I had been taught in school that if chemicals had an ample amount of time to interact in the "warm little ponds" of early earth, eventually the improbable would become probable and life would emerge. Given Bradley's description of what would have to happen, however, I could see why this theory has lost support in recent years.
"Scientists once believed in the idea of random chance plus time yielding life, because they also believed in the steady-state theory of the universe," Bradley said. "This meant the universe was infinitely old, and who knows what could happen if you had an infinite amount of time? But with the discovery of background radiation in 1965, the Big Bang theory came to dominate in cosmology. The bad news for evolution was that this meant the universe was only about fourteen billion years old. More recent work has verified that the earth is probably less than five billion years old."
"Still," I interjected, "that's a long time. A lot can happen in five billion years." "Actually, it's not as long as you think. The earth spent a long time cooling down to a temperature where it could support life. Based on the discovery of micro fossils, scientists have now estimated that the time gap between the earth reaching the right temperature and the first emergence of life was only about four hundred million years. That's not much time for chemical evolution to take place. In fact, Cyril Ponnamperuma of the University of Maryland and Carl Woese of the University of Illinois have suggested that life may be as old as the earth and that its origin may have virtually coincided with the birth of the planet. 33
"And not only was the time too short, but the mathematical odds of assembling a living organism are so astronomical that nobody still believes that random chance accounts for the origin of life. Even if you optimized the conditions, it wouldn't work. If you took all the carbon in the universe and put it on the face of the earth, allowed it to chemically react at the most rapid rate possible, and left it for a billion years, the odds of creating just one functional protein molecule would be one chance in a 10 with 60 zeroes after it."
Those odds are so infinitesimal that the human mind can't comprehend them. "That makes winning the lottery look like a sure thing," I quipped.
"Absolutely. Belie has said the probability of linking together just one hundred amino acids to create one protein molecule by chance would be the same as a blind folded man finding one marked grain of sand somewhere in the vastness of the Sahara Desert-and doing it not just once, but three different times.34 Sir Frederick Hoyle put it colorfully when he said that this scenario is about as likely as a tornado whirling through a junkyard and accidentally assembling a fully functional Boeing 747.
"In other words, the odds for all practical purposes are zero. That's why even though some people who aren't educated in this field still believe life emerged by chance, scientists simply don't believe it anymore."
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