We observe it through the lens of decay. We grow old. Entropy. All we get is a linear view and from that keyhole perspective we drive ourselves crazy trying to understand it. From the planck view, time doesn't seem to have the same properties that we ascribe to it here on Earth. Tomorrow doesn't follow today because there is no tomorrow. It's a moment, an event, a response or simple action (a simple metaphor in the computing world would be the 1 vs. 0 binary structure) followed by another one and then another.
Many physicists speculate that the universe is simply a collection of such events. A vibration or transfer of energy from particle A to particle B and these transfers are knitted together by the exponential millions in a web that make up space-time. The make up of these particles will wait for another discussion.
Okay, where does that leave us fictitious speculators on the subject of large scale time and time travel? For me, I don't believe there's any possibility to travel back and visit Abraham Lincoln in time to save him from that fateful bullet. Makes for good fantasy but doesn't fit with where science now leads us.
In Quantum SF, time travel has to be more on a grand scale. Billions of years in a blow, traveling back to the Big Bang in the same way we do simply by following a beam of light into the past through Hubble. If we influence time on a planck scale, if we can manipulate individual time 'events' and their relationship to gravity and the transfer energy ... who knows what kind of reality we'd end up with.