Slashdot Mirror
Physicists Say Graphene Could Create Mass
eldavojohn writes "Graphene has gotten a lot of press lately. The Nobel prize-winning, fastest-spinning, nanobubble-enhanced silicon replacement is theorized to have a new, more outlandish property. As reported by Technology Review's Physics Blog, graphene should be able to create mass inside properly formed nanotubes. According to Abdulaziz Alhaidari's calculations, if one were to roll up graphene into a nanotube, this could compactifiy dimensions (from the sheet's two down to the tube's one), and thus 'the massless equations that describe the behavior of electrons and holes will change to include a term for mass. In effect, compactifying dimensions creates mass.' What once would require a massive high-energy particle accelerator can now be tested with carbon, electricity, and wires, according to the recent paper."
Scientists have now isolated the particle that causes this strange mass inducing effect, and have dubbed it the "YoMamma".
which is totally what she said
the Mass Effect.
I think they're just claiming the mass they expect to make next year, assuming they'll balance their mass sheets at that point?
The /. title of this article is wrong, stupid and misleading.
The title of TFA is "Dynamical mass generation via space compactification in graphene", which is mostly incomprehensible.
The abstract sez "Fermions in a graphene sheet behave like massless particles. We show that by folding the sheet into a tube they acquire non-zero effective mass as they move along the tube axis. That is, changing the space topology of graphene from 2D to 1D (space compactification) changes the 2D massless problem into an effective massive 1D problem."
A plain english annotated translation is "Electrons in a graphene sheet behave like massless particles. We show that by folding the sheet into a tube they behave like massive particles as they move along the tube axis. That is, changing the shape of graphene from 2D to 1D changes the 2D massless problem into an effective 1D massive problem, which may be easier to solve or model or understand in certain respects.
Note electrons have the same real mass in both cases. Mass is not being created or destroyed.
HCG 50a = 2MASX J11170638+5455016
11h17m06.4s +54d55m02s
Thank God. I thought for sure that George W. Bush had become a /. editor. The extra "i" does leave open the possibility that Dan Quayle is working as a copy editor.
Some mornings it's hardly worth chewing through the restraints to get out of bed.
Sheldon?
Dr. Sheldon Cooper?
Is that you?
Mess not in the affairs of dragons, for you are crunchy and good with ketchup.
It seems to me that it's poorly worded. As far as I can tell, it's not 'creating mass' so much as it is 'creating dependency on mass'
Normally the equations governing movement of electrons are independent of mass. In graphene it appears we should be able to make it dependent on the mass of the electron.
So I believe the article is saying that they believe they can make some particles that didn't appear to have a mass have a new equation for movement that reveals a mass for them. The article mentions that there's a theory that these particles didn't have a mass before this point; that the actual changing of rules that govern movement creates the mass.
I like to think of it as the equivalent of creating charge. You're not actually making anything; you're just moving electrons/protons so they're out of balance. Essentially this could be the same thing with gravity.
Now if this could be reversed to make something mass-less, that would be interesting
It's not the dimensions in which the graphene occupies that is 1D. It's the dimensions along which a particle moves. Graphene, being 1 atom thick, would normally be a sheet, occupying 3 dimensional space. The particles would move along the graphene in 2 dimensional space. If you rolled the sheet into a single atom thick carbon nanotube, it still occupies 3 dimensional space, but the particles will only move along 1 dimension.
Math trick slash analogy. In graphene, electrons behave like massless particles traveling near the speed of light. What this means is that energy increases linearly with particle speed, rather that KE = 0.5 m v^2 , like you learned in physics 101. Particle physics people have argued that adding compact dimensions (rolled up) will change interactions, and these guys have showed that you can also get electrons to act like massive relativistic particles in tubes of graphene. I'm not an expert in the field, but this seems to be a little buzzword-heavy, rather than really groundbreaking. As far as I know, the connection between graphene and relativity had not taught us anything new about relativity, or how mass is generated, but it is kinda cute and gets headlines.
If you RTFA they clarify that the tube is 1 dimensional as far as the electrons and holes are concerned, probably because instead of being able to move across the sheet of graphene in both the x and y directions they're now constrained to move only in one direction, up and down the nanotube. If there's only one possible axis of movement, then you're effectively in a 1 dimensional system.
Murphey's fighting Occam, and we're in the stands.
All science predictions are math tricks. If the prediction holds up, our existing models are correct, otherwise, our existing models are broken. Creating mass from graphene is not a new theory, it is the _consequence_ of our existing theories that someone cleverly derived.
Point is, either way, Abdulaziz Alhaidari is now famous and has done the incredible. He's either famous for making a marvelous derivation of our existing theories, or he's famous for disproving our current models by explaining what our current models predict that would later be experimentally contradicted. Just as the Manhattan project was a test of atomic theory; if it worked, an amazing weapon was created; if it didn't work, it had profound ramifications on invalidating the the atomic theory of the day. Either it's a win for engineering, building something amazing, or a win for science, changing the models to more closely match reality.
We have that already. They're called baristas.
He's not a Muslim, you dumbass. Anyone can extrapolate from his name that he's clearly Japanese.
And if you squeeze the nanotube very, very hard, it disappears!
Of course you know that centrifugal force is not a real force, but a pseudo force you conjure up if you are working on a reference frame attached to the train. From an inertial frame of reference, your velocity is being changed constantly. Change in velocity is acceleration. The change in direction would be towards the center of the circular track. That acceleration is centripetal acceleration. The train is exerting a force centripetal force on you. The reaction from your body on to the train for that force times friction coefficient gives you the force that is holding you still stuck like a fly on the wall of a train moving in a circular track.
As one who has spent years hanging on to the window bars of trains and buses in Chennai, India, let me tell you, no matter how many Einsteins tell you that is a pseudo force, it felt real and that I am still living, not having been run over decades ago by the next bus or train proves that centrifugal force is real. Not pseudo.
Similarly the fermions seem to be having a mass to satisfy some equation in some frame of reference after some coordinate transformation. But really it is not creating any mass.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
I don't think they're suggesting more carbon atoms are being created out of thin air. It seems like they're saying it would have the same size and number of particles, but its mass would go up -- i.e. it would have more inertia. Lots of models in physics require "gaining mass" -- i.e. gaining inertia.
Einstein predicts as you accelerate to the speed of light, you gain mass in your reference frame -- i.e. it becomes harder and harder to accelerate yourself further because you appear to be getting infinitely massive. Einstein is not suggesting that your belly expands and you start generating more particles. He's using "mass" interchangeably with "inertia". Greater mass == greater inertia, when all else is kept constant.
Similarly, the experiment with graphene suggests that a proper configuration of it will yield something with greater inertia (i.e. greater mass) than its constituent masses imply.
I thought that was "Hold my beer and watch my try this... "
The link to the paper just gives the executive summary, which actually conveys little information. Even wikipedia wasn't much help. If there's a physicist out there, I get the impression that somehow leptons are being converted to fermions? If so, how, and why do they? If not, could someone give a good explanation?
This is fascinating, but I can't find much explanation.
http://www.ncbi.nlm.nih.gov/pubmed/17358966
Magnetic confinement of massless Dirac fermions in graphene.
De Martino A, Dell'Anna L, Egger R.
Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
Abstract
Because of Klein tunneling, electrostatic potentials are unable to confine Dirac electrons. We show that it is possible to confine massless Dirac fermions in a monolayer graphene sheet by inhomogeneous magnetic fields. This allows one to design mesoscopic structures in graphene by magnetic barriers, e.g., quantum dots or quantum point contacts.
PMID: 17358966 [PubMed]
Free Martian Whores!
Recall that this method of mass generation has been utilized exclusively in high energy physics, supergravity, string theory and related fields [9]. To the best of our knowledge, the present work constitutes the first successful application of this method in condensed matter physics. Another example of space compactification is found in a system consisting of a stack of graphene sheets with coupling between the layers making the massless 3D problem equivalent to an effective massive 2D problem [8].
In other words: "We applied an existing math trick to a new area of theoretical physics, and things look good so far."
You take that, feed it to the "Technology Review" blog, and you get:
The amazing properties of graphene now include the ability to create mass, according to a new prediction.
...which is not quite the same.
If there's a physicist out there, I get the impression that somehow leptons are being converted to fermions?
When life hands you leptons, make leptonaide.
Indeed, I'm not a physicist. How'd you guess?
Welcome to the Panopticon. Used to be a prison, now it's your home.
Yes, they're actually losing a little mass on each transaction, but they're buying "observations". They'll make is up on volume!
I still cannot find the droids I am looking for...
The bogon.
Seriously, can't anyone at Tech Review spot the flaw here? A tube still has more than one dimension. Even if you managed to create a chain of single carbon atoms, you'd still have multiple dimensions, in that the atoms comprising the chain are not infinitely short and infinitely flat.
Bah. Sensationalist nonsense non-news.
"What in the name of Fats Waller is that?"
"A four-foot prune."
Actually, the abstract nails what the actual news here is.
You can't confine a Dirac electron electrostatically. They show that it can be done with magnetic fields. This is sort of cool because it has potential ramifications for incorporating nanotechnology into electronics.
After the wharrgarbl, it mutates into a headline about creating mass and using it to power FTL starships from video games.
Indeed, I'm not a physicist. How'd you guess?
Um, your user name?
Free Martian Whores!
I asked a similar question, and this guy seems to have nailed it. I hope the mods notice his answer.
Free Martian Whores!
No, more like a Catholic priest. They create mass from hot air, holy water, some wine and a cracker, don't they?
Physics can't do that!
Free Martian Whores!
The /. title of this article is wrong, stupid and misleading.
Seconded. Just to clarify, the only thing that's changing here is the dispersion relationship. In graphene the energy of carriers grows linearly with momentum due to strong spin-orbit coupling. In most materials the energy grows proportional to the momentum squared. People have known for a long time that you can do all sorts of things to graphene to change the dispersion relationship so that it acts like other materials. For a bit of a overview see http://www.lbl.gov/publicinfo/newscenter/pr/2008/ALS-graphene-electrons.html
In graphene, electrons behave like massless particles traveling near the speed of light.
No, electrons do not.
"Charge carriers", which in the case of graphene are quasi-particles that result from the interaction of electrons with the more-or-less 2D medium, do.
The difference is tremendously important, althought admitedly your explaination is about a million times better than the gibberish in the headline and summary.
This is interesting and legitmate physics: charge-carrying quasi-particles in 2D graphene behave as massless particles in a 2+1D spacetime (according to the paper, at least.) If you role the sheet up the dynamics of the quasi-particles becomes that of massive particles in a 1+1D spacetime. This allows experimental realization of systems described by relativistic dynamics (the Dirac Equation) under much simpler circumstances than one might generally expect.
This is similar to the research on "solid state monopoles" which behave like Dirac monopoles over large distance scales. They allow the study of a wide range of phenomena that are otherwise inaccessible (and in the case of Dirac monopoles, entirely theoretical!)
No mass in the ordinary sense of the term is created in the situation the paper describes. If you weighted the system with a sufficiently sensitive balance you would not find that the apparatus weighted more when the graphene sheet was rolled up.
Blasphemy is a human right. Blasphemophobia kills.
Cheers, thanks. The main issue is that the blog really made a hash of the explanation with sensationalist claptrap:
... which is utter hokum. Further down the page, there are a couple breakdowns of the paper itself, which make it clear that what they're doing is what you say -- constraining the physics of a potential experiment to simplify the mathematics involved.
Cheers,
"What in the name of Fats Waller is that?"
"A four-foot prune."
People (i.e., mostly you) seem to blame kdawson, but really, he's just clicking the button when the post bubbles to the top of the Firehose, which happens because the Firehose is an idiocracy. People voting there are mostly ignorant, so anything that is above their understanding gets a positive nod, because most things that reach the front page are above their understanding, so they think that's the criterion.
Sometimes, not voting is better for you than voting is. Like, when you're too uninformed or misinformed to make a correct decision.
Normally the equations governing movement of electrons are independent of mass.
That's only because the mass of the electron (1/1900th the mass of a neutron or proton) is usually negligible in the dynamics you're calculating.
In superconductors, the equations really do eliminate the force of mass*acceleration from consideration, along with any other forces the electrons would normally be expected to react to (that would contribute to transfer of energy that would make the nuclei vibrate randomly in place; i.e., resistance heating).
Apparently all that's happening here is that he's predicting nanotubes not to have all of the properties that flat graphene sheets have. And he's saying it in a way that confuses most people, including many of those who could probably have derived it and described it in a much less confusing way.
If there's a physicist out there, I get the impression that somehow leptons are being converted to fermions?
Leptons (e..g electron) are fermions. However there is something very fishy with this paper. For example 10^6 m/s is not relativistic. If you calculate the gamma factor (gamma=1 is what Newtonian physics assumes) you get 1.0000056. This means they are very non-relativistic and Schrodinger should work fine for them unless there is some subtle effect at play. Indeed to give electrons this energy you need to accelerate them through a potential of 2.8 volts so rather than needed a particle accelerator any one with a vacuum pump, a vacuum-tight container, some wire and two AA batteries can experience the fun of "relativistic" electrons.
What I suspect is happening is that the conditions on graphene have altered the electron behaviour so, rather than test anything fundamental, you are testing the properties of electrons on graphene. You cannot do real relativistic physics with this because if you get an unexpected result you have no idea whether it is because there is some new, unexpected physics at work or whether your approximation of the environment is simply wrong and you need to use a different model for it. Hence, while interesting, this is not the way to do real, relativistic physics: for that you need something that is truly relativistic, not just something which might, under certain conditions, act like something relativistic.