Visualizing Time Dilation
In physics and relativity, time dilation is the difference in the elapsed time as measured by two clocks. It is either due to a relative velocity between them (« kinetic » time dilation, from special relativity) or to a difference in gravitational potential between their locations (gravitational time dilation, from general relativity). When unspecified, « time dilation » usually refers to the effect due to velocity. ( Read more )
Why is time « relative »? How do we explain the twin paradox? Why does a clock inside an airplane seem to tick slower? All these answers in 11 minutes!