Time dilation leads us to time travel!! Sounds great, but kinda weird to explain. Your concept of relative speeds doesn’t work here.
If you and superman are flying with the same speed, then with respect to you, the superman is at rest. This isn’t the case with light, as long as your speed is less than light( though your speed is so close to light), the speed of light doesn’t change with respect to you.
If speed isn’t changing with respect to you, though you are moving, then what is changing? Well… The time is changing. So, this is the key for time travel.
Have you watched the movie “Interstellar”? Yeah you must. When the hero returns to his daughter from another planet probably in other solar system, his daughter becomes more than 90 years old( that is much older than her father). This is time dilation, because of his journey through wormhole.
You could do a flyby of a nearby star and return to Earth at nearly the speed of light, and a few years would pass on Earth while possibly only a few weeks or months would pass for you, depending on how fast you were going and how far away the star was.
Few of my recent articles are related to this one. RELATIVITY (all about the Einstein’s special and general relativity) and the previous one Stars ( which proves that, even light with such great speed takes “Time” to reach us;)
There is another extension to this article, can you guess one?