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Oct 30, 2026 18 min

What is Energy?

from PBS Space Time Hosted by PBS

Viewers like you help make PBS (Thank you 😃) . Support your local PBS Member Station here: https://to.pbs.org/DonateSPACEUploaded 14-02-18Energy is the most powerful and useful concept in all of physics, but what exactly is it?You can start your free trial of The Great Courses Plus at http://ow.ly/E15c30hIv7cYou can further support us on Patreon at https://www.patreon.com/pbsspacetimeGet your own Space Time t­shirt at http://bit.ly/1QlzoBiTweet at us! @pbsspacetimeFacebook: facebook.com/pbsspacetimeEmail us! pbsspacetime [at] gmail [dot] comComment on Reddit: http://www.reddit.com/r/pbsspacetimeHelp translate our videos!https://www.youtube.com/timedtext_cs_...Previous Episode:Kronos: Devourer of Worldshttps://www.youtube.com/watch?v=9-SxVSpSoek&t=1sWritten and Hosted by Matt O'DowdProduced by Rusty WardGraphics by Matthew RankerAssistant Editing and Sound Design by Mike Petrow and Meah Denee Barrington Made by Kornhaber Brown (www.kornhaberbrown.com)In physics energy is not a substance, nor is it mystical. Energy is a number. A quantity. And the quantity itself isn’t even particularly fundamental. Instead, it’s a mathematical relationship between other, more fundamental quantities. It was 17th century polymath Gottfried Leibnitz who first figured out the mathematical form of what we call kinetic energy – the energy of motion. He realized that the sum of mass times velocity squared for a system of particles bouncing around on a flat surface is always conserved, assuming no friction and perfect bounciness. Leibnitz called this early incarnation of energy vis viva – the living force.Special thanks to our Patreon Big Bang, Quasar and Hypernova Supporters: Big BangCoolAsCatsDavid NicklasFaisal SaudAnton LifshitsJoey RednerQuasarTambe BarsbayMayank M. MehrotaMars YenturMark RosenthalDean FuquaJustin LloydRoman PinchukHypernovaShaun WilliamsEdmund FokschanerMax LevineMatthew O’ConnorEugene LawsonMartha HuntJoseph SalomoneChuck ZegarJordan YoungRatfeastJohn HofmannBarry HatfieldCraig PetersonThanks to our Patreon Gamma Ray Burst Supporters: Jane MyersBrandon CookJames FlowersGreg AllenDenys IvanovNick VirtueAlexey EromenkoNicholas RoseScott GossettMark DykstraMark VasilePatrick MurraySultan AlkhulaifiAlex SetoMichal-Peanut KarmiErik SteinDaniel LyonsKevin WarneJJ BagnellJ RejcAvi GoldfingerJohn PettitFlorian StiglmayrBenoit Pagé-GuitardNathan LenizJessica FraleyLoro LukicBrandon LabonteDavid CraneGreg Weiss"The Great Courses Plus is currently available to watch through a web browser to almost anyone in the world and optimized for the US market. The Great Courses Plus is currently working to both optimize the product globally and accept credit card payments globally."

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What is Energy?

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