Please remember that the Earth is constantly revolving around the Sun, so the past and present trajectory of the Earth's motion is a series of doughnuts. If there is a higher dimensional spacetime, what would it be like? I think he should consider the effects of the Earth's movement around the sun. Of course he won't make it, he may enter the multidimensional universe, a false image. Sending information back to the past is to enter the past state of the universe, which is still not possible at present.