20160126

PROBABILITY

Few aspects of life were said to have eluded the touch of chance. For instance "an unpredictable grouping of genes determine a person's physical make–up. An unplanned encounter may decide a person's choice of marriage partner." The word "probability" meant the chance an event would likely to occur or what people expected would happen.

Dr William F Russell made the point, "Many children, and adults as well, use words like 'chance', 'luck', 'odds' and 'coincidence' without any real thought about the likelihood that the event in question might occur. The easiest way to find out what 'pure chance' is, or at least to see how it operates, is to do with our children precisely what the mathematicians in the 17th century did when they began studying the theory of probability. They started tossing coins and throwing dice." 

Dr R.M. Clark added, "Most of us are not aware of it, probability and randomness play an important role in modern society. Although it was as late as the 16th century that philosophers and mathematicians first attempted to organize the concept of chance events into an elementary theory of probability, throughout the history of man chance and games of chance have played an important role in organized society."

"An event whose outcome cannot be predicted is called a random event," it was explained. "The long-term regularity for repeated random events is called the law of large numbers. The laws of chance begin to act as laws when a large number of cases are involved. The law of large numbers gives an individual a remote chance of being consistently lucky – of consistently doing much better than a probability prediction would warrant.

"On the other hand, a long run of good luck does not decrease the chance that an individual will again be lucky on any one occasion. The 'next occasion' is still a random event. For example, the law of large numbers would indicate that throwing 10 heads in a row is unusual but the law of large numbers does not apply to the 11th toss of the coin. The coin could come down heads just as easily as it could come down tails. This basic misunderstanding is even given the name the 'law of averages'. The law of averages is not found to work in practice (the ultimate test for any physical law).

"It was said the important words in probability were "certain", "uncertain", "impossible", "likely" and "unlikely". These words were said would help a person in figuring out what probably could happen. Any event that had a definite probability that did not reduce with time would eventually occur. As pointed out, "No one can predict which way an evenly balanced coin will fall. Nevertheless, it is possible to predict that if a coin is tossed very many times, it will fall heads about the same number of times as it will fall tails. When a coin is spun, various factors combine to determine whether the coin falls head first or not. But these factors are so many and so completely beyond one's control that the result is a matter of pure chance.

"If we toss the coin a very large number of times there will not be very much difference between the number of 'heads' and of 'tails'. The theory of probability is based on a rule – 'the probability of any event occurring is simply proportional to the number of ways in which it is possible for that event to occur'. To illustrate the rule from everyday life: The probability of a street accident has increased in the present generation merely because we have increased the number of ways in which an accident can occur.

"It is important to realize that the laws of chance become exact laws only when we deal with large numbers. Beyond a million spins the 'heads' will equal the 'tails' to within a small percentage, but the probability of 'head' and 'tail' alternating regularly is no bigger than the probability of their being all 'heads'. The tally will fluctuate, now in one direction, now in the other, the fluctuations prevents being sometimes large and sometimes small. Incidentally, these fluctuations account for the fact that in gambling on perfectly even chances the richest man always wins.

"In nature orderly movements are improbable and unstable, and every chance that occurs is in the direction of disorder. Say, for instance, one had a perfect billiard table and say, a dozen balls on it rolling to and fro from cushion to cushion in perfectly parallel lines; this would be an ordered state of movement, and a very unstable one. The slightest deflection given to one of the balls would cause it in time to strike one of the others, and disorder would increase rapidly until in a short while the balls would be rolling about, colliding and rebounding in a perfectly erratic manner – as do the molecules in a gas."

Blog Archive