A Brief History of Time

The Marquis de Laplace, a French scientist, asserted in the early 1800s that the universe is deterministic, which means that if one could know the state of all components of the universe at a single moment, they could develop scientific laws to predict every event in the universe—past, present, and future. Based on this assumption, British scientists Lord Rayleigh and Sir James Jeans made calculations that indicated a body emitting heat and light must do so infinitely. In 1900, Max Planck postulated that light is released in discrete units called quanta, and each quantum contains a specific amount of energy that increases as the frequency of the waves increases. This increase meant that eventually there would be a frequency greater than the amount of energy available to release the quantum, reducing emissions at high frequencies and resulting in a finite loss of energy.

In 1926, Werner Heisenberg used Planck’s ideas to counter determinism in his famous uncertainty principle. Heisenberg postulated that to predict the position of a particle in the future, one must have an accurate assessment of its current position and velocity. Scientists determine a particle’s location and velocity based on light waves reflected off the particle.