Thursday, August 23, 2018

Is Probability a Fundamental Force?

Anyone who has studied both physics and statistics can understand that there are two distinct forms of chance, both of which we call probability (or randomness).  One of them is termed pseudo-randomness.  The other is pure probability, which is the kind found in quantum physics.

The difference is night and day.  The kind of chance with which most of us are familiar is not what we think it is.  Indeed, if one knows all the factors involved, chance events are not chance at all.

A simple example involves a deck of shuffled cards.  When a standard deck of cards is thoroughly shuffled, we assume them to be in random order.  Trying to guess which card is on top gives us a one chance in 52 of being correct.  

But in fact, if one were to very carefully watch the shuffling, and if one had the ability to track each card during the process, then one could know exactly which card ends up on top.  Chance is not involved. 

It only seems to be chance, because it is virtually impossible to keep track of the cards as they are shuffled.  Our ignorance of where the cards are in the shuffled deck forces us to guess.  But the cards are not in truly random order.  They are in what is called, pseudo-random order, or fake-random order.  Computer-generated random numbers are actually the product of a pseudo-random algorithm.  If one knows the algorithm and the seed number, all the resulting numbers can be precisely predicted.

Even dice rolls are not truly random.  If one could know all the factors involved, all the physical parameters, all the velocities and angular momentum, the coefficients of friction, the air density—everything involved—then the outcome of the dice roll is in principle predictable, not random.

The other kind of randomness is truly random.  It applies in quantum physics.  Even Albert Einstein never accepted true randomness, but a century of experiments in quantum physics (QM) leave no doubt that only the theory of true randomness can explain QM.

In other words, unlike with the shuffled deck, no amount of knowledge of the factors involved can predict the outcome of quantum events, such as the spontaneous decay of a radioactive atom.

It is as if, after carefully watching the shuffling of a deck, the top card being known to be red, could suddenly change to a black one with no physical force being applied.  True chance, pure probability (within parameters) is the underlying reality.

Another way of saying this is that in pseudo-randomness, nature knows what the top card is.  But in quantum physics, not even nature knows when the spontaneous decay will occur in a radioactive atom.
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