TIME DILATION EXPERIMENT

In the theory of relativity, time dilation is an actual difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from gravitational masses.
An accurate clock at rest with respect to one observer may be measured to tick at a different rate when compared to a second observer’s own equally accurate clocks. This effect arises neither from technical aspects of the clocks nor from the fact that signals need time to propagate, but from the nature of spacetime itself.

A case of time dilation in action is that astronauts return from missions on the International Space Station (ISS) having aged less than the mission control crew that remained on Earth. Such time dilation has been repeatedly demonstrated (see experimental confirmation below), for instance by small disparities in atomic clocks on Earth and in space, even though both clocks work perfectly (it is not a mechanical malfunction). The laws of nature are such that time itself (i.e. spacetime) will bend due to differences in either gravity or velocity—each of which affects time in different ways.

In theory, and to make a clearer example, time dilation could affect planned meetings for astronauts with advanced technologies and greater travel speeds. The astronauts would have to set their clocks to count exactly 80 years, whereas mission control—back on Earth—might need to count 81 years. The astronauts would return to Earth, after their mission, having aged one year less than the people staying on Earth. What is more, the local experience of time passing never actually changes for anyone. In other words, the astronauts on the ship as well as the mission control crew on Earth each feel normal, despite the effects of time dilation.

The speed of light in a vacuum (c) is constant – 186,000 miles/sec. This is true regardless of the motion of the light source or the observer. Think about that for a second. This means that if you are traveling toward a star at .99c, the light from that star will not pass you at greater than c, it will still pass you at c – relative to you. If you are traveling away from a star at .99c, the light from that star will still pass you at exactly c. This is weird, but it is the way the universe works, as observed for the past century or so.

Now think of yourself sitting on an asteroid and watching a starship pass by. The ship is made of transparent material, and the pilot can be seen, standing on a glass floor. As he passes you, he shines a flashlight downward toward the floor. In his viewpoint, the light beam shines down and straight back up, like this: I. As you see him pass by, however, the light beam forms a V as it travels down and back up. Now the path that you see the light take is longer than the path that the pilot sees. Both of you are correct in seeing the light that way. But distance = rate x time. You see a longer distance for the light than he does. But the rate (the speed of light) IS CONSTANT as described above. Therefore, since the distance is longer and the rate is constant, the time must also be longer. You see the pilot experiencing time slower than you do, because he is moving relative to you. This is not an illusion, and it’s not just a theory. It has been demonstrated repeatedly in laboratory environments.