Tag Archives: Quantum Mechanics

Laplace’s Demon Meets Quantum Mechanics

In 1814, Pierre-Simon Laplace published A Philosophical Essay on Probabilities. He said that given complete knowledge of the present, one could perfectly predict the future:

LaplaceWe may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough … nothing would be uncertain and the future just like the past would be present before its eyes.

Makes sense, right? If atoms are nothing more than tiny billiard balls bouncing around then, in principle, our lives are as predictable and determined as the activity on a pool table.

A century later, along came quantum mechanics, which showed that the activity of the universe at the smallest scales is probabilistic. Laplace’s Demon (as the all-knowing intellect in the quotation above has come to be known) can’t be so sure after all!

What a relief! There is wiggle room for free will after all! By inserting the lever of our wills at this fulcrum of indeterminacy, we can move the world.

Or, as argued in books such asĀ Modern Physics and Ancient Faith, God can influence what happens without violating the laws of physics.

Except that’s not how it works. Both of these views misunderstand what the indeterminacy of quantum mechanics is.

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