Final answer:
Each twin observes the other's time as dilated due to relative motion, but the traveling twin ages less when returning due to acceleration, which breaks the symmetry of the situation. This is aligned with special and general relativity principles and has been confirmed through real-world experiments.
Step-by-step explanation:
Understanding Twin Paradox
The scenario described with the two twins traveling away from each other and observing time dilation is a famous thought experiment in special relativity known as the twin paradox. According to special relativity, time passes slower for an observer moving at relativistic speeds compared to a stationary observer. However, there seems to be a contradiction because each twin sees the other's time as dilated.
This apparent paradox is resolved by recognizing that the situation is not symmetrical. The twin traveling at relativistic speeds is under acceleration when turning back towards the other twin. Thus, special relativity, which only deals with inertial, non-accelerating frames, cannot be applied straightforwardly.
The accelerating twin would indeed age less due to the effects of both special and general relativity, the latter of which accounts for gravity and acceleration in addition to relative motion.
Additionally, length contraction is another phenomenon that arises at relativistic speeds, further affecting measurements of time and space.
Time dilation has been confirmed through experiments, such as those performed by physicists Joseph Hafele and Richard Keating who flew atomic clocks on commercial aircraft, comparing the elapsed time against clocks that remained stationary. Their findings were in line with relativity's predictions, validating the theory at low relative velocities where time dilation effects are small but existent.