In the movie, the "alien" are not perceiving time like us, they experience it in a circular way, they also write in a circular way. There is no beginning and no end to what they write, it just happen. The main character, after having studied them for a long time, start to think like them, and she start to experience time like them. So she merely exist in the present, past and future, she just exist. You can take what you want, but for me it's like we maybe simply exist, at any given time, we can remember or/and live our past but also our future. We just exist, at any given moment of OUR time; You can BE at anytime between your birth and death. We're maybe just stuck in our current concept of time, like we maybe don't perceive other dimensions because they are "hidden" to our way of experiencing our world.
Enough talk anyway.