minutephysics | How Many Fossils to Go an Inch? (ft. Robert Krulwich) @MinutePhysics | Uploaded 2 years ago | Updated 9 hours ago
A beautiful guest video by Robert Krulwich and Nate Milton

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$How to Build a Teleporter with Aliens The first 200 people to use http://skl.sh/minutephysics30 get 30% off a premium Skillshare subscription. Support MinutePhysics on Patreon! http://www.patreon.com/minutephysics Link to Patreon Supporters: http://www.minutephysics.com/supporters/ This video is about the international system of units (SI), the international prototype kilogram (the IPK or le grande k), and specifically, why we need to redefine our base units in terms of fundamental constants - aka, concepts & ideas - rather than physical objects. The second is already defined in terms of a certain number of oscillations of a photon of the ground state hyperfine splitting energy of Cesium, the meter is then defined as how far light travels in a particular fraction of a second, and hopefully soon, the kilogram will be defined either using the Avogadro approach of counting silicon atoms in a sphere, or using the Watt (Kibble) Balance approach of measuring Plancks constant, h, as used in the formula E=hf for the energy of a photon, which relates to mass via Einsteins famous E=mc^2. REFERENCES: Most Recent Kilogram/Planck Constant Measurement: https://www.nist.gov/news-events/news/2017/06/new-measurement-will-help-redefine-international-unit-mass International Bureau of Weights and Measures page: http://www.bipm.org/en/measurement-units/base-units.html Future Definitions of SI Base Units: http://www.bipm.org/en/measurement-units/rev-si/ Resolution to redefine Kilogram, ampere, kelvin and mole based on fundamental constants: http://www.bipm.org/en/CGPM/db/25/1/ Hyperfine levels of an atom (Cesium, in this case): https://en.wikipedia.org/wiki/Energy_level#Hyperfine_structure https://en.wikipedia.org/wiki/Hyperfine_structure Cesium: https://en.wikipedia.org/wiki/Caesium#Atomic_clocks Atomic Clocks: https://en.wikipedia.org/wiki/Atomic_clock MinutePhysics is on twitter - @minutephysics And facebook - http://facebook.com/minutephysics And Google+ (does anyone use this any more?) - http://bit.ly/qzEwc6 Minute Physics provides an energetic and entertaining view of old and new problems in physics all in a minute! Created by Henry Reich$ $Why are Stars Star-Shaped? Thanks to our Subbable subscriber SlugBooks.com - head over to http://www.slugbooks.com to find cheaper textbooks for college or university. And go to http://www.subbable.com/minutephysics if you want to support MinutePhysics on Subbable! And also to our Subbable subscriber Mathias Larssen! Paper on diffraction through the lens of the human eye: http://goo.gl/XEdMVd Shape of stars and optical quality of the human eye by Rafael Navarro and M. Angeles Losada, Vol. 14, No. 2/February 1997/J. Opt. Soc. Am. A Eye Photos courtesy of: Anthony Kelly Elliot Bennett flickr user jyotsna210 flickr user martinak15 wikimedia user Hminden Magdalena Roeseler Michael Gäbler wikimedia user Woodwalker Steve Jurvetson MinutePhysics is on Google+ - http://bit.ly/qzEwc6 And facebook - http://facebook.com/minutephysics And twitter - @minutephysics Minute Physics provides an energetic and entertaining view of old and new problems in physics all in a minute! Music by Nathaniel Schroeder http://www.soundcloud.com/drschroeder Created by Henry Reich$

How Many Fossils to Go an Inch? (ft. Robert Krulwich) @MinutePhysics