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The Nanomechanical Computer
eldavojohn writes "The BBC is reporting on a newly proposed type of nanomechanical computer that mimics J. H. Müller & Charles Babbage's work on mechanical computational devices — just on a much smaller scale. The paper is published today in the New Journal of Physics and cites three reasons to build a computer with nanomechanical transistors over bipolar-junction or field-effect transistors: '(i) mechanical elements are more robust to electromagnetic shocks than current dynamic random access memory based purely on complimentary metal oxide semiconductor technology, (ii) the power dissipated can be orders of magnitude below CMOS, and (iii) the operating temperature of such an NMC can be an order of magnitude above that of conventional CMOS.'"
The paper claims to have shown how to make a nano-mechanical computer using contemporary silicon production facilities. I've gotta wonder, what are you waiting for? Pay the $10,000.. send off your image to be made and test the damn thing.
This is like half science.. "Here's my hypothesis, someone test it for me."
How we know is more important than what we know.
"Order of magnitude" is a pretty silly phrase to use in this context. From the paper: "The operating temperature can be as high as 500C." So I guess they're using Celsius as the scale, not absolute temperature.
This present design is a cool idea. I don't want to take anything away from the presented concept, but I thought it would be important to point out previous work on nanomechanical computers. First of all, Eric Drexler (the guy who popularized the term "nanotechnology" and who basically invented the field now known as molecular nanotechnology) has been advocating the concept of nanomechanical computers for many years now (they are described in his book Engines of Creation (1986) and detailed feasibility calculations, and rough schematics, are presented in his book Nanosystems (1992)). Drexler has been trying to get people on-board with his very foreward-looking ideas for nanotechnology: where nano-sized mechanical systems would be performing computation, and controlling chemical reactions with a precision that currently only biological systems can achieve. (It should be noted that current work in "nanotechnology" is hilariously primitive compared to what Drexler intended the term to describe.) Drexler's vision of nano-mechanical systems has been challenged by many people, most notably by Richard Smalley (the guy who discovered buckyballs).
Beyond Drexler's theoretical work, carbon nanotubes were demonstrated as nano-mechanical transistors in 2000. Basically, the nanotube was positioned over various electric pads. A current could be applied to mechanically deform the nanotube. The deformation was stable, and could be read-out by measuring current across the tube. Since the deformation was stable and reversible, the tubes could be used as persistent storage or as switching/logic elements. In fact, switching speeds of gigahertz were demonstrated. The vision was to have long nanotubes in a huge cross-bar architecture, leading to high-density persistent storage. As is often the case, scale-up was difficult.
This present work appears to pattern a nano-sized post between conducting pads (out of a gold/silicon layered system) , and to use that post as a single-electron transistor. The 'mechanical' part comes from mechanically coupling multiple pillars to use as a gain mechanism for a transistor. This is basically much closer to conventional micro-lithography, and as such, it should fit in with current lithographic infrastructure much more easily than the nanotube concept did.
They're far from the first to propose nanomechanical computing machines like Babbage's original (and failed) machines. A mentor of mine explained to me in 1990 an idea of building nanoscale rod logic in orbit: microgravity, vacuum, solar power. And I don't think he was the first to think of it.
I'll be impressed when someone actually builds some. Or writes a lot more engaging science fiction than the BBC just published.
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make install -not war
If the Nikei stock exchange uses a mechanical computer, then an earthquake in Japan will really send a shudder through the financial markets...
Excuse me, but please get off my Pennisetum Clandestinum, eh!
I'm not a nano-technologist, but I'd doubt that macroscopic ideas of friction and wear would apply to nano-machines.
The reason is that Absolute Zero is a concept that doesn't really exist in nature. Nor does, for all practical purposes, much of the range 'below zero'. Furthermore, to speak of temperature in terms of 'magnitude' and to speak of Absolute Zero (0K) as the default no-magnitude state, is to posit that we all live in a vaccuum. The default no-magnitude state is not absolute zero -- a condition that doesn't really exist. To base an appraisal of the 'magnitude' of an effect on a nonexistent default is to totally mess up the common understanding of the terms, and the destroy the point of even considering what is 'an order of magnitude larger' in its worldly effects. (Again, I stress to you, a world in which the effect 'absolute zero' is not possible.) Therefore, the only real-world meaning that the idea of 'orders of magnitude' can have with regard to a temperature rating is in relation to an arbitrary baseline chosen for convenience. Zero degrees Celsius is a pretty good choice, as it's a temperature low enough that a computer will probably never see it, and that is sufficient, because all magnitudes below this level are completely irrelevant. But as the freezing point of water has no specifically relevant relationship to the performance of nanotechnology, room temperature is a far better choice, representing the 'default heat radiation' in the environment throughout which computers are deployed. So a computer that can run at 320C is an order of magnitude better than one that can only run at 50C (30C above room) -- this should be considered accurate. And since this is the ONLY definition of orders of magnitude that makes ANY real world sense in relation to computer temperature performance, to define magnitude in relation to anything else is just an example of the over-exercise of pedantry rendering a term impossible to use meaningfully -- so a computer that can run at the boiling point of water is only about 37% better in its tolerances than a computer that can't even run above the freezing point? Reductio ad absurdum. QED.
That's not what reversible computing means. Reversible computing allows for power consumption below the 1/2 kT per bit theoretical minimum for energy consumption in a computer. Feynman's lectures on computing describe it pretty well.
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