Molecular assemblers as advanced productive nanosystem (outdated)
(wiki-TODO: Fix translation error molekular to molecular.)
Related: Grey goo horror fable.
UP: Molecular assembler (disambiguation)
Note: The concept of advanced molecular assemblers for diamondoid materials is outdated!
The current concept for advanced productive nanosystems of the "in-vacuum gem-gum technology" type are atomically precise small scale factories.
This page is not about using molecular assemblers for bootstrapping towards diamondoid advanced productive nanosystems
This page is rather about whether molecular assemblers are a good far term target as advanced productive nanosystems.
Spoiler: They are not.
Contents
Why nanofactories are more efficient than molecular assemblers
Consequences of lack of space
Molecular assemblers come with very little internal space. This has several detrimental consequences.
Unlike molecular assemblers nanofactories allow for highly efficient semi hard-coded mass production of standard parts.
Semi hard-coded nanorobotics allow for a much increased spacial reaction site density.
The total throughput results from the product of
- spacial reaction side denstity and
- temporal reaction frequency
In molecular assemblers temporal reaction frequency can't be used to compensate for lower spacial density as friction losses grows quadratically with speed and thus relatively low speeds are (~5 mm/s) are proposed. Bearing area per reaction site assumed to be the same. Furthermore bigger assembly chambers also mean lower frequencies for the same speed.
Standard part mass production may seem like a big restriction but it need not be.
- There will be many standard crystolecules of the same type needed like e.g. standard bearings
- Semi hard-coded structures can be reconfigured. It just needs disassembly and reassembly
- Software will likely be capable to auto-compile a crystolecule design into a specialized assembly-line for this part
- For very few special parts a way slower general purpose cell is still desirable (not a molecular assembler though)
Other benefits of convergent assembly (<= as listed on the page) cannot be reaped too as there's not enough space for higher assembly levels.
Consequences of maximally replicated replication capability
Every molecular assembler needs to carry around stuff for it's replication capability.
The code may be factored out in some models but there is still
a lot of redundant stuff that is just needed for self replication.
This could be called the "replication backpack overhead".
Due to the premise of molecular assemblers being very compact there is a lot
(pretty much maximal) redundancy and associated overhead.
Necessity of product production-device separation
Volumetric scaffolds of molecular assemblers makes separating
the product from the assembler crystal (or soup) way more difficult than in a nanofactory chip.
Especially when solid products are desired fractal like last remaining removal channels
suffer from extreme slowdown. (wiki-TODO: add link to existing relevant page)
Going against natural scaling laws
Due to the scaling law of higher throughput of smaller machinery
only a very small volume suffices for practical levels of throughput.
Filling a whole volume with nanomachinery would lead to uselessly high throughput.
Well, ok, molecular assemblers sabotage themselves in throughput due to
the aforementioned unnecessarily big volume-per-reaction-site.
A thin chip is the natural choice for a highly optimized (target tech) system.
It provides sufficient productive volume and also is easy to cool due to high surface to volume ratio.
Three reasons for the three main problems
Molecular assemblers face three major problems. They are:
- inefficient
- hard to reach
- undesirable
- (but not fundamentally impossible)
inefficiency:
Hypothetical advanced assemblers could be made bigger than a proto-assembler as
they will not face such severe size constraints stemming from the extremely limited
SPM based mechanosynthesis manufacturing speeds. But Still …
Bigger assemblers means either awfully dropping productivity or more than one active reaction sites per assembler.
This is basically the start of a gradual slope towards nanofactories.
difficulty to reach:
Not applicable here as we assume the technology is already reached.
This applies to proto-assemblers only. And there severely.
reason for undesirability:
The grey goo horror fable is still totally over the top.
That is: As in converting the whole biosphere (or more) of Earth surface into replicated assemblers in a matter of a few dozen hours.
Given the assumed very advanced technology level here much more limited accidents or terror acts are thinkable.
Waay toned down to realistic levels.
This is still far down the road in the future (state 2017 .. 2023)
and heavily limited by the requirements of the reproduction hexagon or replication pentagon.
See page: More realistic replication accidents
Related
The three problems of molecular assemblers that make them an outdated concept:
- Why ultra-compact molecular assemblers are too inefficient
- Why ultra-compact molecular assemblers are too difficult
- Why ultra-compact molecular assemblers are not desirable
