It is not possible to make the speed of light appear greater by moving towards or away from the light source.
Consider then, a simple clock consisting of two mirrors relative to the resting frame of the clock (diagram at right), the light pulse is seen as tracing out a longer, angled path.
Time dilation explains why two working clocks will report different times after different accelerations.
For example, at the ISS time goes slower, lagging 0.007 seconds behind for every six months.
All events simultaneous with d in S are on the x-axis, in S′ on the x′-axis.A scenario based on this idea was presented in the novel Planet of the Apes by Pierre Boulle, and the Orion Project has been an attempt toward this idea.With current technology severely limiting the velocity of space travel, however, the differences experienced in practice are minuscule: after 6 months on the International Space Station (ISS) (which orbits Earth at a speed of about 7,700 m/s) an astronaut would have aged about 0.005 seconds less than those on Earth.The reciprocity of the phenomenon also leads to the so-called twin paradox where the aging of twins, one staying on Earth and the other embarking on a space travel, is compared, and where the reciprocity suggests that both persons should have the same age when they reunite.On the contrary, at the end of the round-trip, the traveling twin will be younger than his brother on Earth.For sufficiently high speeds, the effect is dramatic.Space travelers could then return to Earth billions of years in the future.This causes massless particles that travel at the speed of light to be unaffected by the passage of time.Theoretically, time dilation would make it possible for passengers in a fast-moving vehicle to advance further into the future in a short period of their own time.For GPS satellites to work, they must adjust for similar bending of spacetime to coordinate with systems on Earth.According to the theory of relativity, time dilation is a difference in the elapsed time measured by two observers, either due to a velocity difference relative to each other, or by being differently situated relative to a gravitational field.