PROBABILITY AND THE ORIGIN OF LIFE
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© 2009, by John Tors. All Rights Reserved.
It is the common belief that the mechanism for evolution is natural selection acting on random mutations. This means that evolution is fundamentally dependent on chance. This also applies at the pre-biotic stage, which is known as chemical evolution: Simple chemicals, we are told, combined to form basic organic molecules (amino acids) by chance. These simple amino acids came together to form complex proteins, by chance. Extremely complex RNA and/or DNA were formed, by chance. These all came together to form the first cell, by chance. Surely, we are told, given the supposed long age of the earth, currently posited as 13.7 billion years, chance can accomplish all these steps.
This is what the general public believes. This is what is taught in high school classes and promoted in the media. The trade secret, though, is that no origin-of-life scientist believes this anymore. They know it is impossible.
In Darwin’s day, the cell was believed to be very simple, essentially not much more than a homogenous sac of gelatin. It seemed plausible that such a thing could form by chance from simple chemicals. However, it was eventually discovered that the cell was not, in fact, simple at all. As the nature of the cell was elucidated, and particularly after 1953, when the structure and function of DNA was discovered, it became clear that the cell is, after all, extremely complex. Each cell is an automated factory and information processing centre more complex than a large city the size of Los Angeles, were that city an automated factory.
As this reality came to be understood, scientists and mathematicians began to apply probability calculations to ascertain whether or not the assumption that chemical evolution could have proceeded by chance was, in fact, plausible.
First, what can be considered possible and what can be considered impossible, from a probability standpoint? Well, let’s consider an example, rolling dice. What are the chances of rolling a six? It is 1 in 6. If you roll a die six times, you should get one favourable outcome (i.e. a 6), and it should take about six seconds to accomplish it.
What are the chances of rolling two dice and getting both sixes? 1 in 36. So if you roll a pair of dice thirty-six times, you should get one favourable outcome, and it should still take less than a minute.
What about rolling twenty dice and getting all twenty to be sixes? The odds are 1 in 3.656 quadrillion! (A quadrillion is 10 raised to the power 15, or a million times a billion.) At one trial per second, you can expect it to happen once in 115,856,669.7 years! If you had the entire putative 13.7 billion year history of the universe to work at this, you could expect to have this happen a mere 118 times.
Based on this sort of reasoning, mathematicians have worked out what is called the Universal Probability Bound, which is the absolute limit beyond which an event becomes impossible. It is not one in ten raised to the power 15, but one in 10 raised to the power 150 (10150, or 1 followed by 150 zeroes; I won’t type that out, but you can do it yourself, to give you an idea of what constitutes “impossible”). The Universal Probability Bound is based on what is called the “probabilistic resources of the universe.” Any event is possible given infinite time, but we do not have infinite time. Is an event possible given the number of trials that can be attempted?
There are an estimated 1080 atoms in the universe. Multiplying this by theoretical maximum speed at which these atoms can rearrange into new configurations, which is 1045 changes per second (based on the Planck constant) and multiplying that by the commonly accepted age of the universe (1025 seconds) gives us 10150. This allows for all of the atom trying every possible configuration in every moment of the available time. Thus, an event with a probability less than 1 in 10150 (so that every possible combination can be gone through without reaching the favourable outcome) is deemed clearly impossible.
With this understanding, we can now ask whether it is possible that a protein molecule arose by chance. There are about twenty different amino acids used as building blocks for proteins, each with an average of about nineteen atoms that must be arranged in a specific sequence. Even if sufficient quantities of all twenty such amino acids could arise by chance, the odds against correctly assembling a protein chain of even 150 amino acids in the right order is one in 10185, outside the realm of possibility. And the probability of the simplest theoretical cell forming by chance is wildly less than this. Yale University physicist Harold Morowitz calculated the probability for a simple bacterium forming by chance as 1 in 10 to the power 100 billion!
Random chance, then, has no explanatory power for the origin of life. The trade secret of origin-of-life scientists is that, since the late 1960’s, no one has appealed to chance to explain the formation of the first cell. Even Richard Dawkins, in a recent issue of BBC Knowledge, glibly says that
Creationists think evolution is random chance. Any fool can see that if it were random chance it wouldn’t work.
So, although most of the public is still led to believe that evolution could have started through random chance, scientists know that this is impossible. But absent random chance as the creative agent, what alternative is there but an intelligent Creator?