Slashdot Mirror
Self-Assembling Nanocomputers
A Semi-Anonymous Coward writes: "According to this article a researcher at Harvard University has developed techniques for self assembly of nanoscale wires that operate without resistance due to a property called ballistic conductivity. He hopes the research will provide an 'end run' around convential top-down circuit designs, allowing much smaller, faster and more energy efficient computers."
But since this is a Harvard researcher being written up in the Harvard press, my hype-o-meter is on the alert. Then I read this:
Lieber has "philosophical differences" with the industry's "top-down" approach to nanotechnology--taking big things and making them smaller. "The way to truly revolutionize the future," he says, "is to take a completely different approach: build things from the bottom up."
Pardon me, but have these philosophical differences yielded even a working flip-flop yet? The world is littered with "proofs of concept" that are too difficult to implement. I'll admit that this technology is extremely promising, but at this highly experimental stage of development it's hardly time to go bashing the accomplishments of the semiconductor industry. Unless, of course, you're trying to drum up press for yourself.
That said, sounds pretty cool. I'll be even more interested when they can form some basic logic circuits with it.
If guns kill people, then CmdrTaco's keyboard misspells words.
With a statement like that, I bet half of the Army's decision-makers are already lining up to fund these guys.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
Wrong, it would be the case if electricity was flowing infinitely fast. See the lack of resistivity as electricity flowing infinitely well (but still flowing at the speed of light). Actually, the speed of electricity is a little less than the speed of light in silicon, but it's insignificant.
"And it will have very low power consumption, no waste heat, and be incredibly small?"
Hopefully :-)
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I believe people once thought that about what I am using currently to post this message.
just a thought . . .
With reproduction added to the mix, it can be argued that 3 of 4 of these benchmarks are covered. Whose to say that the fourth, evolution, wouldn't follow naturally?
ps: Once these nano-machines develop opposable thumbs, I think we could be in trouble.
The Israelis came up with a dna-based nanowire a couple years back. There's some talk on nanotech mailing lists about using ribosomes (the things inside cells that assemble proteins from instructions encoded in RNA) as organic nano-assemlers. Theroretically (once someone figured out how to code RNA to produce the right molecules), the ribosomes could be used as self-assemblers to churn out miles of organic nanowire. You could even code robosomes to assemble other ribosomes, thus exponentially increasing output. The only costly part would be the (gold) electrodes.
There's certainly a lot to be said for the 'bottom-up' approach to nanotechnology. Cost for starters! One issue though is, how does one address these very tiny devices?
The problem with a whole bunch of identical tiny circuits is of course that they're all identical - there's no way to differentiate between them. There will have to be some way of distinguishing and interacting with these units.
A couple of ideas spring to mind though. One is to encode the position of one of these units in the unit itself as it is being assembled, by interacting with some sort of precisely engineered field. What would work (if anything) depends very much on the chemistry, but it could be something as simple as a gradient in an electrostatic field, to aligning with a very fine grid of polarized light. There are options, but it all sounds Hard. Schemes like this could attack the problem of differentiation, but there's still interaction and addressing.
One way to solve the addressing problem is to bypass it almost entirely. If these structures are sufficiently small, and can be engineered to act as a giant grid of finite-state automata with evolution rules based on neighbouring states, one can simulate a computational device with a version of Conway's Life on speed. Input and output can be done at the edges of the constructed array, which is probably going to be more simple than trying to address the middle of the structure. The problem lies in initialising the state of the array - clearing it is probably easy enough, depending on how state is stored, but priming it with a state that admits the computational task desired seems to be almost as hard as addressing the cells in the first place.
Another approach might be to give each cell some random state as it is constructed (and there should be plenty of sources of randomness at the molecular level to draw on.) Imagine that this state corresponds to an "activation key": when an appropriately modulated high frequency EM signal hits the cell, it pushes it over into an active state. Before this, it's effectively off (perhaps an off cell would simply propogate signals from its neighbours and do no computation). Give each cell some way of indicating that it has been activated (eg, it emits some light upon activation), and then fire random keys at the cells. This solves the addressing problem, and the interaction problem (one could use the same key for changing the cell's state) - but then one has no easy way of telling how the newly identified cell connects to the other addressable cells.
Do any slashdotters have any ideas? Or can point to literature where these problems are (ahem) addressed?
Well, aside from the obvious environmental and geo-political implications of self-replicating machines - there is another important aspect to such machines. Copywrite enforcement.
Just as magical as it would be to make a stable batch of these machines which would reliably work (even in laboratory conditions) - the thought of how these things would possibly be kept from being altered or copied ad infinitum is equal in terms of seeming implausibility.
What methods might work?
Making the constuction materials be of some "special" molecules? Not likely to keep people from making unauthorized copies before too long, plus it makes engineering potentially more difficult.
Adding extra logic to each one to ensure legality? Aside from again the engineering aspects, it is hard to even brainstorm minimally plausible ideas.
Harsh legal enforcement? The sheer convenience of these micromachines would ensure demand is high enough to bypass any law short of complete totalitarianism based on the product. This would be more than yesterday's computer, internet, or cell phone demand - once applications development hit mainstream programming, and then mainstream consciousness, the demand would be levels of magnitude higher than anything we've seen.
The only reliable way I could think to make these machines properly profitable would be to use societal paranoia and fear to convince everyone that these machines are dangerous, and only sell them to 'licensed technicians for clean-room-only use'. But this protection of profitability would only last so long before demand creeped back up, or some major catastrophy renewed the fear factor.
Everything about this sounds like it might make a good story though.
:^)
Ryan Fenton
Robots that can assemble themselves sound great and all...
but can they disassemble themselves and put their parts into the correct bin before its time for bed?
Know what I like about atheists? I've yet to meet one that believes God is on their side.
Resistance, being futile, is not responsible for the light-speed limit for electron flow. That's Einstein's fault. However, if the circuit is considerably smaller than current designs, then all the electrical pathways get drastically shortened and processing gets faster anyway...
Excuse me, I just had an image of a 55-gallon drum of these things sitting by my computer, quietly self-replicating into a Beowulf cluster of a billion-odd submicroscopic quantum computers. It could solve every computational problem currently on the books in the blink of an aibo, render all cryptography (except OTP) useless, and probably faithfully emulate the intelligence of several myriad Ph.D.'s long enough to invent a higher consciousness for itself, becoming an unimaginably transcendent cerebral being to which humans would seem as advanced as bacteria.
And think of the Quake framerates!
T-1000 here we come!
Choose your allies carefully, it is highly unlikely you will be held accountable for the actions of your enemies
Every hardware-scale-advance news article will describe Moores first law.
Ahh, my favourite rhetorical recipe, the tautological soffle.
Since there's no resistivity, that means that calculations will be almost instantaneous, right? And it will have very low power consumption, no waste heat, and be incredibly small?
:-)
I am afraid that most of the power in modern integrated circuits is capacitive not resistive, and though ballistic conductivity would reduce the dynamic heat disapated by signals and eliminate the static heat in the wires the overall difference would not be that great as most of the power is used to switch transistors from one state to another.
So this sort of thing could easily mean that we could have tiny computers that run for a long time on a single battery and are ninety billion times better than anything we currently have, right?
I am afraid not, though it may take a while longer to fry an egg on a processor implementing this technology
Having said that any reduction in static (read useless) heat generation would increase the processor speed as you would be able to increase voltage and hence MOSFET switching speed with the same overall heat generation of a processor no using this technology.
PS: Moderators what are you on, the parent post may be inaccurate but it is NOT a troll.
Physicists are said to stand on one another's shoulders while programmers stand on one another's toes.
Wouldn't having indentical reproducing robots be a violation of the DMCA. Wouldn't one copywrighted robot be plenty?
</sarcasm>
Wheres FMD? Its been completely finished for 3 years now, and no manufacture is touching it because they all want to support DVD, and support technologies approved by the movie and record companies. Technology which is too powerful to control, is surpressed for as long as possible until some small company begins selling a product based on it, THEN big companies jump into the picture because they have no choice.
If you use Linux, please help development of Autopac
The limits on power consumption have relatively little to do with electrical resistance and a great deal to do with erasing bits. As Landauer and Bennett have shown, you can compute for essentially free but you have to pay a price of generating entropy (heat) when you erase bits. To achieve the really significant increases we have to move from non-reversible architectures (all current commercial computers) to reversible architectures that minimize the number of bits erased. Michael Frank is one of the leading people working in this area.
As Drexler discusses in Nanosystems, using reversible rod-logic nanocomputers, one should be able to get from our current 10^9 ops/sec chips to 10^21 ops/sec in 1 cm^3 before one hits the heat removal limits. So the anticipated throughput increase is ~10^12 ops which a trillion vs. your estimate(?) of 90 billion. But it isn't going to run on a single battery. Its consuming (and radiating) 100,000W. Interestingly enough, since such a nanocomputer has ~10^3-10^5 times the processing capacity of the human brain in 10^-3 times the volume such a computer is probably worth a million or more human brains (if we can figure out how to program it...).
The circuits will have zero resistance only when they are in a stable state. Your static memory will not consume power provided you don't try and read it. Unfortunately, most interesting bits of computing will involve changing the electronic states, so there will still be power consumption, and trouble getting rid of heat.
Carbon will probably be the new silicon. It has a big 10eV band gap, and you can make it a resistor, a semiconductor, a conductor, or a superconductor by rearranging the bonds, without doping. If we can crack the self-assembly problems, then you may get a mole of bits in a few tens of grammes of material. Which may not be instantaneous calculations for no energy, but it is pretty good to be going on with.
Making a whole computer is also possible, but this may take a little longer.
Get out of your parents basement........ have you ever even kissed a girl?
Self assembly is how the body builds a lot of its internal structures. I did a bunch of work on this in my doctorate - basically you can get some reasonably complex structures (e.g. a virus shell) from a small set of repeating sub-units.
One of the common structures found in all cells are 'micro-tubules' - long cylinders made of repeating tiles of a protein called, imaginatively, 'tubulin'. They look a bit like a coil of rope; technically it's most common form is a '4-start, 13 unit helix'.
Now the place these protein structures are found *most* commonly is in neurons, which are crammed to the gills with these things. And there is a (way-out, whacky, widely discredited, completely batshit, but still very cool) theory that the way our brains actually work is not just at the synapse level, but at the sub-cell level using these microtubules. (This would add maybe another 5 orders of magnitude to the available computing power of the brain if it were true; these suckers are small and there's *heaps* of 'em!).
The idea (and it keeps cropping up in papers 'cause it's just so appealing :-) ) is that
computations can be done using a 'game of life'
like system of electical charges on the outside
of the microtubule, where each unit adops an
electric polarity, and then 'flips' it's
neighbours depending on a simple set of rules.
It's a very cute idea, completely lacking in
anything so crass as experimental evidence.
These days of course no one believes a word of it.
<false modesty>For some dodgy work on nanoscale self-assembly, and for some half decent pictures of microtubules, check out my thesis at nanoscale simulation </false modesty>
Wer mit Ungeheuern kämpft, mag zusehn, dass er nicht dabei zum Ungeheuer wird.
Self-assembly is very cool. Unfortunately this isn't an example.
He mixes the components together but then pours them onto a matrix. Then he mixes the next one and pours that on the previous one. So still cool, but not "self-assembling"
Self-assembling structures like proteins and DNA do exist, and are more useful. DNA is an example of a structure which includes positional info (i.e. addressing) which an earlier poster indicated would be important.
Likely a cell is a good example of an ideal machine. It's very complex, but it includes power source, self-maintenance and assembly. These little parts he's building (they're not even "machines" yet) don't address these issues.