Precision Measurement - From Atomic Standards to Automated Control - Lecture 3

Explore the fascinating world of precision measurement in this 59-minute Christmas Lecture from The Royal Institution, recorded on December 3, 1981. Discover how modern science has pushed the boundaries of measuring incredibly small scales and learn about the fundamental limits we encounter when trying to observe the tiniest aspects of our universe. Examine the redefinition of the metre in terms of atomic properties using krypton 86 wavelengths, making it a universal standard that transcends earthly catastrophes. Investigate various techniques for measuring extremely short distances using light waves, optical levers, Moiré fringes, and capacitance micrometers, all crucial for modern industries and automated machine tools. Delve into the revolutionary concept of automatic scale reading and computer-controlled measurements that enable precision manufacturing. Confront the fundamental physical limits imposed by Brownian motion - the constant agitation of atoms and molecules that affects both the objects being measured and the measuring instruments themselves. Understand the profound quantum mechanical principle that the very act of observation can alter what is being observed, as the pressure of light used for measurement can physically move the object from its original position. Learn how these measurement principles have driven technological advances from microchips to space probe navigation, while also considering the philosophical boundaries of what can and should be measured in human experience.