Einstein at midnight

One night of this year, near the beginning of the year, I went off studying about the theory of relativity formulated by Albert Einstein. It was very complex to learn what it was about, so I spent hours reading and watching videos until it was five o'clock in the morning, can you believe that the next day I had to go to school !? very crazy but from school I was interested in physics and despite not being good with subjects related to science, I always got very good grades in that subject! I think it really is a very beautiful science that needs a lot of abstract thinking to be understood. I think it's really long to explain with detail and precision everything I read that night (there are things that I still do not quite understand) but I was very impressed to know that light is absolute and at its speed there is no time because it is constant. I remember that I also read that according to this theory time travel would be possible since time passes faster or slower according to the perception of the observer, for example, time off the earth takes place differently or on a trip through space , the time for the person in the spacecraft would be different than on the earth, slower than here.