What is Time Dilation?
Time dilation is basically the difference in elapsed time due to velocity difference between two observers in a same frame of reference. Time will tick slow for a moving observer than for an observer at rest. That is, the Faster you move, the Slower will tick the time for you. For instance, imagine a simple xy-plane. Let on x- axis, it's space and on y-axis it's time. Now if you are at rest reading this post. you are not moving in space (x-axis) but you are moving in time (y-axis). That is, time passing for you even if you are at rest. If you are reading this post while moving, then you are moving in both axes i.e. space and time.
Now what if you move only in space (x-axis) by slowing time (i.e. by reducing y-axis)? Meaning, moving faster almost at speed of light?
This is so called Time travel to the future. Slowing time, you only move in space. Let's say you built a spacecraft that travels almost at the speed of light and you leave Earth at age 15 in the spacecraft traveling at about 99.5% of the speed of light (which is much faster than we can achieve now), and. When you get home at the age of 20, you would find that all your classmates were 65 years old because time passed more slowly for you, you will have experienced only five years of life, while your classmates will have experienced a full 50 years.
