Time?

Sometimes, it is interesting to practice using TOK justifications to advocate a belief that is nigh impossible to properly  justify, given human limitations. What about the shape of time, for example? Does it go in a straight line, or spiral, or a circle or a sphere?   Ok, I realize time is intangible, but I am limited by language, and 'shape' gets close enough. What I really want to know is how do you perceive time?Do you think it is hypothetically possible to skip backwards or forwards within it? Do the future and past exist in tandem with the present? What do you think, and more importantly, why? 

Rachel Dean