Time dilation and length contraction are not just measured effects but are intrinsic properties of spacetime that affect both the traveler and distant observers. They are real phenomena that arise from the fundamental principles of relativity.
According to the theory of relativity, when an object is in motion relative to an observer, time dilation occurs. This means that the moving object experiences time passing more slowly compared to a stationary observer. Similarly, length contraction refers to the phenomenon where the length of an object in the direction of its motion appears shorter to an observer in a different reference frame.
Both time dilation and length contraction are consequences of the fundamental postulates of relativity, which state that the laws of physics should be the same for all observers in uniform motion and that the speed of light is constant for all observers. These principles lead to the conclusion that the passage of time and the measurement of lengths can differ depending on the relative motion between observers.
For example, in the famous thought experiment of the twin paradox, one twin remains on Earth while the other travels through space at high speeds. When the traveling twin returns to Earth, they will have experienced less time passing compared to the twin who stayed on Earth, due to time dilation. This effect is not just an apparent measurement discrepancy but an actual consequence of the relative motion between the twins.
Similarly, in length contraction, an object moving at high speed relative to an observer will appear shorter along its direction of motion compared to its rest length. This effect is not merely an observational artifact but a real change in the spatial dimensions of the moving object.
In summary, time dilation and length contraction are not just measured effects observed by distant observers but are intrinsic properties of spacetime that affect both the traveler and observers in different reference frames. They arise from the fundamental principles of relativity and have been confirmed by numerous experimental observations and measurements.