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Physicists Extend Moore's Law For Tiny Devices
schliz writes to mention that a team of quantum physicists have demonstrated how to significantly reduce the effects of "stiction," or the tendency for two very small, very close objects to stick together as a result of Casimir force. "'The Casimir force might be one of the many reasons that very small, movable components in micromechanical devices sometimes stick together,' said Ho Bun Chan, a assistant professor of physics at the University of Florida who is researching the Casimir force. 'The Casimir effect increases rapidly as the separation between components decreases. It becomes significant when the separation is reduced to below about 400 nm,' he told iTnews."
I always wondered why stuff always sticks to one of my sweaters..
I work for the Department of Redundancy Department.
The Casimir effect is very wierd indeed. If you take two metal plates and put them close together in a vacuum they will attract one another VERY weakly. The effect is caused by fluctuations in the electric charge of the vacuum. Think of it a little like sea level. On average if you measure sea level lots of times you wil get "0" for the height but if you measure it just once the height you get will depend on the tide and the size of any waves. The same is true for a vacuum. Look at a particular volume of space and measure the electric charge. On average you will get zero but for a particular moment in time it may be non-zero.
Ok so far but how do we get an attractive force? Well it turns out that charge must be conserved so if one region of space has a small positive charge at one instant a neighbouring area must have a small negative charge (in quantum terms we say that we pair produce and virtual electron-positron pair) thuse we have a dipole. Now remember the two conductors? Well the one nearest the positive charge will have the electrons in the conductor attracted to it and being a conductor they will move towards it giving the conductor a net negative charge. The opposite will happen in the conductor nearest the negative charged area of space.
So now we have, instantaneously, a conductor with a negative charge and one with a positive charge...so they attract one another. this is the Casimir effect. If you stop to think about it is is VERY strange because it means that two metal plates in vacuum, with no externally applied fields will attract...so you have to ask yourself what exactly is doing the work i.e. where is the energy coming from to move these plates?
I'm not a condensed matter guy so I must admit I don't quite understand why this effect is so important to them. I understood that in molecules it was known as Van der Waal forces and due to periodic dipoles occuring in molecules in much the same way it does ina vacuum. Only, because there is a real electric field, the effect is much larger. So if there are any condensed matter people out there perhaps they would like to explain why it is Casimir and not Van der Waals that is important? or is it just because they have the same origin the name Van Der Waals has been dropped?
Moore's Law has nothing to do with mechanical components. For that matter, strictly speaking, all Moore's Law was ever about was the number of components in an IC. Not speed, not cost, not even size. And definitely not the size of MEMS!
Zero Point Energy will never yield any significant amounts of energy. It's merely an artifact of the way the Universe is constructed, and not a large source of power or fuel. Stargate attempts to remain (somewhat) scientifically accurate by positing that a micro-universe is contained inside each of the ZPM devices, and that the device attempts to extract all energy from that universe via Zero Point Energy extraction. Thus the ZPMs are capable of "running out" of power once all the energy from the micro-universe is exhausted.
Technically, such an idea suggests that the ZPMs should deliver a constant stream of power at all times. Yet in practice, the ZPMs shown in the program appear to behave more like batteries; often providing more or less power depending upon the city's current requirements. However, this appears to be a literary device as it creates a variety of consistency problems within the program. (e.g. If energy can be extracted at such a rate as to exhaust the unit within a few minutes, why can't the city fly on only one ZPM?)
Javascript + Nintendo DSi = DSiCade
And for those of us who couldn't remember which online enclycopedia is a good, free place to look up terms we aren't sure of: http://en.wikipedia.org/wiki/Wikipedia.
:)
Just in case.
You know, just in case somoene forgot.
Forgot about wikipedia, I mean.
Because, apparently, looking something up on wikipedia is esoteric enough that a post with a link to wikipedia (and nothin else!) is informative.
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
The earlier work was completely theoretical - the paper in question here is an experimental result.
Why do we care? A lot of reasons - the casimir effect is deeply rooted in quantum physics, but is observable without having to cool things to quantum temperatures. This sort of research is also potentially very important in nanotechnology - if we want our nanosurfaces to not stick, we should make them corrugated - the opposite of the macroworld!
Many times, people have calculated these casimir forces by assuming that the quantum force between two plates by just adding up the forces between particles (pairwise additivity). This is the first (I believe) research that shows this failing experimentally - there are large-scale geometrical effects. This is exciting, as it means that there may be many ways to tune casimir forces, making them do whatever we want - theoretical predictions on piston-like geometries have forces that are attractive at one distance, and repulsive at another!
If anyone's interested, the actual paper is at http://arxiv.org/abs/0805.3776 and better summaries (Moore's law wtf?) are at http://www.economist.com/science/displaystory.cfm?story_id=11402849 and http://www.azonano.com/news.asp?newsID=6827
The other two replies are correct, but let me give a little more detail - the casimir force is very short-range, and essentially goes to zero over the distance of a micron. The corrugations in the surface are micron-deep trenches, and so the extra surface area is essentially hidden.
ZPM power production[*] is rated in the non-SI unit "Plot" (analogous to J/s, the second derivative of energy[**], and the first derivative of work[***]).
A ZPM's normal production appears to be approximately 0.1 Plot per episode in which it is portrayed, although in some episodes a ZPM shows how powerful a device it can be, delivering just shy of a full Plot.
The third derivative of energy, "Twist", analogous to J/s^2, can be used to analyse the output of the ZPM over the duration of an episode. In some cases the ZPM provides a substantial Twist, progressing from normal power production to zero or to explosive overload within the span of an Act.
A high-Twist, high-Plot device is consistent with the ZPM as portrayed in Stargate SG-1.
I never got into Stargate Atlantis, sorry.
[*] or production power, which may be more appropriate.
[**] Writer's energy, that is.
[***] Professionally employed TV writer, that is.