[HN Gopher] 'Strange metals' point to a whole new way to underst...
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'Strange metals' point to a whole new way to understand electricity
Author : pseudolus
Score : 90 points
Date : 2025-05-25 14:02 UTC (8 hours ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| baerrie wrote:
| Progress is seeing the cloud from the particles I reckon. I am
| excited to see practical uses of measuring entanglement to push
| forward materials research. I'm curious about what other
| materials have linear changes related to temperature or other
| inputs, seems uncommon.
| dinfinity wrote:
| IANAP, but I thought that quantum field theory (which isn't
| incredibly controversial) already treats particles as merely
| emergent convenient ways to describe common excitations of the
| fields. I'm surprised it isn't mentioned here at all.
| tux3 wrote:
| A regular particle isn't really emergent, it corresponds 1:1 to
| the excitation of the field
|
| Quasiparticles arise out of a collection of particles, that's
| why they're emergent
| dinfinity wrote:
| > A regular particle isn't really emergent, it corresponds
| 1:1 to the excitation of the field
|
| Maybe 'emergent' was the wrong word here. I meant that
| particles are convenient ways of describing behavior of the
| fields in many (but not all) cases, with the fields
| themselves considered to be the (more) fundamental
| description of reality.
| colechristensen wrote:
| Eh, in the wave-particle duality wars you may have been
| swayed a bit too strongly into the wave camp.
|
| Quantization _exists_ and isn 't just a convenience.
| dinfinity wrote:
| What? QFT doesn't preclude quantization _at all_. You 're
| attacking a weird straw man here.
| soulofmischief wrote:
| And wave particle duality isn't some kind of scientific
| debate with camps on both sides.
| jfengel wrote:
| QFT is perfect for a single particle, but it gets harder to
| describe the behavior of particles en masse. It's super hard to
| find simplifications that reveal emergent behavior.
| bkcooper wrote:
| I would assume that's mostly a function of this being for a
| general audience. Yes, you absolutely can talk about
| quasiparticles using techniques adapted from QFT. I don't know
| if Landau originally conceived of it that way, but there were
| definitely a bunch of Soviet physicists shortly after him who
| did.
| countWSS wrote:
| so electrons are just like photons being a wave/particle? The
| article seems to suggest in strange metals their particle
| properties are absent and only 'electron field' gradients move,
| like if electrons exhanged their 'charge'.
| toast0 wrote:
| Yeah, electrons are waves and experience quantum tunneling
| which we see in high density electronics and specifically apply
| in flash memories.
| ChrisClark wrote:
| Yeah, everything is just like photons, everything is a
| wave/particle
| rnhmjoj wrote:
| Electrons are not _just like_ photons. It 's tempting to say
| that, but there are some significant differences that can lead
| you in error if you think in this picture.
|
| First of all, if you think of a photon as some small ball, not
| that's not what it is. Mathematically a photon is defined as a
| state of the EM field (which has been quantised into a set of
| harmonic oscillators called "normal modes") in which there is
| exactly one quantum of excitation of a specific normal mode
| (with given wavevector and frequency). Depending on which kind
| of modes you consider, a photon could be a gaussian beam, or
| even a plane wave, so not something localised like you would
| say of a particle.
|
| Unlike photons, electrons have a position operator, so in
| principle you can measure and say where one electron is. The
| same is impossible for photons. Also electrons have a mass, but
| photon are massless. This means you can have motionless
| electrons, but this is impossible for photons: they always move
| at the speed of light. Electrons have a non-relativistic
| classical limit, while photon do not.
|
| W. E. Lamb used to say that people should be required a license
| for the use of the word "photon", because it can be very
| misleading.
| whatshisface wrote:
| Why don't photons have a position operator?
| mcnamaratw wrote:
| It's really not accurate to say that a photon has no
| position at all. How would a photodiode work? You have to
| be careful with this stuff.
| https://physics.stackexchange.com/questions/492711/whats-
| the...
| riskable wrote:
| Think of it like this: From the perspective of the photon,
| it lives and dies in the same instant. Even if it traveled
| across the entire universe.
|
| Since it lives and dies in the same instant, it can't have
| a position--because the moment it exists and the moment it
| doesn't is exactly the same time.
|
| It takes time--even for light--to get from point A to point
| B. However, the _measurement_ of any positions--relative to
| the photon itself--will always be the same. It 's related
| to that property of quantum physics that allows two
| particles to exists in two different places at the same
| time.
| soulofmischief wrote:
| All matter is wavelike. Even some molecules comprised of
| multiple particles have been empirically proven to exhibit
| wavelike behavior.
|
| https://en.wikipedia.org/wiki/Matter_wave
| kens wrote:
| The article says that resisivity in normal metals follows a
| quadratic curve, but the article also says that it follows an
| exponential curve. Does anyone know which it right?
| fwip wrote:
| If I'm reading Wikipedia correctly, the formula is quadratic
| for some metals, and cubic or quintuplic(?) for others:
| https://en.wikipedia.org/wiki/Electrical_resistivity_and_con...
| VygmraMGVl wrote:
| Typically, the behavior of any given metal is a mix of
| mechanisms so the measured behavior is fit to a curve where
| you fit n. So for metals the exponent is typically a decimal
| between 2 and 5.
| fwip wrote:
| Thanks, I appreciate the explanation. :)
| Sniffnoy wrote:
| You would normally just say "5th degree" or "5th power".
| s1mplicissimus wrote:
| afaiu quadratic is a subtype of exponential, so they are not
| mutually exlusive
| Sniffnoy wrote:
| No. Exponential growth or decay is much faster than quadratic
| growth or decay. You may be mixing up exponential functions,
| of the form x maps to a _b^x, with power functions, of the
| form x maps to a_ x^b. These are very different!
|
| Annoyingly, people often use "exponential" colloquially to
| mean anything faster than linear, but in fact lots of things
| are faster than linear.
| sfink wrote:
| Ouch, not a good look for a technical article.
|
| From the other responses, it sounds like "none of the above".
| It's more like a "polynomial curve" that is only sometimes
| quadratic. Is "polynomial curve" a thing? "Power curve" /
| "power function"?
| sfink wrote:
| So superconductivity is a laminar flow of electron goop?
|
| Ok, it's different in that liquid flows through pipes and
| electrons flow through crystal lattices or whatever, so electrons
| go between and around the material while liquid is bounded by it.
|
| It makes me speculate that electron flow through a metal is sort
| of like liquid flowing through a compressible boundary tube,
| whereas flow through a non-metal has rigid walls. Non-metals
| reject the electrons, metals allow them to play Spiderman and
| hitch a temporary ride (if you'll forgive the overly particle-
| centric analogy.)
|
| If resistivity is determined by the equivalent of turbulence,
| though, I've no idea what the graph against temperature should
| be. Do electrons travel faster when there's less resistance?
| whatshisface wrote:
| Turbulence on a small scale acts like increased viscosity on a
| large scale, because they're both forms of momentum diffusion.
| However, current doesn't have any momentum diffusion terms, the
| momentum is lost to the conductor.
| elcritch wrote:
| Great read! One fascinating to me is how the article frames the
| field as progressing once again now that researchers are getting
| over the quasi particle model.
|
| Reminds me of the elephant and rope adage: young elephants are
| trained with small chains, which as they mature they outsized and
| could easily break but don't.
|
| Though to give credit to researchers, those new experiments of
| "listening" for electron perturbations seem amazing. That's just
| a brilliant idea. Theorists often like to pretend they're better
| than the experimentalists, but without proper data the theorists
| get stuck in dead ends. ;)
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