Abstract
What questions can ever be answered by a physical entity? In this essay, we examine this question by studying the predictive powers of Laplace's demon. We find that the powers of a physical Laplace's demon are considerably diminished by limits on what is knowable due to quantum mechanics, (classical and quantum) chaos, incompleteness, and physical limits on computation. Because the helplessness of Laplace's demon naively conflicts with the shocking comprehensibility of the world around us, we imagine a new demon intended to model what questions can ever be answered. The approach and capabilities of this demon are found to strongly resemble those of scientists. We touch on some consequences of our arguments, including for free will and predicting versus understanding.
John Joseph Vastola