Strange Metals: Where electricity may flow without electrons
quantamagazine.org
quantamagazine.org
In maxwell's equations, current density J is defined in terms of the E-field. When talking about electricity, people make the typical quantum mechanical wave-particle mistake. Electricity refers to two things, photons and electrons and how they interact with eachother. Both act as wave-particles, but photons act more like waves and electrons more like particles. The thing that gets people is that photons are the things that move energy around. A photon is an electromagnetic wave. In a wire, you can have an electromagnetic wave traversing the wire at some proportion of the speed of light, while the electrons are moving at speeds closer to meters per second. We defined current to be proportional to the E-field (because that is what is moving the energy) and thus we shouldn't refer to the movement of electrons as current.
It's true that interactions between charged particles invoke photons, but you can have charged particles (and their associated E-fields) travelling at constant velocity in a vaccum and still define an associated current density without considering photons. I'm not sure your interpretation produces a useful intuition for this situation.
One of the underlying ideas of the paper is that, in conventional metals where conduction band electrons are much more wave than particle, you can still measure when they 'enter' and 'exit' the material through perturbations in the field, that is bursts of photons that occur when electron waves interact with an obstacle.
This isn't as unintuitive as it sounds though.
In a water pipe you can have a pressure wave reach from one end to the other very quickly, even as the individual water molecules move very slowly.
If water pressure is voltage, water molecules are electrons, and the pipe is the wire, then it's easy to see how a "voltage" can reach the other end of a "wire" without any of the "electrons" having to move very far at all.
If this is not approximately how electricity works, why does the current stop flowing when you disconnect the wires, or equivalently when you "connect" them via something that doesn't have free electrons (i.e. an insulator)?
TL;DW: the power is transferred by the electric fields, it's the electric fields which move the electrons, if there's a break in the circuit the electrons necessarily accumulate in the places that minimise the electric fields.
As any analogy, it is not the same as the thing it is an analogy of, but an analogy can be useful without being complete.
Plus, with AC, the electrons move back and forth, instead of just moving forward!
It’s not that static electric fields “produce” magnetism. Magnetism is a result of relativity.
(But yes, it is still movement…).
Because of the mass of the electrons moved from one thing to the other.
Imagine a simple circuit, say a light bulb and a battery. Electrons move from the negative terminal, through the bulb, and back to the battery. The net change in number of electrons at any one point is zero. The energy isn't in the electrons themselves, but in the motion of those electrons. Electrons in must equal erlctrons out.
Even a battery doesn't store electrons. It uses the energy carried by those electrons to reverse a chemical reaction. The energy is stored chemically.
If you think about it, the electrons belong to the physical materials in the circuit. You can't really add or remove electrons* as electron count is a fundamental property of those atoms. If you somehow removed electrons from the system, you'd be changing those atoms and the system would no longer be able to pass current at all.
*you can, of course ionize atoms by adding or removing electrons, but that's not exactly what happens in electric circuits
Electrons are not electricity, they just carry it. Kind of. It's really complicated.
However, if you're talking about static electricty, you can actually create a mass imbalance by taking a few electrons away from one side or putting some electrons on the other. It's a very, very, very small change in mass.
Positive charge carriers do not actually exist[0]. There's only electrons and holes they can go into. We can talk about the movement of holes, but that's a virtual charge carrier at best.
Conventional current is just a convention. It's what we started with (because Franklin was wrong) and it's too much effort to change now. In practice, the distinction almost never matters. Sometimes it does, but not enough that it's worth overhauling the entire field of electronics.
[0] of course positrons and protons exist, but they aren't relevant to electronic circuits
If the answer is yes then we have moving electrons.
If the answer is no then maybe we don't.
Imagine a different scenario, where the pipe ends in a big box: This time the box does fill up with water, and gets heavier.
Mapping the analogy from water back to electrons: a loop of pipe is like a loop of wire and a battery; while the pipe ending with a box becomes a capacitor or antenna, and that will leak[0] before you can measure the mass change — but technically yes the the mass of any given wall of a capacitor or of an antenna will be very slightly changed by this sort of thing.
For a sense of scale, to get a total charge of 1 coulomb using electrons, the mass of those electrons will be about 5.7 nanograms, and trying to squeeze that much charge into the last millimetre of some length of a wire 1mm in cross section diameter, involves about 60% of the energy in this explosion: https://www.youtube.com/watch?v=wqKn_3iJOP4
As nothing gets close to being able to hold that kind of energy, even if you're trying to accumulate a lot of excess electrons, those electrons leak well before even coming close to nanograms of excess mass.
[0] The bit on the top with the sparks coming out is a capacitive electrode: https://en.wikipedia.org/wiki/Tesla_coil
You can move whole charged atoms, that's a form of electricity too, and it can add observable amount of mass, like with electroplating or welding. But these very quickly turn electrically neutral after depositing.
https://physics.stackexchange.com/questions/560853/is-electr...
>The idea that electricity "does not exist" is just verbal sophistry along the same lines as "matter does not exist, it is frozen energy" or, "you do not exist, you are a figment of your own imagination". At best these are all just over-dramatic and misleading ways of saying that what these things actually are is not what you probably think they are. At worst, misguided eccentrics create "straw" definitions of such well-known words just so they can burn them and trump them with their own untenable notions.
"You do not exist" or "matter does not exist" might be unhelpful sophistry or they might be thought-provoking invitations to a deeper discussion. It depends on the context and the intent.
If this blogger is "basically sound at an experimental and phenomenological level", isn't demanding public denouncements and retractions from everyone using the term "electricity", and has no shortage of thoughts and elaboration about his "eccentric" thoughts on the subject then what exactly is the harm here? Where is this user's uncharitability and hostility coming from?
Drilling into definitions, or "quibbling over semantics" if you prefer, isn't always fun for everybody but that doesn't mean there's an inherent need to come in and break up the party.
good, can I go home now?
It doesn't quite work as you move beyond that, you get stuff like neutrons decaying into protons and electrons (and some neutrinos somewhere). Unless of course you take seriously consider Wheeler's suggestion that the positrons might be hiding in the protons.
All electric currents transport charges
Students transport charges
Therefore, students are electric currents
All things that transport charges are electric currents.
Students transport charges.
Therefore, students are electric currents.
Humans also contain air, are we also air currents?
Some people hate getting stuck on such semantics, but I find them fascinating.
(For the sake of argument let’s says it’s not connected like a belt would be. )
My not overly confident understanding[1] is that this does in fact break the circuit and prevent the flow of current.
Also worth noting, by choosing a colorful ion choice of ion it is possible to directly observe their formation and travel. You can also use electrons as your negative ion directly in liquid ammonia, forming a pretty deep blue solution.
[0]Aqueous or other electrolyte.
[1]My theoretical echem is a bit rusty, so ymmv.
Keep in mind that the metal has both negatively charged electrons which are reasonably free to move around within the metal and positively charged protons that are generally in the nuclei which are fairly fixed within the metal.
If you have the metal belt moving so that the electrons are not actually moving (from the point of view of a stationary observer outside the belt) that observer would see the protons moving.
You've still got, from the outside observer's point of view, a current. It just is now a proton current instead of an electron current.
https://physics.stackexchange.com/questions/707402/veritasiu...
https://www.reddit.com/r/engineering/comments/qxrsrp/the_big...
For things to get weird you would need to have the belt moving at relativistic speeds, >80% the speed of light.
[0] the speed of light in a given material and conditions. Generally it's a good fraction slower than light, but remember that light also moves slower through different materials.
Of course, what actually happens is that photons always move with speed c, but the path they take through a medium is not straight - they "bump" into other particles, so it takes them longer to reach the end. Higher energy particles can have straighter paths (they "push bumps away"), so that even if their instantaneous speed is always lower than the photons', they take less total time to move through the material.
Entirely speculative, but a larger scale analogy that I can relate to is a set of long pipes that fit together fairly well.
At low temperatures their entanglement (interaction with the rest of the universe) diminishes and they densify into a kind of crystalline arrangement that facilitates fairly unimpeded transfer of whatever energy flow really is; be it electrons, waves, or shifts of field energy in some form outside of my non-expert understanding.
At higher temperatures the material starts to jiggle, to expand, and to not quite align as well because everything's further apart and not quite right. This also causes more of the material to interact with energy that would have passed through at superconductive temperatures.
Maybe the packed pipes analogy is too far. A crystalline lattice where the interconnection between the components offers gaps could behave similarly in 3D space, or whatever N-dimension space might exist if that's something not just in science fiction.
Reflecting further, the densely packed (near absolute zero) conditions might also allow the 'strange material' to transition to a different sort of phase of matter. A state where individual components are packed together so tightly that they cease behaving as the groups we normally model and instead are interchangeable / intermingled with their neighbors. The electrons / waves could join the collective and dislodge a similar composition of material at a 'lower pressure'/'relief of potential' point.
Did you know pure water is an insulator?
the minimum breakdown voltage of distilled water under negative impulse at 2mm inter electrode gap spacing is 27kV with 14us breakdown time. The breakdown strength of distilled water is higher under positive impulse than negative impulse at same electrode gap spacing.
https://digitalxplore.org/up_proc/pdf/149-143254025539-45.pd...
Material conditions still trump material science.
https://philosophynow.org/issues/114/Richard_Feynmans_Philos...
EG: "Feynman says that to be slavish to a received view or even to a method for discovering the facts means that we can never advance scientifically, for the old ‘facts’ may need to be overhauled in order to discover new ones, and how that may be done is, well, up for grabs."
It has been false for a long time since we know electrons dont move that fast. Electricity is a wave.