The reign of Le Grand K has come to an end. After 130 years, this hunk of metal sitting in a Parisian vault will no longer define the kilogram. The new kilogram mass will be defined by Planck’s constant, joining three other units for redefinition by fundamental constants. But as we measure with increasing precision – from cesium atomic clocks to gravity waves 1000th the width of a proton – is something fundamental lost along the way? Meanwhile, the BiPiSci team accepts the banana-measurement challenge. Guests: Jon Pratt – Mechanical engineer and engineer and Chief of the Quantum Measurement Division of the Physical Measurement Laboratory (PML) at the National Institute of Standards and Technology Wolfgang Ketterle – Physicist at MIT, Nobel Laureate Simon Winchester – Author of “The Perfectionists: How Precision Engineers Created the Modern World” Originally aired September 9, 2019 Learn more about your ad choices. Visit megaphone.fm/adchoices