When it comes to time dilation, the theory of relativity predicts that time can appear to pass differently depending on the relative motion between two observers. The two scenarios you mentioned, traveling at near-light speeds and standing still, indeed exhibit different effects of time dilation.
- Traveling at near-light speeds: According to the theory of relativity, as an object approaches the speed of light, time dilation becomes more significant. As the speed of an object increases, time appears to slow down for the moving object relative to a stationary observer. This effect is known as "time dilation." From the perspective of the moving object, time seems to pass normally, but for an observer at rest, the moving object's time appears to be dilated or slowed down.
As the velocity of the object approaches the speed of light (denoted as 'c'), time dilation becomes more pronounced. If an object were to travel at the speed of light, time would effectively stop for that object. However, it is impossible for objects with mass to reach or exceed the speed of light according to our current understanding of physics.
- Standing still (at rest): When an object is at rest, with respect to an observer at rest, there is no relative motion, and time dilation effects are negligible. From the perspective of an observer at rest, time appears to flow at its usual rate.
In summary, traveling at near-light speeds can result in significant time dilation effects, where time appears to slow down for the moving object compared to an observer at rest. On the other hand, when an object is at rest, there is no significant time dilation observed from the perspective of a stationary observer.