Uploaded July 2019 | Updated September 2026, 2 weeks ago

---

Go to audible.com/thescienceasylum or text 'thescienceasylum' to 500 500 to get started today. Is energy always conserved? Well, Noether's theorem in combination with Lagrangian mechanics and general relativity tells us that isn't true in general.
________________________________
VIDEO ANNOTATIONS/CARDS

Lagrangian Mechanics:
youtu.be/MIBfKJHMWHU

What the HECK is Energy?
youtu.be/snj1wBtn6I8

Noether's Theorem Explained:
youtu.be/ahf0zCaqrwM
________________________________
RELATED YOUTUBE VIDEOS

PBS Space Time on Energy Conservation:
youtu.be/PUn2izowBkw
youtu.be/04ERSb06dOg

Physics Girl on Energy Conservation:
youtu.be/GHCc9b2phn0

Minute Physics on Energy Conservation:
youtu.be/PplaBASQ_3M
________________________________
SUPPORT THE SCIENCE ASYLUM

Patreon:
patreon.com/ScienceAsylum

Advanced Theoretical Physics (eBook):
gumroad.com/l/ubSc

Merchandise:
scienceasylum.com
________________________________
HUGE THANK YOU TO THESE PATRONS

Warden of the Asylum:
YDT

Asylum Counselors:
Matthew O'Connor

Asylum Orderlies:
Daniel Bahr, William Morton, I'mKorgThisIsMiek

Einsteinium Crazies:
Albert B. Cannon, Eoin O'Sullivan, Tim Ruffles, LT Marshall Faulds, Ilya Yashin, Wacky

Plutonium Crazies:
JKLMN Anderson, Al Davis, Kevin MacLean

Platinum Crazies:
Fletch, Stephen Blinn, Felipe Cruz, Vittorio Monaco, Mikayla Eckel Cifrese, Evgeny Ivanov
________________________________
OTHER SOURCES

http://www.feynmanlectures.caltech.edu/III_17.html
preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved
http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html
http://math.ucr.edu/home/baez/noether.html
________________________________
LINKS TO COMMENTS

youtube.com/watch?v=MIBfKJHMWHU&lc=UgwcDhibFjRM50T0I5x4AaABAg
youtube.com/watch?v=MIBfKJHMWHU&lc=Ugx8JAGCUpDwPNdxn394AaABAg
youtube.com/watch?v=MIBfKJHMWHU&lc=Ugwx4xFUWhcomS3etsR4AaABAg
________________________________
IMAGE CREDITS

NASA Big Bang:
youtu.be/LeUcjqqhNxM

Nuclear Explosion:
youtu.be/XnrLY-phipw

Emmy Noether:
commons.wikimedia.org/wiki/File:Noether.jpg
________________________________
TIME CODES

00:00 Intro
00:21 Conserved Quantities
01:14 Energy Transformation
01:58 Conservation of Energy
02:27 Noether's Theorem
03:06 Time Translation Invariance
03:39 Principle of Stationary Action
04:20 The Spacetime Lagrangian
05:07 Cosmic Microwave Background
05:46 Dark Energy
06:37 Summary
06:57 Outro
07:21 Sponsor Message
08:19 Featured Comments