The rules of time-travel have been debated by scientists and sci-fi fans alike for years, but now a student physicist has been able to "square the numbers" to show how paradox-free time travel is theoretically possible. This means that should someone be able to time travel, the dreaded butterfly effect might not be as inevitable as has been feared -- but that doesn't mean a time-traveler might not still face unintended consequences. In a peer-reviewed paper published in Classical and Quantum Gravity, University of Queensland student, Germain Tobar, collaborating with the university's physics professor Fabio Costa, mathematically discovered how, "time travel with free will is logically possible in our universe without any paradox.” The math involved in all this is enough to make Will Hunting scratch his head but Tobar, like a different Matt Damon character, has been able to "science the shit" out of theorizing how one could travel through time without causing those pesky logical paradoxes that bedevil many a science-fiction protagonist. [ignvideo url="https://www.ign.com/videos/2019/04/27/explaining-the-most-complicated-part-of-avengers-endgame"] One such example is the so-called grandfather paradox wherein, as their paper puts it, "a time traveller could kill her own grandfather and thus prevent her own birth, leading to a logical inconsistency." Or, someone going back in time to prevent the COVID-19 pandemic from happening would then nix the very reason why they ever traveled through time. Yes, it's like those arguments about time travel in Avengers: Endgame all over again! “This is a paradox – an inconsistency that often leads people to think that time travel cannot occur in our universe," Costa said.