Absolute Zero is oproximently -273.16 degrees Celsius. That is when everything, including molecules, freezes. I believe if you make an object colder than Absolute Zero, the molecules will move backwards. This might make a time flux in which the object also moves "backwards", otherwise none as "Going Back In Time". If my theory is correct, and we could keep a human alive while we freeze him/she, it will seem to the person that time is going back quickly. Since the "time traveler's" molecules are going backwards and ours' are going forward, when the person comes back into our age, it will seem to us that he/she was never gone.