11:25 AM or course.
Actual time travel to the past where the traveller affects the environment even to a minute degree would create a time loop that would go crazy and destroy the Universe. The traveller's actions would have a domino effect and rearrange the future completely to where the traveller himself would never be born and the result would be a discontinuity. So time travel to the past is completely impossible. The version where someone observes the past from the future or alternatively an exact replica of the past found in heaven is possible. Affecting that replica as a "could have been" without affecting the actual past should also be possible, creating a merely hypothetical scenario.