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How could such a complex process develop so early in the history of our planet?
To get an idea of the complexity of putting this process together, let's take a look at just one of its parts--that called photo-system 2, the catalytic core of which is shown in Figure 1. The 4 spheres having a dot in their middle represent manganese atoms, the smallest spheres are hydrogen atoms, middle size is oxygen, and a single calcium atom is at the apex of the box-like structure.
The manganese atoms in the box pass electrons on to the single one outside. Three electrons is enough to give it the potential to split its attached water molecule, which reaction yields an OH (hydroxyl) radical plus a proton. The next electron destroys the radical which becomes an activated oxygen atom.
The single calcium atom at the apex of the box holds its attached water molecule in exactly the right place to be attacked by the activated oxygen, the result being a normal oxygen molecule (O2), plus 2 hydrogens that are at the disposal of the host bacterium to combine with carbon to produce sugars, etc.
This core catalytic center of photosystem 2 has so far resisted all attempts to synthesize it. Yet every single day, using energy from the sun, simple single-cell bacteria produce it by the truck load.
But this is only one cog in a complex wheel. Additionally involved in photosynthesis there is photosystem 1 absorbing light at longer wave lengths, plus chlorophyll, also light absorbing, plus a group of proteins specifically tailored to stabilize the structure of the systems, even repairing or replacing them when necessary.
All of this amazing repertoire would need to have been present by the time these bacteria became effective at oxygenating the oceans sufficiently to precipitate oxidised iron minerals in layers on the floor of the oceans 3.8 billion years ago and build stromatolites almost 4 billion years ago.
Just how many different proteins were present in these very first photosynthetic bacteria almost certainly numbered above a thousand. But even if it had been just a dozen or so, the complexity of producing them is illustrated by calculations of the probability of building just one specific protein molecule through the random choice of the amino-acid building blocks from which all protein is formed.
The sequence of those building blocks is specified by the sequence of units of three nucleotides made up of adenine, guanine, thymine, and cytosine that compose the DNA gene specifying a specific protein. The chances of forming a single functional gene for an average size protein comes out at one in 10150 assuming the random selection of the sequence.
Such probabilities are multiplicative. So if we wish to make a second type of protein molecule we have to multiply 10150 by 10150 which is 10300--an utterly and impossibly remote possiblity.
In considering the origins of life on our planet nobody has yet come up with any reasonable concept of the mechanics of how such a process could have occurred.
But this is not our only set of unknowns for highly improbable events. Example--what are the chances of a universe like ours creating itself by itself? We have touched upon this in an earlier issue of Innerface but it is important enough to merit a reminder.
To actually design a universe like ours, at our present state of knowledge there are about 20 parameters (numbers) that must be entered as a 'best guess.' These include: how strong do we make gravity, or electric charge, or the force that holds an atomic nucleus together, and so on?
Ideally, if we had a perfect theory covering all aspects of material reality, these numbers would naturally fall out from the theory. But, at present, we have two major theories, one covering reality on a large scale (General Relativity), the other covering the scale of the atom and below with a similar degree of accuracy (Quantum Theory)--and they are incompatible!
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