Time Travel:

To be demonstrated: If time travel is possible, then Earth must be motionless.

Proof: Suppose a man travels through time, say, Marty travels from 1985 to 1955 while traveling through space at precisely 88 mph.

In this time (30 years) at a rate of 66,600 mph (where did they get this number from?), the Earth would have traveled more than 175 billion miles, and the DeLorean is stranded in a space vacuum.

Result: Marty is Fooked.

Conclusion: If time travel is possible, then Earth must be motionless.