Is there any scientific evidence that demonstrates why time passes? Or is it just an opened question?
I'm not sure if there's a definitive answer because I've seen it discussed recently at high level. I do think there's some broad agreement that entropy is important because it has an irreversible property: closed systems progress from low entropy states to higher entropy states. So we can define the passage of time more precisely by talking about increasing total entropy.
Sean Carroll of Cosmic Variance has written many interesting posts on the subject. I think his ideas boil down to the Universe was initially in a low entropy state and our conscious experience increases total entropy, so our conscious experience coincides with the time direction being away from what we call the beginning of the Universe. (I stand to be corrected. I'm not even sure the arguments can be stripped down so far.)
Time seems to "pass" because it is not symmetric -- it is T symmetric. This is often called the "arrow of time." The arrow of time points in the direction of increasing entropy.
The real question you are asking is why our minds perceive this direction...