X-Message-Number: 20980
Date: Mon, 27 Jan 2003 10:49:53 +0100
From: Henri Kluytmans <>
Subject: Nanotech / MNT

I wrote :

>> it rotates relatively slowly and it uses binding site "pockets" 
>> (along the rim) to seperate molecules (by Van der Waals force).

 replied :

>and it releases them how?...

A rod in the center of the binding site will protrude when it's 
part of the rim is located inside the reservoir and will 
mechanically press the molecule out off the binding site. 
(Of course this operation requires some energy.)
 
>> Nope, a graphite sheet is only one layer of atoms thick, a diamond 
>> wall can be made as thick as you want, and can thus be made much 
>> stronger. (In this case about 10nm thick.).

>Nanotubes can be produced with multiple sheets, same for buckyballs.

I'm familiar with nested nanotubes, but I never heard about 
nested buckyballs. They seem to me much harder to produce.

But anyway, a nested structure of graphite surfaces of irregular 
shape is more complicated to produce (im assuming advanced MNT 
is being used for manufacturing) and less strong than a 
diamondoid structure of the same thickness (when more than 
10nm thick).

>> "Each storage tank is constructed of diamondoid honeycomb or a geodesic
>> grid skeletal framework for maximum strength. Thick diamond bulkheads
>> separate internal tankage volumes. 

>Do you think one second to the complexity of that 3D structure? To think a 
>(perfect) gas can flow freely in it is beyond my understanding, at best 
>you'll have a kind of very non linear liquid with strong surface effects.

Even when the surface effects are strong that shouldn't interfere much with 
the planned functioning of the device. When the storage tank is filled 
the pressure in it will be very high (1000 bar when completely filled).

>The problem is that diamond (carbon) + O2 = CO2 + energy + destruction. 

Indeed, that could be a problem. But the inside surface of the tank 
can be coated with molecules/atoms that are more inert to O2.

>bad molecule in the rotating part and the system grind to halt or the motor 
>is sufficient to overcome that and you have the activation energy to start 
>the combustion process. 

When that energy is located inside a motor or a sorting rotor that 
shouldn't be able to start a combustion process. The energy will
quickly be conducted away anyway. 

>It may be worst: This system has nearly no thermal sink so any 
>concentrated energy input, for example a cosmic ray particle, 
>could start the fire. 

On the contrary, the device is located inside the bloodstream in 
the human body, a very large heat sink indeed (compared to the 
device). The device itself is mostly constructed of diamondoid which 
serves as an excelent thermal conductor to lead the heat to the 
outside of the device. At microscales it's more of problem to 
contain heat than to loose it, because of the great ratio of 
surface to volume.

>Even thermal energy is a bad concept at that scale, you 
>may have to speak about discrete mechanical vibrations or phonons. 
>Resonance effects may concentrate energy in a particular zone and 
>set a fire. 

The device can be tested and designed to avoid this.

>To make such a structure would be very costly, to make it 
>safe would be quite another challenge.

Wrong!!!

One of the main inherent advantages of advanced MNT (using 
self-reproducing systems) is the low costs of anything produced 
using this technology.

>> And it will not be unstable : in the design an extremely 
>> conservative 100-fold structural safety margin is used.

>The problem here is that you think on a classical physics basis, not a 
>semi-quantum one as you should. 

Only for some exceptions it's is neccesary to use quantum-mechanical 
models (e.g. a reaction to covalently bind a molecule), but for most 
processes in MNT everything van be moddeled using non quantum-mechanical 
models.

>A simple radiography would set fire in all your respirocites for 
>example, simply because you assume there is a bulk, 
>macroscopic thermal sink where there is not. 

But as I explained above, there is a very large heat sink!

>I have read far more than the abstract, but I am not sure it was 
>a good time investment.

Then, I guess you haven't read enough yet.

But as I told before, when you want to criticize the MNT concept,
then you should start with atacking the fundamentals described 
in the book "Nanosystems". (Read "Engines of Creation" first, 
but only as an introduction.)

>True nanotech is at the scale of atoms or a small group of them, most 
>progress seen here are simply biochemistry or plain chemistry in disguise to 
>attract more money. 

Indeed, you're right, if you're talking about all the research 
going on in "nanotechnology" these years. But the systems we 
are talking about can only be produced using "real MNT". 
There is indeed little research going on concentrating on 
real MNT.

>Theoretical large schemes lack the quantum thinking they desserve. 

Nope, not necessary. 

>Assemblers for billion parts systems are no more than dream pipe. 

Nope. Because there seem to be no theoretical arguments against them.

>Self assembly is not best at that scale. You can probably have a self 
>assembly system working on at most ten parts, no more. Ribosomes may do more 
>but they are limited to 20 different building block assembled into a string. 
>Nano systems seem to have far more than 20 different parts and need 3 
>dimensional work, not one.

You're talking about un-controlled self-assembly, in MNT the assembly 
process is controlled. Even much more controlled than in biological 
reproducing systems like cells and bacteria. And I think those last 
examples of reproducing systems are constructed from more than 20 parts.

>To make that (or a small part of that) a reality, you'll need tens of 
>billions dollards/year for one century or so. Where did you find that money? 

Technological development is leading toward MNT anyway, with or without 
direct investment into research concerning "real MNT".
(Read "Engines of Creation".)

>I have never seen a strategy to go from zero to that astounding level of 
>activity. Is it possible, if the market is so great than nobody find in each 
>case a simpler, cheaper solution?

I guess we will have to wait for a couple of decades (without substantial 
investments into real MNT research).

>To a cold eye, nano capacities seem largely overstated. The reality one 
>generation from now may be somewhat biter.

There seems to be no theoretical barrier, even better, biological 
systems seem to be a proof of concept (like birds where for flying 
machines).

Grtz,
>Hkl

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