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Strange Metals: Where electricity may flow without electrons
- bilsbie 3y agoI believe electricity flows in water through ions instead of bare electrons. So that’s another example. Did you know pure water is an insulator?
- robocat 3y agoPure water is an insulator until it breaks down. 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. If the breakdown voltage for air were 10kV/cm, then that would imply pure water is a better insulator than air. Don't bet your life on it though! https://digitalxplore.org/up_proc/pdf/149-143254025539-45.pdf https://digitalxplore.org/up_proc/pdf/149-143254025539-45.pd...
- bilsbie 3y agoI’ve always wondered if you tried to run a current through a metal belt moving in the opposite direction of electron flow at a speed higher than the drift velocity if the circuit would complete? (For the sake of argument let’s says it’s not connected like a belt would be. )
- feoren 3y agoPut yourself in the frame of reference of the moving belt. An electric current is running through you, and also some other machinery around you is moving very slowly in the same direction as the current. So? Why should the movement of some background stuff affect the near-speed-of-light energy propagation passing through you?
- bilsbie 3y agoThat was my first thought. But if it’s not connected like a belt it physically can’t replace any electrons it loses.
- adolph 3y agoIsn't current an instantiation of an electro-magnetic field and so the movement of the belt wouldn't matter? It all lights up at the same time. Considering a conveyer belt portion that is part of a circuit, doesn't the portion of the belt that is energized change as fast as the belt moves? https://physics.stackexchange.com/questions/707402/veritasium-electricity-videos-where-does-the-majority-of-energy-really-flow https://physics.stackexchange.com/questions/707402/veritasiu... https://www.reddit.com/r/engineering/comments/qxrsrp/the_big_misconception_about_electricity_veritasium/ https://www.reddit.com/r/engineering/comments/qxrsrp/the_big... https://www.youtube.com/watch?v=O-WCZ8PkrK0 https://www.youtube.com/watch?v=O-WCZ8PkrK0
- tzs 3y agoMy first impression is that yes, the circuit would complete. 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.
- Workaccount2 3y agoYes, because the circuit is an alignment of charges that creates a electric field. The fact that electrons drift along it is immaterial to the circuit functioning. For things to get weird you would need to have the belt moving at relativistic speeds, >80% the speed of light.
- rcxdude 3y agoIt is very material: the movement of charge is necessary for electricity. In this case electrons are still moving into and out of the belt, even if the bulk is not moving in the direction of the flow of current.
- calamari4065 3y agoYes. Electricity moves at the speed of light[0] and like light will be constant no matter your reference frame. [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.
- im3w1l 3y ago"the speed of light in a given material and conditions" is not constant in different reference frames. Only the vaccum speed of light is.
- tsimionescu 3y agoNot sure why you're getting downvoted, this is an important point. The speed of light that is a constant is c. The actual (average) speed that light travels through a material is not a limit of any kind, and it is very possible for other particles to move through that medium faster than light. For example, Cherenkov radiation is high energy electrons moving faster than light through water (not faster than c). 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.
- thereisnospork 3y agoThis experiment actually gets very feasible if we replace electrons with ions, and the metal carrier with (e.g.) an aqueous electrolyte in an electrochemical circuit. Something like splitting water in H2SO4 would be an easy starting point. This means our charges no longer move at relativistic speeds, and have very short mean free paths, therefore it is possible to flow water[0] against the electrical flow of ions at greater than the mean diffusion speed. 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.
- jocaal 3y ago> Canonically, electric current results from the collective movement of electrons, each carrying one indivisible chunk of electric charge. But the dead steadiness of Chen’s current implied that it wasn’t made of units at all. It was like finding a liquid that somehow lacked individually recognizable molecules 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.
- orra 3y ago> while the electrons are moving at speeds closer to meters per second Plus, with AC, the electrons move back and forth, instead of just moving forward!
- XorNot 3y agoIt is however still movement, which is important because static electric fields don't produce magnetism, whereas moving charges do - which is the principle benefit of AC current.
- andyferris 3y agoWell, technically that depends on your reference frame. If the _observer_ starts moving, they will observe a magnetic field where before there was only electric. It’s not that static electric fields “produce” magnetism. Magnetism is a result of relativity. (But yes, it is still movement…).
- swayvil 3y ago
- ekianjo 3y ago> Canonically, electric current results from the collective movement of electrons, each carrying one indivisible chunk of electric charge It has been false for a long time since we know electrons dont move that fast. Electricity is a wave.
- Workaccount2 3y agoIts travels in waves but it is actually a field.
- ekianjo 3y agoYes, this is correct, was on the phone earlier and had to make it short.
- zeofig 3y agoIt is, in my opinion, still "electrons". More pedantically, the electron field is still the mechanism for nonzero current, regardless of its exotic state. This must be the case as there's no other stable charge-carrying field that's not strongly localised to the nucleii (in this material, or any solid material I can think of). The article does a lot of waffling without admitting this basic point.
- sn00tz00t 3y ago[dead]
- dataflow 3y agoDumb layman question: why is there no mention of the Standard Model and what it would predict/simulate here? Is this too large-scale for that to be realistically usable?
- rcxdude 3y agoPretty much: directly solving the standard model quickly becomes intractable at much smaller scales. Most physics works with simplifications, like the Landau model mentioned in the article.
- 8bitsrule 3y agoAt times like these, I like to turn to this (fairly short) article on what Feynman said about science. https://philosophynow.org/issues/114/Richard_Feynmans_Philosophy_of_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."
- deleted 3y ago[deleted]
- alekseiprokopev 3y agoI remember one of the first question asked in university was "what's an electric current?" I said something along the lines "it's a directed flow of charged particles". The professor asked do you contain charged particles, do you move, are you an electric current?
- patates 3y agoYou may not be a current, hopefully that sparked some lively discussions in the classroom. Humans also contain air, are we also air currents? Some people hate getting stuck on such semantics, but I find them fascinating.
- otikik 3y agoThat professor probably had an electrifying personality
- tux3 3y agoClassic syllogistic fallacy, too! All electric currents transport charges Students transport charges Therefore, students are electric currents Aristotélēs wouldn't approve of this one.
- mydogcanpurr 3y agoNo, it’s valid reasoning. All things that transport charges are electric currents. Students transport charges. Therefore, students are electric currents. It could be that we disagree on what it means to define something.
- mjevans 3y agoMaybe the likening of superconductors and the cuprates resistance behavior is a clue. 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.
- rkwasny 3y agoWe are worried that we don't understand LLMs - well, we also don't quite understand gravity and how electricity works, and we use them every day!
- shenberg 3y agoThere's a confusion this article isn't helpful with: there are physical electrons, the actual physicalparticles. They move in the metal very slowly. But, their motion propagates very quickly, and turns out that the change in motion acts almost exactly like an electron itself, up to having a different mass. This is the "electron" quasi-particle, which is the abstraction that's breaking down. this only shows up about a screen or two deep into the article.
- deleted 3y ago[deleted]
- LargeTomato 3y agoI thought these concepts are lower division EE undergrad concepts? AC power clearly depends on electron motion and electron drift velocity is one of the first things they teach about electricity. Maybe I'm a dummy and I'm missing something but I don't understand why this is groundbreaking.
- LargeTomato 3y agoI read more and I'm a dummy
- varjag 3y agoIn the end, Chen, who successfully earned his doctorate in the spring and has since gone to work in finance, crafted a handful of nearly flawless nanowires. Material conditions still trump material science.
- rafram 3y agoBad edit on the title - electricity doesn’t flow without electrons in all metals, but rather only in some specific “strange” metals that they studied.
- MattRix 3y agoyeah the edit seems unnecessary, though the title still includes “may”.
- Animats 3y agoSo what happened to the discoverer? "In the end, Chen, who successfully earned his doctorate in the spring and has since gone to work in finance..."
- mring33621 3y agoThe saddest part of the story.
- rafram 3y agoHe got his doctorate and now he's getting paid, presumably, the big bucks as a research data scientist at Barclays. Not everyone who gets a PhD actually wants to be an academic!
- KRAKRISMOTT 3y agoI am sure he would stay in academia too if they gave him tenureship immediately after graduation and paid him as much as a quant (academia does pay decently, but only if you are a senior tenured professor).
- contravariant 3y agoI mean you'd really have to love finance to refuse an offer like that, I'm not sure if that says anything.
- spacecadet 3y agoCame for the images of the nanowire
- miika 3y agoSome good conversations on the topic here https://physics.stackexchange.com/questions/560853/is-electricity-really-the-flow-of-electrons-or-is-it-more-involved https://physics.stackexchange.com/questions/560853/is-electr...
- allemagne 3y agoNot a huge fan of the top answer and pretty disappointed by it being voted so highly: >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.
- dekhn 3y agoThere is only one electron in the universe. Also, positrons are electrons travelling backwards in time.
- johndunne 3y agoI remember one of my physics professors at uni explaining this theory and for some reason, I had this weird anxiety at the thought. A lonely electron doing all the work of every electron in the universe. Semifun fact, Feynman used the electron traveling back in time analogy to help teach the principles of QED.