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'Strange metals' point to a whole new way to understand electricity

science.org

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Re: 'Strange metals' point to a whole new way to understand electricity

#11

Post by rnhmjoj »

countWSS wrote: post #5

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'.

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.

Re: 'Strange metals' point to a whole new way to understand electricity

#12

Post by fwip »

kens wrote: post #8

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?

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...

Re: 'Strange metals' point to a whole new way to understand electricity

#13

Post by dinfinity »

tux3 wrote: post #6
dinfinity wrote: post #4

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.

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

> 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.

Re: 'Strange metals' point to a whole new way to understand electricity

#14

Post by colechristensen »

dinfinity wrote: post #13
tux3 wrote: post #6

Earlier quoted context omitted.

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

> 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.

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.

Re: 'Strange metals' point to a whole new way to understand electricity

#15

Post by VygmraMGVl »

fwip wrote: post #12
kens wrote: post #8

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?

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...

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.

Re: 'Strange metals' point to a whole new way to understand electricity

#16

Post by s1mplicissimus »

kens wrote: post #8

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?

afaiu quadratic is a subtype of exponential, so they are not mutually exlusive

Re: 'Strange metals' point to a whole new way to understand electricity

#17

Post by fwip »

VygmraMGVl wrote: post #15
fwip wrote: post #12

Earlier quoted context omitted.

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...

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.

Thanks, I appreciate the explanation. :)

Re: 'Strange metals' point to a whole new way to understand electricity

#18

Post by Sniffnoy »

s1mplicissimus wrote: post #16
kens wrote: post #8

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?

afaiu quadratic is a subtype of exponential, so they are not mutually exlusive

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 ab^x, with power functions, of the form x maps to ax^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.

Re: 'Strange metals' point to a whole new way to understand electricity

#19

Post by Sniffnoy »

fwip wrote: post #12
kens wrote: post #8

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?

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...

You would normally just say "5th degree" or "5th power".

Re: 'Strange metals' point to a whole new way to understand electricity

#20

Post by sfink »

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?

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