1.-Four dimensions world x, y, z, t , not three.
Time goes in different coordinates, shapes and directions: Ahead and also, Back. More importantly, it's traceable. When someday in the future we get to control it, we will travel along this "t" dimension.
2.-Time runs differently for different references. If you use a clock to measure time (T₀) in a frame moving at a velocity V you will find that it runs slow when compared to a clock that is in a fixed frame (T).
For example, at 99.5% the speed of light you will find that time runs 10 times slower: T ~ 10T₀.Time travel.
3.-The gravitational radius=Rs in the picture, is a physical parameter that shows up the radius defining the boundary of a black hole. It is a characteristic radius associated with every quantity of mass. This Schwarzschild radius was named after the German astronomer Karl Schwarzschild, who calculated this exact solution for the theory of general relativity in 1916.
G is the gravitational constant, M is the object mass, and c is the speed of light.
4.-Black holes are the door to see and try to understand time distortion (or time travel), so far we are Not even close to be near by, or to create a black hole. We just took in real time the first photo ever of a real forming black hole (April 2019). However the European Organization for Nuclear Research (CERN) might in the near future provide more insights and information with Lab results.
https://now.northropgrumman.com/time-traveling-tiny-technology-future-particle-accelerator-impact/
https://news.vanderbilt.edu/2011/03/15/hadron-collider-time-machine/
