According to our current understanding of physics, there is no known way to travel back in time by moving at any specific speed. The concept of traveling back in time is still purely speculative and remains within the realm of science fiction.
In theoretical physics, various ideas have been proposed that involve exotic phenomena like wormholes, time machines, or traversable time loops. However, these concepts are highly speculative, and their feasibility is far from established.
It is important to note that time travel to the past raises numerous paradoxes and logical inconsistencies, such as the famous grandfather paradox. The grandfather paradox states that if you were to travel back in time and prevent your own birth by causing harm to your grandparents, it would create a paradox because if you were never born, then you couldn't have traveled back in time in the first place to prevent your birth.
Currently, our understanding of the laws of physics, particularly causality and the conservation of energy, does not provide a clear path or mechanism for traveling back in time. Time travel to the future, however, is a concept that is supported by the theory of relativity. As an object approaches the speed of light or experiences strong gravitational fields, time dilation effects can occur, leading to a difference in the passage of time relative to other observers. This means that a person in a high-speed spacecraft or near a massive object could experience time passing more slowly than someone in a different reference frame, effectively "traveling" into the future.