The Science behind Non Corps



The Science behind Non Corps -->



A universal definition of life relates it to autonomy and open-ended evolution i.e. to autonomous systems with open-ended evolution/self-organization capacities. Thus a number of features follow: some energy transduction apparatus (to ensure energy current/flow); a permeable active boundary (membrane); two types of functionally interdependent macromolecular components (catalysts and records)—in order to articulate a `genotype–phenotype' decoupling allowing for an open-ended increase in the complexity of the individual agents (individual and `collective' evolution) [3]. The energy transduction system is necessary to `feed' the structure; the boundary as well as a property called `autopoiesis' (which is a fundamental complementarity between the structure and function [4, 5]) are necessary to sustain organized states of dissipative structures stable for a long period of time. To maintain a living organic state, it is also necessary to process nutrients into the required biochemical tools and structures through metabolism which in mathematical terms can be seen as a mapping f that transforms one metabolic configuration into another (and is invertible) f(f) = f; i.e. it is a function that acts on an instance of itself to produce another instance of itself [6, 7]. Finally, memory and reproduction of organic life are based on the properties of DNA which are negatively charged macromolecules exhibiting an important property of replication [8].

Self-organization of any structure needs energy sources and sinks in order to decrease the entropy locally. Dissipation usually serves as a sink, while external sources (such as radiation of the Sun for organic life) provide the energy input. Furthermore, memory and reproduction are necessary for a self-organizing dissipative structure to form a `living material'. The well known problem in explaining the origin of life is that the complexity of living creatures is so high that the time necessary to form the simplest organic living structure is too large compared to the age of the Earth. Similarly, the age of the Universe is also not sufficient for organic life to be created in a distant environment (similar to that on the Earth) and then transferred to the Earth.

Can faster evolution rates be achieved for non-organic structures, in particular, in space consisting mostly of plasmas and dust grains, i.e. of natural components spread almost everywhere in the Universe? If yes, then the question to address is: are the above necessary requirements of self-organization into a kind of a `living creature' present in plasmas containing macro-particles such as dust grains? Here, we discuss new aspects of the physics of dust self-organization that can proceed very fast and present an explanation of the grain condensation into highly organized structures first observed as plasma crystals in [9, 10]. We stress that, previously, important features of these structures were not clearly related to their peculiar physics such as plasma fluxes on to grain surfaces, sharp structural boundaries, and bifurcations in particle arrangements that can serve as memory marks and help reproduction. The plasma fluxes strongly influence interactions of dust particles, sustain the boundaries, and realize the energy transduction. We discuss experiments which indicate the natural existence of the memory marks in helical dust structures, similar to DNA, and natural mechanisms of the helical dust structure reproduction.

 '''2. Plasma over-screening and plasma fluxes'''

An important feature of inorganic structures is the presence of `memory marks' existing as `rigid marks' in common crystal systems. In contrast, observations of crystals formed by dust in a plasma (plasma crystals) [9, 10] demonstrate no rigid marks because of unusual properties of plasma crystals such as large coupling constant, low temperature of phase transition, and large separation of grains. These puzzling properties can be resolved by employing the over-screening of grain fields, the effect that was clearly realized only recently. The over-screening appears in the presence of plasma fluxes on to the grain surfaces [11]–[13]. As a result, an attraction well appears as indicated schematically in figure 1. This potential well is usually shallow and located at a distance much larger than the Debye screening length λD (an example shown in figure 1 uses parameters typical for plasma crystal experiments [9, 10]). A shallow potential well explains the large coupling constant as well as the low temperature of phase transitions. By extracting the pure Coulomb potential of interaction and introducing the screening factor ψ, the grain interaction potential is V = Zd2e2ψ/r (Zd is the grain charge in units of electron charge –e). Due to over-screening, the value of ψ changes its sign at large distances as indicated in figure 1. At the potential well minimum, the screening factor ψmin is negative. The value |ψmin| determines the temperature of the associated phase transition Td and also characterizes the distance rd = rd(|ψmin|) of the well minimum (in the simplest case, ). If condensation of grains (or grain pairing) occurs, the grains will be localized at the minimum of the attraction well, rd. The corresponding criterion can be expressed through the coupling constant Γ (which is the ratio of the potential energy of the grain interaction to their kinetic energy) as Γ > Γcr≡Zd2e2/rdTd = 1/|ψmin|. Thus, |ψmin| determines values of the inter-grain distance, the temperature of transition, and the coupling constant. For a shallow attractive well, |ψmin| ≪ 1 and Γ ≫ 1. This qualitatively explains thelarge value of Γ observed in experiments. The model predicts Γcr to be of the order of the difference between the maximum grain interaction and the temperature of transition (about 3–4 orders of magnitude). As a result, the concept of plasma over-screening agrees well [12, 13] with major experimental observations [9, 10]. It also applies for description of dust helical structures and leads to the possibility of unusual `memory marks' impossible in common crystals.

