Final answer:
Time intervals can be dependent on the relative motion of an observer, particularly at high velocities or in precision measurements. Measuring elapsed time is influenced by various factors, including the arrival of light from an event and potential human reaction times, and proper time is the most accurate measurement from an observer at rest relative to the observed event.
Step-by-step explanation:
Do Time Intervals Depend on Who Observes Them?
Time intervals can indeed depend on the relative motion of an observer, which is a concept rooted in Einstein's theory of special relativity. For most everyday situations, such as timing a foot race, the differences in elapsed time due to the observers' motion are so minuscule that they are imperceptible. However, when considering scenarios involving high velocities or in precision measurements, these differences become significant.
In the context of simultaneity, measuring elapsed time is a process that can be influenced by several factors. A stopwatch may be started or stopped based on the arrival of light from an event, such as observing a signal light change. Although, more accurate measurements often employ electronic detection to reduce errors from human reaction times and other complications.
The concept of proper time is important when considering measurements and observations. Proper time (Δt0) is the time measured by an observer at rest relative to the event being observed and is typically considered the most accurate measurement of time intervals for a given process.