cars, buildings, planets, etc.
Ultimately, individual wave-form/particles can be manipulated if you possess the tenacious mind of HPJEV and his high-fidelity imagination/visualization. (Although in my opinion, he shouldn't be able to do that unless he's scrutinizing it under an electron microscope to even begin getting a handle on it.)
u/notmy2ndopinion [+1] Concent of Saunt Edhar (6 hours later)
In regards to Change Storms:
What happens when Elly uses her thread powers on smaller fibers within a thread? Can she "work out" to affect larger coils of rope (as well as whatever large braids of rope are called -- what they use for anchoring big ships)
What if Bag Man (sorry I'm forgetting the names of your characters on my iPad at the moment) -- what if he loaded up his backpack while in atypical environmental situations to stir times with special properties? For example, a sub-zero freezer or in a forge to store frozen water or red-hot pokers?
After her most recent experience, Rachel will really be interested in being able to escape more easily -- so I could see her carrying around her own utility belt with things like grease, lockpick-gun, canisters of liquid nitrogen or acetylene torch. and perhaps have the bag guy store larger items like a bolt cutters, car-jack, arc-welder, jackhammer/other pneumatic/construction equipment, quadcopters/drones, and other things to toss out when she needs extra help during her time-stop phase to turn things into an object she can manipulate. Basically anything she can manipulate while Time-Stopped that can in turn, manipulate things in ways she cannot.
Can Monique practice a series of standard movements like a martial artist and eventually automatically "program and execute macros", allowing her to manipulate a lot more objects in a more systematic way? Can she work on smaller and smaller prisms, and if given a near-infinite supply of millimeter sized prisms covered in superglue, rapidly create a crude utility fog of massive objects?
Edit: (Or even better, they are wrapped with string and a capsule of super glue so Elly choose to glue the prisms together and she/Monique can make it move around by eithe manipulating the strings or the prisms as a crystalline-threaded battle bot)
u/eaglejarl [+1] (8 hours later)
What happens when Elly uses her thread powers on smaller fibers within a thread?
waves hands, talks fast
I don't have a good answer to this. I'll figure something out, though.
Can she "work out" to affect larger coils of rope (as well as whatever large braids of rope are called -- what they use for anchoring big ships)
She can simultaneously straighten all the threads that constitute the cable (assuming it's a cotton / hemp / etc cable instead of steel), but unfortunately her power doesn't work literally simultaneously. Individual threads would straighten slightly sooner than others, and would rip through the others, casing the whole cable to fall apart.
(EDIT: She could also just straighten 1..N of the threads in the cable, which would still shred it.)
What she could do, though, is knit a tube out of one single thread and straighten that. And, in theory, if you got an enormously long thread and doubled it back and forth enough times you could make an anchorline that would both hold a ship and be straightenable. Assuming you did, what happened when she straightened it would depend on how you made the loops; most knots (e.g. a bowline) will tighten down and bell out into indestructible loops. On the other hand, if you made your loops by doubling the cable back on itself and securing it with steel wire, it would straighten and rip the wire apart.
What if Bag Man (sorry I'm forgetting the names of your characters on my iPad at the moment) -- what if he loaded up his backpack while in atypical environmental situations to stir times with special properties? For example, a sub-zero freezer or in a forge to store frozen water or red-hot pokers?
Quinn. Yep, he could do that. He'd need to be careful about pulling the red-hot pokers out, though.
After her most recent experience, Rachel will really be interested in being able to escape more easily -- so I could see her carrying around her own utility belt with things like grease, lockpick-gun, canisters of liquid nitrogen or acetylene torch. and perhaps have the bag guy store larger items like a bolt cutters, car-jack, arc-welder, jackhammer/other pneumatic/construction equipment, quadcopters/drones, and other things to toss out when she needs extra help during her time-stop phase to turn things into an object she can manipulate. Basically anything she can manipulate while Time-Stopped that can in turn, manipulate things in ways she cannot.
Very true, although it wouldn't have helped her in that particular case. All of those things would be great for getting the handcuffs off before she outtimed, but she couldn't use her power right then because she was waiting to pay off the last use. Even if she had been able to, the handcuffs+chain+I-beam was too large for her to bring it into her Time Stop effect so it would have been completely invulnerable and unopenable. If there's an object that she can't timeshift with her she can pick it up and move it around, (e.g., pick up a person and carry them), but she can't change anything about them by, e.g., hitting them with a hammer or unbuttoning their shirt.
Can Monique practice a series of standard movements like a martial artist and eventually automatically "program and execute macros", allowing her to manipulate a lot more objects in a more systematic way? Can she work on smaller and smaller prisms, and if given a near-infinite supply of millimeter sized prisms covered in superglue, rapidly create a crude utility fog of massive objects?
Quite possibly, yes. She's still new to her powers.
Edit: (Or even better, they are wrapped with string and a capsule of super glue so Elly choose to glue the prisms together and she/Monique can make it move around by eithe manipulating the strings or the prisms as a crystalline-threaded battle bot)
This raises issues of shape -- once you glue things together they get counted as one object, so 'triangle + a thread sticking out forward' is not a triangle and therefore she can't control it. The bladesheets are more or less what you're talking about, though -- they are a triangular sheet of fabric with Elly's threads sewed into pockets, sticking out just a millimeter or so in order to not cross her threshold of 'not smooth'.
u/narfanator [+3] (an hour later)
Consideration from actual physics -
I remember this demo from physics class, where we took two crystals or glass or something, and you shined a laser through them at an angle, while moving them closer together. At the start, the laser responded as if traveling through both medium changes (air -> glass -> air -> glass -> air), but when you got close enough, the effect the middle air gap disappeared.
Similarly, everything's got surface tension. Gas, and solids made up of other solids (dirt) are where it gets interesting.
Alternative, based entirely on magic - Magic uses the user's understanding of "object". Change your understanding, change the effect (although this is difficult). Also does interesting things when the user can't actually properly conceive of the entire thing, like "mountain" or "the earth".
u/eaglejarl [+3] (an hour later)
media changes
How would this work in practice when it comes to something like "is this door an object?"
surface tension
Do solids have surface tension? I thought that was only liquids.
user's understanding
This is certainly the fallback, and it does open up interesting story possibilities. It feels like a copout, though.
u/ArgentStonecutter [+2] Emergency Mustelid Hologram (5 hours later)
How would this work in practice when it comes to something like "is this door an object?"
You could say "an object is anything you can separate without breaking atomic bonds". With scale factors to exclude things like van-der-waals forces.
Then you say "no, THAT door wasn't an object, because it was just nailed together, THIS one is because it's glued" or "of course a conventionally hinged door is an object, but that one isn't because it's rusted shut, whack it a few times THEN teleport it out, dummy".
That would actually make an interesting magic system that would be well suited to things like mysteries. "Then I realized that the thief couldn't have come through the window because it was painted shut, so it HAD to be the butler...".
u/eaglejarl [+2] (7 hours later)
Then you say "no, THAT door wasn't an object, because it was just nailed together, THIS one is because it's glued" or "of course a conventionally hinged door is an object, but that one isn't because it's rusted shut, whack it a few times THEN teleport it out, dummy".
Were the "is" and "isn't" in the rust example supposed to be switched?
This is interesting. So, that would mean that each board in a door that was nailed together would be a separate object, and a pair of handcuffs would be three or four separate objects. (The jaws of each cuff are held together with pins.) A one-object-target spell couldn't affect "handcuffs", it would have to affect one piece of a handcuff.
It would be a consistent definition, although I think it would make for some counterintuitive results until the reader got dialed in. It would also be a power-up for a lot of abilities and a nerf for others.
I think I've already locked myself out of this definition in Induction; I wish I'd asked sooner.
u/ArgentStonecutter [+2] Emergency Mustelid Hologram (8 hours later)
Were the "is" and "isn't" in the rust example supposed to be switched?
A hinged door is not part of the frame because the two or three parts of the hinge are separate objects.
If the door is rusted shut it's not an object, the rust is a bond between the hinge and the frame making the frame (and probably the wall, if it's painted) part of the same object.
A one-object-target spell couldn't affect "handcuffs", it would have to affect one piece of a handcuff.
There's no reason that a spell can't effect multiple objects at a time, you'll just have to understand what the parts are and include them all. Like, those little pins and springs inside a lock.
I think it would make for some counterintuitive results until the reader got dialed in.
That's a bonus. Getting people to figure something like that out helps suck them in to the story.
I think I've already locked myself out of this definition in Induction
Rewrite?
u/eaglejarl [+1] (8 hours later)
Rewrite?
After it's published to the web but before publishing to Amazon, sure. I don't want to retcon out from under current readers, though.
Although, if I did go with this definition, Rachel would be nigh-omnipotent. One of the main restrictions on her right now is that she can't open doors, windows, etc.
u/ArgentStonecutter [+1] Emergency Mustelid Hologram (8 hours later)
You could have her suddenly get stymied when someone attaches a thread across the inside hinge-side of a door with superglue.
"YOU GOTTA BE KIDDING ME!?"
u/eaglejarl [+1] (9 hours later)
laugh
True.
u/ArgentStonecutter [+1] Emergency Mustelid Hologram (9 hours later)
Wait a second, Rachel is the time borrowing one. How does that relate to the definition of an object?
u/eaglejarl [+1] (9 hours later)
When she timeshifts (goes into her borrowed time), the world around her is frozen in time. She can bring objects into her time with her if they fit completely within a certain volume. This is really important when she needs to get through a door; if the door is an object unto itself then she can bring it into timeshift with her and open it. If it's part of the wall, then it's an invulnerable barrier.
This was a major plot point, because the team needed to deal with a group of terrorists on a bus and she couldn't get the door of the bus open.
(Note that there are some edge cases on her power. Gases (e.g. air) are sufficiently diffuse that whatever part of it is inside her zone can be treated as an object. The four fundamental forces continue to work normally, so she can see and she could point a laser at something. Once something has been brought into timeshift it remains there even if it goes outside her zone. Certain objects, such as living things, can't be brought into timeshift at all. Freestanding objects, again including living beings, can be picked up and carried around, although they are invulnerable.)
u/ArgentStonecutter [+1] Emergency Mustelid Hologram (10 hours later)
This was a major plot point, because the team needed to deal with a group of terrorists on a bus and she couldn't get the door of the bus open.
Not a problem. The bus door may have all kinds of electrical connections, mechanical connections, gaskets, sealing compounds, etc. So, like, she could open the door, except for this wire that's part of the wiring harness of the whole frigging bus that would have to bend...
Similarly, she can't open the windows because the gasket around the edge of the glass would have to bend, and it's part of the bus object.
Also, she probably tears her shoes up horribly walking on grass.
u/ZeroNihilist [+1] (a day later)
Couldn't Rachel have just stormed the bus in a timeshift once they opened the doors for Elly?
u/eaglejarl [+2] (a day later)
Yes, but by then she was outtime from a prior use of the power.
u/lehyde [+3] Nudist Beach (6 hours later)
(I'd like to remark that the title of this post is not very good. The word "rational" has no business there; a more concrete adjective should be used ("precise" and "useful" come to mind). There is an article by Eliezer somewhere that says something like "every time the word 'rational' is used it loses some of its power". I agree.)
u/eaglejarl [+2] (7 hours later)
Read it as "Seeking a definition of 'object' that readers of /r/rational won't find violates their suspension of disbelief" if that works better for you. Since we talk about "rational stories" on here, I think my version is fair, as well as shorter.
u/DCarrier [+1] (an hour later)
Is there any ambiguity allowed in the definition? Can I say my phone is an object, while still saying that the battery is an object, or does it have to be both or neither?
I'm thinking something about how strongly bonded something is. If two things are sitting on top of each other, they're not an object, but if they're glued by a strong enough adhesive, they are. If you hold onto something hard enough, then the friction is strong enough that it counts as part of you. Although if you go that route then anything sufficiently heavy just becomes part of Earth.
Water doesn't seem like it's held together very well though, so if you counted it as an object, you'd pretty much have to count everything as one giant object. Are you allowed to not count it? This could be a problem because it means your blood doesn't count. You could get around this by saying anything enclosed in an object counts as part of the object so long as the holes are smaller than some really small size.
Does 'wearing' have to be treated differently than 'holding'?
Edit: If I have a screw that I screw into something, does it become part of that object? Does it matter how tightly I screw it? I could see it counting as an object if I'm making a hole in wood by screwing it in, but not if I screw it into a nut where there's room for it and it doesn't press against it.
u/eaglejarl [+1] (an hour later)
Is there any ambiguity allowed in the definition? Can I say my phone is an object, while still saying that the battery is an object, or does it have to be both or neither?
Less ambiguity is always better, but I'm certainly going to insist on perfection.
Liquids really do need to be covered somehow. They're just too common.
I would envision a screw as part of the board it's screwed into, but that opens up questions like "how deep?" as you point out.
u/cae_jones [+2] (8 hours later)
Liquids really do need to be covered somehow. They're just too common.
I ran into the same issue when trying to understand the workings of a hypothetical space-compression tech (Crystals of Holding, basically). Mostly because I needed them to not break and start eating everything, but I also need them to be capable of holding air and other fluids.
I went with the "can an arbitrarily thin sheet wrap around it?" rule for solid objects, so they can't just rip things apart. Since I needed other rules (some shouldn't be capable of holding people, but others should), this comes down to some sort of programmable threshold/scan/etc.
Maybe the object-wrapping sheet behaves like a fluid with arbitrary surface tension, (which also ignores gravity somehow), such that it can wrap water but not penetrate it? This would imply it could penetrate fluids without water-like properties (air, maybe oils, maybe water if the tension is sufficiently broken or irrelevant)? This seems flawed--water wouldn't have much surface tension cupped in your hand, especially on the bottom?--but it might help, if you need a universal solution?
If you could put an adjustable threshold of sorts on your magic--at level x it can only hold solid objects, at x+1 water, at x+5 air, at x-3 objects have to be especially hard, etc--that could avoid weird definition issues, but would introduce more complexity that needs patching (under what circumstances does the threshold change? Can a sufficiently clever/determined mage find ways to use an arbitrary threshold to achieve partial transfiguration, or to turn air into cheese?). Alternatively, you could just find the threshold that permits water with a defined surface, but nothing looser (which means that spells would not be able to cross the boundary between water and air, unless the effect manifests without crossing the space between the caster and the target).
u/DCarrier [+1] (an hour later)
Less ambiguity is always better, but I'm certainly going to insist on perfection.
Specifically, I'm wondering if whoever is doing the magic gets any control over it. Could they consider a grenade an object most of the time, but consider just the pin an object at one point?
u/castleborg [+1] (3 hours later)
In addition to shrink wrap, I posit that the entities must not don't break apart when you tug on 'em with a given force. So two billiard balls touching each other are two objects, not one - unless joined with adhesive.
Some water, cupped in your hand when your hand is in free space
Okay, but only if said forces are lower than the surface tension, and if you set it that low you might let some non-intuitive "objects" in through the filter.
u/None [+1] (10 hours later)
Effects, as a rule, follow the path of least resistance within their scale. There's a fairly significant "cost" when determining the path associated with some quality that makes air preferable to any liquid preferable to any solid. Density, maybe, though that would act oddly with buoyant objects. Have the effect follow friction interfaces, maybe?
u/eaglejarl [+1] (10 hours later)
Could do, although I'm not sure how that would interact with nails and screws. Do you know?
u/None [+1] (10 hours later)
If the energy cost of going around them along the contour of the screw is greater than the cost of going along the contour of the head, go along the screw.
u/eaglejarl [+1] (10 hours later)
Meaning that objects that are screwed together are one object. That makes a lot of sense; thank you.
u/None [+1] (13 hours later)
Only to a certain point, though. At some boundary, it becomes cheaper to excise a screw.
u/None [+1] (11 hours later)
Let's start by dealing with the core issue: yes, the concept of 'object' is an illusion of our perception because quantum mechanics and atoms and physics. We're looking for a definition that will work to keep story magic consistent, not necessarily one that satisfies Newton, Einstein, and Planck.
A block of stuff generating sensory data which plays a unified, easily-compressible role in the world. Or, in more technical terms, anything with its own causal role is in object. To get even more technical, any block of stuff describable via one generative causal model is an object.
u/TimTravel [+1] (12 hours later)
I argue that the definition of an object depends on what object it is. Consider dirt stuck to a car. Is the dirt a part of it? As a car, the dirt is not part of it. As a generic object, the dirt is a part of it. If you want to lift the car you have to lift the dirt too. If you want to fix the car you don't care about the dirt and can safely get rid of it if it's in the way.
u/None [+1] (16 hours later)
A contiguous volume of matter of arbitrary shape mutually connected by some path through the graph of its covalent and ionic chemical bonds.
u/eaglejarl [+1] (18 hours later)
So a board is an object but a door made of boards is not, right?
u/None [+2] (18 hours later)
Actually, no, my definition is horrible. It only lets you take individual molecules.
u/None [+1] (6 days later)
Objects are solids that your protagonist touches that could be moved sideways via a vibration (the "magic vibration") and wouldn't encounter other solids. Maybe limited to a certain mass or volume.
Dresses and shoes fit. Cellphones fit. books, swords, sandwiches fit. Doors and windows don't. Cars, possibly. People, possibly. Holograms, no. Shadows, no. Liquids, possibly (maybe liquids and gas count always but only inside the mass/volume limitations).You should define touch anyway.
This also has interesting outcomes, for example you can't carry things when you're buried underground. You can't carry pants while you sit on a small chair. You would leave shoes back when performing magic in a field of grass. Etc.
u/eaglejarl [+2] (6 days later)
Interesting. I like the slightly non-intuitive examples at bottom; rules that have weird edge cases are always interesting.
u/SoylentRox [+1] (18 days later)
Best and most consistent explanation I can think of is this. Wizard dude tries to target something with a spell. Magical energy, using physics not known to this universe, starts to accumulate in the object, just like electric charge. Magical energy has the property that it conducts to all atoms sharing electron clouds from the target point.
So a single, monolithic block of metal in vacuum is the easiest thing to target. It requires the least amount of energy to cast the spell.
A block of metal in air is harder, because the gas molecules carry away "charge", but doable.
And so on. There's a coupling effect as well, where molecules of the type that is similar to the target point are easier to charge than ones that are not similar.
At least this makes sense and it's not affected by anyone opinion of what should happen. It also means that if you target, say, a specific human, with the spell impacting their chest, if they are holding hands with another human the spell will spread pretty smoothly to them. And so on. A rusted door will be harder to target than a door that isn't rusted to the frame, but a door that is welded to the frame will basically require that your spell act on the frame as well.