Expanded abiogenetic experiment: let us study the origin of life in an enough open system
Enhanced Abiogenesis Experiment
Reproduction of poster report (#22), CAS Conference 2018 "Molecular Origins of Life", 11&12 October,
Literaturhaus Munich
Olexandr Andreev (NTU “KhPI” Laser Laboratory), Anatolii Lazarenko (retired),
Based on the works of Prigogine and von Hayek hypothesis was proposed which allowed developing a new scheme for the origin of life experiments - the logical improvement of classic Miller's experiment in the form of "micro-planet" installation. The improvement is aimed at a production of a wider variety of gradients, degrees of freedom and hence possible ways of development for prebiotic chemical processes. The scheme provides cycles of wetting-drying, evaporation-condensation-solidification etc. in a small confined space along with providing the two-phase mixing and presence of fresh and "ocean" water in conjunction with a variety of minerals, foam etc. It also supposes excitation of the system by different kinds of energy fluxes with various time periods. Different compositions and/or cycling programs can be compared by periodically monitoring of the laser light absorption and scattering spectra richness, as well as by in vitro nanoparticles size measurement with correlation spectroscopy. The installation basic parameters and components, as well as the possibilities of its application, are discussed.
Introduction
For more than 60 years since the first experiment [1] (Miller 1953) no radical breakthroughs in abiogenesis experiment were achieved.
Numerous repetitions of Miller's experiment with various additions and variations finally produce something like tar; even more numerous and diverse attempts to launch replication from RNA [2], metabolism [3], sulfides [4] and others give a lot of useful information about dozen biochemical reactions — but nothing more.
Let us for clarity represent any living creature as a tree branch, starting from its zygote, spore, etc. and ending with the death or decay. Somewhere in between these two ends of the "branches" some new (child) branches can start, continuing (in the presence of natural selection’s "blessing") growth and increasing density of branches "up" - in the future. Fluctuations in habitat conditions and "grinding" by selection (evolution is the action of some more general law, which we shall dare to formulate below) permanently improve living, gradually lengthening (or rather, making them more structured or “poly-articular”) “branches” and hence complicating even the simplest organisms.
At this time, from current "tops" of these "branches", it is almost impossible (through billions of increasingly complex branching ) to see their common beginning as the most simple replication cycles. The simplest known and available for our study replication cycles are still too far from the original, the first ones. Any detailed study of the composition, geometry and other characteristics of the Rhine in Mannheim gives very little information about Rheinwaldhorn Glacier in the Swiss Alps. Or imagine how any Martian can "guess" the form of the first transistor, picking in millions of current ones constituting any mobile phone processor (which itself is not much surpassing in size the first Bell Lab’s transistor).
Most likely, replicators began from some simple vibrations of the "chemical clock" [5] type. Their gradual complexity growth by the inclusion of additional degrees of freedom sooner or later lead to the appearance in those cycles (or Eigen’s hypercycle) some auto-catalytic phase, i.e. reproduction. Reproduction naturally started to decrease a quantity of resources available in the discussed place - and therefore, “turning on” the fight for them and natural selection.
Origin of life was not stohastic one
The closed flows' existence probability in an equilibrium liquid layer (especially being “packed” into regular hexagons), is apparently even less than the correct DNA assembling probability calculated by the ID proponents. But in a layer with appropriate heat flux and temperature gradient (Bénard cells), their occurrence and existence are inevitable.
While trying to reproduce the origin of life as a tricky combination of some pre-designed biochemical reactions, we arrogantly are trying to guess and recreate the way for which nature has spent a billion years instead of trying to create conditions for a significant acceleration of this path (and to learn in the process).
Hypothesis
Life is the most complex form of self-ordering in open systems. The long-known features of such self-ordering, described by Prigogine for physical and chemical processes in [5] and by von Hayek [6], we proposed to be combined into one hypothesis:
There is a law which compels enough diverse and open systems with sufficiently many degrees of freedom and large enough gradients in a distribution of system’s parameters to self-organization and self-development
It should be noted that so far nobody, including Prigogine and von Hayek, has specified that “enough”, “sufficiently”,“many” and “large” should mean in the above formulation. We believe that only specially designed experiments can clarify these meanings, and an experiment on the origin of life seems ideal for this.
A clear and well-known example of self-ordering mentioned is Benard cells example - a macroscopically stationary process, the basis of which are mini-cyclic coherent motions of molecules. Since cyclicity is inherent in all living beings, it is also necessary for the process of the origin of life. Therefore, we propose (the second part of our hypothesis) that the experiment on the origin of life should include the impact on the investigated system of energy flows not only of different physical nature but also of different periods (on Earth, these were heating-cooling, lighting-darkening, wetting-drying, cycles of solar activity [8] e.g). Gradients in the distribution of the system's parameters produce in it a set of continuously distributed mini chemical reactors, while temporary modulation of energy flows also introduces a temporary variety in the conditions of the reactions. Thus, we assume that life has arisen as a manifestation of the law linking physics and chemistry in such a way that a sufficiently diverse system with many freedom degrees and gradients in the parameters' distribution under various periodic effects of different nature energy flows is forced to generate more and more complex structures in the dispersion energy (coming from outside) process.
This law (for short - LED, the law of evolutionary pressure) is universal and is capable of being “sewn” into the new structures it generates, stimulating further development along with natural selection and competition of parallel developing systems. Examples are DNA in biology, and evolution in social and religious systems (or more broadly, cultures or civilizations in the development of mankind).
Various kinds of Miller's experiment for a few months give several amino acids and in the time limit – tar, the Earth for a few giga-years produced biosphere. Our task is to accelerate the processes of self-development as much as possible in a system of limited size and mass, up to cycles-replicators obtaining.
Thus, similar to the plants finding how to grow toward the light, in a rather complex and different-phased system, subjected to the broadband energy duct with flux density above a certain threshold, replicators in a form of Eigen hypercycles can find their “ways” in a space-temporal “net” of chemical reactions and natural selection should start working. Obviously, the simplest replication cycle produced self-copying directly, leaving no place either for “chicken-and-egg” problem nor for mutations, just like stimulated emitted photons are precise copies of initial ones. And only later, under the pressure of both natural selection and above-postulated law (although the first is the part of the second) replication cycles were complicated up to modern level.
Life is a holistic property of a large "planet Earth" system, and it is precisely in the form of a systemic property that one should study its occurrence. This in many respects contradicts all the previous practice of (bio)chemical research by as thoroughly as possible cleaning the used substances and stabilizing the experimental conditions. A rare example of work in which the presence of "contaminants" in the form of the remnants of previous reactions made it possible to find a way to synthesize activated pyrimidine ribonucleotides [9] we may consider as the first experimental confirmation of such "holistic" approach to the abiogenetic experiment.
Life definition at which new abiogenesis experiment is based:
Life is a growth thriving physico-chemical cycles' network with common genetic code obtained,
or, in other words,
physico-chemical cycles' self-developing network bound by common genetic code
( 2019-2020 addition)
The lack of "holistic" experimental and theoretical data on really complex systems prevents us from answering the following very interesting and important questions. What are the minimum dimensions, composition, and number of degrees of freedom that can create regularly reproduced and developing (more complex) structures s (replicators)? What range of parameters and their gradients is necessary and sufficient for this? In other words, what are the quantitative relationships separating the region of the parameter space of the system, suitable for life emergence and existence (zone 1) from the rest one (zone 0)? What is the constant (or are the constants) determining these boundaries (like h and c in hν >> kT or v << c)?
Experiment Scheme Proposed: "svityk" micro-planet
We believe that for enhanced abiogenesis experiment it is necessary to reproduce as much as possible the widest feasible set of physical conditions for a variety of chemical reactions and physical processes (including foaming, drying, freezing and wetting with fresh and seawater, electrical discharges in the air and under water, periodical illumination with light from UV to IR) in the gas and liquid phases and on the surfaces of various minerals in some confined and isolated volume - namely make a "micro-planet" [10].
To ensure the required water and "wind" flows with exclusion of any contamination possibility, we believe it is necessary to use convection, as well as for air-drying in a "dryer" DR (see Fig. 1). The circulation of the liquid and gas phases can be easily realized by the heater-refrigerator pairs in each of the phases (cooler 2 - heater 2 and cooler 1- heater 3 in the figure below, respectively)
A pair cooler 2 - heater 2 can be omitted if average cooling power of freezer 1 (ice generator for ‘Terra firma 3” ) will be both sufficient for continuous ice existence and equal to average heating power produced by foam generator cycles.
The ratio of the duration of the various cycles (for example, “day” : discharges : foaming) must represent significantly not multiples to provide the widest possible range of overlays like 5:17:43, and minimum half cycle duration should exceed the process relaxation time in the system at least several times.
In the diagram of Fig. 1, sensors of temperature, pressure, and concentration of atmospheric gases, as well as valves for their replenishment, and gateway for a sampling of "ocean" water are not shown for simplicity.
To maximize the information obtained in the experiment, we propose to use simultaneously at least two or three (geometrically identical) svityks, controlled by one computer and using the same system of spectrometers, sequentially (alternately) connecting with optical fibers to each of the installations for regular measurements. At the same time, they should differ in pairs, for example, by the composition of the atmosphere (with the same time schedule for switching on effects - light, geyser, foam, etc.) or, on the contrary, by time schedules (with the same atmosphere in both). In all cases, a more rapid growth of the spectra richness and that of the maximum size of nanoparticles in a broth along with the final their values, as well as the richness of the composition of the final broth, should mean shift from zone 0 to zone 1.
We hope that the information obtained in such experiments, especially the final compositions of the broth, will give a clearer idea not only of prebiotic chemistry but also of the necessary (for further progress to zone 1) changes in the following experiments.
It can be assumed that a sufficiently long installation operation (as in the Miller experiment) will lead to the stabilization of composition of the "ocean" and its spectra, as well as will stop the growth of molecules (the latter will be registered by correlation spectroscopy).
The chirality of biomolecules may have been caused by the anisotropy of the electromagnetic fields at the place where they were originated, so we consider not superfluous to include in svityk sources of constant crossed electric and magnetic fields, mutual orientation of which with respect to flows of liquid and "wind" should not be changed during the experiment. And who can guarantee that the chirality of biomolecules is not related to the mutual orientation of these fields relative to the direction of rotation of the circular fluid flow in the "reactor" that gave rise to them (Fig. 2)?
In the diagram of Fig. 1, sensors of temperature, pressure, and concentration of atmospheric gases, as well as valves for their replenishment, and gateway for a sampling of "ocean" water are not shown.
Performing dehumidification and wetting minerals surface with both fresh and «oceanic» water in conditions of complete and reliable isolation of the experimental setup volume from an external environment is significantly more complicated than “winds” and “ sea currents” generation. More of that we believe that the seemingly apparent impossibility of drying a portion of the surface inside a Miller-type installation stopped researchers on this path.
We offer the design of a "dryer" (DR) in the form of a semi-insulated volume with a special heater-refrigerator pair (4-1 on Fig. 1) of approximately equal power. In this case, the temperature of the cooler (which acts as a "cloud") should be kept below the dew point, but above zero by Celsius. This will ensure the gradual filling of the rain generator (RG) capacity with condensed fresh water.
Exceeding the critical level of this water in the tank causes "rain" to flow due to hydrostatic pressure and empties the vessel for further cycle repetition. In this way RG is regularly draining it’s tank to ice and dry and wet mineral surfaces of “Terra firma 3”, “Terra firma 1” and “Terra firma 2” at figure respectively). This reservoir will be emptied after reaching the level shown in Figure 1 and later will be filled again with condensate collected.
It is necessary to have in the "dryer" a certain (limited) free surface of water that communicates with the "ocean" both for foam and "oceanic" water penetration into the "dryer" and for removing the washings from it to the "ocean".
Estimations
The area of this surface determines the lower limit of the amount of water vapor generated in the dryer per unit time and, correspondingly, the minimum capacity of the "cloud "refrigerator for condensing this vapor.
Let us estimate the required power of the refrigerator for dehumidifying air in DR having an open water surface of area A.
Evaporation of water from a free water surface - like a swimming pool or similar - depends on water temperature, air temperature, air humidity and air velocity above the water surface. Using empirical formula [11] for such a process gives us the amount of evaporated water at 300K per second from 1cm2 between 55mg/s (zero «input» air velocity with 10% humidity) and 76mg/s for ( «input» air velocity with 10% humidity 0.5m/s).
Taking into account evaporation heat of water 2454(kJ/kg) leads to needed refrigerator 1 minimun cooling power between 135W and 186W for each 1cm2 of free water surface.
This means that one must diminish this surface to a reasonable minimum (of simple small holes) in order to provide sufficient «drying» power for evaporating water from foam and hard surfaces of minerals. This order of magnitude for dryer productivity (about 60mg/s) means also 216ml/h RG productivity.
Such cooling power can be provided by Peltier thermoelectric elements [17]. For example, TEC1-12715 according it’s data sheet with hot side temperature 300K at 11V and 12A gives 20 degrees temperature difference and cooling power about 90W, so 3 of them can be used for dryer with less then 1cm2 free water surface – if stationary “wind” speed (near water surface) will be less than 0.5m/c.
Let us estimate it. For energy balance in dryer sum cooling power 270W will need about 250W of heater 4 (supposing that 20W difference will be compensated by dryer’s “sun” radiation).
200g of water can be taken off with 1kg (about 1m3 ) of wet air at 65C temperature or 2m3 at 53C [12] so we must provide 1-2 m3 per hour airflow or 0,3-0,6 l/s.
Convective air flow volume in a distance l above the heat source can be calculated as [13]
Q = c2P1/3l5/3 (1)
where
Q - airflow volume(m3/s)
c2 - constant characterizing the actual application, values ranging 0.05 to 0.15 (typical 0.06)
P - heat power from the source (kW)
l - distance above the heat source (m)
For P = 250W and l = 1m Q lies between 31.5 and 94,5 l/s for different c2values, or between 10 and 30 l/s for l = 0,5 m.
This is “upper” estimation because it counts all the flow and does not take into account tubes resistance. More accurate can be an estimation from chimney draft flow formula [14]
Q=C A sqrt[2gh(Ti-T0/Ti)] (2)
where
A
= tube crossection area, m2
C
= friction coefficient usually values from 0.65 to 0.70
g
= acceleration of gravity, 9.807 m/s²
Ti
= mean inner temperature, K
To
= mean outer temperature, K .
For A = 25cm2, C = 0,7, h =1m, Ti =350Kand To = 300K it gives Q = 3l/sthat means air velocity v in the 25cm2tube reasonable v = 1.2m/s well exceeding 1-2 m3 per hour needed for 200ml water drying. If “Terra firma 1” has a profile shown at Fig. 1 (with water surface placed at wells bottom), air flow speed near it will be sufficiently lower both 1.2m/sand 0,5m/s.
We assume that the inclusion of the listed and other (see below) phenomena, as well as the "wind" (cooler 1 + heater 3) and "currents" (cooler 2 + heater 2) with different non-multiple periods will give a very wide variety of combinations of conditions and gradients in different parts of the installation.
So one more estimation which should be made – characteristic time period (or estimated time for “daytime”, or average time between geyser eruptions/rains/foam generations etc). This time can be by the order of magnitude equal to system relaxation time in order that sufficient changes had time to take place. Accordingly for concentration gradients, we obtain
τD = L2/D (3)
for temperature gradients
τT = L2/k (4)
and for velocity gradients
τη = L2/η (5)
where Lis a characteristic dimension of a system, D - diffusivity coefficient and k - coefficient of thermal diffusivity η is the kinematic viscosity of a medium (water or air). For L = 0.1m, T about 300K, D for gases between (0,1 ... 0,7) cm2/s and for water solutions ( 0.04 … 0,8) cm2/day we obtain for τD air in (138 ... 1000)s , τD water in(125 … 2500)days and for τT (with kair = 0.2cm2/s , kwater=0.0015cm2/s :τT air =500s andτT water =1625s =0.45h , and for τη withηair =0,16 cm2/s , ηwater =0.01 cm2/sτηair =156sτηwater=2500s =0.69h. It should be noted thatformula (3), (4) and (5) are valid rather for a stationary case of some fluctuation vanishing than for our one of forced media mixing extinction, where all three processes take place simultaneously.
Foam generator FG at figure can be as simple as (periodically turned in and out) electrical boiler placed under the funnel-shaped and curved tube, so that foam produced can reach both “Terra firma1” in the “dry room” and “Terra firma 2” at wet one. “Terra firma 3” represents an ice produced by Freezer 1.
For impact on “Terra firma 1” of fresh, "oceanic" and diluted water geyser mock-up with special heater-boiler is envisaged in addition to RG. The geyser turns on periodically, pouring out a portion of ocean water for mixing with the rain one in the lake and on the surface of the “Terra firma”. The difference in the periods of rains and geyser eruptions provides a variety of proportions of water salinity in the dryer.
Since the complex of the dryer will greatly weaken the "sun" light in it, it will need a separate light source, designated by “DR Sun” in Figure 1.
So the proposed experimental setup (let us call it for short "svityk"[10]– this Ukrainian word means a small world) must include at least the "ocean" with a sufficient amount of seawater, "Terra firma" as an island or islands, in addition to the "shores" of "the ocean" with relief, providing space for "lakes" and "shoals" with coating of a variety of minerals, including, of course, sulfides of iron, zinc and other prospective catalysts and photovoltaic substrates, as well as the "dark rooms” both in air and underwater as well as different kinds of clays [15].
During the experiment, the concentration of any gas (or gases) in the atmosphere may begin to decrease because of its consumption in irreversible reactions. To maintain the initial concentration, an influx of this gas (or gases) to the composition will be required. This circumstance can be used to introduce another gradient into the system – pH one. It will also allow investigating the role of hydrothermal sources in the emergence of life by simulating these “smokers” in the form of porous nozzles made of an appropriate mineral, placed at the ends of the gas supply pipe and placed into one of the underwater heaters (2 at Figure 1).
The anisotropic shape and orientation, as well as also anisotropic placement of the latter (as well as the supplementary cooler 2) will allow water circulation around the DR island in one direction (in Figure 2 - counter-clockwise). In the same figure, the pH gradients are also shown by color changes when the alkaline and acid "smokers" are simultaneously switched on.
In the meantime, the theory of really complex systems do not even start to be created: there are no clear definitions and thresholds of complexity and that of creating new structures, so we have to handle with rather qualitative considerations. However, for origin of life experiment there is one exception: in the development of the installation, we must focus on the average flow of energy through the system of not less than 340W/m2 order - the value of the solar constant. Thus, we can start with the fact that the total maximum power of both "suns" should be about 340 W per square meter of the horizontal surface of the installation, i.e. for example, for a "bottom" area of 0.25 square meters - 85W.
Then, in such a system, "penetrated" by gradients and mixing there are many places with different combinations of conditions for the occurrence of a variety of reactions and for their products spreads all over the limited volume of installation. This volume limitation in our "Earth model" by eliminating dilution and increasing gradients gives hope for "compression" of the timeline for several (5-7? – of course linear estimations cannot be correct in this sufficiently nonlinear case) orders, as well as a decrease in daytime period and annual cycles, for example, to minutes and hours (2-3 orders of magnitude), which in total can give "transformation" or "compression" to the required 7-10 orders to come from 2-3 billion years to acceptable months or years.
After fixing a combination of factors, giving a steady growth of new structures (by the way, it would be better to start experiments of this kind with anaerobic atmosphere to prevent accidental growing of competing for our form of life, which our one would not be able to "digest"), we can go to the elucidation of the role of each of them (simply by “turning off” appropriate cycle or interaction), and only after this we can try to start to write the equations.
So, we propose to create and continuously to test in parallel 2-3 geometrically identical "svityks" with different atmospheres and/or cycling impacts programs (lighting, electric discharges, "rains", foaming, etc.). A comparison of the changes rates and complexity of the resulting structures will be made by periodically connecting each of the units to a common laser spectrometric system by simile of richness of the absorption, luminescence and scatterings spectra for the liquid phase and by the size and growth rate of nano-particles (big biomolecules), as well as by chemical composition analysis of the resulting "broth".
Yes, we cannot yet say how the work to reduce the structural entropy [16] will be made at least because, unlike Benard cells (where only three forces are involved and we can write the corresponding differential equations), in abiogenesis more than a dozen reactions can be operated in three environments with dozens of different boundary conditions. Even in the Benard cells, it is not possible to clearly point out a “structuring law”, because it manifests itself in the form of coordinated interaction of viscosity, gravity, and thermal expansion forces, that "cooperate" in the transfer of energy flow. Sooner or later we will have to admit that the "inert" matter is "boring" to digest in a fairly complex system supercritical flows of energy (and/or information) without the formation of new structures (examples of what we ourselves are).
Conclusion
The offered enhanced experimental setup must include (in addition to laser spectrometers) heaters and coolers to maintain convection fluxes in "atmosphere" and "ocean", the freezer to create a "circumpolar" area, foam and "rain" generators, "dryer" in the form of an extra pair of heater and refrigerator for providing "dry room", light sources with close to sunny radiation spectrum, air and water dischargers (the latter can add shock waves to our “effects menu”), as well as sources of non-uniform electric and magnetic fields. All these devices need to be fed from the respective computer-controlled power supplies, as well as the system of temperature, humidity, and atmospheric composition sensors. Hard surfaces in contact with "atmosphere", "ocean", and foam must possibly include a wide range of minerals, at least - oxides and sulfides of iron, zinc and other susceptible to a catalytic effect on natural organic substances synthesis. The estimations carried out confirm the possibility of implementing the proposed experimental design with the current level of technology.