09-12-2014, 06:21 PM
Where to begin...
In Physics, one of the most confusing terms that one comes across is "Phonon". It's a lousy term, almost as bad as "Spin".
(The Wikipedia article is nearly worthless; it is pretty much all theoretical, and ignores much of the experimental work done in the last few decades. The Talk section is actually pretty good.)
A single "Phonon" is a curiosity. (The paper admits as much.) Where Phonons come to play is in Collective Action; that is Conduction, from one place to another.
Simply, very simply, phonons conduct Heat, by Mechanical Vibration. These Vibrations have Frequencies, typically starting in the GHz region, and up. This is done in a "stepwise" manner; Phonons are a kind of Quantum Particle: "Quasiparticles". (Phonons have no physical dimensions, or any Mass, in conventional terms.)
So what does all this mean? Take your first Semester course in Classical Electrodynamics: You get introduced to Particles, Waves, and Frequencies, and just enough Quantum Physics to pass a test.
When it comes to what you hear and can pick up on a Cellphone, concepts of Waves are good enough, and Particles can be ignored. When you are counting Gamma Rays from Nuclear waste, individual Particles are just dandy, and Wavelength is immaterial. (It can be measured of course, that is what Gamma Ray Spectroscopy is all about.)
Now stick a Copper Spoon into a cup of hot tea. Energy is certainly conducted; your fingertips tell you this. But not at anywhere near the Speed of Light. (This is where I should use a Car analogy, but screw it.) Energy in the form of Photons get into the spoon, gets converted to Phonons, and at some point leave the spoon- as Photons again... slowly.
Phononics isn't anywhere near being ready for practical Applications, other than the ones that we are already used to. But Superconductorists are very interested in Phonons, it sort of gives them a Purpose in Life, a Goal: Phast Phonons.
Eustace
(Hey, I did this with no Math, and only one Huge glaring obvious mistake!)
In Physics, one of the most confusing terms that one comes across is "Phonon". It's a lousy term, almost as bad as "Spin".
(The Wikipedia article is nearly worthless; it is pretty much all theoretical, and ignores much of the experimental work done in the last few decades. The Talk section is actually pretty good.)
A single "Phonon" is a curiosity. (The paper admits as much.) Where Phonons come to play is in Collective Action; that is Conduction, from one place to another.
Simply, very simply, phonons conduct Heat, by Mechanical Vibration. These Vibrations have Frequencies, typically starting in the GHz region, and up. This is done in a "stepwise" manner; Phonons are a kind of Quantum Particle: "Quasiparticles". (Phonons have no physical dimensions, or any Mass, in conventional terms.)
So what does all this mean? Take your first Semester course in Classical Electrodynamics: You get introduced to Particles, Waves, and Frequencies, and just enough Quantum Physics to pass a test.
When it comes to what you hear and can pick up on a Cellphone, concepts of Waves are good enough, and Particles can be ignored. When you are counting Gamma Rays from Nuclear waste, individual Particles are just dandy, and Wavelength is immaterial. (It can be measured of course, that is what Gamma Ray Spectroscopy is all about.)
Now stick a Copper Spoon into a cup of hot tea. Energy is certainly conducted; your fingertips tell you this. But not at anywhere near the Speed of Light. (This is where I should use a Car analogy, but screw it.) Energy in the form of Photons get into the spoon, gets converted to Phonons, and at some point leave the spoon- as Photons again... slowly.
Phononics isn't anywhere near being ready for practical Applications, other than the ones that we are already used to. But Superconductorists are very interested in Phonons, it sort of gives them a Purpose in Life, a Goal: Phast Phonons.
Eustace
(Hey, I did this with no Math, and only one Huge glaring obvious mistake!)