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:
   • Big Mysteries: Dark Energy  

Quantum foam video:
   • Quantum Foam  

Video talking about why the Planck length is the shortest length consistent with the standard model:
   • 20 Subatomic Stories: Is the Planck l...  

Possible answers:
https://www.scientificamerican.com/ar...

Fermilab physics 101:
https://www.fnal.gov/pub/science/part...

Fermilab home page:
https://fnal.gov