Whether we're talking about 60 seconds, or 6 billion years, they're both measurements of distance traveled / motion. We measure one year by the earth's relationship to the sun.

Time travel cannot exist because the universe does not keep a record of where everything was at any given point in time, such that you can rewind (adjust) it all back to how it was at every or any given point in time. There is nobody recording that, there is nobody to rewind it, there isn't enough energy to attempt either the recording or the rewinding at an independent macro scale (eg could you properly rewind/adjust a solar system while the wider galaxy acts upon it? would you have to rewind the galaxy? and on it goes up).