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More on Spintronics
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.'"
The applied electric force, the spins and the spin current align in three different directions that are all perpendicular to each other ''This is a remarkable thing,'' explains Zhang. ''I push you forward and you move sideways - not in the direction that I'm pushing you.''
Same thing happens with me after about a six pack.
In maybe a 10-year timeframe, spintronics will be on par with electronics
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 going on.
Gentlemen! You can't fight in here, this is the War Room!
I had a prof in college who loved to tell the tale of finishing his bsee at mit, and didn't know what to do next. Being young and stupid (his words) he went down to the army recruiting office and inquired about electronics. The guy behind the desk says he has to come back the next week to take a test.
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.
At subatomic levels, every process is 100% efficient. The basic principles that you learn in mechanics which warn you that there is no such thing as a perpetual motion machine, etc... are results of statistics and macroscopic effects. Microscopic is not miniaturized macroscopic.
effectively allowing communication based upon movement.
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.
the byproduct of years of oppression by the white man
If I recall correctly there are a few problems with this method of transmission:
... its a bit more complicated than that.)
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"
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."
This Space Intentionally Left Blank
Sorry, no.
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).
For to end yet again.