
Researchers Demonstrate Heat and Sound Are Magnetic - bronz
http://spectrum.ieee.org/nanoclast/semiconductors/materials/for-first-time-reseachers-demonstrate-heat-and-sound-are-magnetic
======
tedsanders
I hate to follow the pattern of negative Hacker News comments, but this
article is atrocious. Please don't upvote it.

First, the title is total clickbait. Heat and sound are magnetic??? More like
heat and sound are affected a little bit by magnetic fields. (Giant magnetic
fields at low temperature, no less.)

Second, take a look at the first paragraph:

>"Earlier this month, we reported on research demonstrating that heat
propagates as a wave through graphene rather than as vibrations of atoms the
way it does in 3-D materials. In 3-D materials, the collective state of those
vibrating atoms is known as phonons."

What does it mean to say that heat propagates as a wave rather than as
vibrations of atoms? The definition of phonon is a WAVE of ATOMIC VIBRATIONS.
It makes zero sense to say it travels as wave, but not as vibrations. Also,
there is not a fundamental difference between heat transport in graphene and
normal materials - the main difference is that is just takes a longer distance
before the wavelike motion scatters enough to become diffusive.

Source: Years of work in a materials science lab on 2D materials and a PhD in
Applied Physics

~~~
doingwork
You are correct on all points. I believe the article is trying to refer to the
recent studies:

[http://www.nature.com/ncomms/2015/150218/ncomms7290/abs/ncom...](http://www.nature.com/ncomms/2015/150218/ncomms7290/abs/ncomms7290.html)

[http://www.nature.com/ncomms/2015/150306/ncomms7400/full/nco...](http://www.nature.com/ncomms/2015/150306/ncomms7400/full/ncomms7400.html?WT.ec_id=NCOMMS-20150311)

~~~
bsilvereagle
Press release from the OSU lab that did the study -
[http://news.osu.edu/news/2015/03/23/heatmag](http://news.osu.edu/news/2015/03/23/heatmag)

Having been taught by both Roberto Myers and Dr. Heremans, they wouldn't
release something like this unless they had repeatedly reproduced results and
were extremely confident in their findings.

------
asmithmd1
5 degrees above absolute zero, in a 7 tesla magnetic field produces a 12%
effect by a completely unexplained and unpredicted mechanism.

I will wait for another researcher to confirm before I get too excited.

~~~
stolio
As tbrownaw points out elsewhere they apparently do have an explanation and
maybe even the ability to predict the behavior.

Essentially this isn't _that_ far away from more common things like
paramagnetism and diamagnetism where electron orbitals align with an applied
magnetic field and the properties of the material change, except in those
cases it's their magnetic properties that change. In this case they're saying
the speed at which waves/quasiparticles are transmitted through the material
changes.

I'm not fond of the title but it's an interesting idea.

------
gobengo
I'm just an amateur, but this doesn't actually seem that surprising.

It's also relevant to the part of the book I'm reading now, which I highly
recommend to anyone interested in QED, Electromagnetism, or even just Computer
Science.

"The Emperor's New Mind" by Roger Penrose (1989) -
[http://en.wikipedia.org/wiki/The_Emperor%27s_New_Mind](http://en.wikipedia.org/wiki/The_Emperor%27s_New_Mind)

------
sebkomianos
What I thought the article was about after reading the title here: "Heat and
sound are magnetic"

What I thought the article said after reading the article itself: "Heat
propagates as a wave rather than as atoms. These waves are called "phonos"
(wtf?! #1) and they carry sound too (wtf?! #2)"

What people with knowledge in the field seem to think about the article,
judging from the comments: "Total bullshit".

I'd love someone to elaborate with some patience and simple explanation of
what this is (and isn't) about because it sure sounds very interesting.

------
gaze
In a damned material! If you have the right terms giving a coupling between
the electromagnetic field and phonons, yes, yes that's what happens. No, in
free space, there is no such coupling.

~~~
qnaal
We've been in a low-fun aether pocket for a while now- maybe in a few
centuries..

------
ChuckMcM
Sigh. It is an interesting result, but I expect that you'll find that magnetic
constriction of the structural motion has much more to do with heat
propagation (or not). If someone liberates the actual paper I would be
interested in reading it.

~~~
ISL
The research group put up a PDF (direct DropBox link is theirs) here:

[https://windlgroup.engineering.osu.edu/publications](https://windlgroup.engineering.osu.edu/publications)

[https://dl.dropboxusercontent.com/u/27852198/WW/Jin_NM_2015....](https://dl.dropboxusercontent.com/u/27852198/WW/Jin_NM_2015.pdf)

~~~
tbrownaw
Cool.

"""The displacements of atoms locally affect the orbital motion of valence
band electrons, which, in the presence of an external magnetic field[...]. The
process is modelled by _ab initio_ calculations that, without the use of a
single adjustable parameter, reproduce the observed 12% decrease in the
lattice thermal conductivity[...]"""

 _Because the bonds between atoms are based on electrons, they can be affected
by magnetic fields. Which means that materials can have different properties
when exposed to magnetic fields, even if they 're not magnetic themselves. We
understand this well enough to model it exactly, at least in simple cases._

~~~
throwaway854652
So ... Val Kilmer in "Real Genius" was right that freezing a liquid laser
increases the efficiency, and 30 years ago at that?

[http://en.wikipedia.org/wiki/Real_Genius](http://en.wikipedia.org/wiki/Real_Genius)

------
tbrownaw
How is this any different than materials that change color or refractive index
based on temperature?

Yeah it's kinda cool, but the interpretation (and title) are ridiculous.

"Semiconductor found to have different physical properties when under strong
magnetic field."

------
lotsofmangos
makes perfect sense for materials that allow idealised forms of wave
propagation to behave like this. Might even make a neat sonoluminescent thingy
if you fiddle with it.

