More on Spintronics 202
segment writes "'We have discovered the equivalent of a new 'Ohm's Law' for spintronics - the emerging science of manipulating the spin of electrons for useful purposes,' says Shoucheng Zhang, a physics professor at Stanford. 'Unlike the Ohm's Law for electronics, the new 'Ohm's Law' that we've discovered says that the spin of the electron can be transported without any loss of energy, or dissipation. Furthermore, this effect occurs at room temperature in materials already widely used in the semiconductor industry, such as gallium arsenide.'"
arse.... (Score:2, Funny)
Man it seems like that stuff NEVER goes away. Haven't we invented 10 technologies to get rid of that stuff already?
Gallium replacements (Score:2)
Re:arse...err...GaAs (Score:2)
In the last few years logic speeds have approached this, and you can now by GHz-level gates as part of the ECLinPS family [onsemi.com].
The Article (Score:3, Informative)
dawnlevy@stanford.edu [mailto]
650-725-1944
Stanford University [stanford.edu]
'Spintronics' could enable a new generation of electronic devices, physicists say Moore's Law - a dictum of the electronics industry that says the number of transistors that fit on a computer chip will double every 18 months - may soon face some fundamental roadblocks. Most researchers think there'll eventually be a limit to how many transistors they can cram on a chip. But even if Moore's Law could continue to spawn ever-tinier chips, small electronic devices are plagued by a big problem: energy loss, or dissipation, as signals pass from one transistor to the next. Line up all the tiny wires that connect the transistors in a Pentium chip, and the total length would stretch almost a mile. A lot of useful energy is lost as heat as electrons travel that distance.
Theoretical physicists at Stanford and the University of Tokyo think they've found a way to solve the dissipation problem by manipulating a neglected property of the electron - its ''spin,'' or orientation, typically described by its quantum state as ''up'' or ''down.'' They report their findings in the Aug. 7 issue of Science Express, an online version of Science magazine. Electronics relies on Ohm's Law, which says application of a voltage to many materials results in the creation of a current. That's because electrons transmit their charge through the materials. But Ohm's Law also describes the inevitable conversion of electric energy into heat when electrons encounter resistance as they pass through materials.
''We have discovered the equivalent of a new 'Ohm's Law' for spintronics - the emerging science of manipulating the spin of electrons for useful purposes,'' says Shoucheng Zhang, a physics professor at Stanford. Professor Naoto Nagaosa of the University of Tokyo and his research assistant, Shuichi Murakami, are Zhang's co-authors. ''Unlike the Ohm's Law for electronics, the new 'Ohm's Law' that we've discovered says that the spin of the electron can be transported without any loss of energy, or dissipation. Furthermore, this effect occurs at room temperature in materials already widely used in the semiconductor industry, such as gallium arsenide. That's important because it could enable a new generation of computing devices.''
Zhang uses a celestial analogy to explain two important properties of electrons - their center of mass and their spin: ''The Earth has two kinds of motion. One is that its center of mass moves around the Sun. But the other is that it also spins by itself, or rotates. The way it moves around the Sun gives us the year, but the way it rotates around by itself gives us the day. The electron has similar properties.'' While electronics uses voltage to move an electron's center of mass, spintronics uses voltage to manipulate its spin.
The authors predict that application of an electric field will cause electrons' spins to flow together collectively in a current. The applied electric force, the spins and the spin current align in three different directions that are all perpendicular to each other (see film of the effect at http://news-service.stanford.edu/news/2003/august2 0/zhang-video-820.html [stanford.edu]).
''This is a remarkable thing,'' explains Zhang. ''I push you forward and you move sideways - not in the direction that I'm pushing you.''
So far, only superconductors are known to carry current without any dissipation. However, extremely low temperatures, typically -150 degree Celsius, are required for the dissipationless current to flow inside a superconductor. Unlike electronic superconductors being investigated in advanced laboratories throughout the world, whose operating temperatures are too low to be practical in commercial devices, Zhang, Nagaosa and Murakami theorize that the dissipationless spin cur
Ohms = 0 (Score:2, Interesting)
YEA BABY!
Re:Ohms = 0 (Score:2, Funny)
Not so remarkable (Score:5, Funny)
Same thing happens with me after about a six pack.
Re:Not so remarkable (Score:2)
entanglement? (Score:3, Interesting)
Isn't it a property of these kinds of things that you can seperate two electrons (or some subatomic particle, can't remember) and change one's spin, and the other, no matter how far away, will instantly change? I recall an experiment in which this worked over a distance of six miles. Wouldn't this be the perfect interconnect? No wires at all?
Re:entanglement? (Score:3, Informative)
Re:entanglement? (Score:5, Informative)
1. Once you transmit using a particular electron pair you can't use that pair again, so you have to pre-prepair as many electron pairs as you think you will need for a transmission.
2. Creating perfectly isolated pairs is difficult. The basic problem is making sure the pairs you create aren't entangled with any other qubits (and using extra bits to do error correction because its next to impossible produce pure states) People are working on efficient ways to do this, but although it won't be prohibitive for, say, prearranged data transmission it really wouldn't be economical for circuits.
This article is talking about something else aparently: some kind of wave of spin -- like a current.
(BTW in the method you're talking about one doesn't exactly "change the spin"
Re:entanglement? (Score:2)
You can't actually use it to transmit anything. When either person makes a measurement on their own they always get a random result. It's just that one person's random results will always match up in certain patterns when you compare them with the other person's results.
It does allow something really weird though. If you make a measurement and transmit a single bit in a normal sub-light way and THEN the other person makes a m
Re:entanglement? (Score:5, Informative)
Re:entanglement? (Score:4, Informative)
What does this have to do with ohm's law? (Score:4, Insightful)
Jason
ProfQuotes [profquotes.com]
Re:What does this have to do with ohm's law? (Score:5, Informative)
Ohm's law describes the creation of a current by the application of a voltege. This new law seems to describe the creation of a, um, whatever you want to call the "movement" of the spin of an electron, by the application of an electric field. Or more accuratly, it probably describes the movement of a group of spins.
They're describing generally the same kind of action, at least viewed in a certain way, in two different kind of "substances."
Re:So where's the damn forumula? (Score:2)
Yeah, i have no clue what the actual spintronics formula is, the article didn't say and it would be usefull information to have.
However without knowing any more about it, it's still possible to make comparisons of the nature of this law with the nature of other laws. Equations describing similar
Re:What does this have to do with ohm's law? (Score:5, Informative)
Not all devices are linear and follow Ohm's law over wide ranges of voltages/currents. Sometimes there's an exponential relation, or others. For example, in a superconducting filament, one has bizarre quantum effects kicking in for the effectively 1-D system, and the effective Ohm's law has the voltage proportional to exp[I]. Only linear (and hence Ohmic) at small currents.
Then there's the Hall Effect where a current flowing through a wire (can be a thin foil) with a perpendicular magnetic field will cause the current carriers (either electrons or holes) to drift to one side or the other of the foil [F=q(v x B)] where the F is the force, v is the carrier velocity, and B is the magnetic field. x is a cross-product (v and B are vectors, so is F). In other words, the force acting on the carriers is perpendicular to the B-field and the current velocity, and creates a transverse voltage, often called the "Hall Voltage". So you now have a current creating a transverse voltage, which lets you apply a variant of Ohm's Law to define a Hall Resistance, sometimes called Rxy, where Rxy=Vhall/I (could be a non-linear relation too).
So in this case of spintronics, they define another variant of Ohm's Law to relate the current of the spins in relation to an applied electric field. Note that the transfer of spins across the device probably doesn't correspond to the actual transfer of electrons, but a signal propagation of spins instead.
Finally, there are other cases where one can have current flow without resistance. One case is superconductors. Another is the so-called Quantum Hall Effect. However, both of these occur at cryogenic temperatures.
Re:What does this have to do with ohm's law? (Score:2)
This makes me think of ..... (Score:2, Offtopic)
In theory you take a rod that goes from one galaxy to a distant galaxy many many lighyt years away. With a slight movement on one end of the rod, ina back and forth movement, the other end moves, effectively allowing communication based upon movement. Movement that is far slower than the speed of light but able to communicate to distances beyond the limitation of the speed of light.
Of course that is a simple theory only to communicate the con
Re:This makes me think of ..... (Score:1)
Re:This makes me think of ..... (Score:4, Interesting)
Speed of sound, btw, does not have to involve actual sound waves... the speed of sound is simply the rate at which vibration or motion of molecules within a medium can propogate through the medium by affecting adjacent molecules.
Re:This makes me think of ..... (Score:2, Informative)
Nick Herbert describes this fallacy in Faster Than Light: Superluminal Loopholes in Physics [amazon.com].
Re:This makes me think of ..... (Score:2)
But the point I was making was in regards to aproaching a problem or situation from a different perspecitve and finding a much easier solution.
If two objects are traveling at near the speed of light, but in opposite directions and you were on one of them
Re:This makes me think of ..... (Score:2)
Could they collide if they were traveling in opposite directions? I guess they could, but that would it might make it clearer if you said they were traveling towards each other at the start.
Ok, so I poked a little fun of the question, but really, unless the object travelling towar
Re:This makes me think of ..... (Score:2)
To some extent this can be calculated by using ray tracing animation software. But it should be noted that additional calculations would need to be taken into account as va
Re:This makes me think of ..... (Score:2)
The speed of light is not absolute. Its relative to the movement of the observer. When you say "near the speed of light," you must always specify whose reference point are you referring to? An observer at rest, or the objects reference point? Either way, there is no fallacy.
anyway
Reading it... makes me think of .....even more (Score:2)
This spin issue seems to suggest syncing as well, but without the concerns of tempature constraints below room tempature.
Re:This makes me think of ..... (Score:5, Informative)
The rod would move at the speed of sound through its medium (the speed of sound varies largely depending on its medium). IN any case, it would be MUCH slower than the speed of light.
Currently, the only thing confirmed to move faster than the speed of light (confirmed via the "alan aspect" experiments, if you want to google it), is the spin on a pair of electrons. Two elextrons in a pair alwats spin in reverse directions. Even if the two electrons are 1000 miles apart, if you polarize one (change the spin), then the other spin will reverse itself instaneously.
This was tested by alan aspect (who built upon the EPR thought experiment), who subjected two electrons traveling in opposite directions to a polarizer and found that the correspondency between the two electrons meant that there HAD to be some osrt of faster than light communication (it violated "bells theorum" if you want to do more googling). That is, it wasnt a coincidence, or due to 'hidden variables' as einstien thought. It truly was faster than light communication, somehow, between the electrons.
This is the main discrepancy between Einstein's relativity and Bohr's quanutm theory (Einstein's theories actually pushed quantum theory, ironically). Einstien's relativity theory states that should anything move faster than the speed of light in the spatial dimensions (x,y,z), it must move backwards in the fourth dimension (time). Basically, he argues that everything moves through the four dimensions (x,y,z,t) at the speed of light. Photons move through the spatial dimensions (x,y,z) at the speed of light, and thus do not mvoe through time at all. The photons that exist now have not aged at all since the big bang. This is how einstien explains "Time dilation." This has been confirmed a number of ways, most easily by clocks on airplanes. Clocks put on airplanes, which move through the spatial dimensions(x,y,z) through high speeds (high being relative to normal human movement) have been found to register less time than their "at-rest" counterparts. Of course, quantum theory somehow defies this concept. String theory explains this by offering multiple dimensions past the 4th (I beleive steven hawking's count is at 14 right now)...
Not so sure about quantum computers, but i belive this is the idea behind them. Transistors used now read either High or low, +5v or 0v, which correspond to binary terms of 0 or 1. Thus we can gather data by reading the charges on the transistors. If we could use electrons, a up-spin meaning 0 and a down-spin 1 (not really up or down, but thats how we denote them), then we could use a 100% efficient replacement for transistors.
If anyone wants to correct me, please do. I havent taken a physics course in my life (yet) and am probably wrong about some (most) of what i just said.
Re:This makes me think of ..... (Score:2, Interesting)
Not so sure about quantum computers, but i belive this is the idea behind them. Transistors used now read either High or low, +5v or 0v, which correspond to binary terms of 0 or 1. Thus we can gather data by reading the charges on the transistors. If we could use electrons, a up-spin meaning 0 and a down-spin 1 (not really up or down, but thats how we denote them), then we could use a 100% efficient replacement for transistors.
No, quantum computers aren't about eff
Re:This makes me think of ..... (Score:2)
Mmmm. Prolog would work really well on this computer.
Re:This makes me think of ..... (Score:2)
Not even close. There are TONS of things faster than light. The focal point on a pair of fast-closing scissors, shadows across the moon, etc. Here, imagine this, you are point a super powerful laser at the moon and you move your laser in an arc. Now, from your perspective, the laser dot on the moon moves from one side to
Re:This makes me think of ..... (Score:2)
If the focal point on a pair of scissors is the point at which the two blades meet, the for the focal point to move, would not each of the blades have to be traveling at > 1/2 C to have that point move faster than C? The focal point really isn't an object, just a point that appears to move as the blades cross.
Here, imagine this, you are point a super powerf
Re:This makes me think of ..... (Score:2)
Nope, they can move a fraction of an inch per year.
Imagine a pair of scissors 10 light years long with the tip only open 1/10th of an inch. Move the blades that 1/10th of an inch over the course of an entire year and the intersection point moves 10 times the speed of light.
This is not a violation of the speed of light because the intersection point is not really a "thing". No object is exceeding the spe
Re:This makes me think of ..... (Score:3, Interesting)
Re:This makes me think of ..... (Score:2)
Are you sure about this?
As I remember the initial thought experiment, the two photons have opposite spins and so when you mea
Re:This makes me think of ..... (Score:3, Insightful)
Close, but not exactly. You are not changing the polarization. This is a really bizzare part of quantum mechanics, but neither
Re:This makes me think of ..... (Score:2)
No, that just indicates you have absolutely no understanding of it . It is nothing like that.
You can interpret this as the existence of hidden variables or as spooky action at a distance.
Wrong. Hidden variables was rejected out of mathematical contradiction.
I am reffering t
Re:This makes me think of ..... (Score:2)
XYZ = (-1, -1, -1)
Any pair will yeild the result (-1 * -1 = +1)
Measuring the triple will yield the result (-1 * -1 * -1 = -1)...
If the pairs were to yield -1, This is (algabraically) impossibl
Re:This makes me think of ..... (Score:2)
Re:This makes me think of ..... (Score:2)
Other people have interpreted general relativity as differentiating gravity from the other forces b
Re:This makes me think of ..... (Score:2)
Re:This makes me think of ..... (Score:2)
Gravitational waves, for instance, propagate at the speed of light in general relativity.
Moving at the speed of light does not require that it have an associated "particle". In fact, no o
Re:This makes me think of ..... (Score:3, Informative)
Re:This makes me think of ..... (Score:3, Informative)
Re:This makes me think of ..... (Score:3, Interesting)
Not true. Suppose you have two masses rotating each other like the Moon around the earth. Space time curvature is changing as this happens. One moment it's shaped like X, the next like Y. A test mass will see a lag time in the shape of its local spacetime due to this movement. That is, when the masse
Re:This makes me think of ..... (Score:2)
Not quite. There is no such thing as conservation of charge motion. There IS such a thing as conservation of MASS motion: it's called "momentum", which implies that an oscillating mass does not create gravity waves.
Now, there's no such thing as "conservation of force", so you can have a quadrupole oscillation cause gravity waves, but you can't just wiggle something back and for
Re:This makes me think of ..... (Score:2)
You mean that stuff they sell in e-mails really works?
I don't suppose (Score:1)
You beat me to the punch line (Score:2, Funny)
A decade isn't that much time... (Score:5, Funny)
If the actually manage to go from idea to commerically competitive "spintronic" circuitry in only a decace, I'll consider that proof of some sort of space-alien technology transfer deal [dreamlandresort.com] going on.
Ohm's law (Score:5, Funny)
So, he shows up with a bunch of other hopefuls (again, his words), and takes the test. One of the questions is 'state the 3 forms of Ohm's law." As a good ee, he immediately writes down 'V = IR', no problem. Thinking (!!), he remembers there is a form involving current density, and sets about to derive it (in class this included the steps he took). Now, a third form. He drew a blank, so went and finished other parts of the test.
Coming back to this question, he's suddenly inspired by remembering something based on magnetic density in a coil or transformer. Again, he sets out to derive the equation, but the guy giving the test says 'times up' before he can finish.
The next day, he heads back to the recruiting office, and asks how he did. "Great," says the sargeant, "but, what was up with the Ohm's law question?"
"Oh, the standard form, and then experessed in current density, and...."
"Nah, all we wanted was V = IR, I = V/R, and R = V/I."
Proof of, once again, that engineers, like musicians should not try to be funny.
Does Anyone Remember Cold Fusion? (Score:2, Interesting)
Re:Does Anyone Remember Cold Fusion? (Score:5, Interesting)
Re:Does Anyone Remember Cold Fusion? (Score:5, Insightful)
Entropy is not an absolute law, but a law based on extreme probabilities. In any reaction, certain quantities are completely conserved. One of these is energy.
The increase in entropy that occurs is due to energy being converted into less usable forms, such as from motion (kinetic energy) to heat (thermal energy).
It is not actually a decrease in total energy. Energy is perfectly conserved in any reaction.
In subatomic reactions, there is no place for energy to go, so to speak. In fact, the only thing energy really is is the motion (and mass, though those are remarkably interlinked) of subatomic particles.
When two subatomic particles collide, if neither of them splits or gives of any other particles, the energy remains entirely in the two particle system (that is, all that changes is kinetic energy; speed). Well, direction changes as well.
Mod parent down; he is incorrect. (or not, I'm actually in favor of the mod up only philosophy, but parent would be a good one to mod down if you believe in modding factually incorrect posts down).
Re:Does Anyone Remember Cold Fusion? (Score:2)
But in reality you are right... there is always 100% energy transfer, just that not all of it is necessarily *useful*.
Re:Does Anyone Remember Cold Fusion? (Score:2)
Re:Does Anyone Remember Cold Fusion? (Score:2)
Alternatively, you could say that a system like a single electro
Re:Does Anyone Remember Cold Fusion? (Score:2)
for entropy to decrease.
Re:Does Anyone Remember Cold Fusion? (Score:5, Interesting)
see that they are basically talking about a more
sophisticated version of a quantum-hall effect,
i.e. they are talking about the evolution of a
correlated state, a different one from superconducting
condensate or bose condensate but another type
of correlated state. Correlated states can result
in negligible dissipation (e.g. superconductivity
or superfluidity). They will not be immune from
thermal fluctuations esp. at room temperature nor
will they be immune from dissipation at impurities
and such. But other than that having spin supercurrent
seems quite possible.
And I am a graduate student doing physics research
in the are of high-temperature superconductivity.
Mr. Zhang is quite well known in this area since
he proposed a so called SO5 theory which aimed to
explain everything about high-Tc in one elegant
formalism (his theory is oversimplified at best).
He has worked with Bob Laughlin a lot lately (Laughlin
got a Nobel prize for his theoretical work on, you
guessed it, quantum-hall effect). So these people
are legit, they know what they are talking about
but Zhang has been known to throw wild ideas out
there (and more often than not even those have
at least a grain of truth in them).
Re:Does Anyone Remember Cold Fusion? (Score:3, Interesting)
In general, electons exist in a superposition of two states, "up" and "down", with oppositely directed "spin" (which obeys almost the same mathematical formalism as angular momentum, with some interesting twists). For a free system of electrons, the up and down states occur with equal measure so that the resulting wavefunction is spinless (sum of spin over all electrons is zero) which implies it is rotation
Spins (Score:2, Informative)
Re:Spins (Score:2)
The "electron number" is conserved. The electron and electron neutrino have an electron number of 1, while the positron and the electron antineutrino have an electron number of -1. This is why beta decay produces the antineutrino.
makes me think of... (Score:3, Funny)
Of course, if all his electrons stopped spinning it would probably be the most interesting televised farewell I've ever seen.
Ampere's Law (Score:3, Interesting)
The real question is, what is 'spin current', and how does it relate to the conventional definition of electric current.
Re:Ampere's Law (Score:2)
Spintronics is NOT the next thing (Score:4, Interesting)
Spindizzy (Score:3, Funny)
I want a Spindizzy.
(ref: James Blish, "Cities in Flight")
Scotty (Score:2)
Kirk: Warp Factor Ten Scotty!
Scotty: I'm giving her all the gallium arsenide we've got Captain but she's suckin' mud!
Re:Scotty (Score:2)
Scotty: We haven't go the power capt'n, the electrons are spinning out of control!!!
I'll apply my general rule... (Score:3, Insightful)
The article is misleading on key points (Score:5, Insightful)
The discussion on spin is wrong. Spin has nothing to do with the rotation of macroscopic objects like the Earth, it's an intrinsic quantum property of particles like the electronic with no macroscopic analog. The best explanation I've heard of spin that doesn't involve explaining the details goes like this: spin is a measurement of the number of rotations required to bring a particle back to its initial state. One-half spin particles, like the electron, require, counterintuitively, two full rotations to go back to their initial state.
The physical situation seems to have very little to do with Ohm's Law except in the loosest sense. They're describing a current consisting of electron spins under an external electric field. This has some interesting properties (I'd like to poke at the math, if I could read the paper), one of which seems to be that it is predicted to persist at much higher temperatures than the best superconductors. If so, because this spin current seems to be dissipationless, this would allow information to be transmitted without generating heat.
Interesting stuff; a pity the article was so poor.
Re:The article is misleading on key points (Score:3, Funny)
So then what you're saying is, the article is all spin?
Re:The article is misleading on key points (Score:2)
Spintronics is already in use (Score:2)
From what I understand, the read/write heads of just about every modern disk drive are spintronics devices. Without them, we'd probably still be stuck with 1 GB disk drives.
Re:Spintronics is already in use (Score:2, Informative)
Re:Spintronics is already in use (Score:3, Informative)
With a quick google search, you can find a number of references to the use of spintronics for disk drive heads. Here are just a couple.
Here is something from 1999: [aip.org]
A link to the paper (Score:3, Informative)
Say goodbye to your fans... (Score:4, Interesting)
Re:Say goodbye to your fans... (Score:2, Informative)
Re:Say goodbye to your fans... (Score:2)
This isn't actually an "exponential" decrease.
Yes, I know, I was using the vernacular. Your point is well made, though, so thank you for elucidating.
The hard drive problem isn't likely to go away until we overcome the problem of the read/write lifespan of flash RAM and similar technology, not to mention price, as you say.
Info on -e spin and orbitals from ScienceWorld (Score:2)
This is a new part of (or companion to?) Eric Weisstein's Mathworld [wolfram.com]. It's expanded now into Science World [wolfram.com]. Some of the references to electrons and spin are not yet complete, but there's enough here to get started.
Re:relevant? (Score:2, Informative)
"But even if Moore's Law could continue to spawn ever-tinier chips, small electronic devices are plagued by a big problem: energy loss, or dissipation, as signals pass from one transistor to the next. Line up all the tiny wires that connect the transistors in a Pentium chip, and the total length would stretch almost a mile. A lot of useful energy is lost as heat as electrons travel that distance. Theoretical physicists at Stanford and the University of Tokyo think they've found a way to s
Re:relevant? (Score:1)
Now we can manipulate the spin of the electrons. The article says nothing of how this can be read- that is, is the spin a new bit of information to store, is the goal here simply to reduce resistance, or are they saying we can actually fit more transistors in a smaller space?
Yeah, my post I admit is somewhat stupid, and based largely on the fact that I don't quite understand chip design or theory. But the article says remarkably little all the same.
Re:arsenide? (Score:1)
-Peter
Re:arsenide? (Score:2)
Re:arsenide? (Score:2)
I think it's a publicity ploy (Score:1, Redundant)
No system can be 100% efficient, not now, not ever. The mere fact that they would make the claim of no-energy loss whatsoever is all that it takes to set off the alert flags that this is nothing but a hoax.
Re:I think it's a publicity ploy (Score:2)
Re:100% efficient? (Score:4, Interesting)
-You know its like the earth orbits around the sun and then spins on its access that's how it works.-
Give me a break they are trying to lure in the gullible who know nothing about electronics to give them money. I think the idea of spintronics is great but what they propose is not worth anyone's time there are plenty of others who are doing valid research in this area. If the best they can explain is a planetary analogy or some sort of half assed flash animation then check someone else out.
Re:100% efficient? (Score:2)
Because so many people complained about the "ad" earlier and the lack of real news that was actually for nerds. Unfortunatly, you can't please all the slashdotters even some of the time.
Re:100% efficient? (Score:2)
Re:100% efficient? (Score:4, Insightful)
Re:100% efficient? (Score:2)
I took the time to track down the paper and read it in full I might understand the whole thing years from now but right now I have a few questions you might be able to help with.
I'm no physicist so I could be wrong but how can equations for linear motion describe rotational motion? The part actually intrigues me, according to
Re:100% efficient? (Score:2)
My space heater is 100% efficient, so sure, why not?
Oh... you wanted useful energy conversion.
Re:100% efficient? (Score:2)
It all depends on where you draw your control volume boundary (or mass), and how you define efficiency. If you define efficiency as energy into the device divided by heat energy into the room, then efficiencies > 100% are indeed possible with heat pumps as you describe.
I didn't get into this, but I also believe some electric heaters are far less than 100% efficient. In particular, the radiant heaters have poor efficiencies. How can that be?
I define my control mass as the air in the room. Radiant
Re:but did he find all 3 versions??? (Score:2)
Umm... yeah, that's the point, except the undergrads taking the intro physics sequence (mostly pre-Meds) had a really hard time with that point, and insisted that there were 3 equations, and needed them all written down.
Re:Is this a gag? (Score:2)
Google is your friend. They aren't making this shit up, I promise.
Re:Is this a gag? (Score:2)
Re:It can't really be free (Score:2, Informative)
That is different from what they are talking about in the article. Their goal is to move to essentially reversible reactions using spin rather than current-type electronic phenomena that contain Ohmic irreversibilities. The Ohmic losses dominate the heat generation in current ICs. The next on the list