Einstein's Theory of Relativity indicates that time can be experienced differently by observers moving at different speeds, suggesting that absolute time, as defined by Newton, is a flawed concept.

Einstein’s theory says that time is not a single, fixed quantity that ticks the same way for everyone; instead, it depends on how fast an observer is moving relative to something else. When two people travel at different speeds, the one moving faster will see clocks that tick slower than the other’s, so each measures a different passage of time. This shows that the “absolute time” Newton imagined—where time runs the same everywhere—is not true in the real universe. For example, if one twin travels near light speed and returns, that twin will have aged less than the twin who stayed on Earth, proving that time can stretch or shrink depending on motion. Thus, relativity replaces Newton’s fixed clock with a flexible one that changes with speed and gravity.