Kinematic Self-Replicating Machines
© 2004 Robert A. Freitas Jr. and Ralph C. Merkle. All Rights Reserved.
Robert A. Freitas Jr., Ralph C. Merkle, Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004.
6.4.6 Systems and Proposals for Future Research
Molecular manufacturing is a field of engineering, and the design of molecular assemblers and nanofactories will require expertise in molecular systems engineering. According to a concise definition  offered by the University College London Centre for Systems Engineering:
Systems engineering is the branch of engineering concerned with the development of large and complex systems, where a system is understood to be an assembly or combination of interrelated elements or parts working together toward a common objective.
Systems engineering focuses on: the real-world goals for, services provided by, and constraints on such systems; the precise specification of system structure and behavior, and the implementation of these specifications; the activities required in order to develop an assurance that the specifications and real-world goals have been met; [and] the evolution of such systems over time and across system families. It is also concerned with the processes, methods and tools for the development of systems in an economic and timely manner.
Economically viable molecular manufacturing systems based on molecularly precise massively parallel assembly are likely to take longer to develop than the usual three to five year time horizon of the private sector . The private venture capital sector has shown considerable enthusiasm for funding nanoscale science and engineering projects that focus on novel electrical or physical properties of nanoscale materials. But they are not focusing on the high-risk, high-payoff opportunity of developing molecular manufacturing machine components and systems with complex kinematic nanomachinery. There are some European and Japanese initiatives to develop molecular manufacturing components and systems. The key rationale for U.S. government funding is that molecular manufacturing might not happen first in the U.S., or will happen much more slowly in the U.S., if we rely on the private sector for initial R&D stage funding. The question of who develops this technology first has profound economic, security, military, and environmental significance.
A successful, field-proven, molecular manufacturing system that might be deployed in the mid to longer time frame could be described and analyzed today. Such a system would almost certainly be composed mostly of systems and subsystems that are not experimentally accessible at present, for the simple reason that we cannot yet build the relevant components. But if we are to think about and analyze systems that we cannot build today, and if we are to do so with any certitude, then we must initiate a carefully conceived theoretical and computational R&D program expressly for this purpose. Existing tools in computational chemistry can be harnessed to analyze molecular structures, regardless of whether or not those structures are immediately buildable. Computational modeling of known experimentally accessible structures gives us confidence about the capabilities (and limitations) of the modeling software, and permits us to evaluate structures that have not yet been made – and perhaps cannot directly be made – using our current early 21st century technology base.
The value of such theoretical and computational work, particularly when used to assess systems that exceed our immediate experimental capabilities, is sometimes debated. But the alternative is to abandon active investigation of systems and structures that cannot be built today. Inability to think systematically about what cannot yet be built is very likely to delay our ability to build it. If we are to build machine-phase molecular manufacturing systems in the next two decades – systems that are experimentally inaccessible today – then methodical design work on such systems is both necessary and urgent .
It is important to reiterate the need to develop and analyze systems. The existing evaluation of scientific research is effective in considering specific issues, but is much less effective in generating (possibly complex) systems proposals for engineering assessment and analysis. The story of the scientist who discovers some new and useful property of matter after accidentally leaving the Bunsen burner turned on while away at lunch is well known. But the story of the engineer who accidentally develops a computer or Saturn V booster is not only unknown, but seems remarkably unlikely.
If – as we believe – the successful development of machine-phase molecular manufacturing systems requires the design of massively parallel systems (with some proposals calling for the design of self-replicating systems) then we need to explicitly create programs that solicit systems proposals – proposals that can reasonably be expected to fulfill the goals of molecular manufacturing as outlined above. Systems proposals can be analyzed by theoretical and computational tools that examine the systems as a whole, together with the subsystems and components from which they might be composed.
Last updated on 1 August 2005