Discussion of possible time travel
Disclaimer: Since I have no formal education in advanced physics or advanced mathematics, I am not hindered by the same rules that drive professional physicists and mathematicians. My imagination is unfettered by imposed limits. In effect, my opinions can be considered science fiction. You are free to use these opinions as a basis for your own fiction.
It is generally accepted that our universe, the observable universe we inhabit, is constructed around four dimensions – one of which is time. Time is inseparable from the other physical dimensions. This is Einstein’s Space-time concept. We can move about in the three physical dimensions but movement in time is limited to only one direction – toward the future. As long as we are bound to the physical dimensions we cannot move backward in time. It is possible to move forward in time by traveling very fast in the physical dimensions. This is scientific fact. Approaching the speed of light in any direction causes time dilation, but only in the forward direction. In our space-time universe we are always moving in the three physical dimensions and toward the future in time. Our planet revolves. Our planet orbits the sun. Our sun orbits the Milky-way galaxy. The Milky-way galaxy moves through the intergalactic space. We are always moving and since we are moving in the physical dimensions we are connected to the time dimension as well.
Imagine we could stop our motion in the three physical dimensions. Would that free us from the forward-only direction in time? If we could become “disconnected” from the three physical dimensions we might be able to move backward in time. We do not have a technology to actually stop us. To do so would require precise calculation of the combined motions we are experiencing. An application of some force (a precisely calculated physical force) in opposition to our movement would leave us physically motionless and free to move through time. This is how I see possible time travel. The immense energy requirement is currently beyond our capabilities but who can say what our future might bring.
If nothing else, this idea could become a basis for science-fiction works based on time travel. The possibilities are myriad. I have always opposed time travel fiction because there is always some paradox involved. My concept does nothing to solved the paradoxes inherent in time travel but it does open a path around the limitations imposed by current scientific understanding.