Hara Ra wrote:
> Some musings:
>  Lego Toy Problem
> Yes. A very good way to attempt this is to use Lego blocks. (Seriously!)
> Lego is developing a series of toys which can interface with the PC (about
> $200, available this fall). For the moment these devices will be physically
> too feeble to pick up the Lego blocks and push them together, and the
> sensor technology is also very crude. If you did have adequate actuators
> and sensors (I can see it now, hydraulically driven Lego-Bots!), consider
> the design of a Lego-Assembler, which given a suitable PC, and a suitable
> supply of Lego blocks, is capable of assembling a copy of itself.
> The point of such a 'toy problem' (groan) is to reveal the higher level
> conceptual difficulties of doing such a thing and to reveal the detailed
> problems of actually doing it. (like, how do you sense the difference from
> a Lego block and a sugar cube?)
> The next Lego problem is to eliminate the major non-Lego components,
> especially the PC. Most solutions to this problem (in principle!) involve
> combining a standard set of components, a general purpose assembler, and a
> data tape whose structure as a media is simple. The data tape is read and
> the assembler executes the instructions. It builds the duplicate assembler,
> and then duplicates the tape.
> I imagine such a device would be rather large. The assembler component on
> the order of a cubic meter, and a kilometer of so of Lego blocks data tape
> (if folded or on a spool, about the volume of my house. And it would run
> verrrrrry slowly, maybe a few years to complete the reproduction).
The size of the data tape is dependent on the structure of the media. A 4mm tape cartridge, for example, has anywhere from 60-120 meters of 4mm wide tape on it, and can hold about 250megs per meter at present desk top technology levels. An older media, 9 track tape reels, can hold 6250 bytes per inch, and have anywhere from 800-3600 feet of tape on them. Your Lego brand data tape is going to be what? punch tape??? ;) You could use the pins on a lego block for a media, if you wanted. A 2x8 pin block would represent 1 byte, where every set of 2 pins is your 0 and 1 bit positions. Using this as a media structure, you definitely would have a memory space the size of a house to do anything useful, given a conventional sized Lego block.
To go more compact, you would use a 2x8 block as a punch tape reading head, and a similar block as the writing head. Roll the punch tape up onto a spool. However, using tape is getting away from the standardized Lego building blocks.
> This would provide a look at the challenges involved, given a an assembler
> a priori.
>  The Trouble with Nanobots and a Solution
> We have all seen by now the little video clips of futuristic nanobots
> flying like tiny Tie Fighters though the bloodstream, searching for Bad
> Biological Blobs and replacing them with Beautiful Beneficent Bits. Here
> are a few of the many problems with this dramatic concept:
> Energy source
> Co-ordination with other Bots
> Positional Uncertainty
> The first four are obvious enough. Nanobots will be subject to Brownian
> motion at non cryogenic temperatures. Flying or swimming through a fluid
> medium will always result in this. The fact that you can see Brownian
> motion in a light microscope proves the point. At a less visible level,
> there's the Heisenberg uncertainty to deal with. The smaller the object,
> the more difficult it is to establish the position. The current research
> involves STMs and objects bonded to large substrate, so the uncertainty is
> far smaller than the atoms being manipulated. Nanobots are tiny indeed.
Yes, are we talking bacterial sized bots or smaller??
> An array of assemblers firmly mounted on a suitable support structure
> answers many of these problems. This requires that the object being
> assembled be in the solid state. Assembly at cryogenic temperatures makes a
> lot of sense. Things will stay where you put them, you can use high vacuum
> without damaging the placement of volatile molecules such as H2O, etc. Very
> large computing resources can interfaced to the assembler instead of being
> limited to the tiny volumes of nanobots.
> An assembly plate with a square meter of area would suffice for reanimation
>  Warming Up
> Another advantage of cryogenic temperatures is that cells could be (in
> principle!) constructed in the solid state with every molecule in place. No
> ice crystals. No latent heat to complicate warming. If you can get from 77
> Deg K to 1 Deg K in a very short time (1 millisecond at the most), warming
> from there to body temperature without further damage has been proven (I
> recall a hamster at Alcor).
> To do this, warming elements must be finely distributed through the body,
> close enough that thermal conduction will warm the immediate vicinity
> within the millisecond time frame, which implies a distribution of elements
> a few cell lengths apart. One idea for this is tiny wires coated with or
> comprised of diamondoid material with a conductive center. A 100 Kg body
> requires about 8 x 10^5 joules delivered in a 1 ms pulse of 8 x 10^10 watts
> (100 gigawatts, approximately).
> The wires are assembled into the body during construction, and pulled out
> after the warming pulse. At 1 Deg C, the removal can be done gently over a
> few hours. The wire array would take little volume, say 1 part per thousand
> of the total body volume.
Question, if you are assembling the body as a corrected structure at cryogenic temperatures, what effect will warming the body have on its structure??? Won't there be some significant problems with coefficients of expansion going from 1 degree to 77 degrees?? Since you won't have ice crystals, won't the body be severely dehydrated once it is warmed to the 1 degree point???? Or will there be transport mechanisms to infuse water as temperature rises?? These will be needed alongside the diamondoid warming structures, won't they???