to save the Earth & how?

to have a conversation with a computer?

to Upload a Mind to a New Body?

https://spaceplace.nasa.gov/review/dr-marc-space/time-travel.html

Is time travel possible?

In all time travel theories allowed by real science, there is no way a traveler can go back in time to before the time machine was built. Actually, scientists and engineers who plan and operate some space missions must account for the time distortions that occur because of both General and Special Relativity.