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ISBN 13: 978-1-62183-311-6
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Life on this planet and in this Solar System is unique in many fascinating and unbelievable ways. Is life possible beyond our Solar System? And could it be possible that the seeds of life were brought to our solar system. Perhaps life began from chance encounters at the microscopic level with amino acids and chance chemical encounters. Lets explore some of the many possibilities.
First of all there are those that speculated that life on earth began as a result of millions if not billions of years of chance chemical encounters. To some extent I agree. Over time trillions upon trillions of chance chemical encounters occur. But to create life, as we know it, requires much more than just chance encounters. Fore instance take the relationship between RNA and DNA. The stuff of life. How could these two disparate molecules co-conspire to create a living thing. DNA is the book of life but it cannot do anything on its own. RNA needs to unzip it, check it, throw away what is not needed or recognized, reassemble it to make proteins, know when and where to put those proteins and enzyme's, and know when to begin the process and when to stop. The whole of this process needs to purposefully work together in a self sustaining way to promote life. Obviously, these two molecules need to do more than this but this describes some of the main requirements to make a living thing. This process seems to have been purposefully and intelligently created. However, it could be that we simply cannot fathom the complexity of the universe and the billions of years of its existence. Or the fact the universe is so finely tuned for life that life was inevitable. Let's explore life and its possible history in the following paragraphs..
Are we unique to this universe. I doubt that we are. From the very beginning the cosmological constants required to bring about life as we know it needed to be put in place with exacting precision. I list a few of these exacting requirements in the 'Puzzle Keeper' blog. In order for the universe to exist at all required that at the beginning it needed to be isotropic and homogeneous. In other words: At the moment of creation the energy that appeared out of the vacuum of space needed to exist as a perfectly smooth expanding volume, in an energetically evolving state of expanding density. The slightest difference in energy density or the rate of expansion would be reflected today as areas in the universe that are not like our own, or another possibility would be the universe would not be sustainable, or any number of other possibilities. Without those cosmological constants being exactly as they now appear to have been we would not be here to observe it. (Google: Fundamental and Cosmological constants)
So the universe appears to be the same everywhere we look. That would imply that everywhere we look there is the possibility for life. How far back in time could we expect life to have originated? In order for life to have evolved, certain elements needed to have come into existence and those elements had to form compounds of elements to produce life. Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur are the most common. All of these elements are below Iron in the periodic table. So conceivably these elements could have existed early in the evolution of our universe. Elements above iron are formed by supernovae solar explosions. It has been estimated that the first supernovae's could not have occurred before one to two billion years after the beginning. With the first supernovae explosions came the elements above iron in the periodic table. The heavier elements are needed to form rocky planets in order to sustain living things as we know it. But rocky planets (metalized planets) are not required for life to begin. So pre-living things could have first appeared nine to six billion years ago during the early evolution of galaxies. Existing as free molecules and compounds of molecules having the ingredients of life. A lot depends on our definition of a living thing. And the most basic definition implies that a living thing must be able to reproduce. So if this is our definition than perhaps six billion years ago is logical. If we expand our definition of life to be; 'A living thing must be able to reproduce and metabolize other elements or compounds of element to be considered a living thing,' than that narrows down the time frame to be after the birth of rocky planets where concentrations of heavier elements are found. Keep in mind that planets are not all rocky and all planetary systems take time to coalesce into livable, life sustaining, planetary systems.
Rocky planets could have first existed some nine to seven billion years ago. Over time their numbers increased as the cosmic debris of supernovae explosions coalesced. If we believe that self sustaining life evolved from chance encounters with rudimentary elements and compounds of elements, than it is hard to believe that life was complex, or that RNA and DNA were cooperating to make a living thing much before seven billion years ago. RNA is less stable than is DNA.This fact may have promoted a diversity of RNA and DNA encounters. But still, in order to make a living thing, as we know it, many complex encounters, processes, and environmental incentives needed to be in place. This means that either life is rare and diverse or that life was promoted by some added mechanism. What that mechanism might be is unknown. But somehow RNA and DNA needed to co-conspire to create living things.
The shear complexity of the relationship is beyond comprehension. Independently these two compounds cannot do anything other than to exist as compounds of familiar elements. There had to be an instance, as these two molecules emerged, where they began to interact. How might that interaction have emerged? In today's more complex life forms there is DNA which is encoded with just four common elements, The order, length and encoding of these four elements define a living thing. But that is all it can do on its own. DNA alone is like a book on a shelf collecting dust. It will stay on the shelf collecting dust and deteriorate until something comes along and opens the book. therein lies the mystery. The first 'DNA' books could have been a very small books collecting dust.The story within it remained undiscovered until another molecule 'RNA' opened the book and read it. That's the real mystery. How, and why, did these two very different molecules come together to create a third 'living' entity, defined by the DNA codes. It had to either happen by accident or by design.
In today's more complex living organisms there exists different RNA (mRNA, tRNA) molecules that assist in opening, error checking, and reading life's DNA book and making proteins. These RNA molecules then fold and transport those proteins to where they need to go. All the while keeping the encoded message held within the DNA book intact for future use. What about the first ever attempt at making a living thing using these two molecules? How might that first instance of cooperation between the two have occurred? In my mind it must have evolved in much simpler primitive organisms, and then evolved to become more complex over time. The difficulty with pursuing these questions is that behind the question is an undeniable feeling that the whole of the process has to be purposefully driven. It seems there is an intelligence behind it. It does not seem that given the billions of years of chance encounters, life, as it has come to be known, would ever have occurred given the probability of it occurring by chance alone.
