It seems that predicting the energy density of empty space should be a simple thing, yet it turns out that the two best theories of modern physics (the standard model and the general theory of relativity) make staggeringly different predictions. In this video, Fermilab’s Dr. Don admits to this dirty little secret of physics. Dark energy video: https://www.youtube.com/watch?v=THT_BAdKe6g Quantum foam video: https://www.youtube.com/watch?v=nYDokJ2A_vU Video talking about why the Planck length is the shortest length consistent with the standard model: https://www.youtube.com/watch?v=rzB2R_qiC28 Possible answers: https://www.scientificamerican.com/article/the-cosmological-constant-is-physics-most-embarrassing-problem/ Fermilab physics 101: https://www.fnal.gov/pub/science/particle-physics-101/index.html Fermilab home page: https://fnal.gov/