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Massless particle with promise for next-generation electronics discovered

princeton.edu

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Re: Massless particle with promise for next-generation electronics discovered

#31

Post by losername »

fsloth wrote: post #27
lmm wrote: post #24

Earlier quoted context omitted.

It is as real a particle as any other, no? If you look closely enough all particles are just waveforms in particular fields (e.g. an electron will "interfere with itself" in a double-slit experiment).

I suppose the word 'real' is kinda hard here. From classical experimental point of view electron is a particle that can be observed and has an identity and existence regardless of context, whereas quasiparticles such as phonons manifest only in mathematical models that 'can be instantiated' in specific experimental setup, or describe physics only in specific limited context, such as the experiment here. I'm of the sc…

Don't phonons manifest in sound, which is very audible?

Re: Massless particle with promise for next-generation electronics discovered

#32

Post by jpmattia »

raverbashing wrote: post #15
acjohnson55 wrote: post #9

Earlier quoted context omitted.

But what is a "real" particle anyway?

One example happens in semiconductors You have n-type material, where the charge carriers are electrons. So far so good (a real particle) In p-type material, the charge carriers are the absence of an electron (called a hole). It is of course, not a real particle, but it carries charge as well as a real particle.

> You have n-type material, where the charge carriers are electrons. So far so good (a real particle)

Even that: It's a quasi particle. It's an electron with an effective mass, which differs from the mass of an electron in free space.

The effective mass arises because of the collective electron interaction with the crystal atoms. At a range of high energies, the electron even exhibits the same behavior you'd expect from a relativistic particle (with something different than c for the ultimate velocity.)

Re: Massless particle with promise for next-generation electronics discovered

#33

Post by losername »

raverbashing wrote: post #15
acjohnson55 wrote: post #9

Earlier quoted context omitted.

But what is a "real" particle anyway?

One example happens in semiconductors You have n-type material, where the charge carriers are electrons. So far so good (a real particle) In p-type material, the charge carriers are the absence of an electron (called a hole). It is of course, not a real particle, but it carries charge as well as a real particle.

That's just a figure of speech. The charge of an ion stems from the ratio of electrons to protons. To every "hole" there is a proton, which is a particle. I am repeating myself.

Re: Massless particle with promise for next-generation electronics discovered

#34

Post by fnordfnordfnord »

daveloyall wrote: post #26
dvdkhlng wrote: post #12

Earlier quoted context omitted.

"real" particles are those that can leave the holodeck ([1]) "quasi-particles" vanish at the doorstep :) [1] https://en.wikipedia.org/wiki/Holodeck PS: replace "holodeck" with "tantalum arsenide crystal" to yield a less off-topic comment.

Thank you for this explanation. But hey, speaking of TNG... Can't you just stick on of those fancy crystals in your computer? Wait, computers made out of crystals? Did that just happen? :)

Computers are already made out of fancy crystals. But these new crystals would be even fancier than the old ones.

Re: Massless particle with promise for next-generation electronics discovered

#35

Post by fsloth »

losername wrote: post #31
fsloth wrote: post #27

Earlier quoted context omitted.

I suppose the word 'real' is kinda hard here. From classical experimental point of view electron is a particle that can be observed and has an identity and existence regardless of context, whereas quasiparticles such as phonons manifest only in mathematical models that 'can be instantiated' in specific experimental setup, or describe physics only in specific limited context, such as the experiment here. I'm of the sc…

Don't phonons manifest in sound, which is very audible?

Only in lattices I think - i.e. a specific substrate such as crystals:

https://en.wikipedia.org/wiki/Phonon

Re: Massless particle with promise for next-generation electronics discovered

#36

Post by johntb86 »

losername wrote: post #33
raverbashing wrote: post #15

Earlier quoted context omitted.

One example happens in semiconductors You have n-type material, where the charge carriers are electrons. So far so good (a real particle) In p-type material, the charge carriers are the absence of an electron (called a hole). It is of course, not a real particle, but it carries charge as well as a real particle.

That's just a figure of speech. The charge of an ion stems from the ratio of electrons to protons. To every "hole" there is a proton, which is a particle. I am repeating myself.

It's not just a figure of speech, it's a useful abstraction. The protons don't move, but the holes seem to do that. Not only that, if you pretend the holes have a certain amount of mass you can predict how they move, and they move similarly to how a positibly-charged particle would move in the same circumstances.

Re: Massless particle with promise for next-generation electronics discovered

#37

Post by gus_massa »

lmm wrote: post #24
fsloth wrote: post #8

Earlier quoted context omitted.

Thanks, great summary. To translate to non-physicists: It quacks like a particle, it walks like a particle but it's not really a particle. Like counting stones or apples, the both can be understood in terms of similar arithmetic. Same here, only more maths. And, those properties that were observed, may come in handy.

It is as real a particle as any other, no? If you look closely enough all particles are just waveforms in particular fields (e.g. an electron will "interfere with itself" in a double-slit experiment).

It' more complicated. The electrons are waves in a quantized field, so the math is more complicated. When you try to simplify the math, with some simplifications you get something that looks like a classical particle and with other simplifications you get something that looks like a classical wave. So in some experiments you get electrons that behave like a particle and in some experiments you get electrons that behave like a wave.

Anyway, it's difficult to say what a real particle is. The easiest example is the Z0 particle, because you can think it is a mix of the W0 particles with the B0 particles, https://en.wikipedia.org/wiki/W_and_Z_bosons#Z_bosons

Anyway, if we "agree" that a real particle is something that can travel in vacuum, then the electrons are real and the particles in this experiment are not real. But if you talk with the people in solid state physics, they are totally convinced that phonons are real particles in spite they can travel only inside a solid.

Re: Massless particle with promise for next-generation electronics discovered

#38

Post by Zuider »

gus_massa wrote: post #37
lmm wrote: post #24

Earlier quoted context omitted.

It is as real a particle as any other, no? If you look closely enough all particles are just waveforms in particular fields (e.g. an electron will "interfere with itself" in a double-slit experiment).

It' more complicated. The electrons are waves in a quantized field, so the math is more complicated. When you try to simplify the math, with some simplifications you get something that looks like a classical particle and with other simplifications you get something that looks like a classical wave. So in some experiments you get electrons that behave like a particle and in some experiments you get electrons that beha…

But from the point of view of a phonon, the solid is indistinguishable from a vacuum. What distinguishes the 'real' vacuum from what the phonon sees?

Why is what we call 'the universe' necessarily primal? Maybe it is 'vibrating solids' all the way down. If there is something primal, then what are its characteristics that allows what we see as the vacuum to emerge?

Re: Massless particle with promise for next-generation electronics discovered

#39

Post by Zuider »

yk wrote: post #7

Someone should perhaps point out, that the article talks about quasiparticles. Quasiparticles are a bit similar to the particle aspect of a quantum mechanical wave. So for example deformations of the lattice of an crystal are sound waves, but it is also possible to look at the deformations as a field and then quantize the field. Excitations of this field look suspiciously similar to a particle, as in they are produce…

I read the article as saying that the discovery of the Weyl fermion, (albeit as a quasi-particle) provides a proof of concept that it actually can exist in nature (rather than being just an esoteric theoretical curiosity with no physical analogue) and that its manifestation in this form provides a strong indication that it also exists as a primary particle.
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