Time paradox

071121

We watched the film Déjà Vu (under the pretext that it would be useful to help us think about space) and ended up having a massive argument about time travel afterwards. There was actual shouting. Spoiler time…

Denzel Washington’s character goes back in time to prevent something that happened four days ago and manages to get himself killed in the process. By saving the day though, he gives himself no reason to go back in time in four days time to stop it from happening. Which is where it gets confusing. The film mentions branching realities, and Luke is happy with that explanation. Adam and me however, have a problem with it. The problem is that one reality causes the other to exist, and the reality that is created prevents the previous from happening. At which point a time paradox causes the universe to explode.

It’s all explained in this helpful diagram (which is a recreation of the one I drew at the time).