More ranting about time

You know, I've been wondering something. We perceive there to be this moment called the 'now', which is between "back then" and "in a sec". Everyone recognizes this, as it is the moment where shit goes down, where decisions are made (after all, you can't make a decision in the past).

But this "now" we speak of, are we sure it's universal? If you look at your life as a timeline, you can say that the now is something that moves forward, like a track on itunes. But that doesn't make any sense. What's the speed of that progress bar? One second per second? Infinite nows/hour?