Time is something with which we have tremendous experience, but a detailed and scientific definition of time and how it works eludes even the most educated of minds. In this video, Fermilab’s Dr. Don introduces some of the ways in which time remains puzzling.
Time dilation:
https://www.youtube.com/watch?v=svwWKi9sSAA
Twin paradox (with math):
https://www.youtube.com/watch?v=GgvajuvSpF4
Twin paradox (without math):
https://www.youtube.com/watch?v=noaGNuQCW8A
Fermilab physics 101:
https://www.fnal.gov/pub/science/particle-physics-101/index.html
Fermilab home page:
https://fnal.gov