[HN Gopher] Strange Metals: Where electricity may flow without e...
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Strange Metals: Where electricity may flow without electrons
Author : digital55
Score : 48 points
Date : 2023-11-27 19:18 UTC (3 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| rafram wrote:
| Bad 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 wrote:
| yeah the edit seems unnecessary, though the title still
| includes "may".
| Animats wrote:
| So 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..."_
| rafram wrote:
| He 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 wrote:
| I 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).
| spacecadet wrote:
| Came for the images of the nanowire
| miika wrote:
| Some good conversations on the topic here
|
| https://physics.stackexchange.com/questions/560853/is-electr...
| allemagne wrote:
| Not 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 wrote:
| There is only one electron in the universe. Also, positrons
| are electrons travelling backwards in time.
| johndunne wrote:
| I 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.
| johndunne wrote:
| I think the top answerer had a few electric bugbears they
| wanted to get off their chest. Best skipped over, and time
| spent looking for simple and thoughtful answers. It's a shame
| the stackoverflow model isn't proving effective for that oft-
| asked question.
| bilsbie wrote:
| I 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 wrote:
| Pure 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.pd...
| bilsbie wrote:
| I'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 wrote:
| Put 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 wrote:
| That was my first thought. But if it's not connected like a
| belt it physically can't replace any electrons it loses.
| adolph wrote:
| Isn'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/veritasiu...
|
| https://www.reddit.com/r/engineering/comments/qxrsrp/the_big...
|
| https://www.youtube.com/watch?v=O-WCZ8PkrK0
| tzs wrote:
| My 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 wrote:
| Yes, 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 wrote:
| It 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.
| jocaal wrote:
| > 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 wrote:
| > 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 wrote:
| It 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.
| swayvil wrote:
| Does the thing at one end of the wire get heavier and the thing
| at the other end lighter?
|
| Because of the mass of the electrons moved from one thing to
| the other.
| mike_hock wrote:
| An electron has .05% the mass of a proton, and only a small
| imbalance of electrons and protons is necessary to generate
| extremely strong electric fields by earthly standards.
| swayvil wrote:
| That's fabulous man, but it doesn't actually answer my
| question.
|
| If the answer is yes then we have moving electrons.
|
| If the answer is no then maybe we don't.
| rcxdude wrote:
| Yes, but to an unmeasurably small degree. Electromagnetism is
| _very_ strong, so you never see the density of electrons
| change by very much, or the situation will correct itself
| quite violently.
| swayvil wrote:
| So there is a small but measurable difference. Ok.
| calamari4065 wrote:
| No.
|
| 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.
| ekianjo wrote:
| > 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 wrote:
| Its travels in waves but it is actually a field.
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(page generated 2023-11-27 23:00 UTC)