Re: Cryonet Message #10564 - nanoassembly

Hara Ra (
Tue, 13 Oct 1998 09:19:51 -0700

Charles Platt states in Cryonet Message #10564:

>> From: 
>> Disrupted structures can be repaired by an advanced 

> >nanotechnology. <snip>

> Where my life is at stake, I prefer experimental evidence
> to "opinions." <snip> Until cell structures actually have
> been repaired, we are dealing with (possibly well informed)
> speculation.

Alas, all we have is well informed (possibly) speculation. Death is ultimately caused by the failure or incapability of the body's healing mechanisms. The damage caused by freezing is incomparably greater, so a frozen patient is very dead indeed from the viewpoint of contemporary science. Science is concerned with the provable (as it should be) and at present what is provable is that only a few tissues in the human body can survive freezing to cryogenic temperatures.

Ralph Merkle, et al, argue from the viewpoint that there are no 'in principle' barriers to the eventual development of molecular and atomic level nanotechnology (ie, exact placement of molecules and atoms). I can imagine standing in the Parthenon in Athens conversing with Democritus (sorry, I may not have my names and times correct here), the inventor of the Atomic theory, arguing that if we can manipulate atoms with very tiny tweezers, we can build anything we want. (I see a horde of slaves and waldo-tweezers attempting to build something. Can you say "Avogrado's Number"?)

When I was a software engineer, I learned from bitter experience three things:

  1. Even the smallest tasks take an absurd amount of time and effort.
  2. Once you've stuck all the pieces together, your troubles are only just beginning.
  3. The effects of politics and stupidity.

It is a long, long, long road from principle to product.

> I would find your categorical statements a little easier
> to believe if anyone had done a feasibility study using
> existing macro-scale robots to repair a macro-scale
> simulation of freezing damage. This is a very reasonable
> request, since the predicted onboard computing power of
> nanobots is more modest that the computing power of current
> desktop systems. But no one has a clue how to "train"
> macro-scale robots to repair macro-scale damage. Indeed
> I believe roboticists would tell you that it is impossible
> using this level of processing power.

Some musings:

[1] 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).

This would provide a look at the challenges involved, given a an assembler a priori.

[2] 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.

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 work.

[3] 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.

Final Comment:

We easily become entrained with unworkable concepts. Nanobots may certainly have their uses in medicine, and extending the idea to reanimation is obvious until looked at critically. We are a long way from knowing what will work, how to do it, or even imagining what the workable options are. Despite all this, I remain an optimist and a signed up cryonicist.

| Hara Ra <> | 
| Box 8334 Santa Cruz, CA 95061  |
|                                |
| Death is for animals;          |
| immortality for gods.          |
| Technology is the means by     |

| which we make the transition. |