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Nano-switches and Self-Assembling Nanostructures
emc3 writes "Those wacky scientists are getting small again. Some folks at Yale have come up with a reversible molecular switch. And at Princeton, they've discovered a method of getting a sheet of resin to assemble ordered arrays of nano-pillars. They say that this process could lead to a new generation of flat-panel displays or DRAM.
" Nanites. It's what's for dinner.
Ye Gods (& Goddesses :) - imagine what the synthesis system is going to look like to be able to create a circuit using nano-sized logic gates.
:).
:)
I don't think today's tools are up to it - at the very least, for modeling purposes, there will have to be a quantum-model-simulator like [H]SPICE (QSPICE anyone?
Place & route will be on a massive scale for random logic. Not only will the interconnect dwarf the effects of the nano-gates, but you'll have to model effects like quantum-tunneling & other bizarre features.
Tools will have to automatically provide circuitry with fault tolerance, since a cosmic ray blasting through a molecule-sized switch is going to be a catastrophic event...
I suspect that for large arrays of nano-components, there will be a lot of borrowing from the computations that crystallographers do, since they are used to deriving the gross characteristics of substances by mathematically extending "unit cells" ad infinitum.
A lot of the work of the tools will be to just figure out the "self-assembly" steps - do this to make THIS layer self-assemble, then do this to make THAT layer self-assemble, etc., w/o them interfering with each other.
If all the self-assembly steps are low-power, I wonder if it will be possible to finally make these logic circuits in a cube form? (Building up the cube layer-by-layer, instead of starting w/raw silicon wafer & eating layers away like we currently do).
There are so many things that become possible when this technology reaches some threshholds, that I suspect a lot of people "overload" and start tuning out the potential issues because their brains don't want to deal w/all the possible changes which might occur
instead of grouping NanoTech w/ science we should make its own group. I have also made a picture for the headline on slashdot. Its in between the quotes:
" . "
Nanotechnology is a subject that has had a lot of FUD and a lot of misconceptions floating around.
Everything I'm going to say here I got from Eric K. Drexler's "Engines of Creation" (A very good book IMHO), and my undergraduate biochemistry degree. Nothing is particularly inaccessible to "the general public", in fact Engines of Creation is VERY readable indeed. Yet the majority of people that say things about nanotechnology seem not to have even read this book (and EKD is _THE_ guy who thought up the whole nanotech field!!!)
OK. Enough bull$hit, etc.
Self-Assembly is almost _exactly_ like crystallisation. Essentially, you have a number of components that are complicated enough to only fit together in one configuration - and set things up so that the crystallised configuration has better energy characteristics than the uncrystallised configuration. I suppose one difference is that you don't end up with a single crystal with conceptually infinite dimensions, but instead with a number of discrete entities.
Some simple (and _NATURAL_) examples of self-assembly:
(1) Bilipid layers will spontaneously self-assemble from phospholipids. The reason is this: Phospholipids have a highly hydrophilic (water-attracted) "heads" at one end, and a highly hydrophobic (water-repellant) "tail" at the other (this is actually a fatty acid tail). When a sufficient concentration of these phospholipids are brought together, they tend to clump with the tails pointing inwards and the heads pointing outwards, towards the water. In this manner, they form little spheres. Occasionally, they will also clump in a double layer, with one layer consisting of phospholipids oriented with the heads pointing outwards, and the other layer oriented with the heads pointing INWARDS - you then get a flat sheet which often folds into a hollow sphere, that contains water in the middle.
This process can be made to occur quite easily - yet each and every one of our cells contains a phospholipid bilayer that keeps it as a discrete entity!
(2) Macrophages. These are viruses that prey on bacteria (I suppose as such we should be happy about them!). They are also very cool - after infecting a bacteria, they get it to produce a whole bunch of protein components (as well as a nucleic acid strand). These components SPONTANEOUSLY self-assemble into new macrophages - and these macrophages have quite a complicated structure (they look like eye-droppers with legs).
In both cases, there is absolutely no intelligence and/or control in the actual assembly process. The components naturally assemble by virtue of their shape.
I'm assuming that it's a similar process that is occuring in the case of the switch - each component is fabricated so as to assemble in a particular way. When they are mixed together, they just - assemble!
Another thing that a lot of people seem to be talking about / worried about is the concept of grey goo. I'm not sure whether this concept was invented by EKD or not, but he certainly talks about it.
The concept arose in the context of Von-Neumann machines (sorry if I spelt it wrongly!). These conceptual machines were designed to repclicate themselves. Possible applications of such machines would be as miners on remote planets -send out a Von-Neumann machine, which finds a particular quantity of Iron, replicates itself twice, then comes back to Earth. Each child machine does the same thing, ad infinatum....
The problem here is that such machines could replicate incorrectly (hey, it happens on Earth - we're Von-Neumann machines, and mutations occur quite frequently....it's part of a process called Evolution). Say a Von-Neumann machine was created that "forgot" that Earth was the mother planet, and began finding Iron and replicating ON EARTH....These machines would have been designed to find Iron anywhere they could....I'm sure you begin to see the possible problems here.
Nanomachines could potentially be made as Von-Neumann machines. I won't go into the whole purpose-of-nanomachines-as-Von-Neumann-machines thing, because EKD covers this _VERY_ well.
Grey goo is what happens when self-replicating nanomachines go "out of control", and chew up every available food source (like we're doing on Earth at the moment). Remember that, just as animals on Earth have evolved to get the most of just about any Carbon source, so too (potentially) could sufficiently complicated Von-Neumann machines. We (among other things) are Carbon sources.
So, yes, Grey goo is a BIG potential problem that needs to be addressed very carefully before we start to make self-replicating nanomachines.
Self-assembly, though, is an entirely different thing, one with a lot less inherent danger mainly because machines assemble out of materials that WE provide, and then can not replicate themselves.
I also don't want to sound too much like a scare-mongerer. Nanotechnology in a sufficiently advanced form could provide many benefits to humans - from feeding the world's masses, to space travel, to rapid assembly of products, to extension of life span (possibly indefinitely). Again, these topics are very well covered in EKD's book so I won't go into them too much.
-Shane Stephens