Brief Answers to the Big Questions

The ancients blamed capricious gods for floods, earthquakes, diseases, and other disasters. The stars, though, behaved in a regular manner, and astronomy became the first science. Science evolved as more regularities were found in nature.

Pierre-Simon Laplace claimed that if we knew the initial positions and velocities of every particle in the universe, we’d be able to calculate their activity at any time, past or future. This “scientific determinism” may be impossible because of the complexity of the equations involved and because of the phenomenon of chaos, which introduces unpredictable variety in the way particles interact.

A second problem is that calculating an atomic particle’s speed and location requires firing other particles at it and measuring the results. A high-energy particle can locate another particle somewhat precisely, but the energy of the interaction causes the observed particle to change velocity in unpredictable ways. Conversely, a low-energy measurement doesn’t impart much of a change to the observed particle’s velocity but also doesn’t determine that particle’s location with much precision: “[T]he more accurately you try to measure the position of the particle, the less accurately you can know the speed, and vice versa” (92). At the atomic level, quantum mechanics can predict only probabilities, not certainties.