As long as there is a large enough force to bend the space - time, one can go back to the past or go to the future.
From that theory, scientists came up with the idea of creating a mathematical model to build a time machine for one person, which could help him or her move to the future or back to the past.
According to them, this time machine must be able to distort or bend - the time to connect physical space to something abstract is our time.
In the past, scientists have found evidence that objects that produce tremendous gravitational pull can slow time, and black holes are a concrete example.
Based on that, scientists want to create a powerful force that causes space-time to bend, forming "a circle around the object" and, in theory, if an object can move faster than transport speed of light, that thing is going to the past.
Of course, all is just theory, people still cannot really create a time machine because they have not found material that can bend space-time to an utopian level. Having a space machine for time travel is still a thing of the future, probably quite a bit later.