Why is a world line's proper time the age of an observer moving along this world line?
41340
Why do clocks measure arc-length?
153552
Relativistic mass as seen by different observers
118808
How is it the Voyagers are a few seconds closer to Earth than earlier?
124797
What is the speed of time?
126447
How does velocity cause time dilation?
154529
Redshift and conformal time
27593
Why is travelling around the speed of light a problem?
132106
Why does the speed of light $c$ have the value it does?
115987
How can time be relative?
131384
understanding time: Is time simply the rate change?
84790
Can I measure a journey time < 100 years on a 100 light year voyage?
36719
Gravitational time dilation at the earth's center
92427
Geodesic equation from the proper time integral
52519
The real meaning of time dilation
4132
What is the closest general-relativistic equivalent of a "time slice"?
62168
Hubble time, the age of the Universe and expansion rate
56930
What would an observer see if he/she flew toward a clock at relativistic speeds?