If time travel is possible, how would we know? Wouldn’t there will be time laws to stop time interference?


One of Hawking’s arguments in the conjecture is that we are not awash in thousands of time travelers from the future, and therefore time travel is impossible. This argument I find very dubious, and it reminds me very much of the argument that there cannot be intelligences elsewhere in space, because otherwise the Earth would be awash in aliens. I can think half a dozen ways in which we could not be awash in time travelers, and still time travel is possible.”

– Carl Sagan, American astronomer, astrophysicist, and author.