Some background regarding the mathematical ideas behind Einstein's equations of general relativity:

Einstein's Field Equations of General Relativity Explained

Physics Videos by Eugene Khutoryansky

Aug 12, 2017

• https://www.youtube.com/watch?v=UfThVvBWZxM
  • 28m22s

• WP: Einstein field equations
• Einstein Field Equations: A Step-By-Step Derivation (Two Methods)
• The Einstein Field Equations (PDF 12 pages)