In special relativity, the concept of time dilation does introduce the idea that observers in relative motion can assign different time coordinates to the same events. This is because the perception of time passing can depend on the relative motion between observers.
The key idea behind time dilation is that the passage of time is not an absolute concept but is relative to the observer's frame of reference. Two observers in relative motion will have different perspectives on the timing of events. For example, an event that appears simultaneous to one observer may not appear simultaneous to another observer in a different frame of reference.
This relativistic effect challenges our common-sense notion of a universal "now" because the ordering of events becomes dependent on the observer's reference frame. Different observers moving at different speeds may disagree on the order of events and the time at which they occur.
However, it's important to note that despite these relativistic effects, there are still objective relationships between events in spacetime. While the perception of the timing of events may vary between observers, the causal relationships between events are preserved. In other words, cause and effect relationships are maintained regardless of the observer's frame of reference.
In practice, for everyday situations where relative speeds are much lower than the speed of light, the effects of time dilation are negligible and do not significantly impact our ability to grasp the sequence of events. However, in extreme cases involving very high speeds or strong gravitational fields, the effects of time dilation can become more pronounced and may require careful consideration.
So, while the precise notion of simultaneous events can be relative in special relativity, the overall causal structure of events is preserved, and we can still make meaningful connections between different events in spacetime.