Ep 11. The Persistence of Memory

In Cosmos season 1 episode 11 titled "The Persistence of Memory," renowned astrophysicist Neil deGrasse Tyson guides us through a fascinating exploration of how human beings have grappled with the concept of time throughout history.

The episode begins with a discussion of how ancient peoples used the cycles of the natural world, such as the movements of stars and the changing of the seasons, to mark time. However, as human societies became more complex, our understanding of time had to evolve as well. Tyson explains how the advent of agriculture led to the creation of calendars, which allowed farmers to plan when to plant and harvest their crops.

From there, Tyson delves into the various ways that humans have tried to measure time. He introduces us to early clocks, such as the sundial which relied on the position of the sun to tell time, and the water clock which used the flow of water to mark the passing hours. Tyson then takes us on a trip to see some of the most impressive clocks in the world, including the medieval astronomical clock in Strasbourg, France, and the highly accurate atomic clocks used in modern-day GPS systems.

The episode also examines how our understanding of time has been shaped by our understanding of the cosmos. Tyson tells us about the work of Galileo Galilei and other early astronomers who used observations of the stars and planets to develop the concept of "universal time," a way of measuring time that is consistent no matter where you are.

Finally, the episode explores some of the more abstract and philosophical concepts of time. Tyson delves into the concept of time dilation, which shows that time can actually move slower or faster depending on the speed and gravity of an object. He also discusses the idea of the arrow of time, which postulates that time only moves in one direction, from past to present to future.

Overall, "The Persistence of Memory" is an engaging and thought-provoking exploration of a topic that is fundamental to human understanding. Through Tyson's clear and engaging explanations, we gain a richer appreciation of the many ways that humans have sought to understand and measure time.