Have you ever noticed that most of the units used in science to describe nature (such as meters, kilograms, seconds, etc.) were defined fairly arbitrarily? Have you ever wondered if an alternative set of units could instead be constructed based on nature itself by incorporating some of the fundamental constants of the universe? Well, Max Planck did just that when he created the Planck "natural units" (Planck length, Planck mass, Planck time, etc.) which are used by many theoretical physicists today. In this presentation, I will discuss the history of natural units, show how they can be constructed from simple dimensional analysis, and provide examples from modern physics where natural units are most commonly used.

This presentation was made with undergraduates in mind, and it should be appropriate for anyone with interest in physics despite his or her level of training.