What do physicists mean when they speak of dark energy? Why do they think dark energy exists? What does dark energy have to do with the cosmological constant? What is the difference between dark matter and dark energy? Is the cosmological constant really the worst prediction ever? This video will tell you! The article I mention at the end is this one https://www.aanda.org/articles/aa/abs/2019/11/aa36373-19/aa36373-19.html Which was covered by Physics World here https://physicsworld.com/a/dark-energy-debate-reignited-by-controversial-analysis-of-supernovae-data/ Support me on Patreon: https://www.patreon.com/Sabine