The Evidence for Modern Physics: How We Know What We Know

Dr. Lincoln opens the series with the observation that all matter is made of atoms. But how do we know? The atomic hypothesis goes back to antiquity, although that was just an inspired guess. Survey the contributions of later scientists such as John Dalton and Albert Einstein. Discover why atoms are invisible to light microscopes, but not to the scanning transmission electron microscope.

Peer inside atoms to find mostly empty space, along with electrons and a compact nucleus, composed of protons and neutrons. These particles were all discovered indirectly through painstaking but straightforward experiments. Learn how physicists used more complex tools to uncover hundreds of even smaller objects. It took the quark theory to bring simplicity and unity to this seeming chaos.

Probe one of the most baffling mysteries of physics: the wave-particle duality of light. Trace the debate over the nature of light to its apparent solution in 1801, when Thomas Young demonstrated that light is a wave. A century later, Einstein proved that light also behaves as a particle. Astonishingly, further work showed that electrons and other matter also have this Janus-faced identity.

Dr. Lincoln boldly confronts the paradox of quantum entanglement, which governs the behavior of particles that share the same quantum state. Discover that the rules of quantum mechanics defy every attempt to explain what seems inexplicable—implying, for example, that a cat could be simultaneously dead and alive in Erwin Schrödinger’s famous thought experiment. Explore other spooky examples.

Learn how Dr. Lincoln routinely conducts experiments that show the bizarre effects of Einstein’s special theory of relativity, which come into play at speeds approaching that of light. Like quantum theory, relativity strains credulity, but clocks really do slow down and length contracts at relativistic speeds; we just don’t notice these effects in our relatively slow-moving lives.

How can the speed of light be the same for everyone, regardless of their state of motion? First, investigate how the speed of light is determined. Next, consider the hypothesized medium for light propagation—the aether—which was dealt a fatal blow by the Michelson-Morley experiment in the 1880s. Finally, examine laboratory proof that the speed of light is constant for all observers.